Chlorinated dibenzodioxins and dibenzofurans.

The problems and universal concern about chlorinated dibenzodioxin and dibenzofuran compounds were brought to the forefront by the scientific community during the National Institute of Environmental Health Sciences' (NIEHS) Conference on this subject which was held at Research Triangle Park, North Carolina, April 2 and 3, 1973. This idea for this literature collection emanated from that scientific gathering and resulted in this annotated bibliography of 242 references. These references are categorized by year and arranged alphabetically by author. The number of references per year are: 56/1973; 67/ 1972; 66/1971; 24/1970; 29/1969-1934. Sources searched are summarized in Table 1. Due to the time available to complete this collection, some errors and omissions were inevitable; we apologize for these and hope those using this literature survey will supply us with past, present, and future topical

reprints or citation information. We plan to maintain and up-date this file continually.
Most of the nomenclature or terms searched are listed in Table 2. Each particular author, journal, secondary abstracting service, and news copy unfortunately utilizes separate and distinct terminology when reporting on the chlorinated dibenzodioxins and dibenzofurans. As can be seen from Table 2, it is vitally important, therefore, to become thoroughly familiar with the sources being utilized before mounting a massive effort to collate all that is written or reported about a particular compound, series, or class of compounds, or subject. The magnitude of the search effort for this report is selfevident when noting all the necessary terms used.
Teratogenic effects of the 2,4,5-T contaminant, 2,3,7,8-tetrachlorodibenzo-p-dioxin (dioxin), are well known and the effect of this compound on liver enzymes resembles that of certain carcinogens. Dioxin has also been associated with mutagenic properties through its possible intercalation with DNA; the observed effects resemble those of acridine.
EPA was asked to suspend the remaining uses of 2,4,5-T until the extent, if any, of TCDD-contaminated food chains is determined. TCDD was labeled a cumulative poison and one of the most potent agents of birth defects in animals ever discovered.
A selected summary report of the National Institute of Environmental Health Sciences meeting on chlorinated dibenzodioxins and dibenzofurans held at Research Triangle Park in North Carolina on April [2][3]1973. The conference as a whole, however, seemed to raise as many questions as it answered. From the data discussed there is no doubt that these contaminants are highly toxic and teratogenic, but there is still some doubt as to how much of an actual hazard they represent to human health.
Embryonic deaths have been recorded in the laboratory among birds treated with PCB. These deaths have been attributed to chlorinated dibenzofuran contaminants. Also, birth defects in wild populations of birds and sea lions are believed caused by chlorinated dibenzodioxins. High-resolution mass spectrometry was used to examine prepared from aborted sea lions and dead embryos of the herring gull and osprey. CROSBY, D. G., MOILANEN, K. W., and WONG, A. S. Environmental generation and degradation of dibenzodioxins and dibenzofurans. Environ. Health Perspect. (No. 5): 259 (1973).
Both the chlorinated dibenzodioxins and dibenzofurans are unstable to light in the presence of organic substrates. Even if generated under environmental conditions, light provides a mechanism for rapid destruction.
Technical grade 2,4,5-T which contained less than 0.05 ppm 2,3,7,8-tetrachlorodibenzo-p-dioxin was administered orally to forty pregnant Rhesus monkeys daily from day 22 through day 38 of gestation. Dose levels used in the experiment were 0.05, 1.0, and 10.0 mg/kg. Hematology, clinical. chemistry, and urinalysis data were recorded for all females before and at various times following treatment until parturition; no toxicity was observed. Examination of live born infants revealed no terata. Early work indicated that chick edema factors (CEF) were chlorinated aromatic compounds; later, the compounds were shown to belong to a family of chlorodibenzo-p-dioxins. Further investigation showed that (a) chlorophenols were precursors of the chlorodioxins and (b) chlorodioxins and related compounds are commonly present as minor components in commercial chlorophenols. Characteristic chick edema disease symptoms include excessive fluid in the heart sac and abdominal cavity followed by high mortality starting in the third week. Ultrastructure changes in rat liver microsomes and mitochondria were examined at various intervals from 1 to 30 days following a single TCDD injection of 0, 5, or 25 ug/kg. No histologic difference was noted between groups. Observed changes included: proliferation of smooth endoplasmic reticulum (SER), mild increase in rough endoplasmic reticulum (RER), moderate swelling of mitochondria; at 7 days, large aggregates of SER, massive amounts of RER, and small numbers of moderately swollen mitochondria were seen from the 25 mg/kg dosed rats. GREIG, J. B. Biochemical toxicity of TCDD in rat liver. Environ. Health Perspect. (No. 5): 211 (1973).
The persistent toxic effect of 2,3,7,8-tetrachlorodibenzodioxin in rats is evidenced by death as long as 15 weeks after a single oral dose. Alterations, however, in liver constitution (microsomes and cytochrome P-450) and drug metabolism (zoxazolamine and hexobarbital) occurred within 24 hr after dosing.
Gross and microscopic examinations were performed on rats, guinea pigs, and mice treated with TCDD. A spectrum of dose ranges and schedules were used. Lymphoid organs (thymus, spleen, and lymph nodes) were affected consistently. Thymus atrophy (dose related decrease in weight) was found to be a sensitive index of TCDD exposure. The most severe hepatic effects were seen in rats that received a lethal dose of TCDD. The magnitude of the degenerative and necrotic liver changes were diminished in guinea pigs and mice. Albino rats were grouped and treated with single oral doses of 0, 5, 25, 50, or 100 ,ug/kg TCDD in an acetone-corn oil mixture. Animals that eventually died continued to lose weight until death while survivors exhibited a depressed weight gain. Ruffled hair coat, hunched posture, inactivity, and jaundice were the overt signs seen in the high dose group. Daily oral administration of 10 ,ug/kg caused death in 15/16 rats with a mean time of 21.8 days. Death resulted in 9/10 female guinea pigs after receiving an oral dose of 3 ,ug/kg; the mean survival time was 18.1 days. A single oral dose of 1, 10, or 50 ,ug/kg to adult mice had no effect on appearance or body weight. HUTZINGER, O., SAFE, S., WENTZELL, B. R., and ZITKO, V. Photochemical degradation of diand octachlorodibenzofurans. Environ. Health Perspect. (No. 5): 267 (1973).
Irradiation of 2,8-dichlorodibenzofuran (low chlorine content) and octachlorodibenzofuran (high chlorine content) in hexane and methanol caused decomposition to compounds which are formed by reductive dechlorination as well as polar substances. HWANG, S. W. Effect of TCDD on biliary excretion of indocyanine green. Environ. Health Perspect (No. 5): 227 (1973).
Bile flow and biliary excretion of indocyanine green (ICG) in male rats 1, 7, and 16 days after receiving a single oral dose of 5 or 25 ,ug/kg TCDD. Bile flow rate increased at day 1 through day 16. During a 20-min. collection period, both the concentration and total ICG excreted in bile decreased. ICG disappearance rate decreased with time. These effects were dose related. In contrast, the 5 ,ug/kg dosed rats accumulated more ICG in liver. JENSEN, S., and RENBERG, L. Various chlorinated dimers present in several technical chlorophenols used as fungicides. Environ. Health Perspect. (No. 5): 37 (1973).
Pentachlorophenol enjoys widespread use as a wood preservative. Commercial grades have been found to contain up to 2500 ppm chlorinated dibenzop-dioxins. The predominant dioxin is octachlorodibenzo-p-dioxin, one of the least toxic members. Evaluating pentachlorophenol toxicity in animals revealed that some untoward effects (chloracne, chick edema disease, and histopathologic alterations) were caused by chlorinated dibenzo-p-dioxin content. Purified pentachlorophenol did not produce these effects. A new procedure was capable of producing pentachlorophenol containing lowered concentrations of chlorinated dibenzo-p-dioxin and devoid of dioxin-like toxic effects. Chlorodioxins are formed in a two-step condensation reaction from ortho-substituted halophenoxy radicals or anions. Reaction of chlorine with pentachlorophenol at elevated temperature proceeds by radicals; anionic condensation products result from strongly exothermic reactions of alkali metal salts of chlorinated phenols above 300' C. Reaction product distribution depends on the total number of halogen substituents, the crystal lattice arrangement of the molecule, steric effects, and an electronic effect. Dioxin formation was the major condensation product only for sodium pentachlorophenate. LUCIER, G. W., MCDANIEL, 0. S., FOWLER, B. A., FAEDER, E., HOOK, G., and SONA-WANE, B. R. Studies on TCDD-induced changes in rat liver microsomal and mitochondrial enzymes. Environ. Health Perspect. (No. 5): 199 (1973).
A single oral dose of 5 or 25 Ag/kg was administered to male rats and time-course measurements were made on some hepatic microsomal and mitochondrial enzymes. Cytochrome P-450 and b-5 contents were increased, hydroxylation of aniline Environmental Health Perspectives was induced, microsomal protein contents were increased, aminopyrine demethylation rates were decreased, and most strikingly UDP glucuronyitransferase was increased about 8-fold. Samples of fish and crustaceans caught in Vietnam in September 1970 were analyzed for dioxin content by using mass spectrometry. Dioxin concentrations ranged from 18 to 814 ppt; Dong Nai river carp averaged 540 ppt dioxin. MILLER, R. A., NORRIS, L. A., and HAWKES, C. L. Acute and chronic toxicity of 2,3,-7,8-tetrachlorodibenzo-p-dioxin (dioxin) in aquatic organisms. Environ. Health Perspect. (No. 5): 177 (1973).
Guppies and coho salmon fingerlings were exposed to dioxin concentrations ranging from 0.056 ppt to more than 0.2 ppb for 24, 48, and 96 hrs. The initial concentration was found to be more important in causing death than duration of exposure. The coho salmon fingerlings threshold response level for all exposure periods was between 0.056 and 0.56 ppt dioxin. Mosquito larvae, oligochaete worms, and pulminator snails were maintained in water initially dosed with 0.2 ppb dioxin. These aquatic organisms were less sensitive than fish. MOORE, J.; GUPTA, B.; VOS, J.; ZINKL, J.
Maternal exposure of C5731/6 mice to TCDD caused dose-related variations in fetal kidney maturation and development. Thymuses were reduced in size; cystic kidneys developed. Mean body weights and thymus and spleen weights (absolute and relative) were reduced in litters whose mothers received 10 ,ug/kg TCDD; the 3 ,Lg/kg dose group exhibited no weight deviations. Kidney effects were seen at both dose levels.
NEUBERT, D., ZENS, P., and ROTHENWALLNER, A. Survey of the teratogenic effects of 2,3,7,8-tetrachlorodibenzo-p-dioxin in mammalian species. Environ. Health Perspect. (No. 5): 67 (1973 Radioactivity from orally intubated 6Cl-labeled octachlorodibenzo-p-dioxin in rats was confined to the liver, adipose tissue, and skin after 7 weeks on a control diet; concentrations were about 20%o that in tissues of rats after 21 days. NORBACK, D. H., ENGBLOM, J. F., and ALLEN, J. R. Chlorinated dibenzo-p-dioxin distribution within rat tissues and subfractions of the liver. Environ. Health Perspect. (No. 5): 233 (1973). Male rats received daily for 21 days 100 ,Ag 'Cllabeled octachlorodibenzo-p-dioxin by gastric intubation. Feces contained 95% of the total dose and urine 4%o. Significant levels were found in the kidneys, heart, and serum. The liver contained the highest concentration per unit weight; adipose tissue had 1/3 that of the liver. Microsomes (rough and smooth fractions) had 95% of the liver radioactivity. Urine  The presence of contaminant dioxins and dibenzofurans in some samples of technical pentachlorophenol were confirmed by using mass spectrometry. Three samples collected in 1970 contained hexachlorodibenzo-p-dioxin (0.5 to 37 ppmw) and heptachlorodibenzo-p-dioxin (90 to 135 ppmw). It was reemphasized that high-resolution spectra do not provide chlorine orientation information. PLIMMER, J. R. Technical pentachlorophenols-origin and analysis of base-insoluble contaminants. Environ. Health Perspect. (No. 5): 41 (1973).
Fats used as feed additives from hides preserved with technical pentachlorophenol have been implicated as a source of chick edema factor. Polychlorinated dibenzodioxins and dibenzofurans have been identified in the neutral fractions of pentachlorophenol by gas chromatography, mass spectrometry, and a combination of these two. POHLAND, A. E., YANG, G. C., and BROWN, N. Analytical and confirmative techniques for dibenzo-p-dioxins based upon their cation radicals. Environ. Health Perspect. (No. 5): 9 (1973).
Chlorinated dibenzo-p-dioxins form cation radicals when dissolved in strong acids such as trifluoromethane sulfonic acid, in the presence of ultraviolet light, or an oxidizing agent like potassium nitrate.
These cation radicals are quantified by using electron spin resonance and visible spectroscopic techniques. A general bathochromic shift was observed with increasing chlorine content. These shifts were dependent upon the position of the chlorine atoms. POLAND, A. P., and GLOVER, E. 2,3,7,8-  2,7-Dich1orodibenzo-(DCDD), 2,3,7,8-tetrachlorodibenzo-(TCDD), hexachlorodibenzo-(HCDD), and octachlorodibenzo-p-dioxin-( OCDD) were evaluated toxicology. TCDD and HCDD were acnegenic, embryo toxic (TCDD markedly so), teratogenic, and positive for chick edema factor (CEF). DCDD and OCDD were negative for acnegenicity, teratogenicity, and CEF; OCDD was embryotoxic, while DCDD was not. The lethal dose range for DCDD, TCDD, HCDD, and OCDD was g/kg, Ag/kg, mg/kg, and g/kg, respectively. S-IAPLEY, D. Herbicides: AAAS study finds dioxin in Vietnamese fish. Science 180 (4083): 285-286 (April 20, 1973). Fish and shellfish from areas of South Vietnam that were heavily sprayed during the U. S. defoliation campaign contained significant quantities of dioxin. This is a news report on the data R. Baughman and M. Meselson presented to the NIEHS Conference on chlorinated dibenzodioxins and dibenzodifurans. TCDD at sublethal dose levels caused atrophy of the thymus, suppressed the cell-mediated immunity in both guinea pigs and mice, but did not affect the humoral immunity in guinea pigs.
Dioxin compounds are listed with other environmental pollutants as examples of airborne pollutants. These substances are contaminants of the popular weed killer, 2,4,5-T. Dioxins caused death and gastrointestinal hemorrhage in rat fetuses when mothers were treated with doses of 0.125 to 8 ,ug. The mutagenic effects are due to its intercalation with DNA. Dibenzofurans were implicated as being responsible for some of the toxic effects attributed to PCBs. WEBBER, T. J. N., and Box, D. G. The examination of tetrachlorvinphos and its formulations for the presence of tetrachlorodibenzo-p-dioxins by a gas-liquid chromatographic method. Analyst 98: 181-189 (1973).
A gas-liquid chromatographic analytical method was developed for use in detecting tetrachlorodibenzo-p-dioxin impurities in samples of the insecticide tetrachlorvinphos and its formulations. Tetrachlorvinphos is the Zor trans-styrene isomer of 2chloro-1-(2,4,5-trichlorophenyl)vinyl dimethyl phosphate. Sequential use of silica gel and aluminum oxide column chromatography followed by concentrated sulfuric acid treatment of the resultant eluate made it possible to detect TCDD levels down to a limit of 0.025 ppm with electron-capture detection. Tetrachlorodibenzo-p-dioxins were not detected in any of the 21 tetrachlorvinphos samples or any of its formulations selected for analysis either before or after accelerated storage at 550 C for 2 weeks. WEISSBERG, J., and ZINKL, J. Effects of TCDD upon hemostasis and hematologic function in the rat. Environ. Health Perspect.
No differences in hepatic 8-aminolevulinic acid synthetase activity were seen in control rats and those receiving orally 5, 25, or 100 gg/kg TCDD for up to 30 days. Mice and guinea pigs were also nonreactive. Thus, TCDD is not porphyrogenic in mammals, even at several times the LD50 dose levels. TCDD-induced changes observed in female rats after 10 days treatment with 10 ,ug/kg and 17 days at 1 ag/kg were increases in serum glutamic oxaloacetic transaminase. After 13 days treatment with 10 ,ug/kg serum glutamic pyruvate transaminase was increased. Platelet depression was observed after 10 days at all dose levels.
Dry fish food was fed to juvenile Atlantic salmon contaminated with a mixture of 2.7 ,ug/g di-, 5,7 tri-, 2.8 tetra-, and 9.1 octachlorodibenzofuran. Median mortality was 12 ± 30 days. Only octachlorodibenzofuran was found in tissues of dead fish (0.03 sAg/g in muscle and 0.2 ,ug/g in the gut). The most toxic chlorine-containing compound known is 2,3,7,8-tetrachlorodibenzodioxine (C,2H402-C14), often called dioxin. The acute oral LD5o dose in male guinea pigs is about 10' g/kg. In spite of its toxicity, the behavior of dioxin in the food chain has not been worked out.
Certain polychlorinated biphenyls may contain traces of tetrachlorodibenzofuran. A contaminant found in PCB's, not conclusively identified, has the same mass spectrum as tetrachloro-p-dibenzofuran.
During a manufacturing plant explosion, dioxin was formed by the interaction of sodium 2,4,5-trichlorophenate molecules under the influence of the exothermic decomposition of sodium 2-hydroxyethoxide.
Responding to challenges on 2,4,5-T cancellation, EPA concentrated its replies on lack of proof that 2,4,5-T and contaminants are not teratogens. The dose-response curves for 2,4,5-T and dioxin (TCDD) have not been determined, and the possibility of no effect levels is only a matter of conjecture.
In the herbicide section of its 1971 annual report, FDA said the toxicity of 2,4,5-T is chiefly due to dioxins.
Three-dimensional single-crystal x-ray diffraction data revealed the crystal and molecular structure of 2,7-dichlorodibenzo-p-dioxin. The C-Cl bond distance is 1.742 A, the C-0 distances are 1.380 and 1.382, and the 6 C-C distances range between 1.370 and 1.397. The C-O-C angle in the heterocyclic ring is 116.30. BOER, F. P., VAN  The preparation, isolation, and isometric structures of 2,3,7,8-tetrachloro and 2,7-dichlorodibenzop-dioxin are described.
2,3,7,8-Tetrachlorodibenzo-p-dioxin was studied by using three-dimensional single-crystal x-ray diffraction. The four unique C-Cl distances range from 1.726 to 1.730 A, the 4 C-0 distances from 1.377 to 1.379, and the 12 C-C bonds are all between 1.374 and 1.388. The C-0-C angles are 115.60 and 115.80. BRENNER, K. S., MULLER, K., and SATTEL, P.
Dioxin separation from the herbicide phenoxyalkane acids was accomplished by extractive distillation of the potassium salts with n-hexane in the Bleidner apparatus. Quantitative determination of the hexane extracts for dioxin was done by gas chromatography. Sensitivity was about 0.1 ppm. The reported teratogenic effects of 2,4,5-T in mammals and the isolation of the highly toxic contaminant tetrachlorodibenzo-p-dioxin are cautionary, but 2,4,5-T has been used in Europe for nearly 15 years without evidence of ill effects. More studies are needed in comparative detoxication between mammals, birds, fishes, and insects. Low temperature (77°K) luminescence techniques could in principle be applied to a wide variety of compounds including the highly toxic chlorinated dibenzofurans and dibenzo-p-dioxins. Buu-HoI, N. P., CHANH, P-H., SESQUE, G., AzuM-GELADE, M. C., and SAINT-RUF, G. Enzymatic functions as targets of the toxicity of "dioxin" (2,3,7,8-tetrachlorodibenzo-p-dioxin). Naturwiss. 59 (4): 173-174 (1972).

BROOKS, G. T. Pesticides in
Following a single I.P dose of 10 mg/kg dioxin to rats, deep pertubations in several enzymatic systems were observed, i.e., a decrease in cholinesterase or an increase in serum glutamic oxaloacetic acid transaminase. Effects in homeostasis indicate the liver is one of the main targets for dioxin intoxication.
Organ damage was found along with weight loss and hematologic effects following IP injection of 1 and 10 mg/kg dioxin to rats. Ten days after treatment, damage was observed to the liver, thymus, heart. Less damage was observed in the lungs and blood cells.
Effect of tetrachlorodibenzo-p-dioxin on growth rate and the synthesis of lipids and proteins in rats. Bull. Environ. Contam. Toxicol. 7 (1) : 45-51 (1972)., Protein concentration in the rat liver was slightly reduced 3 days after dioxin treatment. This decrease was accompanied by a significant increase in "4C-leucine incorporation into liver proteins. The lowest single dose of dioxin that caused an increase in rat liver weight was 0.1 /Ag/kg CURLEY, A., BURSE, V. W., and JENNINGS, R.
Metabolite or contaminant of Aroclor 1254® found in rat urine. Division of Pesticide Chemistry, 163rd National Meeting of the American Chemical Society, Boston, April 9-14, 1972, Abstract No. 5.
Mass spectra of urine collected from rats on dietary levels of 100 or 500 ppm Aroclor 1254 for intervals up to eight months indicated the presence of a molecular ion at m/e 304 and the characteristic isotopic cluster of 4 chlorine atoms. Others have shown the presence of tetra and pentadibenzofurans (mass numbers 304 and 338) as contaminants in the foreign products.

ENVIRONMENTAL PROTECTION AGENCY, PUB-LICATIONS AND INFORMATION SECTION.
Chemistry and residues of 2,4,5-T (includes dioxins). Bibliography Number 72-59 (1972 Toxicity testing must not be confined to the test agent per se, but should be extended to its chemical and metabolic derivatives, its pyrolytic and degradation products and its contaminants and reaction products, especially when various derivatives or de-gradation products are of toxicologic or environmental consequence. Dioxin pyrolytic products in phenoxy herbicides are illustrative. Twenty-one commercial chlorophenols were dissolved separately in aqueous alkali, extracted with petroleum ether, fractionated on an alumina column, and examined by electron capture gas chromatography and combined gas chromatography-mass spectrometry. The 2,3,7,8-tetrachlorodioxin was found in 3 of 6 samples of 2,4,5-trichlorophenol but not in any of the 11 samples of tetra-and pentachlorophenol. Hexachlorodioxin, present in all 8 pentachlorophenols tested, ranged from 0.17 to 39 ppm. Hexa-, hepta-, and octachlorodioxins and chlorofurans were present in most of the tetra-and pentachlorophenols. Work reported previously in the literature was summarized. Emphasis was placed on the tetra-and pentachlorodibenzofuran impurities in commercial PCB products; the triand tetrachlorodibenzofuran single oral liver necrotic dose (0.5 to 1.0 mg/kg) in rabbits; and the 2,3,7,8-tetrachlorodibenzo-p-dioxin contaminant in 2,4,5-T and 2,4,5-trichlorophenol caused lethal liver necrosis and chloracne in rabbits at a dose range of 0.05 to 0.1 mg/kg. Chromatographic methods of analysis for chlorinated dibenzofurans were reviewed as part of a more extensive review of polychlorinated biphenyls. FISHBEIN, L., and FLAMM, W. G. Potential environmental chemical hazards. Part II. Feed additives and pesticides. Sci. Total Environ. 1: 31-64 (1972).
Occupational and case histories are reported describing 2,3,6,7-tetrachlorodibenzodioxin as the causative agent in 42 cases of serious skin changes, 14 cases of internal organ damage, and 7 cases of nervous system disturbances.
Rats given a single oral 200 jug/kg dose of dioxin exhibited a decreased duration of zoxazolamine (100 mg/kg IP) induced paralysis by 54%. After 200 ,Ag/kg oral dioxin, sleeping time induced by hexabarbital, 150 mg/kg (male rats) or 75 mg/kg (female rats), was prolonged-more than double at 3 days. These results indicate that dioxin has simultaneous stimulatory and inhibitory effects on different pathways of oxidative drug metabolism in the rat liver. Results from three distinct bacterial assay systems showed TCDD to be mutagenic: (1) reversion to streptomycin independency in E. coli (2) reversion to histidine prototrophy in Salmonella typhimurium strains, and (3)  Inhibition of mitosis and development of cytological abnormalities observed in dividing endosperm cells of the African blood lily were believed caused by 2,3,7,8-tetrachlorodibenzo-p-dioxin, a contaminant of 2,4,5-T, rather than the herbicide itself. In contrast to 2,4,5-T, which has no effect, dramatic inhibition of mitosis was observed in cells subjected to 0.2 to 1.0 jug/l dioxin, 0.2 ,sg/l dioxin plus 10'M 2,4,5-T, or 10-4M 2,4,5-T containing dioxin as a contaminant. These preparations also induced formation of dicentric bridges and chromatin fusion with formation of multinuclei or a single large nucleus.
Octachlorodioxin and 2-hydroxynonachlorodiphenyl ether (labeled predoxin) were identified in technical pentachlorophenate using ion exchange, diazomethane treatment, gas chromatography-mass spectrometry, and thinlayer chromatography. Predioxins have not been discovered or detected previously because: (1) clean-up procedures remove the substance, e.g., alumina column chromatography or concentrated sulfuric acid treatment of extract, (2) predoxin spontaneously forms dioxin in a gas chromatograph.
2,4,5-T (containing less than 0.5 mg/kg 2,3,7,8tetrachlorodibenzo-p-dioxin) induced fetopathy and skeletal anomalies in progeny from females treated with a single daily oral dose of 100 to 150 mg/kg on gestation days 6 to 15. Number of conceptions and numbers of viable and dead fetuses per litter gave no indication that in utero treatment of offspring with up to 100 mg/kg 2,4,5-T had impaired fertility. KIMBROUGH, R. D. Toxicity of of chlorinated hydrocarbons and related compounds. A review including chlorinated dibenzodioxins and chlorinated dibenzofurans. Arch. Environ. Health 25 (2): 125-131 (1972).
A modification of the official electron capture-gas chromatographic AOAC assay for chick edema factor, e.g., hexa-, hepta-, and octachlorodibenzo-p-dioxins, was presented to shorten the assay time and eliminate problems in the alumina column fractionation. In place of the alumina fractionation following 2,2,4-trimethylpentane extraction, a second sulfuric acid treatment and a caustic wash were done before the final sulfuric acid wash.  A contaminant of 2,4,5-T (2,3,7,8-tetrachlorodibenzo-p-dioxin) caused serious acne in man and produced fetal death in hamsters at 9.1 ,ug/kg. Modern methods of synthesis now limit the dioxin concentration in 2,4,5-T to less than 0.5 ppm. Chlorinated dibenzo-p-dioxins have been classified as terminal residues-chemicals which accumulate in biologic material in the environment as a result of pesticide introduction. The presence of terminal residues in the environment is due to stable pesticides, conversion products, and chemical impurities (dioxins) that remain in the environment longer than the principal pesticides. The importance of such terminal residues in relation to the final magnitude of environmental hazardousness needs further definition.
Oral doses of 1 ,pg/kg 2,3,7,8-tetrachlorodibenzo-pdioxin (TCDBD) in NMRI mice on days 6 to 15 of gestation produced cleft palate; embryo mortality was significant for doses of 4.5 ,ug/kg or more. Cleft palate without pronounced embryo lethality was produced in mice with high single doses (20--50 ,Ag/kg) TCDBD given between days 7 and 13 of pregnancy. A maximum teratogenic effect was Environmental Health Perspectives 29t; observed on day 11 of gestation, but another peak in cleft palate frequency occurred when TCDBD was given on day 8 of pregnancy. NEUMAN, M. A., NORTH, P. P., and BoER, F. P. Crystal and molecular structure of octachlorodibenzo-p-dioxin. Acta Crystallogr. B28 (8): 2313-2317 (1972).
Three-dimensional single-crystal x-ray diffraction was used to elucidate the crystal and molecular structure of octachlorodibenzo-p-dioxin. The four unique C-Cl distances ranged from 1.714 to 1.718A, the two C-0 distances were 1.373 and 1.374, and the six C-C bonds ranged between 1.382 and 1.396. The C-0-C angle was 115.80. Separate groups of rats were fed diets containing 1% highly chlorinated triphenyls (PCTs, Aroclor 5460), 0.02%o polychlorinated biphenyls (PCBs, Arochlor 1254), and 0.002% chlorinated diphenyl-p-dioxin. The dioxin and PCT groups ate readily and attained 80%o of control weight in 3 weeks. Liver hypertrophy varied from moderate enlargement (dioxin group) to an increase in relative liver weight of 8/100 body weight for the PCB and PCT groups. A series of 13 chlorinated dibenzo-p-dioxins (nine of these were new and previously unreported) was prepared containing from 1 to 8 chlorine atoms to provide pure standards of the various chlorinated derivatives for use in methods development and toxicology studies. Synthesis, utility, yield, purity, and physical and chemical properties were presented and discussed. Stability, color reactions, and infrared, ultraviolet, nuclear magnetic resonance, and phosphorescence spectra were also reported. Phosphorescence and triplet state lifetime wavelengths were dependent on the number of chlorine atoms and their positions on the dibenzo-p-dioxin nucleus. The main impurity of commercial samples of pentachlorophenol was 3,4,5,6-tetrachloro-2-(2,3,4,5,pentachlorophenoxy) phenol; this compound underwent ring closure during gas chromatography to 1,2,3,4,6,7,8,9-octachlorodibenzo-p-dioxin. SAINT-RUF, G. Formation of "dioxin" in the pyrolysis of sodium a-(2,4,5-trichlorophenoxy)-propionate. Naturwiss. 59 (12): 648 (1972).
A residue of 2,3,7,8-tetrachlorodibenzo-p-dioxin resulted from the pyrolysis (500'C for 5 hr) of sodium-a-(2,4,5-trichlorophenoxy)-propionate, a compound used in the synthesis of Sylvex. The dioxin impurity yield was much less than that observed during 2,4,5-T synthesis. This report emanated from a six-month review on the polychlorinated biphenyls by five Federal agencies. The main emphasis was PCBs; however, numerous statements and discussions centered on chlorinated dibenzodioxins and dibenzofurans. For example, fractionated samples of some PCBs of foreign manufacture contained as contaminants tetra-and pentachlorodibenzofurans. The task force recommended: (1) toxicological evaluation of a select number of representative, purified PCB isomers as well as purified trace contaminants such as the chlorinated dibenzofurans; (2) definitive mammalian elaboration of the kinetics, absorption, distribution, metabolism, and excretion of the technical PCBs as well as a number of key isomers and the chlorinated dibenzofurans; and (3)  Reaction of 2,7-dichlorodibenzo-p-dioxin with chloroacetic acid in the presence of aluminum chloride and carbon disulfide gave the corresponding 3monoacetyl derivative. Confirmation was by infrared spectra. The most toxic impurities in polychlorinated biphenyls were found to be chlorinated benzofurans.
The major acnegenic action of crude PCB mixtures originates from chlorinated dibenzofurans. The probable contribution of chlorinated dibenzofuran and pure PCB to the toxicity of technical PCB preparations in rabbits is discussed: chloracne (-furan ++, PCB +), edema formation (++, -), liver damage (+ +, +), and hepatic porphyria The chlorodibenzo-p-dioxins were chlorinated to octachlorodibenzo-p-dioxin and identified by electron capture-gas-liquid chromatography. 2,3,7,8-Tetrachlorodibenzo-p-dioxin was determined at the 1 ppm level in corn oil. This method should be considered as a screen for dioxins, since it does not distinguish among the large number of isomers. Absorption, distribution, and excretion of octachlorodibenzo-p-dioxin in the rat were examined. The AOAC method was used to analyze organs and tissues for dioxin content. The only gross pathology observed was congestion of the liver. Octachlorodi-benzo-p-dioxin was absorbed by the rat mainly in the liver with small amounts in the adipose tissue and bile. WILLIAMS, D. T., and BLANCHFIELD, B. J. Improved screening method for chlorodibenzo-p-dioxins. J. Assoc. Offic. Anal. Chem. 55 (6): 1358-1359 (1972).
A chronology of the hazards of 2,4,5-T was presented. The report issued by the President's Science Advisory Committee appointed to study the 2,4,5-T question served as the basis for this review. The dioxin contaminant of 2,4,5-T, 2,3,7,8-tetrachlorodibenzo-p-dioxin, was discussed briefly as a toxicogen.
Electron spin resonance spectra were obtained for chlorinated dibenzo-p-dioxins in trifluoromethane sulfonic acid (MSA); no oxidizing agents were used to produce the spectra in sulfuric acid. An oxidizing agent or ultraviolet light was needed for octachlorodibenzo-p-dioxin to yield a spectum in MSA; no spectrum was shown in sulfuric acid. Contamination of the Bay of Fundy-Gulf of Maine area with polychlorinated biphenyls, polychlorinated terphenyls, chlorinated dibenzodioxins, and dibenzofurans. Environ. Health Perspect. 1: 47-50 (1972).
No residues of chlorinated dibenzodioxins and dibenzofurans were found in the samples analyzed: muscle and liver of white shark, eggs of doublecrested cormorants and herring gulls, commercial herring oil, and ground fish herring meal. Detection limits ranged from 0.01 ,ug/g octachlorodibenzofuran wet tissue to 0.04 utg/TCDD/g wet tissue.
1971 ANONYMOUS. A close look at TCDD. Agr.
The toxicological properties of tetrachlorodibenzo-p-dioxin were investigated following the discovery that the mutagenic and teratogenic potential of The President's Science Advisory Committee's report on 2,4,5-T and its dioxin impurity is reviewed. The panel made a number of recommendations, including one asking for a mechanism that would temporarily restrict the use of certain registered pesticides on the basis of information that implicates the chemical as a possible health hazard, pending the collection of more conclusive information.
An advisory committee's report submitted to the Environmental Protection Agency concerning 2,4, 5-T and its dioxin contaminant was criticized by a dissenting advisory committee member and the Committee for Environmental Information. Specifically stated was that a level at which TCDD is not teratogenic has not been established and that the report did not consider the consequences of the fate of TCDD in food chains and animal tissue. ANONYMOUS. A taste of honey (flavoured with 2,4,5,-T). Food Cosmet. Toxicol. 9: 152 (1971). This is a commentary on the teratogenic evaluation of 2,4,5-T by K. D. Courtney, et al.; a note added in proof indicate the 2,4,5-T contained 30 ppm dioxin. Thus, conclusions from the paper labeling 2,4,5-T teratogenic must be considered tentative.
Lesions resembling those produced by chick edema factor were traced to a PCB contaminant, chlorinated dibenzofurans which is present in some commercial PCBs.
ANONYMOUS. Working with 2,4,5-T. Food Cosmet. Toxicol. 9: 908-909 (1971 Although such effects as described by Buu-Hoi, et al. of the carcinomimetic activity of TCDD exist, the relationship is by no means exclusive. For example, stimulation of hydroxylating enzymes can be induced by many compounds, including BHT, which has been shown not to be carcinogenic in longterm feeding studies.
The President's Science Advisory Committee (PSAC) report on 2,4,5-T is questioned: justification by the PSAC concerning permissable levels of dioxin in 2,4,5-T was not based on scientific review; also, the need for establishing a dose-response curve for the teratogenicity of 2,4,5-T should have been cited.
The response of the Committee for Environmental Information (CEI) to the scientific advisory committee's recommendation that 2,4,5-T be restored was one of strong opposition. With respect to dioxins, the GEI indicated that dioxins may accumulate in the soil and that present analytical techniques were not sensitive enough to detect them. Furthermore, lack of concrete proof that the use of 2,4,5-T was correlated with the occurrence of birth defects in Vietnam did not mean that no correlation existed. BAUGHMAN, R. W., and MESELSON, M. An improved analysis for 2,3,7,. Division Pesticide Chemistry, 162nd National Meeting of the American Chemical Society, Washington, D.C., Sept. 12-17, 1971, Abstract No. 89. Current analytical methods for the detection of potentially hazardous levels of 2,3,7.8-tetrachlorodibenzo-p-dioxin are inadequate. A combined gas chromatography-mass spectroscopy method was utilized with modifications in extraction concentration and detection. W. X-ray diffraction studies of chlorinated dibenzo-p-dioxins. Division Pesticide Chemistry, 162nd National Meeting of the American Chemical Society, Washington, D.C., Sept. 12-17, 1971;Abstract No. 82.

Buu
Criticism by the Committee for Environmental Information levied against the Advisory Committee's report on 2,4,5-T centered on the following areas: no effect levels; environmental accumulation, transmission and degradation; human hazards from Environmental Health Perspectives dioxins; 2,4,5-T teratogenicity; and the benefits vs. 2,4,5-T and 2,3,7,8-tetrachlorodibenzo-p-dioxin homologs photodecompose rapidly in an alcohol solution exposed to artificial light and natural sunlight. The decomposition rate was correlated with the degree of chlorination. Negligible photodecomposition was observed in aqueous suspensions and on wet or dry soil.
A gas chrormatographic method is described for the detection of 2,3,7,8-tetrachlorodibenzo-p-dioxin impurities in herbicides. Dioxin recoveries ranged from 89 to 98%; limit of detection was 0.05 ppm.
High resolution mass spectrometry was reported to offer a sensitive method for detecting specific dioxins after adequate sample cleanup, e.g., chromatography and gas chromatography.  (6): 1293-1298 (1971).
Chickens fed toxic animal fat containing 9.9 ppm chlorinated dibenzo-p-dioxins excreted over 90% the ingested hexa-, hepta-, and octachlorodioxins. Decreased chlorination resulted in greater body retention. Residues were found in many tissues but was most prominent in the liver. 2,4-D preparations, having undetectable levels of 2,7-dichlorodibenzo-p-dioxin or 2,3,7,8-tetrachlorodibenzo-p-dioxin, were tested for chronic toxicity in rats and dogs. No significant effect on growth, survival, organ weight, or hematologic values were noted.
Possible health implications to humans and wildlife from environmental pollution with chlorinated dibenzofurans are reviewed.
HELLING, C. S. Pesticide mobility in soils.
Relative mobility by thin-layer chromatography and diffusion in moist and air-dry soils were used to test pesticide movements. The two chlorinated dibenzo-p-dioxins were immobile. HOLDEN, C. Critics weigh EPA herbicide report, find it wanting. Science 173(3994): 312 (1971).
Measured uptake of "4C-labeled 2,7-dichloroand 2,3,7,8-tetrachlorodibenzo-p-dioxin from nutrient solution, soil, and foliage by oats and soybeans indi- A review presenting the myriad historical aspects of the dioxin-2,4,5-T( and other herbicides) picture. The potential adverse health effects from phenoxy herbicides were documented. One conclusion reported was that impurities-particularly the chlorodibenzop-dioxins-can be an important factor, but these can be controlled by proper manufacturing techniques. Experiments using 2,4,5-T alone and in combination with dioxin allowed the conclusion that commercially produced 2,4,5-T containing less than 1 ppm dioxin does not present a hazard to health. JOHNSON, J. E. Safety in the development of herbicides. Down to Earth 27(1): 1-7 (1971).
After the discovery of highly toxic dioxin residues in the herbicides 2,4,5-T, precautionary control measures were instituted to insure greater quality control in pesticide production. Pregnant rats were treated orally with 2,4,5-T at doses of up to 100 mg/kg/day. No symptoms of teratology were pro-duced in the offspring. Dioxin was toxic to embryos at 0 125 ug/kg/day, whereas 0.03 ,g/kg/day was below the "no-effect" level. Some aspects of production and costs are discussed. KEARNEY, P. C., and WOOLSON, E. A. Persistence and metabolism of 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD) in soils. Division Pesticide Chemistry, 161st National Meeting of the American Chemical Society, Los Angeles, March 28-April 2, 1971;Abstract No. 21.
Studies on TCDD under controlled environmental conditions revealed that TCDD was persistent and immobile in soil, not readily absorbed by plants, subject to photodecomposition, and slowly degraded to polar metabolites. Other studies revealed that the environmental contamination is small and not detectable in biological samples. KHERA, K. S., and RUDDICK, J. A. Perinatal effects of dibenzodioxins in Wistar rats. Division Pesticide Chemistry, 162nd National Meeting of the American Chemical Society, Washington, D.C. Sept. 12-17, 1971;Abstract No. 87.
Results from teratogenic studies with rats treated with 2,4,5-T, 2,4-D, and several derivatives were Environmental Health Perspectives either negative or inconclusive. The 2,3,7, levels in these preparations were not known in all cases, but most were suspected to be less than 0.5 ppm.
Chlorophenols in aqueous solution were exposed to the action of light in wavelengths greater than 280 nm. Products were characterized by gas chromatography and mass spectrometry. Possible chlorinated dibenzo-p-dioxins from ring closure of a 2-phenoxyphenol derivative were not detected in the photolysis products. Under environmental conditions, dioxins are unlikely products of lower chlorinated phenols or phenoxy-alkanoic acids. POHLAND, A. E., YANG, G. C., and HANSEN, E. A. The preparation and characterization of chlorinated dibenzo-p-dioxins. Division Pesticide Chemistry, 162nd National Meeting of the American Chemical Society, Washington, D.C., Sept. 12-17, 1971;Abstract No. 77. Twelve chlorinated dibenzo-p-dioxin standard compounds containing from one to eight chlorine atoms were prepared as standards to develop analytical techniques and to use in toxicity studies. The wavelength associated with the observed phosphorescence and the triplet state lifetime were dependent upon the number of chlorine atoms and their positions on the dibenzo-p-dioxin nucleus. POLAND, A. P., SMITH, D., METTER, G., and POSSICK, P. A health survey of workers in a 2,4-D and 2,4,5-T plant. Arch. Environ. Health 22:316-327 (1971).
A study and review of employee health in a plant producing 2,4,5-T and 2,4-D. Chloracne was found in 13/73 male workers and was believed caused by chlorinated dioxins. The plant has begun several programs to reduce dioxin levels in 2,4,5-trichlorophenol; the contaminant concentration has dropped from 10 to 25 ppm to 1 ppm. PORTER, M. L., and BURKE, J. A. Separation of three chlorodibenzo-p-dioxins from some polychlorinated biphenyls by chromatography on an aluminum oxide colum.
The teratogenicity of 2,4-D was investigated in the rat. Formation of 2,3,7, in the manufacture of 2,4-D is not theoretically possible. The 2,4-D sample used was analyzed for the TCDD contaminant with a method having a 0.2 ppm sensitivity and none was found. Doses of 12.5,25,50,75,and 87.5 mg/kg 2,4-D were administered orally on days 6-15 of gestation. High dose levels caused signs of embryotoxicity and fetotoxicity.
The sources, occurrences, and some of the toxicological effects of polychlorinated biphenyls and chlorodioxins were discussed. Chlorophenols exposed to high temperatures may form chlorinated derivatives of dibenzo-p-dioxin. Inadequate methodolgy prevents analysis for these contaminants in foods. SPARSCHU, G. L., DUNN, F. L., LISOWE, R. W., and ROWE, V. K. Study on the effects of high levels of 2,4,5-trichlorophenoxyacetic acid on foetal development in the rat. Food Cosmet Toxicol. -9(4): 527-530 (1971).
2,3,7,8-Tetrachlorodibenzo-p-dioxin was administered orally to pregnant rats during days 6 to 15 of gestation in doses of 0, 0.03, 0.125, 0.5, 2.0, and 8.0 g/kg/day [sic]. No effect was observed on the fetus or mother at the 0.03 dose level. However, at the 0.125 level and above, fetal mortality, early and late resorptions, and fetal intestinal hemorrhage occurred. The effects became more pronounced with the increase in dose. Maternal toxicity was noted beginning at the 0.5 level which also increased with the dose. SPARSCHU, G. L., DUNN, F. L., and ROWE, V. K. Study of the teratogenicity of 2,3,7,8-tetrachlorodibenzo-p-dioxin in the rat. Food Cosmet. Toxicol. 9(3): 405-412 (1971).
Investigations of the teratogenicity of 2,3,7,8-tetrachlorodibenzo-p-dioxin in rats revealed that this compound is capable of inducing a high degree of adverse effects in the fetus and mother. Doses of 0, 0.03, 0.125, 0.5, 2.0, and 8.0 ,ug kg/day were given orally to pregnant rats during days 6 to 15 of gestation. Effects such as fetal mortality, intestinal hemorrhage, and early and late resorptions began appearing at the 0.125 level and increased with dose. It is suggested that the teratogenic effects of 2,4,5-T observed in other studies may have been due to this contaminant (30 ppm Analytical techniques for the detection of neutral impurities (chlorinated dibenzo-p-dioxins) in chlorinated phenols, were ion-exchange chromatography for removal of the matrix, liquid-liquid chromatography for separation of the various neutral components, followed by gas chromatographic examination of the separated components using electron capture detection. 2,4,5-T was investigated for its effects on fetal development in the rat and rabbit. Doses ranging from 1 to 50 mg/kg were administered during days 6 to 15 of gestation. No clinical or gross pathology was observed. Detailed examination of the visceral and skeleton revealed no teratogenic effects. However, rats receiving 100 mg/kg during day 6 to 10 of gestation did produce maternal toxicity and death, early fetal resorptions, fetal toxicity, but no malformations. CURRIER, W. F., GRAHAM, C., GRATKOWSKI, H., and NORRIS, L. A., U.S. Forestry Service. Report on background information for the phenoxy herbicides 2,4-D-2,4,5-T-2,4,5-TP. U.S. Forestry Service Report, pp. 1-165 (1971).
Preparation of tritium-labeled 2,3,7,8-tetrachlorodibenzo-p-dioxin was investigated. One approach used was the tritiation of 2,4-dichlorophenol or 2,4,5trichlorophenol, lithiummetalation and subsequent aqueous hydrolysis of a chlorinated dibenzo-p-dioxin, and the catalytic reduction of a chlorinated dibenzop-dioxin. The use of herbicides as chemical warfare agents is reviewed with respect to the Geneva Protocol of 1925. The total impact of these agents on the environment and man is not usually known or considered before widespread use. For example, 47 million lb of 2,4,5-T was used in Indochina over an 8yr period before it was discovered that about 1000 lb dioxin was also being applied as an unsuspected contaminant.
Thin layer chromatographic separation of two chlorodibenzo-p-dioxins from some polychlorinated biphenyls and organochlorine pesticides. J. Assoc. Offic.
Thin-layer chromatography was used for the isolation of 2,3,7,8-tetrachlorodibenzo-p-dioxin and octachlorodibenzo-p-dioxin from polychlorinated biphenyls and organochlorine pesticides. After isolation, these dioxins were analyzed by the electron capturegas chromatography. The 2,4,5-T Scientific Advisory Committee's report to the U.S. Environmental protection Agency was stimulated after experimental results and environmental indicators pointed to a potential health threat to humans. This nine-member committee was selected from a list of names supplied by the National Aca-demy of Science. The Committee recommended by an 8 to 1 vote to restore registration of 2,4,5-T with certain conditions; those applicable to TCDD were: (1) a limit of 0.5 ppm TCDD on existing 2,4,5-T inventories and 0.1 ppm on future 2,4,5-T production, and (2) conduct specific research on TCDD for potential soil accumulation and food drain magnification.
WOOLSON, E. A., REICHEL, W. L., and YOUNG, A. L. Dioxin residues in lakeland sand and eagle samples. Division Pesticide Chemistry, 162nd National Meeting of the American Chemical Society, Washington, D.C., Sept. 12-17, 1971. Abstract No. 91. Between 1962 and a lakeland region in Florida was treated with 912 lb 2,4,5-T per acre. To assess the ecological importance of chlorinated dioxins in the environment, samples of soil to a depth of 3 ft, and tissues from eagles were analyzed for dioxins by electron capture-gas chromatography. No dioxins were detected at a minimum detection limit of 50 ppb for the eagle tissue samples and 5 ppb for the soil samples. Small residues of about 20 ppb 2,4,5-T were found in soil samples. When manufacture of 2,4,5-T is controlled carefully, dioxin contamination is less than 1 ppm. Dioxin was identified in 1962 as the culprit of damage and death in 1957 of uncounted numbers of chicks. Dioxin produces neurological disturbances and is teratogenic. The acute LD50 for male guinea pigs is 0.000001 g/kg.
Because early studies indicated that most of the adverse toxicological effects of 2,4,5-T were due to high dioxin contamination (27 ppm) of test samples, the USDA did not feel obligated to cancel registration of currently manufactured 2,4,5-T containing about 1 ppm dioxin. Preliminary tests have shown that 2,4,5-T containing 1 ppm dioxin is not teratogenic. However, problems may still exist, since excessive heat exposure of the trior pentachlorophenols, used as intermediates in 2,4,5-T production, liberates dioxins.
Evidence from Congressional hearings catalyzed the government's eventual suspension and cancellation of consumer and food crop usage of 2,4,5-T and curtailment of its use in Vietnam. HEW and the USDA issued a joint statement declaring that both 2,4,5-T and its dioxin contaminant may cause birth defects. The pesticide industry reacted adversely to these actions and statements.
The politics and pressures brought about by the 2,4,5-T/dioxin controversy between government and industry were reviewed. The Chairman of the Secretary's Pesticide Advisory Committee (SPAC) castigated both the federal government and the pesticides industry for failure to avoid the panicky crises which brought about an "era of chemical McCarthyism." ANONYMOUS. The strange case of the government vs. 2,4,5-T. II. Farm Chem. 133 (3): 26 (1970).
A review of the government involvement in the 2,4,5-T controversy which began after preliminary research reports indicated 2,4,5-T was teratogenic. These government studies were instituted in an attempt to determine whether 2,4,5-T or its dioxin contaminant was the causative agent of these effects.
A commentary was presented to clarify the controversy of whether 2,4,5-T or 2,3,7,8-tetrachlorodibenzo-p-dioxin was the causative teratogenic and mutagenic agent. Hearings with government and industrial representatives were held before the Subcommittee on Energy, Natural Resources and the Environment of the Senate Committee on Commerce.
Use of 2,4,5-T has been restricted where foodstuffs for human consumption might be contaminated. The possibility exists that dioxin (2,3,7,8-tetrachlorodibenzo-p-dioxin) may be the contaminant in 2,4,5-T formulations or that there may be a synergistic effect between 2,4,5-T and dioxin. Hypothetically, if dioxin contaminated the 2,4,5-T reported in food in the U.S. to the extent of 1 ppm, it would take 100 years for a normal person to accumulate a dose 600 times less than that which produced toxic effects during the pregnancy of a rat. 2,4,5-T samples were evaluated in rats and mice for teratogenicity. Results indicated that 2,4,5-T s.c. or orally administered was teratogenic and fetotoxic The teratogenicity of 2,4,5-T containing 1 ppm of 2,3,7,8-tetrachlorodibenzo-p-dioxin was evaluated in rats. No teratogenic effects from 1,3,6,12, or 24 mg/ kg/day 2,4,5-T or other pathological signs were observed. These results do not substantiate the adverse effects observed with 2,4,5-T containing 27 ppm dioxin. EPSTEIN, S. S. A family likeness. Environment 12(6): 16-25 (July/August, 1970).
The human and environmental implications of the widespread chemical exposure problem have been accentuated by the increased use of herbicides during the past ten years. For example, although recently dioxin impurities in 2,4,5-T have been reduced, dioxin is still present; even minute concentrations are potential hazards. The analysis, formation, and teratogenic and other toxicological consequencies of dioxins were reviewed. EPSTEIN, S. S. Testimony on teratogenic effects of 2,4,5-T formulations. U.S. Senate Hearing before the Subcommittee of Energy, Natural Resources and the Environment of the Committee on Commerce (April 15, 1970).
Polychlorophenol contaminants and their dioxin pyrolytic products in phenoxy herbicides are of toxi-cologic and environmental consequence. Some dioxins are highly toxic and teratogenic at the microgram per kilogram level; most dioxins are, however, toxicologically uncharacterized. GALSTON, A. W. Herbicide usage. Science 168 (3939): 1607.
The phenoxyacetic acid herbicides should not be used until all questions regarding the teratogenicity of 2,4,5-T have been resolved. A tetrachlorodibenzodioxin impurity found in some commercial preparations of 2,4,5-T was the teratogenic agent in 2,4,5-T samples tested for teratogenicity by the Bionetics Research Laboratories. The possibility that phenoxyacetic acids may be degraded in plants and soil or by fire or bright sunlight into dioxin-like teratogens should be studied. Extensive research should be accomplished on all aspects of the biomedical and environmental consequences of dioxins.
Hearings Before the Subcommittee on Energy, Natural Resources and the Environment of the Committee on Commerce, U. S. Senate, Serial 91-60, Governmental Printing Office, Washington, D.C. (1970).
An impurity in 2,4,5-trichlorophenol was found to be 2,3,7,8-tetrachlorodibenzo-p-dioxin, a compound with a high mammalian toxicity and teratogenic effect. The official first action gas chromatographic method for chick edema factor is presented in Section 28 on oils and fats. Fat, oil, fatty acid, or lipid is treated with H2S04, and extracted with petroleum ether. The extract is purified on an A1203 column, further treated with H2S04, and examined by electron capture-GLC. Peaks with retention times relative to aldrin (Ra) between 8 and 45 indicate presence of chick edema factors (hexa-, hepta-, and octachlorodibenzo-p-dioxins). KEARNEY, P. C. Paper presented before a joint (United Kingdom, Canada, and United States) meeting on Pesticides, Washington, D.C., (November 5, 1970).
The Agricultural Research Service, USDA, began a program to assess the significance of chlorinated dioxin impurities in currently registered pesticides. Theoretically, any pesticide with a chlorinated phenoxy nucleus or which is derived from a chlorinated phenol precursor could contain chlorinated dioxin contaminants. Environmental Health Perspectives 308 Chicks afflicted with edema, or hydropericardium, suffer an accumulation of fluid in the heart sac and gross kidney and liver damage; as little as 5 ,ug can kill a chick. X-Ray crystallographers have determined the molecular structure of one of the toxic compounds known as the chick edema factor. Singlecrystal structural analysis showed that the structure is 1, 2,3,7,8,9-hexachlorodibenzo-p-dioxin. Two crystals, each about 0.2 x 0.1 x 0.1 mm and weighing about 3/Ag were recrystalized from a benzenehexane solution. The final data showed that the 1,2,3,7,8,9hexachlorodibenzo-p-dioxin molecules are nearly planar, and are packed in the 044 crystallographic planes, with an interplanar separation of about 3.3 A. No unusual bond lengths or angles were apparent.