New Exposure Biomarkers as Tools for Breast Cancer Epidemiology, Biomonitoring, and Prevention: A Systematic Approach Based on Animal Evidence

Background: Exposure to chemicals that cause rodent mammary gland tumors is common, but few studies have evaluated potential breast cancer risks of these chemicals in humans. Objective: The goal of this review was to identify and bring together the needed tools to facilitate the measurement of biomarkers of exposure to potential breast carcinogens in breast cancer studies and biomonitoring. Methods: We conducted a structured literature search to identify measurement methods for exposure biomarkers for 102 chemicals that cause rodent mammary tumors. To evaluate concordance, we compared human and animal evidence for agents identified as plausibly linked to breast cancer in major reviews. To facilitate future application of exposure biomarkers, we compiled information about relevant cohort studies. Results: Exposure biomarkers have been developed for nearly three-quarters of these rodent mammary carcinogens. Analytical methods have been published for 73 of the chemicals. Some of the remaining chemicals could be measured using modified versions of existing methods for related chemicals. In humans, biomarkers of exposure have been measured for 62 chemicals, and for 45 in a nonoccupationally exposed population. The Centers for Disease Control and Prevention has measured 23 in the U.S. population. Seventy-five of the rodent mammary carcinogens fall into 17 groups, based on exposure potential, carcinogenicity, and structural similarity. Carcinogenicity in humans and rodents is generally consistent, although comparisons are limited because few agents have been studied in humans. We identified 44 cohort studies, with a total of > 3.5 million women enrolled, that have recorded breast cancer incidence and stored biological samples. Conclusions: Exposure measurement methods and cohort study resources are available to expand biomonitoring and epidemiology related to breast cancer etiology and prevention. Citation: Rudel RA, Ackerman JM, Attfield KR, Brody JG. 2014. New exposure biomarkers as tools for breast cancer epidemiology, biomonitoring, and prevention: a systematic approach based on animal evidence. Environ Health Perspect 122:881–895; http://dx.doi.org/10.1289/ehp.1307455

NHANES and others have used biomarkers in blood and urine to assess exposure to acrylamide in occupational settings and in the general population, while at least one study has measured acrylamide in breast milk and human placenta, and a method has been attempted in rats for measuring acrylamide exposure in cerebral spinal fluid. NHANES has used Edman reaction followed by HPLC-MS/MS to measure N-terminal hemoglobin adducts of acrylamide and its metabolite glycidamide in blood from over 7000 subjects in (CDC 2008a, 2009Vesper et al. 2010). Both adducts were found in most subjects, at higher levels in children than in adults (Vesper et al. 2010), and there was a small but significant correlation between dietary acrylamide intake (assessed by food frequency questionnaire) and adduct levels (Tran et al. 2010). CDC is planning to add UPLC-ES-MS/MS testing for the AA and GA-derived urinary mercapturic acids N-acetyl-S-(2-carbamoylethyl)-L-cysteine (AAMA; LOD 2.2 ng/mL) and N-acetyl-S-(2-carbamoyl-2-hydroxyethyl)-Lcysteine (GAMA; LOD 9.4 ng/mL) to future NHANES reports (Alwis et al. 2012). Others have used similar methods to NHANES, GC-NCI-MS/MS (T. , SPE-LC-ESI-MS/MS (Bjellaas et al. 2007a), or immunoassays (Preston et al. 2009) to measure HbAA and HbGA. Levels are generally higher in smokers than non-smokers (Bjellaas et al. 2007a;Bjellaas et al. 2007b;Hagmar et al. 2005;von Stedingk et al. 2010), but apparently not higher in people exposed to secondhand smoke (T. . Adduct levels are higher in maternal blood than corresponding cord blood samples (Schettgen et al. 2004;von Stedingk et al. 2011). Many more studies have used LC-MS/MS to measure AAMA, GAMA, N-acetyl-S-(1-carbamoyl-2-hydroxyethyl)-cysteine (GAMA2), and N-acetyl-S-(propionamide)-cysteine (NAPC) in urine in samples from exposed workers and controls Huang et al. 2011a;Huang et al. 2011b;Kopp et al. 2008), and in samples from general population groups including pregnant women and children as young as five (Brantsaeter et al. 2008;Hartmann et al. 2008;Heudorf et al. 2009;C-M Li et al. 2005). Levels of acrylamide-derived mercapturic acids have been found to be higher in exposed workers and in smokers (Alwis et al. 2012;Huang et al. 2011a;Huang et al. 2011b; CM Li et al. 2005). At least one study has measured acrylamide in breast milk and placenta (Sörgel et al. 2002). Additional studies using biomarkers of acrylamide exposure are reviewed in Il'yasova et al. (2009), Dybing et al. (2005, Knudsen et al. (2007), and Ogawa et al. (2006).

Name
Chemical group Exposure summary Biomarker summary 119-90-4 3,3'-Dimethoxybenzidine (o-Aromatic amine Exposure could occur from trace A few relatively old studies have measured 3,3'-dimethoxybenzidine in human urine, and a few have investigated other methods to dianisidine) contaminants in products that are made with measure biomarkers of exposure. Lowry et al. (1980) used a colorimetric screening method to detect trace 3,3'-dimethoxybenzidine in 3,3'-dimethoxybenzidine. It is used as a dye urine from occupationally exposed workers. Bowman et al. (1976) used a spectrophotoflourometric method to measure 3,3'-dimethoxy for paper, plastics, rubber, and textiles (NTP benzidine in human urine and rat blood. Birner et al. (1990) measured hemoglobin adducts in rats, and Rodgers et al. (1983Rodgers et al. ( ) measured 2011. It is listed as a Proposition 65 3,3'-dimethoxybenzidine and a few metabolites in rat urine. Methods for measuring exposure to benzidine might be adaptable to measure carcinogen (California OEHHA 2014). It is an EPA Action Plan Chemical, under the class of benzidine dyes (CDC 2012a). exposure to 3,3'-dimethoxybenzidine. 119-93-7 3,3'-Dimethylbenzidine Aromatic amine Swimming pool water test kits contain 0.5% to 1.0% 3,3´-dimethylbenzidine. Exposure may occur if the test solutions are emptied into the pool. Residual levels of 3,3´dimethylbenzidine may be present in dimethylbenzidine-based dyes and pigments and in the final consumer products (IARC 1993c;NTP 2005).
A few relatively old studies have measured 3,3'-dimethylbenzidine in human urine, and a few have investigated other methods to measure biomarkers of exposure. Lowry et al. (1980) used the colorimetric screening method to detect trace 3,3'-dimethylbenzidine in urine from occupationally exposed workers. Bowman et al. (1976) used a spectrophotoflourometric method to measure 3,3'-dimethylbenzidine in human urine and rat blood. Birner et al. (1990) measured hemoglobin adducts in rats, and Rodgers et al. (1983) measured 3,3'dimethylbenzidine and a few metabolites in rat urine. Methods for measuring exposure to benzidine might be adaptable to measure exposure to 3,3'-dimethylbenzidine.
101-14-4 4,4'-Methylene-bis(2chloroaniline) Aromatic amine The general population can be exposed to MOCA in contaminated areas or upon consumption of certain types of plants grown in MOCA-contaminated soil (IARC 1993c). It is used as a curing agent for roofing and wood sealing in Japan and Asia (IARC 1993c). CPSC reported that residual levels may be present in final products, such as polyurethane foam and other plastic components. However, data describing actual levels of impurities and the potential for consumer exposure are lacking (IARC 1993c;NTP 2005). It is a TSCA Work Plan Chemical, identified as low likelihood of exposure. Relatively small releases to the environment have been reported (US EPA 2012). It is listed as a Proposition 65 carcinogen (California OEHHA 2014). It is on the REACH SVHC Candidate List, with occupational exposure from dermal contact, and little information about consumer exposure (ECHA 2013).
A few studies have measured MOCA or its metabolites in the urine of occupationally exposed subjects, and methods have been developed to measure exposure to MOCA in blood. NIOSH uses GC-ECD (NIOSH 1994b), to measure MOCA in urine with LOD 1 µg/L and LLOQ 10 µg/L given initial samples of 50 to 100 mL. Among others, Cocker et al. (2009), Keen et al. 2011Keen et al. (2011, Shih et al. (2007), and Murray and Edwards (1999) measured MOCA and a few metabolites in the urine of exposed workers, with detection frequencies varying between studies from 51% to 100%. Shih et al. (2007), using SPE-LC-MS/MS, reports LODs for MOCA and a metabolite at ~200-400x below mean levels in urine from exposed workers, and ~40-60x below medians. Murray and Edwards (1999) detected MOCA in the urine of each of 12 exposed workers, and not in the urine of 18 control subjects. Keen et al. (2011) found no correlation between isocyanates and MOCA in urine. Vaughn and Kenyon (1996) developed a GC-MS method to test MOCA and its protein adducts and conjugates in blood, with LOD "well below the levels found for occupationally exposed individuals", and detected MOCA in the blood of all 5 exposed workers tested.
92-67-1 4-Aminobiphenyl Aromatic amine The potential for exposure to 4aminobiphenyl is low because it has no current commercial uses. It formerly was used as a rubber antioxidant, as a dye intermediate, and in the drug and cosmetic color additive D&C yellow no. 1, which was discontinued in the 1970s. Mainstream cigarette smoke was reported to contain 4aminobiphenyl at levels of 2.4 to 4.6 ng per cigarette (unfiltered) and 0.2 to 23 ng per cigarette (filtered), and sidestream smoke to contain up to 140 ng per cigarette (NTP 2011). It is listed as a Proposition 65 carcinogen (California OEHHA 2014). It is on the REACH SVHC Candidate List (ECHA 2013).
Many general population and occupational studies have used biomarkers of exposure to 4-aminobiphenyl (4-ABP) in blood and urine. Breast milk, bladder tissue and saliva have also been used. The most common biomarkers are adducts of 4-ABP and hemoglobin (4-ADP-Hb) measured in blood, and 4-ABP measured in urine. Many studies, using either GC-MS (often with NCI) or HPLC-MS/MS, have found higher levels of 4-ABP-Hb in smokers than in non-smokers, and higher levels among heavier smokers compared to lighter smokers (Dallinga et al. 1998;Hammond et al. 1993;Mendes et al. 2009;Myers et al. 1996;Roethig et al. 2009;Sarkar et al. 2006;Seyler and Bernert 2011). 4-ABP-Hb levels tend to be higher in maternal blood than in corresponding cord blood samples (Myers et al. 1996), and among smokers they were higher in older people compared to younger, males compared to females, and white people compared to black people (Mendes et al. 2009). Peluso et al. (2008) found small but significant inverse relationships between fiber intake, fruit intake, and BMI and 4-ABP-Hb levels. Others have investigated associations between 4-ABP-Hb and bladder cancer or other diseases, often finding higher adduct levels in cases than in controls (Airoldi et al. 2005;Del Santo et al. 1991;Skipper et al. 2003). Richter et al. (2001) found higher levels of 4-ABP-Hb in children living in bigger cities than those in smaller cities. A study in dye factories in India found much higher levels of 4-ABP-Hb in workers exposed to benzene as opposed to those exposed to dyes (Beyerbach et al. 2006), while a study in rubber factory found no difference in 4-ABP-Hb levels between exposed and unexposed workers (Ward et al. 1996). Multiple studies, mostly using GC-MS, have found higher levels of 4-ABP in the urine of smokers compared to non-smokers (Riedel et al. 2006;Seyler and Bernert 2011), although at least one study (Grimmer et al. 2000) found no such difference. A recent meta-analysis (Van Hemelrijck et al. 2009) found an association between urinary or blood 4-ABP and secondhand smoke exposure but not bladder cancer.  couldn't detect 4-ABP in urine of two subjects after they had applied hair dye, but Ambrosone et al. (2007) found ABP-DNA adducts in epithelial cell DNA isolated from human breast milk in women using hair dyes. Bessette et al. (2010) used LC-ESI/MS/MS to measure 4-ABP-derived DNA adducts in saliva, but adducts were only detectable in the saliva of two smokers out of 37 volunteers. Zayas et al. (2007) used LC-MS/MS to measure DNA adducts in bladder tissue from 27 bladder cancer patients, detecting DNA adducts in samples from 12. Zayas et al. (2007) found no correlation between levels of 4-ABP-Hb and DNA adducts in bladder tissue. Gu et al. (2012) attempted to measure 4-ABP derived DNA adducts in 70 tumor-adjacent mammary tissue samples, but did not detect any. Birner et al. (1990) found that 4-ABP-Hb adducts are formed in benzidene-treated rats. 99-59-2 5-Nitro-ortho-anisidine Aromatic amine 5-nitro-ortho-anisidine is used as a chemical intermediate in the production of C.I. Pigment Red 23 which is used as a colorant in a wide variety of commodities including printing inks, interior latex paints, lacquers, rubber, plastics, floor coverings, paper coatings, and textiles (NLM 2011).
No studies were found using biomarkers of exposure to 5-nitro-ortho-anisidine.

Name
Chemical group Exposure summary Biomarker summary 92-87-5 Benzidine Aromatic amine Uses of benzidene and some related chemicals have decreased, particularly in the US and Europe, because they are known to cause bladder cancer in humans (NTP 2011). However many benzidine-based dyes are still produced and used in significant quantities in the US and elsewhere (US EPA 2010a). Benzidine-based and related dyes are used in the production of textiles, paints, printing inks, paper, and pharmaceuticals; as reagents and biological stains in laboratories; in the food industries; and in laser, liquid crystal displays, ink-jet printers, and electrooptical devices (US EPA 2010a). Some dyes used to color paper, cloth, leather, food and drinks may contain benzidine as a contaminant or other impurities that can be broken down into benzidine once inside the body (IARC 2010;NLM 2011). It is on the Canadian Priority Substances List, with limited environmental exposures (Health Canada 2007c). Proposition 65 carcinogen (California OEHHA 2014). It is an EPA Action Plan Chemical, under the class of benzidine dyes (US EPA 2010a).
Benzidine biomarkers can indicate exposure to benzidine and to benzidine-based azo dyes. Occupational studies have detected parent, metabolite, and adducted forms of benzidine in blood and urine, but more sensitive methods are in development in animal studies. Hemoglobin adducts have been detected in 33 exposed workers with GC-MS (Beyerbach et al. 2006). Older human occupational studies used 32P postlabeling on white blood cells, urine, and sputum in exposed workers and controls. Parent benizidine and two metabolites (N-acetylbenzidine and N,N'-diacetylbenzidine) were detected in worker's urine with LODs in ppt via GC-MS (Hsu et al. 1996). Two NIOSH methods detect benzidine in urine via visible absorption/TLC extraction with estimated LOD 0.1 µg/dL urine (NIOSH 1993) and via GC-ECD, estimated LOD 5 µg/L, LLOQ 10 µg/L (NIOSH 1994a). Animal studies have measured DNA adducts with HPLC-MS/MS with LOD 22 pg on column (Means et al. 2003) and Birner et al. (1990) identified several hemoglobin adducts including benzidine metabolite 4aminobiphenyl. A more sensitive method has been developed on treated animal blood and tissue samples using supercritical fluid chromatography with LLOQ 0.10 ng/mL (Patel and Agrawal 2003).

6459-94-5 C.I. Acid Red 114
Aromatic amine The general population may be exposed via dermal contact by direct dyeing of wool and silk using consumer products containing the compound (NLM 2004). CI Acid Red 114 is used to dye wool, silk, jute, and leather. It is metabolized to 3,3'-dimethylbenzidine (NTP 2011). It is listed as a Proposition 65 carcinogen (California OEHHA 2014).
No studies were found using biomarkers to measure exposure to CI Acid Red 114 569-61-9 C.I. Basic Red 9 monohydrochloride Aromatic amine Consumer exposure could possibly occur through contact with products containing residual dye (NTP 2011). CI Basic Red 9 monohydrochloride is used to dye textile fibers, in the preparation of pigments for printing inks, and in other specialty applications (IARC 1993d). It is one of three components of commercial magenta which is used as a dye for coloring textiles (cotton, wool, silks, and acrylics), china clay products, leather, printing inks, and as a filter dye in photography. Its specialty applications include tinting automobile antifreeze solutions and toilet sanitary preparations (NTP 2011). It is listed as a Proposition 65 carcinogen (California OEHHA 2014).
No studies were found using biomarkers to measure exposure to CI Basic Red 9 monohydrochloride 1937-37-7 C.I. Direct Black 38 Aromatic amine C.I. Direct Black 38 and other azo dyes are used on textiles such as cotton, silk, wool, nylon, acetate and leather, and used in aqueous printing inks and as biological stains, plastics, wood stains, wood flour, and hair dyes (NTP 1978b). It is listed as a Proposition 65 carcinogen (California OEHHA 2014).
No studies were found using biomarkers specifically to measure exposure to C.I. Direct Black 38. Metabolites include benzidine, 4aminobiphenyl, monoacetylbenzidine, and acetylaminobiphenyl; biomarker methods for benzidine could be used to assess exposure to C.I. Direct Black 38.

Name
Chemical group Exposure summary Biomarker summary 636-21-5 Ortho-toluidine hydrochloride Aromatic amine The general population may be exposed to low concentrations of o-toluidine in ambient air, tobacco smoke, food, or dermal contact with commercial products (NTP 2011). Exposure has also been reported during its use in production of dyestuffs and rubber chemicals (IARC 2000a). It is listed as a Proposition 65 carcinogen (California OEHHA 2014).
Many studies have measured o-toluidine or its adducts in the blood and urine of the general population, smokers, patients receiving certain drugs, and exposed workers, and one study has measured o-toluidine in exhaled breath. Gaber et al. (2007) measured hemoglobin adducts of o-toluidine by GC-MS in blood collected from 10 surgical patients and 6 healthy volunteers before and 24 hours after receiving the anesthetic prilocaine, and found 6-360-fold increases, from a baseline mean of 0.54 ng/g hemoglobin to a mean of 22 ng/g 24 hours after treatment, excluding one patient with very high initial levels (40.9 ng/g before, 64.4 ng/g after).
Smoking status did not affect background or posttreatment levels. Kutting et al. (2009) found o-toluidine levels were significantly higher in the urine of smokers, with o-toluidine above the LLOQ in urine samples from 178 of 1004 Bavarian subjects. Riedel (2006), using GC-MS with negative ion chemical ionization, detected o-toluidine above the LOD of 4 ng/mL in 10 urine samples from non-smokers and 10 urine samples from smokers; smokers had higher levels. Labat et al. (2006) used GC-MS with negative chemical ionization, with LOD 0.02 µg/L, to measure o-toluidine in 5 ml urine samples from workers involved in the demolition of an old chemical plant. Levels in samples from unexposed controls ranged from 0.17 to 2.46 µg/g creatinine, while levels in samples from exposed workers ranged from 26.17-462 µg/g, but went down to 2.35-20.11 ng/g after the introduction of new protective measures. Rieder et al. (2001) used proton transfer mass spectroscopy for the measurement of VOCs including o-toluidine (which they describe as endogenously produced) in exhaled breath. 26471-62-5 Toluene diisocyanate mixtures Aromatic amine Because of the high volatility of toluene diisocyanates, exposure can occur in all phases of its manufacture and use. Exposure can occur from use of products containing uncured TDI and related polyisocyanates, such as spray foam insulation and sprayapplied sealants and coating, and incidental exposures to the general population while such products are used in or around buildings including homes or schools (US EPA 2011) Household products employing polyurethane varnishes or foam such as furniture, carpet underlay, and bedding may volatize unreacted toluene diisocyanates. FDA has determined that levels of toluene diisocyanates in food, food additives, or food packaging are very low (NTP 2011). It is an EPA Action Plan Chemical, with exposures from building materials and some hobby products (US EPA 2013a). It is listed as a Proposition 65 carcinogen (California OEHHA 2014).
Biomarkers in blood and urine have been widely used to measure exposure to toluene diisocyanate in occupational and exposedvolunteer studies. The diamine derivative of TDI, toluene diamine (2,4-diaminotoluene) and the diamine derivatives of other diisocyanates can be detected after lysis from protein adducts in urine or blood through gas chromatography-mass spectrometry, with LODs around 1 nmol per liter in urine (about 0.1 micromole diamine per mole creatinine) (Cocker 2011). Measurements of isocyanate derived diamines in blood and urine have been well correlated with TDI measurements in air in volunteer and occupational studies, but these measurements may reflect exposure to toluene diamine as well as toluene diisocyanate (Cocker 2011). Studies have also examined levels of TDIalbumin adducts and TDI-specific antibodies in serum (Brown and Burkert 2002). See reviews by Cocker et al. (2011) and Brown and Burkert (2002). See also methods for 2,4-diaminotoluene.

71-43-2 Benzene Benzene
The primary sources of exposure to benzene for the general population are ambient air containing tobacco smoke, air contaminated with benzene, drinking contaminated water, or eating contaminated food (IARC 1982). Exposure to benzene is highest in areas of heavy motor vehicle traffic and around gasoline filling stations. Consumer products containing benzene include carpet, pesticide products, adhesive removers, and home-use paints, sealants, finishers, and auto oils (NLM 2013;NTP 2011). Major contributors to benzene emissions into air include: (1) gasoline production, storage, transport, vending and combustion; (2) production of other chemicals from benzene; and (3) indirect production of benzene (coke ovens), which is a major source of benzene emissions into water (IARC 1982 NHANES and others have measured benzene in blood samples taken from the general population, generally detecting benzene in all or most samples. Other researchers have measured unmetabolized benzene in urine and breath, benzene metabolites in urine, and adducts to proteins and DNA in blood and dried blood spots. NHANES detected benzene in over half the population via HS-SPME-GC-MS on 3 mL (minimum) to 10 mL (optimal) whole blood, with LOD 0.024 ng/mL (Blount et al. 2006;CDC 2008bCDC , 2009. CDC is planning to add UPLC-ES-MS/MS testing for the urinary benzene metabolites trans trans muconic acid (ttMA; LOD 12 ng/mL) and s-phenyl mercapturic acid (sPMA; LOD 0.3 ng/mL) to future NHANES reports (Alwis et al. 2012). A CDC pilot study found that ttMA and sPMA levels were significantly higher in smokers than in non-smokers (Alwis et al. 2012). Unmetabolized benzene can be measured in blood, urine, and breath samples from the general population by purge and trap, headspace, SPE, or SPME extraction followed by GC-MS, with LODs in pg/mL (Weisel 2010), but it has a half-life of only minutes to hours, and samples can easily become contaminated with benzene from the environment (Johnson et al. 2007). Nonetheless, benzene levels in blood can differentiate between exposed and unexposed workers, smokers and non-smokers, and pre-and post-shift samples, and urinary benzene levels were associated with workspace air benzene concentrations in at least one study (Weisel 2010). Hemoglobin, albumin, and DNA adducts have also been measured, with much longer half-lives (2 to 3 weeks for albumin adducts, about 4 months for hemoglobin adducts, and longer for DNA) (Johnson et al. 2007;Weisel 2010). Funk et al. (2008) demonstrated that benzene oxide-hemoglobin adducts could be measured in dried blood spots by GC-MS. Urinary metabolites ttMA and sPMA have been measured by SPE or SPME followed by HPLC-UV, HPLC-MS/MS, or GC-MS, typically with LODs between 5-10 µg/L (Weisel 2010). Both are generally well correlated with benzene exposures from 0.1-20 ppm, but ttMA is also a metabolite of the food additive sorbic acid, whereas sPMA has no known sources beside benzene (Weisel 2010). Researchers have also measured the urinary benzene metabolites phenol, catechol, and hydroquinone via liquid extraction, SPE, or SPME followed by GC FID, GC-MS, HPLC UV, or HPLC-MS/MS (Weisel 2010).

Name
Chemical group Exposure summary Biomarker summary 75-21-8 Ethylene oxide Ethylene oxide The general population may be exposed to ethylene oxide (EtO) through use of products that have been sterilized with the compound, such as medical products, foods, clothing, cosmetics, beekeeping equipment, and other products. EtO has been detected in tobacco smoke, automobile exhausts, and in some foods and spices (NTP 2011). It is found in household rust neutralizer, driveway cleaner, and transmission fluid (NLM 2013). It is on the Canadian Priority Substances List, with exposures from indoor air, food, spices, and medical equipment sterilized with EtO (Environment Canada 2011). It is listed as a Proposition 65 carcinogen (California OEHHA 2014).
Methods for detecting urinary metabolites, DNA adducts, and hemoglobin adducts of ethylene oxide (EtO) have been employed in occupational and general population studies. NHANES has measured 2-hydroxyethyl mercapturic acid (HEMA), a common metabolite of 1,2-dibromoethane, vinyl chloride, acrylonitrile, and EtO, in urine by isotope dilution and HPLC-MS/MS, detecting it in 71% of samples, with higher levels in smokers (Calafat et al. 1999). CDC is planning to add UPLC-ES-MS/MS testing for urinary HEMA (LOD 0.6 ng/mL) to future NHANES reports (Alwis et al. 2012 Yong et al. (2007) detected DNA adducts in granulocytes in blood from hospital workers using HPLC-GC-EC-MS. The lowest concentration of adducts was 1.6 per 10^7 nucleotides. They note that adducts in lymphocytes would be more informative for longer term (up to one year) exposures. Huang et al. (2008) looked for the same adduct (N7 (2'-hydroxyethyl)guanine) in urine of nonsmokers, and detected adducts in 40/46 samples with LOD 0.25 ng/mL using LC-MS/MS. Yong et al. (2007) warns that since DNA adducts are thought to have a short half-life, hemoglobin adducts may be more useful for understanding long term exposures. von Stedingk et al. (2010) developed a method for detecting hemoglobin adducts by LC-MS/MS with LLOQ 1pmol adduct/g Hb. A GC-EI-MS method has LOD 1.8 pmol/g in 0.1 g hemoglobin and LLOQ 12 pmol/g in human blood samples . The 95th percentile for N-2-hydroxyethylvaline (HEV) was 1280 pmol/g globin (=29.4 microg/l blood) in blood from exposed workers compared with 100 pmol/g globin (or 2.3 microg/l) in controls (Schettgen et al. 2002). HEMA was measured in urine from non-smokers (median 2 µg/L) and smokers (median 5.3 µg/L) via HPLC-MS/MS with LOD 0.5 µg/L (Schettgen et al. 2008). 75-56-9 Propylene oxide Propylene oxide General population exposure may occur through ingestion of propylene oxide residues in foods from its use as an indirect registered food additive (gas sterilant) (US FDA 2013) and tobacco smoke. Exposure may also occur by contact with consumer products containing the chemical, especially automotive and paint products which have been found to contain high concentrations of PO. It is also used to manufacture polyurethane foam (NTP 2011). It is listed as a Proposition 65 carcinogen (California OEHHA 2014). It is on the REACH SVHC Candidate List, with low exposures from the environment and consumer products, such as brake fluid (ECHA 2013).
CDC has developed a method to measure PO exposure in urine from the general population. A number of studies have used biomarkers in blood and urine to investigate exposure to PO in occupationally-or tobacco-exposed humans and controls with no known exposure, and one study measured PO in the exhaled breath of humans intentionally exposed to propylene. CDC is planning to add UPLC-ES-MS/MS testing for the PO-derived mercapturic acid urinary metabolite N-acetyl-S-(3-hydroxy propyl-1-methyl)-L-cysteine (2HPMA; LOD 1.3 ng/mL) to future NHANES reports (Alwis et al. 2012). A CDC pilot study found that urine 2HPMA levels were significantly different in smokers and non-smokers (Alwis et al. 2012). The NHANES method for measuring acrylamide-derived hemoglobin adducts in blood was originally developed to measure EtO, PO and styrene oxide adducts (CDC 2008a).  measured the n-terminal hemoglobin adduct N-(R,S)-2-hydroxypropylvaline (HPVal) in blood from 104 non-smokers via gas chromatography after Edman degradation and acetonization, with LOD OF 0.5 pmol/g globin, and found similar levels (median ~4 pmol/g) in those exposed to passive cigarette smoke and the unexposed. Shin et al. (2006) used Edman degradation and ethyl ether extraction, followed by GC-MS, with LOD 10 pmol/g Hb to measure HPVal ranging from below the LOD to 1100 pmol/g Hb. Czene et al. (2002) measured 1-2hydroxypropyladenine DNA adducts in blood by (32)P-postlabeling and HPVal by GC-MS/MS in 8 exposed workers and 8 controls. DNA adducts were present in blood from 7 of the 8 exposed workers and none of the controls. HPVal was detected in all subjects, with much higher levels in workers (mean 2.7 pmol/mg globin) than in controls (mean 0.006 pmol/mg). DNA adducts, hemoglobin adducts, and sister chromatid exchanges were all correlated.  and Ball et al. (2005) used ELISA in whole blood to measure HPVal, both with LLOQ 2 pmol/g globin.  reports that most of 800 samples collected over a two-year period from workers at 3 European manufacturing sites contained less than 50 pmol HPVal/g globin. Schettgen et al. (2002) measured HPVAL in blood from exposed textile workers and controls, but all were below the LOD of 80 pmol/g HB. Schettgen et al. (2008) used HPLC-MS/MS, with LOD 5 µg/L, to measure N-acetyl-S-2-hydroxypropyl-cysteine (2-HPMA), a mercapturic acid metabolite of propylene oxide, in the urine of 14 smokers (median 41.7 µg/L) and 14 non-smokers (median 7.1 µg/L). Filser et al. (2008) measured PO in exhaled breath by GC-MSD after subjects were exposed to 9-24 ppm propylene for 180 minutes. 3296-90-0 2,2-Bis(bromomethyl)-1,3propanediol Flame retardant The primary routes of exposure to bis(bromomethyl)-1,3-propanediol are inhalation and dermal contact. It is a flame retardant used in polyester resins and polyurethane foams and may enter the environment as dust and through wastewater. It is expected to be persistent in water (IARC 2000c;NTP 2011). It is listed as a Proposition 65 carcinogen (California OEHHA 2014).
No studies were found using biomarkers to measure exposure to bis(bromomethyl)-1,3-propanediol in humans. A pharmacokinetic study in rats found that the main route of excretion was as a gluconoride metabolite in urine (Hoehle et al. 2009), but humans are much slower than rats at producing the glucuronide metabolite. Possibly this compound could be measured using a GC-MS method that also can measure 2,3-dibromopropanol (De Alwis et al. 2007) or an LC-MS/MS method for bis(1,3-dichloro-2-propyl) phosphate (BDCPP), a metabolite of a chlorinated tris organophosphate flame retardant (Cooper et al. 2011).
96-13-9 2,3-Dibromo-1-propanol Flame retardant The primary routes of exposure are inhalation 2,3-dibromo-1-propanol (DBP) has been measured in urine. De Alwis et al. (2007) used SPE-GC-MS on spiked human urine, reporting and dermal contact. DBP is a metabolite and 96% recovery and LOD 0.1 ng/ml. Blum et al. (1978) detected DBP in urine of children wearing pajamas treated with the flame retardant degradation product of tris(2,3-tris(2,3-dibromopropyl) phosphate. Based on studies with the chlorinated analog of this flame retardant, tris(dichloropropyl)phosphate, the dibromopropyl) phosphate, a flame retardant that was used in children's sleepwear in the 1970s. DBP was detected in urine of children wearing sleepwear treated with Tris (NTP 2011). DBP is also a potential metabolite, impurity, and degradation product of a newer flame retardant, tetrabromobisphenol A bis(2,3-dibromopropyl ether), which is an HPV chemical that has been proposed for carcinogenicity testing at NTP (Haneke 2002). DBP is a listed Proposition 65 carcinogen (California OEHHA 2014).
bis-metabolite may be more stable and easier to detect in urine via LC-MS/MS (Cooper et al. 2011).

Name
Chemical group Exposure summary Biomarker summary 75-34-3 1,1-Dichloroethane Halogenated organic solvent The general population may be exposed via inhalation (for those people living near source areas), ingestion of contaminated drinking water, and use of consumer products, such as paint removers, that may contain this compound (NLM 2011 NHANES has used HS-SPME-GC-MS on 3 mL (minimum) to 10 mL (optimal) whole blood, but less than 5% of the population had levels above the LOD of 0.01 ng/mL (Blount et al. 2006;CDC 2008bCDC , 2009. Possibly a method to measure non-specific urine metabolites such as haloacetic acids and haloalcohols could be developed.
96-18-4 1,2,3-Trichloropropane Halogenated organic solvent The general population may be exposed by ingestion of contaminated well water or by inhalation of contaminated air (NTP 2011). Detected in water, including drinking-water, and in soil as a result of its presence as an impurity in a commercial nematocide. Formerly produced as paint and varnish remover and as a cleaning and degreasing agent. Also fomerly used as soil fumigant, until 1991fumigant, until (IARC 1994. It is listed as Proposition 65 carcinogen (California OEHHA 2014). It is listed on the REACH SVHC Candidate list as carcinogenic and toxic for reproduction, with exposures from air and water from the production of chlorinated compounds (ECHA 2011a).
No studies were found using biomarkers of exposure to 1,2,3-trichloropropane 106-93-4 1,2-Dibromoethane Halogenated For the general population, the most No studies were found using specific biomarkers of exposure to 1,2-dibromoethane, although NHANES measured 2-hydroxyethyl (ethylene dibromide) organic solvent important current exposure is through mercapturic acid (HEMA), a common metabolite of 1,2-dibromoethane, vinyl chloride, acrylonitrile, and ethylene oxide, in urine by isotope contaminated drinking water due to 1,2dibromoethane's former use as a gasoline additive (NTP 2011). It was also used historically and is still used outside of the US as a pesticide, and exposure may also occur in pest control, petroleum refining and waterproofing. It has been detected in ambient air, soil, groundwater, and food. Historically, concentrations in ambient air were an important source of exposure, especially near automobiles or filling stations (IARC 1999f;NTP 2011). This is a TSCA Work Plan Chemical, identified as a low likelihood of exposure. It is used in commercial and industrial products and present in indoor environments and soil. Relatively small releases to the environment have been reported (US EPA 2012). It is listed as Proposition 65 male developmental toxicant (California OEHHA 2014). dilution and HPLC-MS/MS, detecting it in 71% of samples, with higher levels in smokers (Calafat et al. 1999).

Name
Chemical group Exposure summary Biomarker summary 107-06-2 1,2-Dichloroethane Halogenated organic solvent The greatest source of exposure to 1,2dichloroethane for the general population is inhalation of the compound in contaminated air (NTP 2011). It has been detected at low levels in ambient and urban air, groundwater and drinking water due to its former use as a gasoline additive, and it has also been detected in food items, possibly due to its use as an extractant in certain food processes (IARC 1999i;NTP 2011). It is mainly used in the production of vinyl chloride and is a biodegradation product of tetrachloroethane. It is used in some consumer products (adhesives, rug cleaners), and it was historically used as a fumigant (IARC 1999i;NTP 2011 NHANES has used HS-SPME-GC-MS on 3 mL (minimum) to 10 mL (optimal) whole blood, but less than 5% of the population had levels above the LOD of 0.01 ng/mL (Blount et al. 2006;CDC 2008bCDC , 2009. Possibly a method to measure non-specific urine metabolites such as haloacetic acids and haloalcohols could be developed.
78-87-5 1,2-Dichloropropane Halogenated organic solvent The general population may be exposed via inhalation of ambient air, ingestion of drinking water, and dermal contact with consumer products containing 1,2-dichloropropane (IARC 1986a;NLM 2011). This is a TSCA 2013/2014 Work Plan Chemical, identified as having a high likelihood of exposure. It is used in consumer products and present in biomonitoring, drinking water, indoor environments, and soil. High releases to the environment have been reported (US EPA 2012). It is listed as a Proposition 65 carcinogen (California OEHHA 2014).
NHANES has measured 1,2-dichloropropane in blood samples from the general population, and others have attempted to measure it in the blood of occupationally exposed populations. NHANES has used HS-SPME-GC-MS on 3 mL (minimum) to 10 mL (optimal) whole blood, but less than 5% of the population had levels above the LOD of 0.008 ng/mL (Blount et al. 2006;CDC 2008bCDC , 2009). Occupationally, unmetabolized 1,2 dichloropropane measured by SPME-GC-MS was below the LOD (0.2 µg/L) in the urine of 9 "handicraft" automobile mechanics (Vitali et al. 2006). Possibly a method to measure non-specific urine metabolites such as haloacetic acids and haloalcohols could be developed.

56-23-5 Carbon tetrachloride Halogenated organic solvent
The general population is most likely exposed to carbon tetrachloride through air and drinking water (NTP 2011). It may be used in paint and varnish remover, cleaning and sanitation products, auto products, and hobby/craft products, and it is found in household plastic and epoxy binders (NLM 2013). It was formerly used as dry cleaning agent, aeresol propellant, pesticide/fumigant and fire extinguisher (NLM 2011). It is detected at low levels in ambient air and water (IARC 1999a). It is a TSCA Work Plan Chemical, identified as low likelihood of exposure. It is present in drinking water and soil. High releases to the environment have been reported (US EPA 2012). It is a Proposition 65 carcinogen (California OEHHA 2014).
NHANES has used HS-SPME-GC-MS on 3 mL (minimum) to 10 mL (optimal) whole blood, but less than 5% of the population had levels above the LOD of 0.005 ng/mL (Blount et al. 2006;CDC 2008bCDC , 2009). Occupationally, carbon tetrachloride has been measured in urine (Gobba et al. 1997), and a method to measure non-specific urine metabolites such as haloacetic acids and haloalcohols could be developed. Methylene chloride has been measured in blood, urine, and exhaled breath in population and occupational studies. NHANES has used HS-SPME-GC-isotope dilution MS on 3-10 mL whole blood, but less than 5% of the population had levels above the LOD 0.07 ng/mL (Blount et al. 2006;CDC 2008bCDC , 2009).  measured methylene chloride and other VOCs via HS SPE GC-MS in urine from 24 healthy elderly men, detecting methylene chloride in all samples; methylene chloride was still detectable after 8 hours frozen or unfrozen storage. Poli et al. (2005) used HS SPME GC-MS with LOD 0.005 µg/L to measure methylene chloride in urine from 120 unexposed individuals, with a median concentration of 0.68 µg/L. In two cases of acute methylene chloride poisoning, Poli et al. (2005) calculated urinary half-lives of 7.5 and 3.8 hours, and blood half-lives of 4.3 and 8.1 hours. Hoffer et al. (2005), using HS SPME-GC, found 0.02-0.06 mg/L methylene chloride in urine from 7 exposed workers. Based on experiments with spiked urine, they stress the importance of promptly sealing urine collection and headspace chamber containers, and of analyzing samples within 2 weeks of collection. Sakai et al. (2002) used HS GC-FID with LLOQ 0.01 mg/L, and found that exposure levels and urinary concentrations were highly correlated in an occupationally exposed group. Delfino et al. (2003) detected methylene chloride in over 75% of 106 exhaled breath samples from 21 Hispanic children with mild asthma living near major sources of vehicle exhaust in LA, but found that ambient VOC measurements were better predictors of symptoms than VOCs in exhaled breath. Thrall et al. (2001) found that concentrations in exhaled breath samples from exposed workers increased by up to 573 ppb after performing tasks involving methylene chloride. Possibly a method to measure non-specific urine metabolites such as haloacetic acids and haloalcohols could be developed.

75-01-4
Vinyl chloride Halogenated organic solvent The general population may have some limited exposure to vinyl chloride, particularly through direct or indirect contact with polymer products (IARC 1979). It is used almost exclusively by the plastics industry to produce polyvinyl chloride (PVC), a plastic used in many consumer and industrial products. It was previously used as a refrigerant and in aerosol propellants, including hairsprays, but these uses were banned in 1974 (NTP 2011). It is a TSCA Work Plan Chemical, identified as having a high likelihood of exposure. It is present in drinking water, indoor environments, surface water, ambient air, groundwater, and soil. High releases to the environment have been reported (US EPA 2012). It is listed as a Proposition 65 carcinogen (California OEHHA 2014).
Two studies were found using urine biomarkers of exposure to vinyl chloride (VC), one in the general population, one in an occupational setting. In addition, NHANES has measured 2-hydroxyethyl mercapturic acid (HEMA), a common metabolite of 1,2-dibromoethane, vinyl chloride, acrylonitrile, and ethylene oxide, in urine by isotope dilution and HPLC-MS/MS, detecting it in 71% of samples, with higher levels in smokers (Calafat et al. 1999). CDC is planning to add UPLC-ES-MS/MS testing for HEMA (LOD 0.6 ng/mL) to future NHANES reports (Alwis et al. 2012). Gonzalez-Reche et al. (2002) used HPLC-ESI-MS/MS (and confirmatory GC-MS) to detect etheno-DNA adducts (1,N2-ethenoguanine, N2,3-ethenoguanine), in urine from 13 healthy subjects without known occupational exposure to industrial chemicals such as VC and ethyl carbamate, exposure to both of which forms such adducts. They found adducts in the range <0.3-8 nmol/l, and proposed endogenous mechanisms for the formation of adducts at these "background" levels. Chang et al. (2001) measured levels of the VC metabolite thiodiglycolic acid (TdGA) in the urine of 16 PVC manufacturing workers at the end of one shift and at the beginning of the next. This study found a significant difference in TdGA levels for workers exposed to more than v less than 5 ppm VC, and a significant correlation between air VC concentration and urinary TdGA concentration. TdGA levels were higher at the beginning of a shift than at the end of the previous one.

75-02-5 Vinyl fluoride Halogenated organic solvent
Vinyl fluoride is used in the production of polyvinylfluoride which has been used to cover walls, pipes, and electrical equipment and inside aircraft cabins (NTP 2011). It is listed as a Proposition 65 carcinogen (California OEHHA 2014).
No studies were found using biomarkers for vinyl flouride.

75-35-4 Vinylidene chloride Halogenated organic solvent
The general population may be exposed via inhalation of ambient air, ingestion of food and drinking water, and dermal contact with consumer products, such as plastic wrap which contains residual monomer (NLM 2011). Migration of vinylidene chloride into food wrapped in plastic is likely. It is detected in wastewater (IARC 1999l).
NHANES has used HS-SPME-GC-MS on 3-10 mL whole blood, but less than 5% of the population had vinylidene chloride levels above the LOD of 0.009 ng/mL (Blount et al. 2006;CDC 2008bCDC , 2009). Waksman and Phillips (2004) briefly review research on the metabolism and biomonitoring of vinylidene chloride, noting that metabolites such as dithioglycolic acid are sometimes used, but that many DCE metabolites are also metabolites of other chlorinated hydrocarbons.
Heterocyclic amine Consumption of charred fraction of cooked fish is a source of exposure for the general population (IARC 1983b). It is listed as a Proposition 65 carcinogen (California OEHHA 2014).
Trp-P-2 has been measured in the blood, urine, and bile of healthy volunteers and hospital patients. Manabe et al. (1992) used HPLC on plasma and red blood cells from healthy volunteers and patients with uremia, detecting Trp-P-2 at higher levels in uremic patients but also detecting it in samples from healthy subjects. Ushiyama et al. (1991) used HPLC on urine from 10 healthy volunteers on "normal" diets and 3 patients on IV feeding. Trp-P-2 levels ranged from 0.03-0.68 ng in 24h urine samples from healthy volunteers, with none detected in the patients' urine. Using HPLC on human bile from seven subjects with catheterized bile ducts and external biliary drainage, Manabe et al. (1990) found an average of 864 fmol Trp-P-2 excreted per day. Baranczewski et al. (2004) was able to detect Trp-P-2-DNA adducts in the livers of mice dosed with Trp-P-2. 76180-96-6 2-Amino-3methylimidazo[4,5-f]quinoline (IQ)

Heterocyclic amine
Exposure occurs primarily through the consumption of cooked meats; it is also detected in processed food flavorings, beer, wine, and cigarette smoke (IARC 1993a, c;NTP 2005). It is listed as a Proposition 65 carcinogen (California OEHHA 2014).
No studies were found using biomarkers to measure exposure to IQ in humans, though methods have been developed for measuring IQ and its metabolites in urine. Yoxall et al. (2004) developed a method for the extraction of IQ and other heterocyclic amines from human urine using blue rayon. Gerbl et al. (2004) describes HPLC with coulometric electrode array detection for measurement of IQ in rat urine. Hsu et al. (2009) and Lakshmi et al. (2009) identify multiple metabolites in the urine of mice dosed with IQ.

Heterocyclic amine
Exposure occurs primarily through the consumption of cooked meats; MeIQ is also detected in processed food flavorings, beer, wine, and cigarette smoke (NLM 2011;NTP 2011). The associated chemical MeIQx has also been found in air and surface water (NTP 2011). It is listed as a Proposition 65 carcinogen (California OEHHA 2014).
No studies were found using biomarkers to measure exposure to MeIQ in humans, though one method exists for measuring MeIQ in urine: Gerbl et al. (2004) describes HPLC with coulometric electrode array detection for measurement of MeIQ in rat urine.

105650-23-5 PhIP Heterocyclic amine
Exposure occurs primarily through the consumption of cooked meats, and PhIP has been also detected in processed food flavorings, beer, wine, and cigarette smoke. It is present in air and surface water (NTP 2011). It is listed as a Proposition 65 carcinogen (California OEHHA 2014).
Many studies have measured exposure to PhIP in the general population or in volunteers fed cooked meat. Studies used blood, urine, hair and pancreatic tissue. Magagnotti et al. (2000) measured serum albumin (SA) and globin (Gb) adducts in blood by GC-MS and LC-MS/MS. Magagnotti found PhIP-SA levels (mean +/-SD) of 6.7 +/-1.6 and 0.7 +/-0.3 fmol/mg, and PhIP-Gb levels of 3.0 +/-0.8 and 0.3 +/-0.1 fmol/mg in meat eaters and vegetarians respectively. Ushiyama et al. (1991) used HPLC to measure PhIP in urine of 10 healthy volunteers eating their normal diets and 3 patients on IV nutrition, and found 0.12-1.97 ng in 24-h samples from the healthy volunteers and no PhIP in the IV-fed patients' urine. Viberg et al. (2006) used SPE-capillary electrophoresis-MS to detect PhIP in urine, with a DL of 65 pM, finding 1.8 nmol/L (=0.4 pg/ul) PhIP in urine collected 12 h after subjects had eaten fried chicken. Reistad et al. (1997) used GC-MS to measure PhIP in urine, measuring 2-23 ng or 24-100 ng (depending on sample prep) in 24-h urine samples from subjects who had eaten cooked meat. Walters et al. (2004) found the metabolites N(2)-OH-PhIP-N(2)-glucuronide and N(2)-OH-PhIP-N(3)-glucuronide in urine by LC-MS/MS, with levels varying depending on whether subjects were avoiding or eating cruciferous vegetables. Kulp et al. (2004) analyzed the same two metabolites as Walters et al. (2004), as well as 4'-PhIP-sulfate, and found all three in the urine of 8 volunteers after they had eaten cooked chicken, but not before the meal. Bessette et al. (2009) used LC-MS/MS for PhIP detection in hair, with LLOQ around 50 pg/g. This study found PhIP at 290-890 pg/g in the hair of meat eaters, and from below the LOD to 65 pg/g in vegetarians. Alexander et al. (2002) describes findings of <50-5000 pg PhIP/g hair. Kobayashi et al. (2007) determined that hair PhIP levels correlate with those estimated from a food frequency questionnaire, if hair results are adjusted for melanin. Zhu et al. (2006) described immunochemistry and image analysis of DNA adducts in pancreatic tissues from pancreatic adenocarcinoma patients and from healthy volunteers. Zhu et al. (2006)  Amsonic acid Hormone or EDC Potential sources of exposure include clothing, especially when moistened by perspiration, packaging materials, some foods, such as fish, and insufficiently rinsed dishes. There is little if any direct use of the parent compound by consumers. It is used in the manufacture of dyes and fluorescent whitening agents or optical brighteners with a range of uses, including in laundry detergents (NTP 1992).
No studies were found using biomarkers for exposure to amsonic acid.
1912-24-9 Atrazine Hormone or EDC The general population may be exposed to atrazine via inhalation of ambient air, ingestion of drinking water, and ingestion of foods that may contain atrazine (NLM 2011). It is a commonly used herbicide and found widely, together with its dealkylated degradation products, in rivers, lakes, estuaries, groundwater and reservoirs (IARC 1999g).
NHANES, NIOSH, and others have measured atrazine and its metabolites in urine of the general population and exposed farmers.

Name
Chemical group Exposure summary Biomarker summary 12789-03-6 Chlordane Hormone or EDC Although use of this organochlorine insecticide has been banned, human exposure continues because of its persistence in the environment, especially in indoor air in previously treated buildings and in meat, fish and other fat-containing foodstuffs (IARC 2001b). It was used starting in the 1950s for termite control, on agricultural crops, on lawns, on livestock, and for other purposes, and is commonly detected in indoor air and house dust in the US (Rudel et al. 2003).
NHANES and others have measured chlordane and its metabolites in the blood of the general population, and some studies have measured chlordane or its metabolites in human breast milk and adipose tissue. NHANES measured the chlordane metabolites oxychlordane and trans-nonachlor in serum via SPE followed by gas chromatography/isotope dilution high-resolution mass spectrometry (CDC 2006(CDC , 2013Everett and Matheson 2010;Lee et al. 2006Lee et al. ) in 1999Lee et al. -2001Lee et al. , 2001Lee et al. -02, and 2003. Others have also measured cischlordane, trans-chlordane, and cis-nonachlor in blood (Cao et al. 2012;Rudge et al. 2012;Varona et al. 2010). Many studies (Haraguchi et al. 2009;Hedley et al. 2010;Tanabe and Kunisue 2007;Zhou et al. 2011) have used GC-MS or other methods to measure chlordane or chlordane related chemicals in human breast milk, mostly in Asia. A few researchers have measured chlordane in human adipose tissues (Kunisue et al. 2006;Kutz et al. 1991;Nakata et al. 2005).

Conjugated estrogens Hormone or EDC
Conjugated estrogens can be measured in domestic wastewater and surface water polluted by wastewater, following urinary excretion. They are used for estrogen replacement therapy and oral contraceptives (Kolpin et al. 2002). The use of postmenopausal estrogen therapy became common in the United States in the 1960s. By 1967, approximately 13% of the women in the United States 45 to 64 years old used this type of therapy. The number of prescriptions for estrogens, not counting those used for oral contraceptives, increased from approximately 15 million in 1966 to more than 25 million in 1976, when prescriptions declined because of concerns about endometrial cancer, but then increased rapidly to approximately 40 million by 1992. In 2002, more than 100 million prescriptions were filled for brand-name and generic products containing estrogens (either conjugated or esterified) as an active ingredient (NTP 2011). Observed increased breast cancer risk associated with exposure to pharmaceutical estrogens has raised concern about possible risk associated with chemicals that mimic estrogen or are endocrine disruptors. Most commercial chemicals have not been screened for endocrine disruption. Also, as discussed by Rudel et al. (2007;, the typical cancer bioassay design may not be sensitive to hormonally-induced mammary tumors. Conjugated estrogens are listed as Proposition 65 carcinogens (California OEHHA 2014).
See summary for estradiol. Many methods used to measure non-conjugated estrogens can also measure conjugated estrogens in blood and urine either by quantifying the conjugated forms specifically via LC-MS/MS and presumably GC-MS/MS (Ziegler et al. 2010), or by subtracting concentrations of unconjugated hormone from total hormone concentration measured after lysis of the conjugate groups (Blair 2010).

Name
Chemical group Exposure summary Biomarker summary 56-53-1 Diethylstilbestrol Hormone or EDC DES is a synthetic estrogen that was prescribed to pregnant women from the 1950s until the early 1970s to prevent miscarriage. It was later shown to be a transplacental carcinogen, causing a rare vaginal cancer in daughters of exposed women. It has been demonstrated to increase breast cancer risk in exposed mothers and their daughters, and to cause reproductive system abnormalities (Hoover et al. 2011). An estimated 5-10 million people were exposed in utero in the US (IARC 2012; NTP 2011). DES is now occasionally used to treat prostate cancer, but this use is rare because of its side-effects. It is occasionally used in postmenopausal women with breast cancer (IARC 2012). It has also been found in animal feed (NLM 2004) and was historically used as a growth promoter in sheep and cattle (NTP 2011). It is listed as a Proposition 65 carcinogen and developmental toxicant (California OEHHA 2014) A few studies have described methods for measurement of DES in human urine, and more have measured it in bovine urine. Zou et al. (2012) used HPLC with novel extraction methods to detect DES with LOD 0.1 ng/mL in human urine, while Wu et al. (2009) used GC-MS in human urine, with a limit of detection of 0.28 ng/mL, and concluded that their method was sufficiently sensitive to use for "routine assessment and monitoring... in the human body". Measurements of DES in bovine urine have used LC-MS/MS (Kaklamanos et al. 2009;Schmidt et al. 2008), HPLC-MS (Rubies et al. 2007), LC-ES-MS (Msagati and Nindi 2006) and GC-MS (Aman et al. 2006;Dickson et al. 2003).

50-28-2 Estradiol-17b
Hormone or EDC Estradiol can be measured in domestic wastewater and surface water polluted by wastewater, following urinary excretion (Kolpin et al. 2002). It is used pharmaceutically as an estrogenic hormone, estrogen replacement therapy, and oral contraceptive (NLM 2011). Monitoring data indicate that the general population may be exposed to estradiol at well below the therapeutic dose via ingestion of drinking water and dermal contact with contaminated sediments (NLM 2004). It is listed as a Proposition 65 carcinogen (California OEHHA 2014).
Clinical and research laboratories have used many methods to measure estradiol and other steroid hormones in human blood and urine. "Direct" radio immunoassay (RIA), with no extraction or chromatography steps, is commonly used to measure estradiol in serum or plasma in clinical practice, but is imprecise and prone to interference from other hormones and hormone-binding proteins in serum or plasma (Blair 2010;Cao et al. 2004;Rosner et al. 2013). Additionally, standard direct RIA can't detect the low levels found in small blood samples from people other than healthy premenopausal adult women (Blair 2010;Rosner et al. 2013). HPLC-RIA is somewhat more sensitive and precise, but suffers from many of the same problems as direct RIA (Blair 2010). GC-MS and LC-MS methods in blood and urine are more precise, sensitive, and specific, but many require specialized derivatization and ionization steps to achieve low detection limits (Blair 2010;Rosner et al. 2013;Stanczyk and Clarke 2010). Additional reviews are available (Honour 2006(Honour , 2010Kushnir et al. 2010;McDonald et al. 2011;Taylor 2006). The MCF-7 cell proliferation assay has been used to measure estrogenic activity in extracts of adipose tissue in breast cancer cases and controls (Fernandez et al. 2007). The development of methods to conduct a similar assay in blood, and to distinguish endogenous and exogenous estrogen signals, would allow integrated assessments of exposure to xenoestrogens.
There are case reports of children with premature breast development associated with these exposures. It is listed as a Proposition 65 carcinogen (California OEHHA 2014).
See summary for estradiol. Methods used to measure estradiol can also measure estrone (Blair 2010;Stanczyk and Clarke 2010;Ziegler et al. 2010).

Name
Chemical group Exposure summary Biomarker summary 57-83-0 Progesterone Hormone or EDC Human placental extracts, of which progesterone is believed to be the main constituent, have been used in preparations for cosmetic use (at levels of 0.1% to 1.0%), hair conditioners, shampoos, and grooming aid tonics (<0.1%). There are case reports of children with premature breast development associated with these exposures. Progesterone has been detected in cow's milk, milk products, certain plant species, and meat from animals treated with a progesterone implant. Progesterone is also used in pharmaceuticals including birth control (NTP 2011). Monitoring data indicate that the general population may be exposed to progesterone at well below the therapeutic dose via ingestion of drinking water (NLM 2011). It is listed as a Proposition 65 carcinogen (California OEHHA 2014).
See summary for estradiol. Methods similar to those used to measure estradiol can also measure progesterone in blood and urine (Honour 2010;McDonald et al. 2011;Stanczyk and Clarke 2010). Progesterone has also been measured in human saliva (Honour 2010).
122-34-9 Simazine Hormone or EDC The general population may be exposed to simazine via ingestion of contaminated drinking water, ingestion of food, and inhalation of ambient air (NLM 2011). Exposure could also occur through consumption of foods containing residues, though residues were not detected in largescale surveys of food products in Canada and the USA (IARC 1991a). It is a widely used herbicide to control grasses and weeds in food crops, and it is also used for selective control of algae and submerged weeds in ponds, large aquaria, ornamental fish ponds, and fountains. Prior to 1994 it was approved for use to control algae in hot tubs and swimming pools. Simazine and its degradation products have been detected at low levels in ambient rural and urban air, rainwater, surface and groundwater and, less frequently, in drinking water samples (IARC 1999h). It is listed as a Proposition 65 carcinogen (California OEHHA 2014).
At least one study has measured simazine and its metabolites in the urine of the general population, and NIOSH includes it in a published method. NIOSH method 8315, exposure to triazine herbicides, measures simazine, atrazine, desethyl atrazine, and desisopropyl atrazine via GC-MS in at least 15 mL urine, LOD 20-47 nmol/L. Chevrier et al. (2011) measured multiple urinary simazine metabolites, detecting simazine or simazine mercapturate in the urine of 8% of pregnant women (n= 579) in Brittany in 2002-2006, while dealkylated and hydroxylated triazine metabolites were detectable in 20% and 40% of samples, respectively. Simazine and atrazine are structurally similar and share many metabolites, so methods for measuring atrazine exposure should be applicable to simazine as well.
77439-76-0 MX (3-chloro-4-MX The general population may be exposed via No studies were found using biomarkers to measure exposure to MX. Weisel et al. (1999) and others have used urine trihaloacetic acid (dichloromethyl)-5-hydroxy-treated (chlorinated) drinking water. MX is a levels as markers of exposure to drinking water disinfection by-products. 2(5h)-furanone) by-product of drinking water disinfection that has been found at nanogram-per-liter levels in drinking water as a result of chlorination or chloramination (IARC 2004). One study identified MX as the primary contributor to genotoxicity of finished drinking water (Brunborg et al. 1991) but other compounds contribute as well. It is listed as a Proposition 65 carcinogen (California OEHHA 2014). 75321-20-9 1,3-Dinitropyrene NitroPAH 1,3-dinitropyrene is found at low concentrations in ambient air and associated with diesel exhaust and air pollution (IARC 1989c). It is listed as a Proposition 65 carcinogen (California OEHHA 2014).
No studies were found using biomarkers of exposure to 1,3-dinitropyrene. Methods for 1-nitropyrene may be adapted.
42397-65-9 1,8-Dinitropyrene NitroPAH The primary route of potential human exposure is inhalation. Detectable levels have been found in respirable particulates from ambient atmospheric samples. Associated with particulate emissions from diesel engines, kerosene heaters, and gas burners. It has also been found at low concentrations in ambient air (IARC 1989e;NTP 2011). It is listed as a Proposition 65 carcinogen (California OEHHA 2014).
No studies were found using biomarkers of exposure to 1,8-dinitropyrene. Methods for 1-nitropyrene may be adapted.

Name
Chemical group Exposure summary Biomarker summary 5522-43-0 1-Nitropyrene NitroPAH The general population may be exposed via inhalation of ambient air, ingestion of food and drinking water, and dermal contact. Diesel exhaust is considered the major source of exposure, and 1-nitropyrene is commonly detected in ambient air. 1nitropyrene has also been detected in the air near coal plants, in fumes from soybean cooking oil, and in dried herbs (NTP 2011). It is listed as a Proposition 65 carcinogen (California OEHHA 2014).
Metabolites and adducts of 1-nitropyrene have been measured in the urine and blood of the general population and in workers and experimental volunteers exposed to diesel exhaust. Huyck et al. (2010) and Laumbach et al. (2009) measured the 1-nitropyrene metabolite 1-aminopyrene in the urine of volunteers experimentally exposed to diesel exhaust. Zwirner-Baier and Neumann (1999) measured hemoglobin adducts derived from 1-nitropyrene in blood samples from bus garage workers, urban hospital workers, and 14 controls via hydrolysis followed by GC-MS, with LOD 0.01-0.08 pmol/g Hb. (Differences between populations were only evident when multiple NitroPAH adducts were summed). Neumann et al. (1995) used the same method to detect 1-nitropyrene-derived adducts in coke oven workers and controls living in the same area. Toriba (2007), using LC-MS/MS with blue rayon extraction, detected multiple isomers of the 1-nitropyrene metabolites hydroxy-N-acetyl-1-aminopyrene and hydroxy-1-nitropyrene in all tested urine samples from the general population; 4 metabolites had mean levels in the hundreds of pmol/mol creatinine. Seidel et al. (2002) measured metabolites of 1nitropyrene and other PAHs in pre-and post-shift urine samples from salt miners exposed to diesel exhaust, and found large differences in the levels of many metabolites between smoking and non-smoking workers. 607-57-8 2-Nitrofluorene NitroPAH General exposures occur via urban Two studies were found measuring biomarkers of exposure to 2-nitroflourene in the blood of occupationally exposed workers and atmospheres, contaminated drinking water controls. Zwirner-Baier and Neumann (1999) measured a hemoglobin adduct derived from 2-nitroflourene in bus garage workers, urban supplies and recreational activities at hospital workers, and 14 controls via hydrolysis followed by GC-MS, with LOD 0.01-0.08 pmol/g Hb. (Differences between populations contaminated waterways (NLM 2011). 2-were only evident when multiple nitroPAH adducts were summed). Neumann et al. (1995) used the same method to detect adducts of a nitroflourene is found at low concentrations in ambient air and detected in particulate emissions from diesel engines, kerosene heaters, and gas burners (IARC 1989d). It is listed as a Proposition 65 carcinogen (California OEHHA 2014).
2-nitroflourene metabolite in coke oven workers and controls living in the same area. Newer methods for 1-nitropyrene may be adapted.

57835-92-4 4-Nitropyrene NitroPAH
The primary route of potential exposure is inhalation. 4-nitropyrene has been measured in diesel exhaust particulate extracts and in particulates derived from coal-burning (NTP 2011). It was found at low concentrations in ambient air in one study (IARC 1989a). It is listed as a Proposition 65 carcinogen (California OEHHA 2014).
No studies were found using biomarkers of exposure to 4-nitropyrene. Newer methods for 1-nitropyrene may be adapted.
7496-02-8 6-Nitrochrysene NitroPAH 6-nitrochrysene has been measured in diesel Two studies were found measuring biomarkers of exposure to 6-nitrochrysene in the blood of occupationally exposed workers and exhaust particulate extracts (NTP 2011), and controls. Zwirner-Baier and Neumann (1999) measured hemoglobin adduct derived from 6-nitrochrysene in bus garage workers, urban was found in ambient air at a low hospital workers, and 14 controls via hydrolysis followed by GC-MS, with LOD 0.01-0.08 pmol/g Hb. (Differences between populations concentration in one study (IARC 1989b). It is were only evident when multiple NitroPAH adducts were summed). Neumann et al. (1995) used the same method to detect adducts of a listed as a Proposition 65 carcinogen (California OEHHA 2014).
6-nitrochrysene metabolite in coke oven workers and controls living in the same area.

303-47-9
Ochratoxin A OTA Exposure can occur through consumption of contaminated grain, nuts, and pork products. It is a naturally occuring mycotoxin with widespread occurrence in food and animal feed (IARC 1993b;NTP 2011). Ochratoxincontamination of grains is prevalent in some areas of Balkan countries. Ochratoxin exposure has also been demonstrated in a subset of people in the US exposed to moldcontaminated environments or buildings (Hooper et al. 2009). It is a Proposition 65 carcinogen (California OEHHA 2014).
Many studies have used biomarkers in blood and urine to investigate exposure to ochratoxin a (OTA) in general populations, especially in Turkey and other Mediterranean and Balkan countries. Studies have also measured OTA in human breast milk, amniotic fluid, sputum, and biopsies of the lung, liver, and brain. Scott et al. (2005) Scott et al. (2005) describes various methods of reversed phase LC-FD as the most common for measuring OTA in biological liquids, with typical LODs between 0.01-0.1 ng/mL. Many but not all studies find OTA in the majority of blood, urine, or breast milk samples from the general population (Coronel et al. 2009;Duarte et al. 2010;Erkekoğlu et al. 2010;Gürbay et al. 2009;Lino et al. 2008;Scott 2005). Many studies have found regional and seasonal differences in blood and urine levels (Akdemir et al. 2010;Duarte et al. 2010;Erkekoğlu et al. 2010;Lino et al. 2008;Scott 2005). At least one study found levels higher in healthy workers in food factories than in controls (Iavicoli et al. 2002). Ritieni et al. (2010) used LC-MS/MS on 21 amniotic fluid samples, detecting OTA in one sample at 4.26 µg/l, despite not detecting it in blood or urine from the same woman. Hooper et al. (2009) used immunoaffinity columns and fluorometry (LOD: 2 ppb) on urine, sputum, and biopsies of lung, liver, and brain of patients known to be exposed to toxic molds and control patients. Levels in samples from exposed patients from below the LOD to >10 ppb; there was no detectable OTA in samples from control patients. Kovacs et al. (1995)  3-Methylcholanthrene PAH Exposure is associated with the use of 3-MC in biochemical research, and it may also be present in industrial air pollutants, smoke from coal or coke-burners, and in tobacco tar (NLM 2011). It is listed as a Proposition 65 carcinogen (California OEHHA 2014).
No studies were found measuring 3-MC in humans or other mammals. Choudhury et al. (1990)  Many studies have investigated markers of benzo[a]pyrene (BaP) in blood in general populations, and in urine from occupationally exposed populations. Methods have also been developed for measuring BaP or markers in breast milk, placental tissue, aborted fetal tissue, follicular fluid, semen, and lung tissue. The most commonly measured biomarkers of BaP exposure are DNA and protein adducts measured in blood. BaP-specific adducts, including BPDE-DNA and BPDE-protein (albumin and hemoglobin) adducts, are typically measured by HPLC-FD or GC-MS (Boysen and Hecht 2003;Käfferlein et al. 2010). Nonspecific "bulky" or "BaP-like" DNA adducts have been detected by 32-P-post labeling and immunoassays, which are more sensitive but typically cannot differentiate between PAHs (Boysen and Hecht 2003;Käfferlein et al. 2010). Epidemiologists have used immunoassays to measure nonspecific PAH-DNA adducts in cancer studies (Gammon et al. 2002;Rundle et al. 2002). Researchers have had limited success differentiating between exposed and unexposed populations through use of BaP-specific adducts (Boysen and Hecht 2003;Käfferlein et al. 2010).  used HPLC-FP/UV to detect BaP itself in blood from children in India, finding a median level of 4 ppb. Although at least one study using HS-SPME (Waidyanatha et al. 2003) failed to detect BaP itself in urine from exposed coke plant workers, multiple studies have detected 3-OHBaP in urine from occupationally exposed workers using HPLC (Szaniszló and Ungváry 2001) or LLE-GC-MS (Rossella et al. 2009). Szaniszlo and Ungvary (2001) found higher levels of 3-OHBaP in urine from smokers than non-smokers, but found no difference between healthcare workers, policemen, and asphalt production workers. BaP exposure has been measured in many other biological media as well. Madhavan and Naiku (1995) found "relatively high concentrations" of BaP in umbilical cord blood and breast milk collected from women in India. Toriba et al. (2003) developed an HPLC-FD method to measure BaP and other PAHs in human hair.  found BaP levels measured by HPLC-FD elevated, but not significantly, in 29 placental tissues from preterm pregnancies, compared to 31 from full-term pregnancies. BaP has also been measured in lung samples collected during surgery (Bartsch et al. 1993) or autopsy (Lodovici et al. 1998); in both cases, levels of BAP in lung tissue were correlated with levels of BAP derived DNA adducts. Additional studies have measured BaP or its metabolites or adducts in aborted tissue (Wu et al. 2010), follicular fluid, in which levels were higher in smokers than non-smokers (Neal et al. 2008), and semen (Zenzes et al. 1999 One study of smokers measured exposure to dibenzo(def,p)chrysene (also known as dibenzo(a,l)pyrene or DB(a,l)P) in human blood, nasal cells, and lung cells. Another study used mouse skin. Peluso (2004), studying smokers, measured specific DNA adducts for DB(a,l)P and DBA in nasal and bronchial mucosa, as well as in lymphocytes, finding the highest levels in nasal mucosa. Mean 10^8 relative adduct levels were 1.10 in nasal samples, 0.82 in lung samples and 0.54 lymphocytes. Roberts et al. (2001) describe using HPLC-fluorescence line-narrowing spectroscopy to measure and analyze DNA adducts in mouse skin that had been exposed to DB(a,l)P.
335-67-1 Perfluorooctanoic acid PFOA PFOA is widely detected in blood samples in the US. It is used in non-stick and stainresistant coatings on rugs, furniture, clothes, cookware, fire-fighting applications, cosmetics, lubricants, paints, and adhesives. Former use in insecticide and herbicide formulations resulted in its direct release to the environment (NLM 2011). It is an EPA Action Plan Chemical, with exposures from drinking water, aquatic organisms, soil, and consumer products (US EPA 2013b).
NHANES and others have measured PFOA in blood from the general population, as well as from groups exposed occupationally or through industrial contamination. PFOA has also been measured in human milk samples and human thyroid tissue. NHANES uses online SPE-HPLC-MS/MS for the measurement of PFOA and 17 other perfluorinated chemicals in 100 µm of serum, with LOD 0.1 ng/mL and LLOQ 0.3 ng/mL (Bartell et al. 2010;Calafat et al. 2007a;Kuklenyik et al. 2005). NHANES has used off-line SPE in the past, with similar results (Calafat et al. 2007b 121-66-4 2-Amino-5-nitrothiazole Pharmaceutical The general population may be exposed through residues of 2-amino-5-nitrothiazole in food products. It is a synthetic veterinary antiprotozoal agent (NTP 1978a).
No studies were found using biomarkers of exposure to 2-amino-5-nitrothiazole.

23214-92-8 Adriamycin
Pharmaceutical Adriamycin is a chemotherapeutic drug used to treat a variety of cancers. National Occupational Exposure Survey estimated that 17,132 health-services workers were potentially exposed from 1981-1983. It can be found unchanged in human waste (NTP 2011).
A few studies have described methods for measuring adriamycin in urine. Sottani et al. (2008)

Name
Chemical group Exposure summary Biomarker summary 50-18-0 Cyclophosphamide Pharmaceutical Cyclophosphamide has been widely used since the early 1950s in the treatment of malignant lymphoma, multiple myeloma, and cancers of the breast, ovary and lung. It has also been used in the treatment of certain chronic diseases, such as rheumatoid arthritis and chronic glomerulonephritis and other nonmalignant diseases (IARC 1981). It is listed as a Proposition 65 carcinogen and developmental toxicant (California OEHHA 2014).
There have been many studies of cyclophosphamide (CP) levels in urine of healthcare workers and a few of CP levels in urine and blood of chemotherapy patients. Fransman et al. (2007), reviewing three studies in the Netherlands, reports that between 1997 and 2000 the proportion of samples with measurable CP levels went down fourfold, and the median concentration in samples with detectable CP went down threefold. Frequency of detection in occupational studies varies widely, with some studies finding CP in no (Turci et al. 2011;Ziegler et al. 2002) or very few (Favier et al. 2003) subjects' urine, and some finding CP in urine from over half of subjects (Minoia et al. 1998;Sessink et al. 1997;Sugiura et al. 2011). In plasma, LC-MS/MS has been used with LOD 0.02 ng/ml (Hedmer et al. 2008). B'Hymer and Cheever (2010) describe LLE-HPLC-MS/MS to detect cyclophosphamide and its metabolite 4-ketocyclophosphamide in urine, with LODs 1 ng/mL for the metabolite and 0.1 ng/mL for CP. Villarini et al. (2011) and Moretti et al. (2011) describe a study design using urinary cyclophosphamide as a biomarker of exposure to antineoplastic drugs, to be compared with biomarkers of DNA damage.
No studies were found measuring biomarkers of exposure to dacarbazine.

54-31-9
Furosemide Pharmaceutical Furosemide is a potent, short-acting sulfonamide diuretic chemically similar to the thiazides, commonly used as a medical treatment in a variety of situations ranging from the control of hypertension to the reduction of edema of cardiac, hepatic, or renal origin. It is particularly useful in the management of acute pulmonary edema and may be used in premature infants to promote the diuresis that usually follows birth. The number of prescriptions for furosemide in the United States increased from 16 million in 1973 to 23 million in 1981 (NTP 1989).
Methods have been developed to measure furosemide (FD) concentrations in blood and urine from patients or volunteers receiving FD. Reeuwijk et al. (1992)  A few studies have measured griseofulvin in plasma or other fluids from patients or volunteers who had been administered griseofulvin, and more describe pharmacokinetic studies. Mistri et al. (2007) described ESI LCM SMS to measure griseofulvin, with LLOQ 20 ng/mL, in plasma from six healthy subjects after they ingested 500 mg griseofulvin as part of a bioequivalence study. Pacifici (2006), reviewing transplacental transfer of multiple antibiotics, reports that griseofulvin has been measured in cord plasma as well as maternal plasma. Additional pharmacokinetic studies have measured griseofulvin in human intestinal mucus (Gramatte 1994), and griseofulvin and its metabolites varied fluids from experimental animals (Ahmed and Aboul-Einien 2007;Fujioka et al. 2008;Poullain-Termeau et al. 2008). Gramatte et al. (1994) measured griseofulvin in intestinal mucus as part of an availability study. 53-86-1 Indomethacin Pharmaceutical Indomethacin is a non-steroidal antiinflammatory used to treat rheumatoid disorders (NLM 2011. Isoniazid Pharmaceutical Isoniazid is an anti-infective agent, used to treat tuberculosis. The National Occupational Exposure Survey estimated that 2,924 workers (1,480 female) were potentially exposed to isoniazid in the US from 1981-1983 (NLM 2011) Isoniazid has been measured in blood, urine, breastmilk, and cerebrospinal fluid from patients prescribed isoniazid for clinical monitoring and pharmacokinetics studies. However, Peloquin (2002) reported that limits of detection were generally only sufficient to measure isoniazid within a few hours of dosing. HPLC appears to be the most common method for measurement in plasma and serum (Ge et al. 2008;Huang et al. 2009;Xu et al. 2013;Zhao et al. 2011;Zhou et al. 2010), with detection and quantification limits around 0.2-0.5 µg/mL (Huang et al. 2009;Zhou et al. 2011). Other methods used in blood include "cation selective exhaustive injection sweeping micellar electrokinetic chromatography" (Tsai et al. 2011). HPLC and other methods have been used to measure isoniazid and metabolites in urine ( Nithiazide Pharmaceutical Exposure may result from the use of nithiazide in veterinary medicine (IARC 1983a). It may persist in the tissues and eggs of treated poultry (NTP 1979).
No studies were found using biomarkers to measure exposure to nithiazide.

CAS
67-20-9 Nitrofurantoin Pharmaceutical Nitrofurantoin has been used since 1972 in Some studies described testing of human urine, plasma, and breast milk after administration of nitrofurantoin. Muth et al. (1996) described treatment of urinary tract infection (IARC LLE-HPLC to detect nitrofurantoin in plasma and urine, with LLOQ 0.01 µg/ml in plasma and 0.38 µg/mL in urine. Aufrere et al. (1977Aufrere et al. ( ) 1990). It is a Proposition 65 male toxicant described HPLC in 0.2 mL samples of plasma and urine, with LLOQ 0.02 µg/ml in both media. Arancibia et al. (2003) used SPE-HPLC to (California OEHHA 2014). detect nitrofurantoin and a radical anion metabolite in urine with detection limits of 12.1 uM and 0.9 uM, respectively. Xu et al. (2009) used an immunochromatographic assay to detect the nitrofuran metabolite 1-aminohydantoin in urine with a detection limit of 10 ng/ml. Pons et al. (1990) used HPLC to measure nitrofurantoin levels in breast milk and blood of women taking nitrofurantoin, quantifying levels in the 10s of ug in 6-h milk samples (Pons et al. 1990). 59-87-0 Nitrofurazone Pharmaceutical Nitrofurazone is a synthetic furan derivative active against a broad spectrum of bacteria, and has been used widely in veterinary and human medicine as well as (NTP 1988) pet care products, specifically fish care (NLM 2013). It is listed as a Proposition 65 carcinogen (California OEHHA 2014).
No occupational or general population studies were found for nitrofurazone, but method development studies described testing of human urine and plasma. Du et al. (2007) used flow induction chemiluminescence, with LOD 20 ng/ml and LLOQ 100ng/ml in both plasma and urine. Aufrere et al. (1977) used HPLC, with LLOQ 200 ng/mL in plasma and urine, to measure nitrofurantoin and stated that the method was also applicable to nitrofurazone.

62-44-2 Phenacetin
Pharmaceutical Until 1983, phenacetin was used in over-thecounter remedies for pain and fever; however, it no longer is used in drug products in the United States. Also, it was once used as a stabilizer for hydrogen peroxide in hairbleaching preparations (NTP 2011). It is listed as a Proposition 65 carcinogen (California OEHHA 2014).
Some older methods-development and dosing experiment studies have investigated possible biomarkers of phenacetin. Gotelli et al. (1977) used HPLC on 0.1 ml plasma samples, obtaining LLOQ 0.5 µg/ml for phenacetin. Garland et al. (1977) used GLC-chemical ionization MS on 1 ml plasma samples, obtaining a "sensitivity limit" of 1 ng/ml. Murray and Boobis (1991) used GC-MS to quantify phenacetin and its metabolite paracetamol (Tylenol) in plasma, detecting amounts equivalent to 1 pg of parent compound. Davies et al. (1984) used TLC-MS with multiple-peak monitoring for paracetamol in urine. Dittman and Renner (1977) used silica-gel TLC to measure the metabolite 4-acetominophenoxyacetic acid in rat, dog and human urine, detecting 0.04% of a 200 mg/kg dose.

50-55-5 Reserpine
Pharmaceutical Reserpine is an anti-hypertensive, recently A few studies have described methods for measurement of reserpine in human blood and urine. Tas et al. (1986) used LC-MS with a not widely used. The National Occupational detection limit around 10 pg to measure reserpine in human serum, for use in testing poisoning victims for overdoses. Owen et al. (1985) Exposure Survey estimated that 5611 described in HPLC method for the analysis of reserpine and related compounds in blood, with detection limits around 50 pg/mL. Li et al. workers (2414 female) were potentially exposed to reserpine in the US from 1981-1983 (NLM 2011).
(2011) used HPLC to measure reserpine in human urine with LOD 7.1 ng/mL and LLOQ of 23.6 ng/mL.
No studies were found measuring thioTEPA in the general public or in occupational settings, but methods have been developed for blood and urine. Van Maanen et al. (1997) obtained LLOQ 1 ng/ml in 100 ml samples of plasma and urine with capillary GC with a thermionic N-P detector. LC-MS/MS was validated over 5-2500 ng/ml for the metabolite TEPA (and thioTEPA) in 100 ml blood samples (de Jonge et al. 2004). In urine, GC with selective N-P detection, was linear from 25-5000 ng/ml for TEPA, and from 25-2500 ng/ml for the metabolite monochloroTEPA (van Maanen et al. 2000). Also in urine, LC-MS with direct sample injection with sulphadiazine as internal standard was linear from 1-25 µg/ml for the metabolite thioTEPA-mercapture (van Maanen and Beijnen 1999). 100-42-5 Styrene Styrene Exposure to the general population occurs at levels of micrograms per day due mainly to inhalation of ambient air and cigarette smoke and intake of food that has been in contact with polystyrene. Styrene is also present in a number of consumer products including carpets, adhesives, hobby and craft supplies and glues, and home maintenance products (IARC 2002;NLM 2013;NTP 2011 NHANES and others have measured styrene and its metabolites and adducts in blood samples from the general population and urine from general population and occupationally exposed groups, and a few studies have measured styrene in human saliva and breast milk. In 2001-2002 and 2003-2004, NHANES used HS-SPME-GC-MS, LOD 0.03 ng/mL on 3 mL (minimum) to 10 mL (optimal) whole blood and detected styrene in less than half of the general population (CDC 2012b), determining that cigarette smoke is "a primary source of" styrene in the blood of the US population. CDC is planning to add UPLC-ES-MS/MS testing for urinary phenylglyoxylic acid (PGA, a metabolite of styrene and ethyl benzene, LOD 12 ng/mL), mandelic acid (MA, LODs 12 ng/mL), and N-acetyl-S-(1-phenyl-2hydroxypropyl)-L-cysteine (PHEMA, LOD 0.7 ng/mL) to future NHANES reports (Alwis et al. 2012). A CDC pilot study found that MA and PGA levels were significantly different in smokers and non-smokers, but PHEMA was not detected in the urine of either (Alwis et al. 2012). Fustinoni et al. (2008) found that styrene derived albumin adducts but not hemoglobin adducts were higher in exposed workers than in controls. Reska et al. (2010) used online extraction-HPLC-MS/MS, with a combined LLOQ of 0.3 µg/L, to measure 2 mercapturic acids of styrene in urine from 18 smokers (<0.3-2.8 µg/L, median 0.46 µg/L) and from 22 non-smokers (0.3-1.1 µg/L, median <0.3 µg/L). Gagne et al. (2012) used UPLC-MS/MS for measurement of mandelic acid and phenylglyoxylic acid in urine; neither was detectable in non-occupationally exposed workers, but both were present between 0.2-9 mMol in urine from occupationally exposed workers. Fustinoni et al. (2010) measured urinary styrene, mercapturic acids, mandelic acid, phenylglyoxylic acid, phenylglycine, and 4-vinylphenol conjugates in 10 varnish workers and 8 plastic workers, finding higher levels in plastics workers and good "within worker" reproducibility for most metabolites, and good agreement between metabolite levels and styrene concentrations in air. Many studies have found that styrene metabolism and urinary excretion are influenced by polymorphisms in cyp and GSTM genes (Hirvonen 2005 NHANES has used HS-SPME-GC-MS on 3 mL (minimum) to 10 mL (optimal) whole blood, but less than 5% of the population had levels above the LOD of 0.01 ng/mL (Blount et al. 2006;CDC 2008bCDC , 2009).

CAS
123-91-1 1,4-Dioxane Miscellaneous Exposure of the general population to 1,4dioxane could possibly occur from contact with products containing residues of the compound. According to the Consumer Product Safety Commission (CPSC), consumers may possibly be exposed to residual levels of 1,4-dioxane formed during the manufacture of detergents, shampoos, surfactants, and certain pharmaceuticals. It is also found in home and auto-use adhesives (NLM 2013). CPSC reported that the presence of 1,4-dioxane, even as a trace contaminant, is cause for concern and the Commission monitors its use in consumer products. Residues may be present in food packaged in 1,4-dioxane-containing materials or on food crops treated with 1,4-dioxanecontaining pesticides (NTP 2011). It is detected in ambient air (IARC 1999c) and monitoring data also indicate that the general population may also be exposed to 1,4dioxane via ingestion of drinking water (NLM 2004). It is a TSCA Work Plan Chemical, identified as having a high likelihood of exposure. High releases to the environment have been reported (US EPA 2012). It is listed as a Proposition 65 carcinogen (California OEHHA 2014).
No studies were found using biomarkers of exposure to 1, 4-dioxane.

532-27-4 2-Chloroacetophenone Miscellaneous
The use of "Chemical Mace" to disable attackers causes direct exposure to 2chloroacetophenone through eye and skin contact and inhalation (NLM 2011).
No studies were found using biomarkers of exposure to 2-chloroacetophenone.

75-55-8 2-Methylaziridine Miscellaneous
Potential consumer exposure could occur as a result of handling products coated with 2methylaziridine or its derivatives; however, there are few ongoing consumer uses of this compound (NTP 2011). It is listed as a Proposition 65 carcinogen (California OEHHA 2014).
No studies were found using biomarkers for 2-methylaziridine 107-13-1 Acrylonitrile Miscellaneous The general population may be exposed through consumer product usage such as acrylic carpeting, rubber, food containers, and toys or by ingestion of contaminated foods. Foods most likely to contain measureable acrylonitrile are high-fat or highly acidic items, such as luncheon meat, peanut butter, margarine, vegetable oil, or fruit juice. Exposure is thought to be low because there is little migration of the monomer into such products (NTP 2011). Acrylonitrile has been measured in the vapor phase of mainstream tobacco smoke and has been detected rarely and at low levels in ambient air and water (IARC 1999b;NTP 2011). It is found in household spackling and caulk (NLM 2013 Many studies have measured acrylonitrile, its metabolites, or its adducts in the blood and urine of smokers and non-smokers. NHANES has measured 2-hydroxyethyl mercapturic acid (HEMA), a common metabolite of 1,2-dibromoethane, vinyl chloride, acrylonitrile, and ethylene oxide, in urine by isotope dilution and HPLC-MS/MS, detecting it in 71% of samples, with higher levels in smokers (Calafat et al. 1999). CDC is planning to add UPLC-ES-MS/MS testing for HEMA (LOD 0.6 ng/mL) and for the AN-specific mercapturic acid N-acetyl-S-(2-cyanoethyl)-L-cysteine (CYMA; LOD 0.5 ng/mL) to future NHANES reports (Alwis et al. 2012). A CDC pilot study found that CYMA levels were significantly different in smokers and non-smokers (Alwis et al. 2012), consistent with many other reports of higher levels of CYMA (Minet et al. 2011;Scherer et al. 2010;Schettgen et al. 2009) and acrylonitrile (Perbellini et al. 2003a) itself in urine from smokers compared to non-smokers. In blood, acrylonitrile-derived hemoglobin adduct levels are well correlated with self-reported smoking levels (Kütting et al. 2008;Schettgen et al. 2002). Though many studies detected the adduct in both non-smokers and smokers,  using isotope dilution GC NCI MS/MS, with LOD 0.5 pmol/g globin did not detect it in the majority of blood samples from nonsmokers who were not exposed to secondhand smoke at home, and did detect it in the majority of samples from those exposed. Similarly, Schettgen (2004) detected the adduct in maternal and umbilical cord blood from one smoker, but not from any of the 10 non-smokers tested, or in the umbilical cord blood of their recently delivered infants. Schettgen (2009) andFennell (2000) found that genotype of glutathione transferase gene had little effect on adduct levels.

NA
Bracken fern (and its extracted chemicals)

Miscellaneous
Exposure to bracken fern and its constituents occurs by direct ingestion of the fronds in some regions of the world, or by ingestion of dairy products from cattle grazing on the fern. In the past, other uses for bracken fern have been in bread flour and medicinals (IARC 1986b). The component ecdysone is being researched as an insecticide or insect repellent (Hami et al. 2005) and may be sold as muscle growth supplement. It is listed as a Proposition 65 carcinogen (California OEHHA 2014).
No studies were found using biomarkers to measure exposure to bracken fern, nor to ptaquiloside, the major carcinogen it produces.

2425-06-1 Captafol Miscellaneous
The fungicide captafol is not currently registered for use as a pesticide in the US (NTP 2011). It was widely used after 1961 for the control of fungal diseases in fruits, vegetables, some other plants, and lumber (IARC 1991b;NLM 2011). It is listed as a Proposition 65 carcinogen (California OEHHA 2014).
Multiple studies have measured tetrahydrothalidomide (THPI), a common metabolite of captafol and the related pesticide captan, in blood and urine of farm workers, intentionally dosed volunteers, and populations with high use of pesticides in the home. Most of these studies focus on assessing captan exposure and toxicokinetics. Whyatt et al. (2003) used SPE-isotope dilution GC-high resolution MS with LOD 1 pg/g to measure THPI in plasma from 230 African-American and Dominican mothers from northern Manhattan and their newborn infants, detecting THPI in 50% of maternal samples. Berthet et al. (2011) describes LC-atmospheric pressure chemical ionization-MS/MS to measure THPI and thalidomide in blood (LOD 0.58 µg/L) and urine (LOD 1.47 µg/L), and Berthet (2012a; 2012b) measured toxicokinetics of captan in urine and plasma after voluntary dermal and oral exposure, finding half-lives ranging from 16 to 27 hours depending on route of exposure and matrix. McCauley et al. (2008) found significant differences in urinary THPI between 134 workers in Oregon berry fields (mean 0.14 µg/mL) and control non-agricultural workers (mean 0.078 µg/mL). Hines et al. (2008) found a difference in urinary THPI levels between captan applicators using different methods. De Cock et al. (1995) found THPI levels in urine of fruit growers was strongly tied to captan exposure estimates from skin pads on ankles and neck, and lower in growers using more protective measures. 126-99-8 Chloroprene Miscellaneous Although few data are available on environmental occurrence, general population exposures to 2-chloroprene are expected to be very low or negligible (IARC 1999e). It is used almost exclusively for the production of neoprene elastomers and latexes, a synthetic rubber used in the production of automotive and mechanical rubber goods, adhesives, caulks, flameresistant cushioning, construction goods, fabric coatings, sealants for dams or locks in waterways, roof coatings, fiber binding, and footwear (NTP 2011). It is listed as a Proposition 65 carcinogen (California OEHHA 2014).

1420-04-8 Clonitralid Miscellaneous
The major route of population exposure to clonitralid is presumably dermal contact with or ingestion of treated water or ingestion of contaminated fish. It is directly applied to control sea lamprey larvae in tributaries to the Great Lakes and widely applied to control water snails (NTP 1978c).
No studies were found using biomarkers to measure human exposure to clonitralid, although a method has been developed to measure it in nonhuman biological samples. Caldow et al. (2009) used reverse phase LC-MS/MS with solvent extraction with 1% acetic acid in acetone and clean-up via mixed-mode anion-exchange SPE to measure clonitralid and other anthelmintics in bovine kidney tissue.

62-73-7 Dichlorvos Miscellaneous
Household uses of dichlorvos represent the main sources of human exposure (IARC 1991c). The general population may be exposed via inhalation of air and dermal contact when no-pest strips, sprays or flea collars contain this insecticide. Exposure could also result from ingestion of food which has been prepared in rooms where dichlorvos is used for insect control (NLM 2011). It is listed as a Proposition 65 carcinogen (California OEHHA 2014).
NHANES and others have measured urinary dimethyl phosphate (DMP), a metabolite of dichlorvos and many other organophosphate pesticides, in the general population and in exposed subjects. DMP has also been measured in hair samples from unexposed and exposed subjects. More specific biomarkers have been measured in the urine and blood of poisoning victims. Since 1999, NHANES has used isotope dilution GC-MS/MS to measure DMP in urine, with LOD 0.5 µg/L, estimating detectable levels in between 25% and 50% of the population (CDC 2009). Multiple studies have found higher levels of urinary DMP and other OP metabolites in farmworkers and their children (Coronado et al. 2011;Lee et al. 2007) than in nonfarm workers and their children. Urinary DMP levels are also higher in people living closer to farmland (Bradman et al. 2011;Coronado et al. 2011). Tsatsakis et al. (2010) measured DMP and three other dialkyl phosphates in hair samples from the general population and from occupationally exposed subjects via methanolic extraction, derivatization with pentafluorobenzylbromide, and GC-MS, detecting large and significant differences between the groups (DMP was detectable in 63% of general population hair samples and 100% of occupationally exposed samples). Biomonitoring of dichlorvos-specific biomarkers has focused on cases of acute poisoning (often suicide attempts), in which dichlorvos or its metabolites have been detected in hair, blood, and urine (Abe et al. 2008;Heinig et al. 2000;Inoue et al. 2007;Bin Li et al. 2010;Musshoff et al. 2002;Takayasu et al. 2001).  (California OEHHA 2014).

CAS
No studies were found using biomarkers to measure exposure to FD&C Violet no.1.

51630-58-1 Fenvalerate Miscellaneous
Use as a contact insecticide releases fenvalerate directly to the environment in sprays, dusts, concentrates and other routes of application (NLM 2011). It is detected in consumer products, including pesticide products, landscaping/yard products, and pet care products (NLM 2013). It is listed as a Proposition 65 carcinogen (California OEHHA 2014).
NHANES and others have measured urinary 3-phenoxybenzoicacid (3 PBA), a metabolite of fenvalerate and other pyrethroid pesticides, in the urine of the general population and people who are occupationally exposed, and methods have been developed to measure fenvalerate and esfenvalerate in urine. In 99-00 and 01-02, NHANES measured urinary 3 PBA via organic liquid extraction and LC-MS/MS in 75% of samples, with LOD 0.1 µg/L (CDC 2009;Riederer et al. 2008). NHANES, 2003-2004 also measured 3 PBA, but withdrew the data "due to unacceptable measurement variance at or near the LOD" (CDC 2011). Other studies of 3-PBA levels are reviewed in the 3rd NHANES exposure report (CDC 2005) and by Egeghy (2011). Ramesh and Ravi (2004) tested 73 blood samples from occupationally exposed people via negative ion channel ionization GC-MS for fenvalerate and other pyrethroid pesticides, and did not detect any above the LOD of 0.2 pg/mL. Loper and Anderson (2003) described liquid chromatography with diode array detection for the detection of fenvalerate and other pyrethroid and pyrethrin pesticides in 5 mL of urine, with LODs between 0.002 and 0.04 µg/mL. Shan et al. (1999) described ELISA with SPE to measure PBA and esfenvalerate in urine, with LLOQ 1 µg/L.

4680-78-8
Guinea Green B Miscellaneous Guinea Green B is used to dye wool, silk, leather, paper, and wood. In the past, it was used as a food, drug and cosmetic dye to color gelatin desserts, frozen desserts, sweets and confections which did not contain fats and oils, bakery products and cereals, and drug capsules. However, its use as color additive for foods, drugs and cosmetics was forbidden in the USA in late 1966 and its use as a food additive was forbidden in Japan in 1967. It is considered to be unsafe for use in food throughout the world. In Western Europe, Guinea Green B can provisionally be used in cosmetics that do not come into contact with mucous membranes; and in Japan, it is used in externally applied cosmetics (NLM 2011).
No studies were found measuring biomarkers of exposure to Guinea Green B.

302-01-2 Hydrazine Miscellaneous
The potential for exposure of the general population to hydrazine is low, but it may occur through inhalation of cigarette smoke or ingestion of trace amounts in processed foods (NTP 2011). Another possible exposure includes dermal contact with vapors and other products manufactured with hydrazine such as textile dyes, pharmaceuticals, and photography chemicals (NLM 2011). A major source of hydrazine to the environment is from discharge of cooling water from nuclear power facilities and, to a lesser degree, from fossil fuel-based power facilities (Environment Canada 2011), and it has been detected at low levels in wastewater (IARC 1999k). It is listed as a Proposition 65 carcinogen (California OEHHA 2014). REACH SVHC Candidate List, with use in fuel, propellant, gas, corrosion inhibitors, and and in polymerisation reactions (ECHA 2013).
No occupational or general-population studies could be found for hydrazine, though there was one study of blood hydrazine levels in humans after administration of specific drugs, as well as multiple methods-development studies on blood and urine. Blair et al. (1985), using GC-MS, detected hydrazine in plasma from 8/8 volunteers taking isoniazid and 8/14 patients taking hydralazine chronically. Kirchherr et al. (1993) used HPLC to test for hydrazine in plasma and serum and obtained LOD 1 ng/ml, and LLOQ 5ng/ml. Von Sassen et al. (1985) used HPLC to detect the metabolites acetylhydrazine and diacetylhydrazine in plasma, with DLs of 0.5 nmol/ml and 1 nmol/ml respectively. Von Sasssen et al. (1985) also used HPLC to analyze urine, with DLs of 10 nmol/ml for acetylhydrazine and 20 nmol/ml for diacetylhydrazine. Seifart et al. (1995) used GCMS to detect hydrazine in unspecified (in abstract) "biological fluids," with LLOQ 10ng/ml.

78-79-5 Isoprene Miscellaneous
Isoprene is formed endogenously in humans, emitted from plants and trees, and is widely present in the environment at low concentrations. Sources of anthropogenic releases of isoprene to the atmosphere include ethylene production by petroleum processing, wood pulping, oil fires, woodburning stoves and fireplaces, other biomass combustion, tobacco smoke, gasoline, and exhaust of turbines and automobiles (NTP 2011). It is listed as a Proposition 65 carcinogen (California OEHHA 2014).
Isoprene is believed to be involved in the cholesterol synthesis pathway (Stone et al. 1993) and is associated with factors including heart rate, sleep or wakefulness, recent exercise, and age (Cailleux et al. 1993;Kushch et al. 2008;Turner et al. 2006). It is therefore unlikely to be a good marker of exposure to products of combustion, though methods exist to study levels in blood and exhaled breath. Concentrations in blood samples from a general population range from 15 to 70 nmol/l with mean of 37 nmol/l and SD of 25 nmol/l (Cailleux et al. 1992). Csanady et al. (2001) predict that the blood concentration in nonexposed humans should be about 9.5 nmol/l. In the general population, concentration in exhaled breath was found to range from 0-474 ppb with a mean of 118 ppb and a SD of 68 ppb (Turner et al. 2006). For blood, the most sensitive method found was SPME/GC-MS, with LOD between 0.02 and 0.1 nmol/l (Miekisch et al. 2001). The most sensitive method for breath was proton-ion-transfer-MS (PIT-MS) with an LOD between 0.05 and 0.3 ppb (Mieth et al. 2009).

Name
Chemical group Exposure summary Biomarker summary 129-73-7 Leucomalachite green Miscellaneous The general public may become exposed to leucomalachite green through the consumption of fish treated with this compound, which is also used as an antibacterial agent in aquaculture (NTP 2004)). This compound is also used in processing malachite green, used for dyeing silk, wool, jute, cotton, and leather (NLM 2011). Also see malachite green.
No studies were found measuring malachite green or leucomalachite green biomarkers in humans. Several LC-based methods have been used on tissues of fish, shrimp, and other aquatic organisms Long et al. 2008;Mitrowska et al. 2005;Wu et al. 2007;Zhu et al. 2007)., the most sensitive having a detection limit of 0.25 ng/g ).

2437-29-8 Malachite green Miscellaneous
The general public may become exposed to malachite green through the consumption of fish treated with this compound, which is also used as an anti-bacterial agent in aquaculture (NTP 2004). Also used for dyeing silk, wool, jute, cotton, and leather (NLM 2011) See entry for leucomalachite green.
No studies were found measuring malachite green or leucomalachite green biomarkers in humans. Several LC-based methods have been used on tissues of fish, shrimp, and other aquatic organisms Long et al. 2008;Mitrowska et al. 2005;Wu et al. 2007;Zhu et al. 2007), the most sensitive having a detection limit of 0.25 ng/g ).

93-15-2 Methyleugenol Miscellaneous
Methyleugenol is a naturally occurring substance, present in many essential oils, including rose, pimento, basil, hyacinth, citronella, anise, nutmeg, mace, cinnamon leaves, pixuri seeds, and laurel fruits and leaves. It is a registered food additive used in commercial products as a flavorant and a fragrance at small concentrations in jellies, baked goods, nonalcoholic beverages, chewing gum, candy, pudding, relish, and ice cream (NTP 2011;US FDA 2013). It is listed as a Proposition 65 carcinogen (California OEHHA 2014).
Two general-population studies were found measuring methyleugenol (ME) levels in blood. One study described detection in rat liver. Barr et al. (2000) described SPE-GC-MS, with a DL of 3.1 pg/g wet weight. Testing a subset of the US NHANES population, Barr et al. (2000) found ME in 98% of serum samples, with a mean concentration of 24 pg/g, and a maximum of 390 pg/g. Schecter et al. (2004) found that ME levels in blood increased from a mean of 16.2 pg/g fasting to a mean of 63.9 pg/g 15 minutes after a high-ME snack. Gardner (1996) described ELISA and immunoblotting to detect ME in rat liver.

98-95-3 Nitrobenzene Miscellaneous
Nitrobenzene has been detected in surface and groundwater (IARC 1996a). The general public may be exposed to nitrobenzene in the environment through inhalation of ambient air, ingestion of water, or dermal contact with products or water containing nitrobenzene. Nitrobenzene is found in soaps and shoe and metal polishes and is used as a preservative in spray paints, constituent of floor polishes, substitute for almond essence, and in the perfume industry (NLM 2011;NTP 2011). It is listed as a Proposition 65 carcinogen (California OEHHA 2014).
NHANES has measured nitrobenzene in blood samples from the general population, and other studies have measured nitrobenzene exposure in blood of occupationally or otherwise exposed humans. Methods also exist for determination of nitrobenzene in urine and bone marrow. NHANES has used HS-SPME-GC-MS on 3 mL (minimum) to 10 mL (optimal) whole blood, but less than 5% of the population had levels above the LOD (0.3 ng/mL) (Blount et al. 2006;CDC 2008bCDC , 2009). Thier et al. (2001) measured aniline, benzidine, and 4-aminodiphenyl adducts of hemoglobin and human serum albumin in 80 male employees of a nitrobenzene reduction plant, finding a large difference between smokers and non-smokers in hemoglobin-ADP adducts but not in aniline adducts, which they concluded were dominated by occupational exposure. Martinez et al. (2003) used GC-FID and GC-MS on the blood of a patient suffering from symptoms of poisoning, and detected 3.2 µg nitrobenzene/mL whole blood 48 hours after the eventually fatal dose. Dangwal and Kadam (1980) used microdiffusion to measure nitrobenzene in urine, with LOD 0.2 mg/L. Chen et al. (2004) detected nitrobeneze and other nitro metabolites of benzene in the bone marrow of mice that had been treated with benzene 1 hour before.

75-52-5 Nitromethane Miscellaneous
The general population may be exposed by inhalation of nitromethane in motor vehicle exhaust and cigarette smoke (NTP 2011). Exposures may also occur from the use of solvents, aeresol propellants, and fuels containing nitromethane (IARC 2000b). It is found in craft model fuels (NLM 2013) and is listed as an ingredient in manicuring preparations and rubber adhesives. Nitromethane has been detected in air, surface water, and drinking water. It is listed as a Proposition 65 carcinogen (California OEHHA 2014).
One study has measured nitromethane in blood from the general population. Alwis et al. (2008) used SPME-GC-HRMS with LOD 0.01 µg/L to measure nitromethane in the blood of 632 people with no known occupational exposure. Concentrations ranged from 0.28-3.97 µg/L, with a median of 0.66 µg/L. The authors of the study point out that nitromethane in the blood can indicate exposure to nitromethane itself or to halonitromethanes, and that it can be formed from peroxynitrite. Other studies (e.g. Mullins and Hammett-Stabler 1998) have noted that high blood levels of nitromethane can interfere with creatinine measurements.

Name
Chemical group Exposure summary Biomarker summary 924-16-3 n-Nitroso-di-n-butylamine Miscellaneous Estimates indicate that air, diet, and smoking contribute to potential human exposure to nnitroso-di-n-butylamine at levels of a few µg per day. This compound and other nnitrosamines are frequently produced during rubber processing and may be present as contaminants in the final rubber product. Nitrosamines present in pacifiers and baby bottle nipples can migrate from the pacifier or nipple into saliva, which could result in ingestion of nitrosamines (IARC 1993c;NTP 2005). Nitrosamines are found in cosmetics, lotions, shampoos, cutting fluids, certain pesticides, antifreeze, cooked fish, pork luncheon meat, the interior of new cars, cigarette smoke, and an aqueous rubber extract; nitrosamines are formed within these products by reactions of precursors or introduced through the use of contaminated raw materials (NLM 2011;NTP 2011). It is listed as a Proposition 65 carcinogen (California OEHHA 2014).
No studies were found using biomarkers for n-nitroso-di-n-butylamine

88-72-2 o-Nitrotoluene Miscellaneous
The general population may be exposed to onitrotoluene as a result of its occurrence in the environment from inadvertent spills of onitrotoluene or chemical mixtures containing o-nitrotoluene, emissions directly into the environment, or breakdown products of dinitrotoluenes (DNT) and trinitrotoluenes (TNT) (NTP 2011). Exposure to nitrotoluenes can also occur during their production and use, although few data are available. Consumer products that may contain this chemical include: art materials, putty, glazing, wood preservatives and brush cleaners (US EPA 2010b). It has been detected in effluents from the manufacture or use of nitrotoluenes and in surface and groundwater (IARC 1996b) and has been detected in U.S. air and water (NTP 2011). It is listed as a Proposition 65 carcinogen (California OEHHA 2014).
Two studies were found measuring exposure to o-nitrotoluene (2NT) in the blood or urine of exposed workers.  measured hemoglobin adducts in the blood of Chinese workers exposed to nitrotoluenes, finding that the Hb-2NT adduct was the most abundant mononitrotoluene adduct.  found nitrobenzoic acid metabolites of 2NT in the urine of 96% of exposed workers.
No studies were found measuring biomarkers of exposure to propane sultone 95-06-7 Sulfallate Miscellaneous Sulfallate was used as an herbicide until the early 1990s and is no longer used in the United States. In the past, the general population may have been exposed to sulfallate through ingestion of residues in food crops (NTP 2011). It is listed as a Proposition 65 carcinogen (California OEHHA 2014).
No studies were found using biomarkers of exposure to sulfallate.

51-79-6 Urethane Miscellaneous
The general population may be exposed to urethane via ingestion of fermented foods and alcoholic beverages. Urethane is used as a solvent for organic materials and co-solvent in the manufacture of pesticides, fumigants, and cosmetics. It has been found in foods made by a fermentation process, including ale, beer, bread, wine, soy sauce, yogurt, and olives (NLM 2011;NTP 2011). It is listed as a Proposition 65 carcinogen (California OEHHA 2014).
No studies were found using specific biomarkers to measure exposure to urethane. Sun et al. (2006) and Bartsch et al. (2000) describe measurement of etheno-DNA adducts in urine as markers of exposure to urethane, vinyl chloride, or endogenous oxidative stress processes. Bartsch et al. (2000) reviews measurement of etheno-DNA adducts in other organs.

Name
Chemical group Exposure summary Biomarker summary NA X-rays, gamma rays (ionizing radiation)

Miscellaneous
The greatest exposure of the general population to X-rays and gamma rays comes from natural terrestrial radiation. The next most significant source is the use of X-rays and radiopharmaceuticals in various medical diagnostic and therapeutic procedures. Exposures may also occur from the generation of energy by nuclear reactors or accidents at these facilities. Exposures from the atmospheric testing of nuclear weapons have diminished (NTP 2011).
No methods are currently available that detect internal ionizing radiation exposure retrospectively, although research is underway to develop a method that can detect recent exposure by evaluating expression of DNA-repair genes (Budworth et al. 2012).   (1980,1984,1986 and every four years since); Quality of Life surveys (1992 and every four years since); toenail samples (68,000 sets in 1982-1984); and blood (33,000 samples in 1989-1990 and 18,700 samples in 2000-2001).   1986-present Measurements include cord blood samples, multiple blood and hair samples from children, blood, hair, breast milk, and urine samples from mothers, and urine, hair, and semen samples from fathers, as well as questionnaire and health data. Biological samples have been analyzed for biomarkers of many organic chemicals and metals.
This study is focused on allergies and asthma, but outcomes include pubertal timing (age at voice change, pubertal stage).