Baseline blood trihalomethanes, semen parameters and serum total testosterone: A cross-sectional study in China
Highlights
► We performed the first study on the effects of baseline blood THMs on human male reproductive health. ► Moderate levels of BDCM and DBCM resulted in declined sperm count and linearity, respectively. ► Elevated blood TCM or ∑ THM concentrations might result in decreased sperm concentration. ► Elevated blood DBCM concentrations might lead to decreased serum total testosterone.
Introduction
Chlorination of drinking water in public water supplies successfully reduces the risk of water-borne infection disease. However, harmful disinfection by-products (DBPs) form when chlorine reacts with natural organic and inorganic compounds during preparation of drinking water. To date, more than 600 kinds of DBPs with different physicochemical and toxic properties have been identified (Richardson et al., 2007). The most abundant classes of DBPs are trihalomethanes (THMs), including chloroform (TCM), bromodichloromethane (BDCM), dibromochloromethane (DBCM), and bromoform (TBM). Humans are exposed to THMs through ingestion, inhalation and dermal absorption during their routine water-use activities such as water consumption, bathing, showering, and swimming in a lifelong time (Nieuwenhuijsen et al., 2009). Potential adverse health effects of THMs have been public health concerns worldwide.
Previously, some epidemiological studies have focused on an association between THM exposure and increased risk of cancer such as bladder and colon cancer (Cantor et al., 1998, Villanueva et al., 2004, Young et al., 1987). Epidemiological studies have also suggested associations between THM exposure and adverse reproductive outcomes such as low birth weight, spontaneous abortion, and birth defects (Toledano et al., 2005, Waller et al., 1998, Yang et al., 2007). The evidence for the relationship between THM exposure and male reproductive health in humans is limited, although toxicological studies showed that THMs, especially the brominated THMs, had the capacity to impair male reproductive health. Klinefelter et al. (1995) reported that exposure to BDCM in drinking water reduced sperm motility as assessed by significantly decreased mean sperm straight-line, average path, and curvilinear velocities. Potter et al. (1996) found that exposure to all four individual THMs produced a decrease in serum testosterone concentrations.
To our knowledge, there are only two epidemiological studies which have explored the relationship between THM exposure and semen quality (Fenster et al., 2003, Luben et al., 2007). However, the results from the two studies were inconsistent. In these studies, THM exposures were assessed by using THM concentrations in distribution systems as exposure surrogates, which may result in exposure misclassification because of temporal and spatial variability and various exposure routes for THMs (Parvez et al., 2011, Wei et al., 2010). Exposure biomarkers provide an alternative measurement to improve exposure assessment in epidemiological studies. Two biomarkers have been used to assess internal dose levels of THM exposure, including THMs in whole blood and expired air (Aggazzotti et al., 1998, Blount et al., 2006). Morning blood samples collected prior to any major water-use activity can be expected to yield baseline THM exposures (Weisel and Jo, 1996). Although breath samples are less invasive and result in better subject participation, blood levels are generally more sensitive to low exposure and represent an integrative measure of exposures from various routes (Miles et al., 2002).
We conducted a cross-sectional study in Wuhan, China, to examine the relationships between THM exposure, semen parameters and serum total testosterone. In this study, we measured THM concentrations in morning whole blood to assess internal doses of baseline THM exposure. To our best knowledge, our study is the first one using whole blood THMs as an exposure biomarker to evaluate the effects of THM exposure on male reproductive health in humans.
Section snippets
Study participants and data collection
We recruited study participants from men who presented to the Reproductive Center of Tongjing Hospital in Wuhan, China, to seek semen examination. During April 2011 to May 2012, a total of 467 men agreed to participate in the study and provided blood samples for analysis regardless of their prior knowledge of fertility status. We excluded 30 azoospermic men because the mechanism responsible for azoospermia may be related to an obstructive mechanism or Y-chromosome deletions. The study was
Characteristics of the study participants
The distribution of characteristics among the study population is shown in Table 1. Study participants were primarily Han (97.3%), with a mean age of 30.5 (± 5.8) years and BMI of 23.4 (± 3.8) kg/m2. There were 122 men (30.4%) who reported their abstinence time as more than six days. Among the all study participants, 295 men (73.7%) reported their total boiled tap water consumption as less than 1000 mL per day, 145 men (36.2%) reported their showering time as less than 10 min per day. However, only
Discussion
Our results showed that baseline blood THM concentrations were not associated with decrements in sperm motility, sperm VSL and VCL. However, we found that moderate levels of BDCM and DBCM were associated with decreased sperm count and sperm LIN compared with low levels respectively. We also observed suggestive dose–response relationships of elevated blood TCM and ∑ THM concentration with decreased sperm concentration. In two previous studies of THM exposure (using THMs in distribution systems
Conclusions
Our study found no evidence for the relationships between elevated blood THM concentrations and decreased sperm motility, sperm VSL or VCL. However, we found that moderate levels of BDCM and DBCM were associated with decreased sperm count and declined sperm LIN compared with low levels, respectively. We also observed a suggestive dose–response relationship of elevated blood TCM and ∑ THM concentration with decreased sperm concentration, and elevated blood DBCM concentration with decreased serum
Acknowledgments
We sincerely thank all participants for providing blood and semen samples in this study, as well as the others who gave their technical assistance. This study was supported by the National Natural Science Foundation of China (No. 81072264) and the National Key Technologies R&D Program of China (No. 2006BAI19B02).
References (40)
- et al.
Blood and breath analyses as biological indicators of exposure to trihalomethanes in indoor swimming pools
Sci Total Environ
(1998) - et al.
Quantification of 31 volatile organic compounds in whole blood using solid-phase microextraction and gas chromatography–mass spectrometry
J Chromatogr B Analyt Technol Biomed Life Sci
(2006) - et al.
Preliminary screening for the potential of drinking water disinfection byproducts to alter male reproduction
Reprod Toxicol
(1995) - et al.
Temporal variability in trihalomethane and haloacetic acid concentrations in Massachusetts public drinking water systems
Environ Res
(2011) - et al.
Effects of four trihalomethanes on DNA strand breaks, renal hyaline droplet formation and serum testosterone in male F-344 rats
Cancer Lett
(1996) - et al.
Occurrence, genotoxicity, and carcinogenicity of regulated and emerging disinfection by-products in drinking water: a review and roadmap for research
Mutat Res
(2007) - et al.
In vitro biotransformation and genotoxicity of the drinking water disinfection byproduct bromodichloromethane: DNA binding mediated by glutathione transferase theta 1–1
Toxicol Appl Pharmacol
(2004) - et al.
Sensitivity of Sertoli and Leydig cells to xenobiotics in in vitro models
Reprod Toxicol
(1993) - et al.
Activation of chloroform and related trihalomethanes to free radical intermediates in isolated hepatocytes and in the rat in vivo as detected by the ESR-spin trapping technique
Chem Biol Interact
(1985) - et al.
Spatial and temporal evaluations of disinfection by-products in drinking water distribution systems in Beijing, China
Sci Total Environ
(2010)
Association between trihalomethane concentrations in drinking water and adverse pregnancy outcome in Taiwan
Environ Res
Chlorinated river and lake water extract caused oxidative damage, DNA migration and cytotoxicity in human cells
Int J Hyg Environ Health
Clinical relevance of oxidative stress in male factor infertility: an update
Am J Reprod Immunol
Exogenous and endogenous determinants of blood trihalomethane levels after showering
Environ Health Perspect
Measurement of trihalomethanes and methyl tert-butyl ether in whole blood using gas chromatography with high-resolution mass spectrometry
J Anal Toxicol
Drinking water source and chlorination byproducts. I. Risk of bladder cancer
Epidemiology
Treatment of vacutainers for use in the analysis of volatile organic compounds in human blood at the low parts-per-trillion level
J Chromatogr Sci
Environmental and urinary markers of prenatal exposure to drinking water disinfection by-products, fetal growth, and duration of gestation in the PELAGIE birth cohort (Brittany, France, 2002–2006)
Am J Epidemiol
The relationship between environmental exposure to phthalates and computer-aided sperm analysis motion parameters
J Androl
Trihalomethane levels in home tap water and semen quality
Epidemiology
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These two authors equally contributed to this work.