Comparison of trihalomethanes in tap water and blood: a case study in the United States

Environmental exposure and child health in China

Chinese children are exposed to broad environmental risks ranging from well-known hazards, such as pesticides and heavy metals, to emerging threats including many new man-made chemicals. Although anecdotal evidence suggests that the exposure levels in Chinese children are substantially higher than those of children in developed countries, a systematic assessment is lacking. Further, while these exposures have been linked to a variety of childhood diseases, such as respiratory, endocrine, neurological, behavioral, and malignant disorders, the magnitude of the associations is often unclear. This review provides a current epidemiologic overview of commonly reported environmental contaminants and their potential impact on children's health in China. We found that despite a large volume of studies on various topics, there is a need for more high-quality research and better-coordinated regional and national data collection. Moreover, prevention of such diseases will depend not only on training of environmental health professionals and enhanced research programs, but also on public education, legislation, and networking.

Separating Measurement Error and Signal in Environmental Data: Use of Replicates to Address Uncertainty

Measurement uncertainty has long been a concern in the characterizing and interpreting environmental and toxicological measurements. We compared statistical analysis approaches when there are replicates: a Naı̈ve approach that omits replicates, a Hybrid approach that inappropriately treats replicates as independent samples, and a Measurement Error Model (MEM) approach in a random effects analysis of variance (ANOVA) model that appropriately incorporates replicates. A simulation study assessed the effects of sample size and levels of replication, signal variance, and measurement error on estimates from the three statistical approaches. MEM results were superior overall with confidence intervals for the observed mean narrower on average than those from the Naı̈ve approach, giving improved characterization. The MEM approach also featured an unparalleled advantage in estimating signal and measurement error variance separately, directly addressing measurement uncertainty. These MEM estimates were approximately unbiased on average with more replication and larger sample sizes. Case studies illustrated analyzing normally distributed arsenic and log-normally distributed chromium concentrations in tap water and calculating MEM confidence intervals for the true, latent signal mean and latent signal geometric mean (i.e., with measurement error removed). MEM estimates are valuable for study planning; we used simulation to compare various sample sizes and levels of replication.

Urinary trihalomethane concentrations and liver function indicators: a cross-sectional study in China

While it is known that exposure to disinfection by-products (DBPs), including trihalomethanes (THMs), impairs liver function, few epidemiological studies have explored this association. Here, we determined the concentrations of four urinary trihalomethanes (chloroform [TCM], and three Br-THMs, bromodichloromethane [BDCM], dibromochloromethane [DBCM], and bromoform [TBM]), and nine serum liver function indicators in 182 adults ≥ 18 years of age, examined at a medical examination center in Wuxi, China, in 2020 and 2021. Generalized linear model analysis revealed positive associations between urinary DBCM and alanine aminotransferase (ALT), aspartate aminotransferase (AST), total bilirubin (TBIL), total protein (TP), and albumin (ALB). Urinary Br-THMs and total THMs (TTHMs) were positively associated with ALT, AST, TBIL, indirect bilirubin (IBIL), TP, and ALB (all P < 0.05). Urinary THMs were not associated with alkaline phosphatase (ALP) or glutamine transaminase (GGT) (all P > 0.05). Generalized additive model-based penalized regression splines were used to confirm these associations. In conclusion, THM exposure was associated with altered serum biomarkers of liver function.

Blood trihalomethane concentrations in relation to sperm mitochondrial DNA copy number and telomere length among 958 healthy men

BACKGROUND

In animal and human studies, exposure to trihalomethanes (THMs) has been associated with reduced semen quality. However, the underlying mechanisms remain poorly understood.

OBJECTIVE

To investigate the associations of blood THM concentrations with sperm mitochondrial DNA copy number (mtDNAcn) and telomere length (TL) among healthy men.

METHODS

We recruited 958 men who volunteered as potential sperm donors. A single blood sample was collected from each participant at recruitment and measured for chloroform (TCM), bromodichloromethane (BDCM), dibromochloromethane (DBCM), and bromoform (TBM) concentrations. Within a 90-day follow-up, the last semen sample provided by each participant was quantified for sperm mtDNAcn and TL. We used multivariable linear regression models to assess the associations between blood THM concentrations and sperm mtDNAcn and TL. We also performed stratified analyses according to the time intervals between baseline blood THM determinations and semen collection (i.e., 0-9, 10-14, 15-69, or >69 days) to explore potential windows of susceptibility.

RESULTS

After adjusting for potential confounders, we found inverse associations between quartiles (or categories) of blood TBM, brominated THM (Br-THM, the sum of BDCM, DBCM, and TBM), and total THM (TTHM, the sum of all four THMs) concentrations and sperm mtDNAcn (all P for trend≤0.03). Besides, we found inverse associations between quartiles of blood TCM, Br-THM, chlorinated THM (Cl-THM, the sum of TCM, BDCM, and DBCM), and TTHM concentrations and sperm TL (all P for trend<0.10). Stratified analyses showed stronger associations between Br-THM concentrations and sperm mtDNAcn determined 15-69 days since baseline exposure determinations, and between blood TCM and TTHM concentrations and sperm TL determined >69 days since baseline exposure determinations.

CONCLUSION

Exposure to THMs may be associated with sperm mitochondrial and telomeric dysfunction.

Alternative Ecosorbent for the Determination of Trihalomethanes in Aqueous Samples in SPME Mode

A new sorbent material based on modified clay with ionic liquid immobilized into an agarose film was developed as part of this study. It was applied to determine organochlorine pollutants, like disinfection byproducts, through headspace solid-phase microextraction-gas chromatography-electron capture detection (HS-SPME-GC-ECD). The disinfection byproducts determined in this study were used as model molecules because they were volatile compounds, with proven severe effects on human health. Their presence in aquatic environments is in trace concentrations (from pg L^-1 to mg L^-1). They are classified as emergent pollutants and their determination is a challenge for analytical chemists. The parameters which affected the extraction efficiency, i.e., number and distance between SPME discs, salt concentration, the temperature of extraction, extraction time, and desorption time, were optimized. A wide linear dynamic range of 10-1000 ng mL^-1 and coefficients of determination better than 0.997 were achieved. The limits of detection and the limits of quantitation were found in the ranges of (1.7-3.7) ng mL^-1 and (5.6-9.9) ng mL^-1, respectively. The precision, expressed as relative standard deviation (RSD), was better than 8%. The developed sorbent exhibits good adsorption affinity. The applicability of the proposed methodology for the analysis of trihalomethanes in environmental and water samples showed recoveries in the range of 86-95%. Finally, the newly created method fully complied with the principles of green chemistry. Due to the fact that the sorbent holder was made of agarose, which is a wholly biodegradable material, sorbent clay is a widespread material in nature. Moreover, the reagents intercalated into the montmorillonite are new green solvents, and during the whole procedure, low amounts of organic solvents were used.

Removal assessment of disinfection by-products (DBPs) from drinking water supplies by solar heterogeneous photocatalysis: A case study of trihalomethanes (THMs)

Solar heterogeneous photocatalysis was used to remove trihalomethanes (THMs) from drinking water. THMs, mainly trichloromethane (TCM), tribromomethane (TBM), bromodichloromethane (BDCM) and dibromochloromethane (DBCM) are one of the main class of disinfection by-products (DBPs). THMs were determined by HSGC-MS with detection limits (LODs) ranging from 0.5 μg L^-1 to 0.9 μg L^-1 for TCM and BDCM, respectively. Results show that a great proportion of THMs present in water are finally transferred to air as a result of their high volatility in the order TCM > BDCM > DBCM > TBM. The use of band-gap semiconductor materials (TiO₂ and mainly ZnO) used as photocatalysts in combination with Na₂S₂O₈ as electron acceptor and sulfate radical anion (SO₄^•-) generator enhanced the photooxidation of all THMs as compared to photolytic test. The time required for 50% of THMs to disappear (DT₅₀) from water calculated for the most effective treatment (ZnO/Na₂S₂O₈) were 12, 42, 57 and 61 min for TCM, TBM, BDCM, and DBCM, respectively. Therefore, solar heterogeneous photocatalysis can be considered as an interesting strategy for THMs removal, especially in sunny areas like Mediterranean basin.

Potential risks and approaches to reduce the toxicity of disinfection by-product - A review

Water contamination through anthropogenic and industrial activities has led to the emergence and necessity of disinfection methods. Chlorine and bromine gases, often used to disinfect water, resulted in the by-product formation by reacting with organic matter. The Disinfectant by-products (DBP) led to the formation of Trihaloaceticacid (TAA), Trihalomethane (THM), and other minor components. The release of chemicals has also led to the outbreak of diseases like infertility, asthma, stillbirth, and types of cancer. There are new approaches that are found to be useful to compensate for the generation of toxic by-products and involve membrane technologies, namely reverse osmosis, ultrafiltration, and nanofiltration. This review mainly focuses on the toxicology effects of DBPs and various approaches to mitigate the same. The health hazards caused by different DBPs and the various treatment techniques available for the removal are discussed. In addition, a critical comparison of the different removal techniques was discussed.

Multi-exposure human health risks assessment of trihalomethanes in drinking water of Egypt

The present study aims to assess the probable lifetime cancer and non-cancer risks of exposure to the trihalomethanes in Egypt's drinking water through ingestion, dermal contact, and inhalation. A total of 1667 drinking water samples were collected from twenty-three Egyptian governorates over a three-years period. The concentrations of total trihalomethanes ranged between 29.07 and 86.01 μg/L and were always below the maximum contamination level recommended by the Egyptian standards (100 μg/L). Chloroform was the most prominent trihalomethanes species, while bromoform was rarely detected. The cancer risk study revealed that, among the investigated paths, inhalation poses the greatest risk. And bromodichloromethane had the highest impact to cancer (69%), followed by chlorodibromomethane (28%). Geographically, the highest cancer risk value was found in Matruh governorate (42.2 × 10^-6) and the lowest was in Minya governorate (1.0 × 10^-6). The cancer risk for the studied governorates, except Minya governorate, was higher than the level recommended by the USEPA (1.0 × 10^-6). Hazard index (HI) study revealed that the ingestion pathway caused higher HI values than the dermal pathway and that chloroform had the highest contribution to HI value. However, the values of HI were below unity in all studied governorates demonstrating that there would be negligible non-cancer risk.

Urinary biomarkers of exposure to drinking water disinfection byproducts and ovarian reserve: A cross-sectional study in China

Experimental studies have demonstrated that disinfection byproducts (DBPs) can cause ovarian toxicity including inhibition of antral follicle growth and disruption of steroidogenesis, but there is a paucity of human evidence. We aimed to investigate whether urinary biomarkers of exposure to drinking water DBPs were associated with ovarian reserve. The present study included 956 women attending an infertility clinic in Wuhan, China from December 2018 to January 2020. Antral follicle count (AFC), ovarian volume (OV), anti-Mullerian hormone (AMH), and follicle-stimulating hormone (FSH) were measured as indicators of ovarian reserve. Urinary dichloroacetic acid (DCAA) and trichloroacetic acid (TCAA) were assessed as potential biomarkers of drinking water DBP exposures. Multivariate linear and Poisson regression models were applied to estimate the associations of urinary DCAA and TCAA concentrations with indicators of ovarian reserve. Elevated urinary DCAA and TCAA levels were monotonically associated with reduced total AFC (- 5.98%; 95% CI: - 10.30%, - 1.44% in DCAA and - 12.98%; 95% CI: - 17.00%, - 8.76% in TCAA comparing the extreme tertiles; both P for trends ≤ 0.01), and the former was only observed in right AFC but not in left AFC, whereas the latter was estimated for both right and left AFC. Moreover, elevated urinary TCAA levels were monotonically associated with decreased AMH (- 14.09%; 95% CI: - 24.79%, - 1.86% comparing the extreme tertiles; P for trend = 0.03). These negative associations were still observed for the exposure biomarkers modeled as continuous variables. Our findings suggest that exposure to drinking water DBPs may be associated with decreased ovarian reserve.

Pilot-scale expanded assessment of inorganic and organic tapwater exposures and predicted effects in Puerto Rico, USA

A pilot-scale expanded target assessment of mixtures of inorganic and organic contaminants in point-of-consumption drinking water (tapwater, TW) was conducted in Puerto Rico (PR) to continue to inform TW exposures and corresponding estimations of cumulative human-health risks across the US. In August 2018, a spatial synoptic pilot assessment of than 524 organic and 37 inorganic chemicals was conducted in 14 locations (7 home; 7 commercial) across PR. A follow-up 3-day temporal assessment of TW variability was conducted in December 2018 at two of the synoptic locations (1 home, 1 commercial) and included daily pre- and post-flush samples. Concentrations of regulated and unregulated TW contaminants were used to calculate cumulative in vitro bioactivity ratios and Hazard Indices (HI) based on existing human-health benchmarks. Synoptic results confirmed that human exposures to inorganic and organic contaminant mixtures, which are rarely monitored together in drinking water at the point of consumption, occurred across PR and consisted of elevated concentrations of inorganic contaminants (e.g., lead, copper), disinfection byproducts (DBP), and to a lesser extent per/polyfluoroalkyl substances (PFAS) and phthalates. Exceedances of human-health benchmarks in every synoptic TW sample support further investigation of the potential cumulative risk to vulnerable populations in PR and emphasize the importance of continued broad characterization of drinking-water exposures at the tap with analytical capabilities that better represent the complexity of both inorganic and organic contaminant mixtures known to occur in ambient source waters. Such health-based monitoring data are essential to support public engagement in source water sustainability and treatment and to inform consumer point-of-use treatment decision making in PR and throughout the US.

Effects of environmental contaminants in water resources on nonalcoholic fatty liver disease

The global prevalence of nonalcoholic fatty liver disease (NAFLD) has been increasing rapidly in recent years, which is now estimated to be over 25%. NAFLD is one of the most common chronic liver diseases in the world. At present, with the rapid development of economy and industrialization, many chemicals are released into the environment. These chemical contaminants in the environment might cause harm to human health and result in lipid metabolism disorder during long-term exposure. Moreover, the incentive of many NAFLD cases is unknown, and the environmental risk factors of NAFLD need to be urgently identified. Hence, we focus on the impacts of several popular environmental contaminants in water environment on the development and progression of NAFLD. These contaminants mainly include microcystins (MCs), disinfection by-products (DBPs), heavy metals (HMs), dioxins and polychlorinated biphenyls (PCBs). Through analyzing a great many epidemiological and toxicological studies, we have found positive associations between NAFLD and chronic exposure to these contaminants at the environmental levels. This review may enhance the understanding of liver damage caused by environmental pollutants, which are considered as tangible environmental risk factors for NAFLD.

Public and private tapwater: Comparative analysis of contaminant exposure and potential risk, Cape Cod, Massachusetts, USA

BACKGROUND

Humans are primary drivers of environmental contamination worldwide, including in drinking-water resources. In the United States (US), federal and state agencies regulate and monitor public-supply drinking water while private-supply monitoring is rare; the current lack of directly comparable information on contaminant-mixture exposures and risks between private- and public-supplies undermines tapwater (TW) consumer decision-making.

METHODS

We compared private- and public-supply residential point-of-use TW at Cape Cod, Massachusetts, where both supplies share the same groundwater source. TW from 10 private- and 10 public-supply homes was analyzed for 487 organic, 38 inorganic, 8 microbial indicators, and 3 in vitro bioactivities. Concentrations were compared to existing protective health-based benchmarks, and aggregated Hazard Indices (HI) of regulated and unregulated TW contaminants were calculated along with ratios of in vitro exposure-activity cutoffs.

RESULTS

Seventy organic and 28 inorganic constituents were detected in TW. Median detections were comparable, but median cumulative concentrations were substantially higher in public supply due to 6 chlorine-disinfected samples characterized by disinfection byproducts and corresponding lower heterotrophic plate counts. Public-supply applicable maximum contaminant (nitrate) and treatment action (lead and copper) levels were exceeded in private-supply TW samples only. Exceedances of health-based HI screening levels of concern were common to both TW supplies.

DISCUSSION

These Cape Cod results indicate comparable cumulative human-health concerns from contaminant exposures in private- and public-supply TW in a shared source-water setting. Importantly, although this study's analytical coverage exceeds that currently feasible for water purveyors or homeowners, it nevertheless is a substantial underestimation of the full breadth of contaminant mixtures documented in the environment and potentially present in drinking water.

CONCLUSION

Regardless of the supply, increased public engagement in source-water protection and drinking-water treatment, including consumer point-of-use treatment, is warranted to reduce risks associated with long-term TW contaminant exposures, especially in vulnerable populations.

Mixed organic and inorganic tapwater exposures and potential effects in greater Chicago area, USA

Safe drinking water at the point of use (tapwater, TW) is a public-health priority. TW exposures and potential human-health concerns of 540 organics and 35 inorganics were assessed in 45 Chicago-area United States (US) homes in 2017. No US Environmental Protection Agency (EPA) enforceable Maximum Contaminant Level(s) (MCL) were exceeded in any residential or water treatment plant (WTP) pre-distribution TW sample. Ninety percent (90%) of organic analytes were not detected in treated TW, emphasizing the high quality of the Lake Michigan drinking-water source and the efficacy of the drinking-water treatment and monitoring. Sixteen (16) organics were detected in >25% of TW samples, with about 50 detected at least once. Low-level TW exposures to unregulated disinfection byproducts (DBP) of emerging concern, per/polyfluoroalkyl substances (PFAS), and three pesticides were ubiquitous. Common exceedances of non-enforceable EPA MCL Goal(s) (MCLG) of zero for arsenic [As], lead [Pb], uranium [U], bromodichloromethane, and tribromomethane suggest potential human-health concerns and emphasize the continuing need for improved understanding of cumulative effects of low-concentration mixtures on vulnerable sub-populations. Because DBP dominated TW organics, residential-TW concentrations are potentially predictable with expanded pre-distribution DBP monitoring. However, several TW chemicals, notably Pb and several infrequently detected organic compounds, were not readily explained by pre-distribution samples, illustrating the need for continued broad inorganic/organic TW characterization to support consumer assessment of acceptable risk and point-of-use treatment options.

Mixed organic and inorganic tapwater exposures and potential effects in greater Chicago area, USA

Safe drinking water at the point of use (tapwater, TW) is a public-health priority. TW exposures and potential human-health concerns of 540 organics and 35 inorganics were assessed in 45 Chicago-area United States (US) homes in 2017. No US Environmental Protection Agency (EPA) enforceable Maximum Contaminant Level(s) (MCL) were exceeded in any residential or water treatment plant (WTP) pre-distribution TW sample. Ninety percent (90%) of organic analytes were not detected in treated TW, emphasizing the high quality of the Lake Michigan drinking-water source and the efficacy of the drinking-water treatment and monitoring. Sixteen (16) organics were detected in >25% of TW samples, with about 50 detected at least once. Low-level TW exposures to unregulated disinfection byproducts (DBP) of emerging concern, per/polyfluoroalkyl substances (PFAS), and three pesticides were ubiquitous. Common exceedances of non-enforceable EPA MCL Goal(s) (MCLG) of zero for arsenic [As], lead [Pb], uranium [U], bromodichloromethane, and tribromomethane suggest potential human-health concerns and emphasize the continuing need for improved understanding of cumulative effects of low-concentration mixtures on vulnerable sub-populations. Because DBP dominated TW organics, residential-TW concentrations are potentially predictable with expanded pre-distribution DBP monitoring. However, several TW chemicals, notably Pb and several infrequently detected organic compounds, were not readily explained by pre-distribution samples, illustrating the need for continued broad inorganic/organic TW characterization to support consumer assessment of acceptable risk and point-of-use treatment options.

Maternal urinary levels of trichloroacetic acid and association with adverse pregnancy outcomes

The current study aimed to determine the association between trichloroacetic acid (TCAA) levels and adverse pregnancy outcomes among third-trimester pregnant women who were exposed to chlorinated drinking water. A total of 205 pregnant women who participated in the disinfection by-products exposure and adverse pregnancy outcome study in South Africa were randomly asked to participate in this study by providing their morning urine sample voids. Samples were analysed for urinary creatinine and TCAA. Furthermore, participants gave individual data using a structured questionnaire. The mean (median) concentration of creatinine-adjusted urinary TCAA was 2.34 (1.95) μg/g creatinine. Elevated levels of creatinine-adjusted TCAA concentrations showed an increased risk of premature birth, small for gestational age (SGA) and low birth weight. There was no significant statistical correlation observed between creatinine-adjusted TCAA concentrations and the total volume of cold water ingested among the study population. No statistically significant association was observed between creatinine-adjusted urinary TCAA and premature birth, SGA and low birth weight newborns among the study subjects. However, the urinary TCAA concentrations identified in this study suggest potential health risks towards women and foetus. Therefore, further studies are warranted to prevent further adverse pregnancy outcomes.

Profiles, variability and predictors of concentrations of blood trihalomethanes and urinary haloacetic acids along pregnancy among 1760 Chinese women

Blood trihalomethanes (THMs) and urinary haloacetic acids (HAAs) are the leading candidate biomarkers for disinfection byproduct (DBP) exposure. However, no studies have assessed the exposure profiles, temporal variability, and potential predictors of these biomarkers during pregnancy. Here we collected blood (n = 4304) and urine samples (n = 4165) from 1760 Chinese pregnant women during early, mid-, and late pregnancy, which were separately analyzed for 4 THMs and 2 HAAs. We calculated the intraclass correlation coefficients (ICCs) to assess the variability of these biomarkers and estimated their correlations with sociodemographic, water-use behavioral, dietary and sample collection factors using mixed models. The median concentrations of TCM, BDCM, Br-THMs [sum of BDCM, dibromochloromethane (DBCM), bromoform (TBM)], total THMs (TTHMs, sum of TCM and Br-THMs), DCAA and TCAA in the water distribution system were 4.2 μg/L, 1.7 μg/L, 2.9 μg/L, 7.1 μg/L, 3.4 μg/L and 8.2 μg/L, respectively. Chloroform (TCM), bromodichloromethane (BDCM), dichloroacetic acid (DCAA) and trichloroacetic acid (TCAA) were detected in > 75% of the biospecimens. Repeated measurements of blood TCM, BDCM, Br-THMs and TTHMs and urinary DCAA and TCAA uniformly exhibited high variability (ICCs = 0.01-0.13); the use of a single measurement to classify gestational average exposure resulted in a high degree of exposure misclassification. The sampling season was a strong predictor of all analyzed DBPs. Additionally, we detected a positive association of blood TCM and BDCM with household income, urinary DCAA with age, and urinary TCAA with tap water usage, education level and amount of tap water consumed. Inverse associations were found between blood BDCM and vegetable consumption, and between blood Br-THM and TTHM and time interval since the last bathing/showering. Afternoon samples had lower DCAA concentrations than did early morning samples. Our results indicate that blood THM and urinary HAA concentrations vary greatly over the course of pregnancy and are affected by sampling season, time of day of blood/urine collection, sociodemographic factors, recent water-use activities and dietary intake.

The Assessment of Trihalomethanes Concentrations in Drinking Water of Hamadan and Tuyserkan Cities, Western Iran and Its Health Risk on the Exposed Population

BACKGROUND

The aim of the present study was to calculate and to assess the potential lifetime cancer risks for trihalomethanes from consuming chlorinated drinking water in Hamadan and Tuyserkan cities, western Iran in 2016-2017.

STUDY DESIGN

A cross-sectional study.

METHODS

Seventy-two water samples were collected from the distribution systems and from the outlet of water treatment plants (WTPs) and the experiments were carried out to determine the desired parameters. All the sampling and measurement methods were according to Standard Methods. The obtained data were analyzed using SPSS software.

RESULTS

The mean concentration of total THMs in the summer and winter was 42.75 and 17.75 μg/L, respectively, below the WHO and Iranian standard. The positive correlation was observed between temperature and THMs levels. Moreover, THMs concentration in Shahid Beheshti's WTP was several times lower than in Ekbatan's WTP. Chloroform, the dominant species of THMs, was identified at different sampling points. The highest cancer risk in Hamadan was 1.4×10-5 and 4.8×10-5 for male and female, respectively; and the cancer risk was obtained to be 5.6×10-7-2.26×10-6 in Tuyserkan.

CONCLUSION

The drinking water obtained from the studied area is safe in terms of THMs concentration. Nevertheless, the highest cancer risk was higher than the EPA's acceptable level of 10-6.

Urinary biomarker of late pregnancy exposure to drinking water disinfection by-products and ultrasound measures of fetal growth in Wuhan, China

BACKGROUND

Disinfection by-products (DBPs) have been shown to be reproductive and developmental toxicity. However, few studies examine the effect of prenatal exposure to DBPs on fetal growth via ultrasound measures.

OBJECTIVE

To investigate the associations between maternal exposure to DBPs during late pregnancy and ultrasound measures of fetal growth.

METHODS

We included 332 pregnant women who presented to a hospital to wait for delivery in Wuhan, China. Ultrasound parameters of fetal growth including femur length (FL), head circumference (HC), abdominal circumference (AC) and biparietal diameter (BPD) were assessed. We measured maternal TCAA concentrations in first morning urine collected from late pregnancy as a biomarker of in utero DBP exposure levels. Multivariable linear regression models were used to examine the associations between maternal urinary TCAA concentrations during late pregnancy and ultrasound parameters of fetal growth.

RESULTS

We found that elevated maternal creatinine (Cr)-adjusted urinary TCAA levels had negative associations with BPD, HC and FL in boys but not in girls (P interaction = 0.04, 0.05 and 0.08, respectively). Male fetal BPD, HC and FL had decreases of 0.21 cm (95% CI: -0.35, -0.07; P for trend = 0.003), 0.46 cm (95% CI: -0.81, -0.10; P for trend = 0.01) and 0.17 cm (95% CI: -0.30, -0.04; P for trend = 0.01) for the highest vs. lowest tertile of Cr-adjusted urinary TCAA, respectively. These negative associations persisted for maternal Cr-adjusted urinary TCAA concentrations modeled as continuous variables.

CONCLUSION

The results from our study suggest that maternal exposure to TCAA during late pregnancy may have adverse effects on male fetal growth.

Exposure Characterization of Haloacetic Acids in Humans for Exposure and Risk Assessment Applications: An Exploratory Study

Disinfected water is the major source of haloacetic acids (HAAs) in humans, but their inter- and intra-individual variability for exposure and risk assessment applications is under-researched. Thus, we measured HAAs in cross-sectional and longitudinal urine and water specimens from 17 individuals. Five regulated HAAs-mono, di, and trichloroacetic acid (MCAA, DCAA, and TCAA) and mono- and dibromoacetic acid (MBAA and DBAA)-and one unregulated HAA-bromochloroacetic acid (BCAA)-were measured. Urinary DCAA, MBAA, DBAA, and BCAA levels were always below the limits of detection (LOD). Measured levels and interindividual variability of urinary MCAA were higher than urinary TCAA. Longitudinal urinary specimens showed MCAA levels peaked in after-shower specimens, while TCAA levels remain unchanged. Correlation between urinary MCAA and TCAA was moderate but statistically significant. The prevalence of MCAA and TCAA in urine suggest they can be considered as biomarkers of HAA. Peak urinary MCAA in post-shower specimens suggest MCAA captures short-term exposure via dermal and/or inhalation, while urinary TCAA captures long-term exposure via ingestion. However, further research is warranted in a large pool of participants to test the reliability of MCAA as exposure biomarker.

Maternal swimming pool exposure during pregnancy in relation to birth outcomes and cord blood DNA methylation among private well users

Swimming in pools during pregnancy may expose the fetus to water disinfection by-products (DBP). As yet, our understanding of the impacts on DBPs on the fetus is uncertain. Individuals with public water systems are typically exposed to DBPs through drinking, showering and bathing, whereas among those on private water systems, swimming in pools may be the primary exposure source. We analyzed the effects of maternal swimming on birth outcomes and cord blood epigenetic changes in the New Hampshire Birth Cohort Study, a cohort of pregnant women with households on private water systems. Information about swimming in pools during pregnancy was obtained from 1033 women via questionnaires. Swimming pool use and duration were modeled using linear regression with newborn weight, length, and head circumference (z-scores) and genome wide cord blood DNA methylation as the outcomes and with adjustment for potential confounders. Overall 19.7% of women reported swimming in a pool during pregnancy. Among swimmers, duration of swimming was inversely related to head circumference (-0.02 z-score per 10% increase in duration, P = 0.004). No associations were observed with birth weight, length or DNA methylation modifications. Our findings suggest swimming pool exposure may impact the developing fetus although longer-term studies are needed.

Coupling external with internal exposure metrics of trihalomethanes in young females from Kuwait and Cyprus

The Eastern Mediterranean and the Middle Eastern regions are both understudied in terms of possible environmental health risks for their populations. Water scarcity and desalination treatment provide the general population of countries from these regions (e.g., Kuwait and Cyprus) with unique tap water characteristics. This study investigated the association between external (tap water and 24 h personal air samples) and internal (urine) THM exposure metrics that reflected information about THM-related habits and activities collected using questionnaires and time activity diaries. The study population comprised of young females residing in either Kuwait (n=13) or Cyprus (n=22). First morning urine voids were collected on 2 consecutive days. Urinary creatinine-adjusted total THM (TTHM) levels were higher in Kuwait (median (interquartile range): 1044 (814, 1270) ng/g) than in Cyprus (691 (510, 919) ng/g, P<0.05). Median personal air TTHM levels in Kuwait (1.4 (0.7, 1.7) μg/m³) were higher than those in Cyprus (0.9 (0.5, 1.4) μg/m³), but did not reach statistical significance (P=0.17). Median tap water TTHM in Kuwait (6.7 (5.4, 11.6) μg/l) did not correlate with urinary or air THM and they were lower than those in Cyprus (29.5 (20.1, 48.0) μg/l; P<0.01). Despite that tap water did not contain chloroform (TCM), TCM was detected in both air and urine samples in Kuwait, suggesting other TCM exposure sources, such as household cleaning activities. Total duration of activities and mopping were significantly correlated with air and urine THM in Kuwait, as reported in the time activity diary. Personal air and urine exposure metrics were correlated in Kuwait (TTHM ρ=0.62, P<0.05), but not in Cyprus (TTHM ρ=-0.32, P>0.05). Time-activity diaries and urinary THM seemed to be useful measures of THM exposures in Kuwait. Coupling both external with internal exposure metrics could find use in population health studies towards further refining the association between environmental exposures and health outcomes.

Biomarkers of end of shift exposure to disinfection byproducts in nurses

Increased disinfectant use commonly takes place in hospitals and other health care settings. A cross-sectional study among active nurses in two Cypriot public hospitals (n=179) was conducted to examine the prevalence of exposure to disinfection byproducts (DBPs), such as trihalomethanes (THMs) using both self-reported information and biomarker measurements. The objectives of this study were to: i) quantify the magnitude and variability of occupational exposure to disinfectants/DBPs in nurses, ii) generate job exposure matrices (JEM) and job task exposure matrices (JTEM) for disinfectants, and iii) assess the major determinants of urinary THMs in nurses. End of shift urinary total THM values showed high variability among the nurses, but did not differ between hospitals. The disinfectant group of alcohols/phenols was used by >98% of nurses, followed by octenidine (82%), iodine and chlorine (39%, each), chlorhexidine (25%), formaldehyde (12%), hydrogen peroxide (11%), and peracetic acid/ammonia/quaternary ammonium compounds (QACs), all being <8% each. Chlorine use during the past 24hr was associated with significantly (p<0.05) lower brominated THMs (BrTHMs) after adjusting for age, gender and BMI, while a positive association was shown for TCM and the sum of all THMs (TTHMs), albeit not significant. Nurses were exposed to nearly double the levels of TTHMs and BrTHMs (median and IQR, 1027 [560, 2475] ng/g and 323 [212, 497] ng/g, respectively) when compared to those of the general population (552 [309,989] ng/g and 152 [87,261] ng/g, respectively). This was the first occupational health dataset reporting measurements of biomarkers of end of shift exposures to disinfectants/DBPs.

Evaluation of Drinking Water Disinfectant Byproducts Compliance Data as an Indirect Measure for Short-Term Exposure in Humans

In the absence of shorter term disinfectant byproducts (DBPs) data on regulated Trihalomethanes (THMs) and Haloacetic acids (HAAs), epidemiologists and risk assessors have used long-term annual compliance (LRAA) or quarterly (QA) data to evaluate the association between DBP exposure and adverse birth outcomes, which resulted in inconclusive findings. Therefore, we evaluated the reliability of using long-term LRAA and QA data as an indirect measure for short-term exposure. Short-term residential tap water samples were collected in peak DBP months (May–August) in a community water system with five separate treatment stations and were sourced from surface or groundwater. Samples were analyzed for THMs and HAAs per the EPA (U.S. Environmental Protection Agency) standard methods (524.2 and 552.2). The measured levels of total THMs and HAAs were compared temporally and spatially with LRAA and QA data, which showed significant differences (p < 0.05). Most samples from surface water stations showed higher levels than LRAA or QA. Significant numbers of samples in surface water stations exceeded regulatory permissible limits: 27% had excessive THMs and 35% had excessive HAAs. Trichloromethane, trichloroacetic acid, and dichloroacetic acid were the major drivers of variability. This study suggests that LRAA and QA data are not good proxies of short-term exposure. Further investigation is needed to determine if other drinking water systems show consistent findings for improved regulation.

Prenatal exposure to drinking water disinfection by-products and DNA methylation in cord blood

Maternal exposure to drinking water disinfection by-products (DBPs) during pregnancy has been related to adverse birth outcomes. While experimental studies have shown that exposure to DBPs induce DNA hypomethylation, evidence from humans is limited. This study aimed to examine whether prenatal exposure to drinking water DBPs was associated with DNA methylation in cord blood. Maternal biomarkers of exposure to drinking water DBPs including blood trihalomethanes [THMs, including chloroform (TCM), bromodichloromethane (BDCM), dibromochloromethane (DBCM), and bromoform (TBM)] and urinary trichloroacetic acid (TCAA) were measured during late pregnancy. DNA methylation in Alu and long interspersed nucleotide element-1 (LINE-1) repetitive elements from cord blood samples (n=115) was measured by pyrosequencing. We used multivariable linear regression to estimate the associations of DNA methylation in cord blood with maternal blood THMs and urinary TCAA. We found no statistically significant association between urinary TCAA and DNA methylation. However, we found that blood TBM was associated with decreased Alu methylation (-0.39%; 95% CI: -0.83%, 0.05% for the highest versus lowest exposure group; p for trend=0.08) and decreased LINE-1 methylation (-1.27%; 95% CI: -2.91%, 0.36% for the highest versus lowest exposure group; p for trend=0.06). Our results suggest that prenatal exposure to drinking water TBM is associated with DNA hypomethylation in cord blood. However, further studies are needed to confirm our findings.

Volatile and semi-volatile organic compounds of respiratory health relevance in French dwellings

Over the last decades, the prevalence of childhood respiratory conditions has dramatically increased worldwide. Considering the time spent in enclosed spaces, indoor air pollutants are of major interest to explain part of this increase. This study aimed to measure the concentrations of pollutants known or suspected to affect respiratory health that are present in dwellings in order to assess children's exposure. Measurements were taken in 150 homes with at least one child, in Brittany (western France), to assess the concentrations of 18 volatile organic compounds (among which four aldehydes and four trihalomethanes) and nine semi-volatile organic compounds (seven phthalates and two synthetic musks). In addition to descriptive statistics, a principal component analysis (PCA) was used to investigate grouping of contaminants. Formaldehyde was highly present and above 30 μg/m(3) in 40% of the homes. Diethyl phthalate, diisobutyl phthalate, and dimethylphthalate were quantified in all dwellings, as well as Galaxolide and Tonalide. For each chemical family, the groups appearing in the PCA could be interpreted in term of sources. The high prevalence and the levels of these compounds, with known or suspected respiratory toxicity, should question regulatory agencies to trigger prevention and mitigation actions.

Predictors of Third Trimester Blood Trihalomethanes and Urinary Trichloroacetic Acid Concentrations among Pregnant Women

Prenatal exposure to disinfection byproducts (DBPs) has been associated with a variety of adverse birth outcomes. However, little is known about predictors of prenatal biomarkers of exposure to DBPs among pregnant women. We aimed to identify predictors of third trimester blood trihalomethanes (THMs) and urinary trichloroacetic acid (TCAA) concentrations, two biomarkers of exposure to DBPs, among pregnant women. Blood samples, urine samples, and questionnaires on individual characteristics and water-use activities were collected from 893 pregnant women in a Chinese cohort study. Maternal blood THM [chloroform (TCM), bromodichloromethane (BDCM), dibromochloromethane (DBCM), and bromoform (TBM)] and urinary TCAA concentrations were measured. We used multivariable linear regression to identify the predictors of third trimester blood THM and creatinine-adjusted urinary TCAA concentrations. The geometric mean of blood TTHM (sum of TCM, BDCM, DBCM, and TBM) and creatinine-adjusted urinary TCAA concentrations were 51.90 ng/L and 9.66 μg/g creatinine, respectively. Study city was the strongest significant predictors of blood THM and creatinine-adjusted urinary TCAA concentrations. Prenatal body mass index (BMI) was associated with decreased blood THM and decreased creatinine-adjusted urinary TCAA concentrations. Age was associated with increased blood Br-THM (sum of BDCM, DBCM, and TBM) concentrations. Intake of boiled water and passive smoking were associated with lower blood THM concentrations. The predictors of blood THM and urinary TCAA concentrations identified in this study provide potential health implications on how to reduce DBP exposure during pregnancy.

Blood trihalomethane levels and the risk of total cancer mortality in US adults

BACKGROUND

Although animal data have suggested the carcinogenic activity of trihalomethanes (THMs), there is inconsistent evidence supporting the link between THM exposure and cancers in humans.

OBJECTIVES

We investigated the association between specific and total blood THM levels with the risk of total cancer mortality in adults.

METHODS

We analyzed data from the 1999-2004 Third National Health and Nutrition Examination Survey and the Linked Mortality File of the United States. A total of 933 adults (20-59 years of age) with available blood THM levels and no missing data for other variables were included. Four different THM species (chloroform, bromodichloromethane (BDCM), dibromochloromethane (DBCM) and bromoform) were included, and the codes associated with cancer (malignant neoplasm) were C00 through C97, based on the underlying causes of death listed in the International Classification of Disease 10the Revision.

RESULTS

Compared with adults in the lowest DBCM, bromoform, and total brominated THM tertiles, those in the highest DBCM, bromoform, and total brominated THM tertiles exhibited adjusted hazard ratios (HR) of total cancer mortality of 4.97 (95% confidence interval (CI) = 1.59-15.50), 4.94 (95% CI = 1.56-15.61), and 3.42 (95% CI = 1.21-15.43) respectively. The risk of total cancer mortality was not associated with increases in blood chloroform and total THM levels.

CONCLUSIONS

We found that the baseline blood THM species, particularly brominated THMs, were significantly associated with total cancer mortality in adults. Although this study should be confirm by other studies, our findings suggest a possible link between THM exposures and cancer.

Joint effects of trihalomethanes and trichloroacetic acid on semen quality: A population-based cross-sectional study in China

Exposure to trihalomethanes (THMs) and haloacetic acids (HAAs) has been individually associated with adverse male reproductive effects; however, their joint male reproductive toxicity is largely unknown. This study aimed to explore the joint effects of THMs and trichloroacetic acid (TCAA) on semen quality in a Chinese population. A total of 337 men presenting to the Reproductive Center of Tongjing Hospital, in Wuhan, China to seek semen analysis were included this study. Baseline blood THMs [chloroform (TCM), bromodichloromethane (BDCM), dibromochloromethane (DBCM), and bromoform (TBM)] and urinary TCAA were analyzed and dichotomized at their median levels. The joint effects of THMs and TCAA on below-reference semen quality parameters were evaluated by calculating the relative excess risk due to interaction (RERI). After adjusting for potential confounders, we found a suggestive synergistic effect between Br-THMs (sum of BDCM, DBCM, and TBM) and TCAA for below-reference sperm count (RERI = 2.14, 95% CI: -0.37, 4.91) (P = 0.076); men with high Br-THMs and TCAA levels (above the median) had 3.31 times (95% CI: 1.21, 9.07) elevated risk of having below-reference sperm count than men with low Br-THMs and TCAA levels (below the median). No apparent joint effects were observed between THMs and TCAA for other semen quality parameters. Our results suggest that co-exposure to Br-THMs and TCAA is associated with additive effects on decreased semen quality. However, further studies in a larger sample size and mechanistic studies are needed to confirm the findings.

Interactions between CYP2E1, GSTZ1 and GSTT1 polymorphisms and exposure to drinking water trihalomethanes and their association with semen quality

Trihalomethanes (THMs) have been reported to be associated with altered semen quality, and this association may be modified by inherited differences in cytochrome P450 (CYP2E1) and glutathione S-transferase (GSTZ1 and GSTT1), which metabolize THMs. We conducted a cross-sectional study to examine the interactions between CYP2E1, GSTZ1 and GSTT1 polymorphisms and exposure to THMs on semen quality among 401 men from the Reproductive Center of Tongji Hospital in Wuhan China. The baseline blood concentrations of four individual THMs, chloroform (TCM), bromodichloromethane (BDCM), dibromochloromethane (DBCM) and bromoform (TBM), were measured as biomarkers of exposure to drinking water THMs. Genotypes were determined by real-time PCR, and semen-quality parameters were evaluated according to the World Health Organization guidelines. GSTT1 genotype significantly modified the association between exposure to Br-THMs (sum of BDCM, DBCM and TBM) and below-reference sperm motility (Pint=0.02). Men with above-median blood Br-THM levels had an increased odds ratio (OR) of below-reference sperm compared to men with below-median blood Br-THM levels (OR=2.15, 95% CI: 1.11, 4.19) in the GSTT1 null genotype only. In addition, we found that men with a TT of CYP2E1 rs 915,906 had higher blood TCM and TTHM (sum of TCM, BDCM, DBCM and TBM) concentrations than men with a CT/CC of CYP2E1 rs 915,906. Our results suggest that GSTT1 polymorphisms modify Br-THM exposure relation with semen quality, and CYP2E1 polymorphisms are associated with internal levels of exposure to THMs.

Blood Biomarkers of Late Pregnancy Exposure to Trihalomethanes in Drinking Water and Fetal Growth Measures and Gestational Age in a Chinese Cohort

BACKGROUND

Previous studies have suggested that elevated exposure to disinfection by-products (DBPs) in drinking water during gestation may result in adverse birth outcomes. However, the findings of these studies remain inconclusive.

OBJECTIVE

The purpose of our study was to examine the association between blood biomarkers of late pregnancy exposure to trihalomethanes (THMs) in drinking water and fetal growth and gestational age.

METHODS

We recruited 1,184 pregnant women between 2011 and 2013 in Wuhan and Xiaogan City, Hubei, China. Maternal blood THM concentrations, including chloroform (TCM), bromodichloromethane (BDCM), dibromochloromethane (DBCM), and bromoform (TBM), were measured as exposure biomarkers during late pregnancy. We estimated associations with gestational age and fetal growth indicators [birth weight, birth length, and small for gestational age (SGA)].

RESULTS

Total THMs (TTHMs; sum of TCM, BDCM, DBCM, and TBM) were associated with lower mean birth weight (-60.9 g; 95% CI: -116.2, -5.6 for the highest vs. lowest tertile; p for trend = 0.03), and BDCM and DBCM exposures were associated with smaller birth length (e.g., -0.20 cm; 95% CI: -0.37, -0.04 for the highest vs. lowest tertile of DBCM; p for trend = 0.02). SGA was increased in association with the second and third tertiles of TTHMs (OR = 2.91; 95% CI: 1.32, 6.42 and OR = 2.25; 95% CI: 1.01, 5.03; p for trend = 0.08).

CONCLUSIONS

Our results suggested that elevated maternal THM exposure may adversely affect fetal growth.

CITATION

Cao WC, Zeng Q, Luo Y, Chen HX, Miao DY, Li L, Cheng YH, Li M, Wang F, You L, Wang YX, Yang P, Lu WQ. 2016. Blood biomarkers of late pregnancy exposure to trihalomethanes in drinking water and fetal growth measures and gestational age in a Chinese cohort. Environ Health Perspect 124:536-541; http://dx.doi.org/10.1289/ehp.1409234.

Overview of Disinfection By-products and Associated Health Effects

The presence of chemical compounds formed as disinfection by-products (DBPs) is widespread in developed countries, and virtually whole populations are exposed to these chemicals through ingestion, inhalation, or dermal absorption from drinking water and swimming pools. Epidemiological evidence has shown a consistent association between long-term exposure to trihalomethanes and the risk of bladder cancer, although the causal nature of the association is not conclusive. Evidence concerning other cancer sites is insufficient or mixed. Numerous studies have evaluated reproductive implications, including sperm quality, time to pregnancy, menstrual cycle, and pregnancy outcomes such as fetal loss, fetal growth, preterm delivery, and congenital malformation. The body of evidence suggests only minor effects from high exposure during pregnancy on fetal growth indices such as small for gestational age (SGA) at birth. Populations highly exposed to swimming pools such as pool workers and professional swimmers show a higher prevalence of respiratory symptoms and asthma, respectively, although the direction of the association, and thus causality, is not clear among professional swimmers. The risk of asthma, wheezing, eczema, and other respiratory outcomes among children attending swimming pools has been the object of extensive research. Early studies suggested a positive association, while subsequent larger studies found no correlations or showed a protective association. Future research should develop methods to evaluate the effects of the DBP mixture and the interaction with personal characteristics (e.g., genetics, lifestyle), clarify the association between swimming pools and respiratory health, evaluate the occurrence of DBPs in low- and middle-income countries, and evaluate outcomes suggested by animal studies that have not been considered in epidemiological investigations.

Trihalomethane exposure and biomonitoring for the liver injury indicator, alanine aminotransferase, in the United States population (NHANES 1999-2006)

Exposure to trihalomethanes (or THMs: chloroform, bromoform, bromodichloromethane, and dibromochloromethane [DBCM]) formed via drinking water disinfection has been associated with adverse reproductive outcomes and cancers of the digestive or genitourinary organs. However, few studies have examined potential associations between THMs and liver injury in humans, even though experimental studies suggest that these agents exert hepatotoxic effects, particularly among obese individuals. This study examined participants in the National Health and Nutrition Examination Survey (1999-2006, N=2781) to test the hypothesis that THMs are associated with liver injury as assessed by alanine aminotransferase (ALT) activity in circulation. Effect modification by body mass index (BMI) or alcohol consumption also was examined. Associations between blood THM concentrations and ALT activity were assessed using unconditional multiple logistic regression to calculate prevalence odds ratios (ORs) with 95% confidence intervals (CIs) for exposure among cases with elevated ALT activity (men: >40IU/L, women: >30IU/L) relative to those with normal ALT, after adjustment for variables that may confound the relationship between ALT and THMs. Compared to controls, cases were 1.35 times more likely (95% CI: 1.02, 1.79) to have circulating DBCM concentrations exceeding median values in the study population. There was little evidence for effect modification by BMI, although the association varied by alcohol consumption. Among non-drinkers, cases were more likely than controls to be exposed to DBCM (OR: 3.30, 95% CI: 1.37, 7.90), bromoform (OR: 2.88, 95% CI: 1.21, 6.81), or brominated THMs (OR: 4.00, 95% CI: 1.31, 12.1), but no association was observed among participants with low, or moderate to heavy alcohol consumption. Total THM levels exceeding benchmark exposure limits continue to be reported both in the United States and globally. Results from this study suggest a need for further characterization of ALT activity and possibly other hepatic or metabolic diseases in populations with elevated drinking water THM concentrations.

Passive exposures of children to volatile trihalomethanes during domestic cleaning activities of their parents

Domestic cleaning has been proposed as a determinant of trihalomethanes (THMs) exposure in adult females. We hypothesized that parental housekeeping activities could influence children's passive exposures to THMs from their mere physical presence during domestic cleaning. In a recent cross-sectional study (n = 382) in Cyprus [41 children (< 18 y) and 341 adults (≥ 18 y)], we identified 29 children who met the study's inclusion criteria. Linear regression models were applied to understand the association between children sociodemographic variables, their individual practices influencing ingestion and noningestion exposures to ΣTHMs, and their urinary THMs levels. Among the children-specific variables, age alone showed a statistically significant inverse association with their creatinine-adjusted urinary ΣTHMs (rS = -0.59, p < 0.001). A positive correlation was observed between urinary ΣTHMs (ng g(-1)) of children and matched-mothers (rS = 0.52, p = 0.014), but this was not the case for their matched-fathers (rS = 0.39, p = 0.112). Time spent daily by the matched-mothers for domestic mopping, toilet and other cleaning activities using chlorine-based cleaning products was associated with their children's urinary THMs levels (rS = 0.56, p = 0.007). This trend was not observed between children and their matched-fathers urinary ΣTHMs levels, because of minimum amount of time spent by the latter in performing domestic cleaning. The proportion of variance of creatinine-unadjusted and adjusted urinary ΣTHMs levels in children that was explained by the matched-mothers covariates was 76% and 74% (p < 0.001), respectively. A physiologically-based pharmacokinetic model adequately predicted urinary chloroform excretion estimates, being consistent with the corresponding measured levels. Our findings highlighted the influence of mothers' domestic cleaning activities towards enhancing passive THMs exposures of their children. The duration of such activities could be further tested as a valid indicator of children's THMs body burden.

Preliminary evidence of the association between monochlorinated bisphenol A exposure and type II diabetes mellitus: A pilot study

Evidence for the association of bisphenol A (BPA) with type II diabetes mellitus (T2DM) has been inconsistent in human studies. In-vitro and animal studies indicate that chlorinated BPA derivatives aggravate BPA health effects via higher estrogenic activity and alteration of membrane-initiating signaling pathways. We evaluated the association between urinary monochlorinated BPA (mono-ClBPA) concentrations and the incidence of T2DM. In our cross-sectional study, we identified 20 adult participants (≥18 yr) who reported having T2DM (doctor-diagnosed) and 131 adults with normal health. First morning void urine samples were analyzed for total BPA and mono-ClBPA. Detection limits of the analytical method were 95 ng L(-1) for BPA and 32 ng L(-1) for mono-ClBPA. Multivariable logistic regression analyses and additive Bayesian network modeling were performed. After adjusting for age, gender, BMI, urinary total BPA and other confounders, the odds of having T2DM was 3.29 times higher (95% confidence interval, CI: 1.10, 11.4; P < 0.05) per unit increase in log-transformed and creatinine-adjusted urinary mono-ClBPA levels (n = 151); this relation did not hold for total BPA. The globally optimum Bayesian model corroborated the results of the logistic regression by expressing mono-ClBPA in the pathway of T2DM, and not for total BPA. An age-matched sensitivity analysis confirmed the increase in OR of T2DM by 3.04 times (95% CI: 1.10, 11.0; P < 0.05) per unit increase in log-transformed and creatinine-adjusted urinary mono-ClBPA concentration (n = 68). The urinary monochlorinated BPA derivative was significantly associated with T2DM, whereas the parent compound (total BPA) was not. Caution should be applied in interpreting these findings, as this is the first study to report this association and the sample size of participants with T2DM is small. Additional research with a larger sample size coupled with relevant toxicological studies is warranted.

Spatial and seasonal variability of urinary trihalomethanes concentrations in urban settings

A complex network of sources and routes of exposure to disinfection by-products (DBP), such as trihalomethanes (THM) has been driving the wide variability of daily THM intake estimates in environmental epidemiological studies. We hypothesized that the spatiotemporal variability of THM exposures could be differentially expressed with their urinary levels among residents whose households are geographically clustered in district-metered areas (DMA) receiving the same tap water. Each DMA holds unique drinking-water pipe network characteristics, such as pipe length, number of pipe leaking incidences, number of water meters by district, average minimum night flow and average daily demand. The present study assessed the spatial and seasonal variability in urinary THM levels among residents (n=310) of geocoded households belonging to two urban DMA of Nicosia, Cyprus, with contrasting water network properties. First morning urine voids were collected once in summer and then in winter. Results showed that the mean sum of the four urinary THM analytes (TTHM) was significantly higher during summer for residents of both areas. Linear mixed effects models adjusted for age, season and gender, illustrated spatially-resolved differences in creatinine-adjusted urinary chloroform and TTHM levels between the two studied areas, corroborated by differences observed in their pipe network characteristics. Additional research is warranted to shed light on the contribution of spatially-resolved and geographically-clustered environmental exposures coupled with internal biomarker of exposure measurements towards better understanding of health disparities within urban centers.

Predictors of urinary trichloroacetic acid and baseline blood trihalomethanes concentrations among men in China

Urinary trichloroacetic acid (TCAA) and baseline blood trihalomethanes (THMs) have been measured as biomarkers of exposure to drinking water disinfection by-products (DBPs) that have been associated with increased risk of cancers and adverse reproductive outcomes. This study aimed to identify predictors of urinary TCAA and baseline blood THMs among men in China. Urine samples, blood samples, and information on socio-demographic factors and water-use activities were collected from 2216 men who participated in a cross-sectional study of exposure to drinking water DBPs and reproductive health during 2011 to 2012. Urinary TCAA and baseline blood THMs including chloroform (TCM), bromodichloromethane (BDCM), dibromochloromethane (DBCM), and bromoform (TBM) were analyzed. Multivariable linear regression was used to evaluate predictors of urinary TCAA and baseline blood THM concentrations. Tap water consumption was significantly associated with creatinine-adjusted urinary TCAA concentration (β = 0.23 μg/g creatinine per log10 unit; 95% CI: 0.12, 0.35). Men with surface water source had 0.13 (95% CI: 0.00, 0.27) higher mean creatinine-adjusted urinary TCAA concentrations than those with ground water source. Smoking was associated with lower concentration of creatinine-adjusted urinary TCAA. Age was significantly associated with baseline blood Br-THM (sum of BDCM, DBCM, and TBM) concentration (β = 0.01 ng/L per unit; 95% CI: 0.00, 0.02). Increased household income was associated with decreased concentrations of baseline blood BDCM and Br-THMs. Our results suggest that tap water consumption, water source, smoking, age, and household income as the primary determinants of exposure to drinking water DBPs should be considered in exposure assessment.

Influence of household cleaning practices on the magnitude and variability of urinary monochlorinated bisphenol A

Low-dose health effects of BPA have not been adequately explored in the presence of BPA metabolites of chlorinated structure that may exert larger estrogenic effects than those of their parent compound. We hypothesized that chlorine-containing cleaning products used in household cleaning activities could modify the magnitude of total urinary BPA concentration measurements via the production of chlorinated BPA (ClBPA) derivatives. Our objective was to investigate the influence of typical household cleaning activities (dishwashing, toilet cleaning, mopping, laundry, etc.) on the magnitude and variability of urinary total BPA and mono-ClBPA levels in the general adult population. A cross-sectional study (n=224) included an adult (≥18 years) pool of participants from the general population of Nicosia, Cyprus. First morning urine voids were collected, and administered questionnaires included items about household cleaning habits, demographics, drinking water consumption rates and water source/usage patterns. Urinary concentrations of total BPA (range: 0.2-82 μg L(-1)), mono-ClBPA (16-340 ng L(-1)), and total trihalomethanes (0.1-5.0 μg L(-1)) were measured using gas chromatography coupled with triple quadrupole mass spectrometry and large volume injection. Linear multiple regression analysis revealed that dishwashing along with age and gender (females) were able to predict urinary mono-ClBPA levels (ng g(-1)), even after adjusting for covariates; this was not the case for urinary total BPA levels (ng g(-1)). Significant (p<0.001) association was observed between urinary mono-ClBPA and THM levels, underlying the important role of disinfectant (chlorine) in promoting formation of both ClBPA and THM. Urinary mono-ClBPA levels were measured for the first time using an appreciable sample size, highlighting the co-occurring patterns of both total BPA and mono-ClBPA. Epidemiological studies and probabilistic BPA risk assessment exercises should consider assessing daily intake estimates for chlorinated BPA compounds, as well.

Drinking-water disinfection by-products and semen quality: a cross-sectional study in China

BACKGROUND

Exposure to disinfection by-products (DBPs) has been demonstrated to impair male reproductive health in animals, but human evidence is limited and inconsistent.

OBJECTIVE

We examined the association between exposure to drinking-water DBPs and semen quality in a Chinese population.

METHODS

We recruited 2,009 men seeking semen analysis from the Reproductive Center of Tongji Hospital in Wuhan, China, between April 2011 and May 2012. Each man provided a semen sample and a urine sample. Semen samples were analyzed for sperm concentration, sperm motility, and sperm count. As a biomarker of exposure to drinking-water DBPs, trichloroacetic acid (TCAA) was measured in the urine samples.

RESULTS

The mean (median) urinary TCAA concentration was 9.58 (7.97) μg/L (interquartile range, 6.01-10.96 μg/L). Compared with men with urine TCAA in the lowest quartile, increased adjusted odds ratios (ORs) were estimated for below-reference sperm concentration in men with TCAA in the second and fourth quartiles (OR = 1.79; 95% CI: 1.19, 2.69 and OR = 1.51; 95% CI: 0.98, 2.31, respectively), for below-reference sperm motility in men with TCAA in the second and third quartiles (OR = 1.46; 95% CI: 1.12, 1.90 and OR = 1.30; 95% CI: 1.00, 1.70, respectively), and for below-reference sperm count in men with TCAA in the second quartile (OR 1.62; 95% CI: 1.04, 2.55). Nonmonotonic associations with TCAA quartiles were also estimated for semen parameters modeled as continuous outcomes, although significant negative associations were estimated for all quartiles above the reference level for sperm motility.

CONCLUSION

Our findings suggest that exposure to drinking-water DBPs may contribute to decreased semen quality in humans.

Predictors of blood trihalomethane concentrations in NHANES 1999-2006

BACKGROUND

Trihalomethanes (THMs) are water disinfection by-products that have been associated with bladder cancer and adverse birth outcomes. Four THMs (bromoform, chloroform, bromodichloromethane, dibromochloromethane) were measured in blood and tap water of U.S. adults in the National Health and Nutrition Examination Survey (NHANES) 1999-2006. THMs are metabolized to potentially toxic/mutagenic intermediates by cytochrome p450 (CYP) 2D6 and CYP2E1 enzymes.

OBJECTIVES

We conducted exploratory analyses of blood THMs, including factors affecting CYP2D6 and CYP2E1 activity.

METHODS

We used weighted multivariable regressions to evaluate associations between blood THMs and water concentrations, survey year, and other factors potentially affecting THM exposure or metabolism (e.g., prescription medications, cruciferous vegetables, diabetes, fasting, pregnancy, swimming).

RESULTS

From 1999 to 2006, geometric mean blood and water THM levels dropped in parallel, with decreases of 32%-76% in blood and 38%-52% in water, likely resulting, in part, from the lowering of the total THM drinking water standard in 2002-2004. The strongest predictors of blood THM levels were survey year and water concentration (n = 4,232 total THM; n = 4,080 bromoform; n = 4,582 chloroform; n = 4,374 bromodichloromethane; n = 4,464 dibromochloromethane). We detected statistically significant inverse associations with diabetes and eating cruciferous vegetables in all but the bromoform model. Medications did not consistently predict blood levels. Afternoon/evening blood samples had lower THM concentrations than morning samples. In a subsample (n = 230), air chloroform better predicted blood chloroform than water chloroform, suggesting showering/bathing was a more important source than drinking.

CONCLUSIONS

We identified several factors associated with blood THMs that may affect their metabolism. The potential health implications require further study.

Obesity-mediated association between exposure to brominated trihalomethanes and type II diabetes mellitus: an exploratory analysis

With the exception of chloroform, the rest of trihalomethanes (THM), the so-called brominated THM (Br-THM) are composed of bromine-substituted molecules with increased lipophilicity and potency to biological tissues. The THM are formed within disinfected tap water and their health effects, under research, range from cancer to adverse reproductive outcomes. However, the association between human exposures to Br-THM and the risk of developing type II diabetes mellitus (T2DM) and metabolic co-morbidities, such as obesity and non-alcoholic steatohepatitis has never been previously explored. The objective of this exploratory analysis was to address obesity-mediated associations between urinary concentrations of brominated THM and incidences of T2DM in a Cypriot adult population (n=326). First morning urine voids were collected once during summer and another time during winter while a detailed questionnaire was administered to participants. Creatinine-adjusted urinary Br-THM analyte concentrations were significantly (p<0.05) higher in T2DM cases when compared with those in healthy individuals. Multivariate logistic regression models adjusted for potential confounders showed that participants with ≥30 kg m(-2) BMI were at a higher T2DM risk (OR=8.42, 95% CI: 1.97, 45.5; p<0.01) when compared with that of normal weight participants (<25 kg m(-2)). About 4 times higher risk for developing T2DM was observed for individuals in the upper tertile of urinary Br-THM levels (OR=3.99, 95% CI: 1.07, 19.7; p<0.05) when compared with the lower tertile participants. Among the participants with BMI≥25 kg m(-2), urinary Br-THM levels were significantly (p<0.001) higher in diabetics than in healthy individuals. Ingestion and non-ingestion exposures to Br-THM deserve careful consideration in relevant epidemiological studies, as a possible environmental risk factor of T2DM.

Household cleaning activities as noningestion exposure determinants of urinary trihalomethanes

Previous epidemiological studies linking drinking water total trihalomethanes (THM) with pregnancy disorders or bladder cancer have not accounted for specific household cleaning activities that could enhance THM exposures. We examined the relation between household cleaning activities (washing dishes/clothes, mopping, toilet cleaning, and washing windows/surfaces) and urinary THM concentrations accounting for water sources, uses, and demographics. A cross-sectional study (n = 326) was conducted during the summer in Nicosia, Cyprus, linking household addresses to the geocoded public water pipe network, individual household tap water, and urinary THM measurements. Household tap water THM concentrations ranged between 3-129 μg L(-1), while the median (Q1, Q3) creatinine-adjusted urinary THM concentration in females (669 ng g(-1) (353, 1377)) was significantly (p < 0.001) higher than that in males (399 ng g(-1), (256, 681)). Exposure assessment, based on THM exposure equivalency units, showed that hand dishwashing, mopping, and toilet cleaning significantly (p < 0.001) increased urinary THM levels. The effect of dishwashing by females ≥36 y of age remained significant, even after adjusting for potential confounders. No significant (p > 0.05) association was observed between ingestion-based THM exposure equivalency units and urinary THM. Noningestion routes of THM exposures during performance of routine household cleaning activities were shown for the first time to exert a major influence on urinary THM levels. It is warranted that future pregnancy-birth cohorts include monitoring of noningestion household THM exposures in their study design.

Occurrence and distribution of organic trace substances in waters from the Three Gorges Reservoir, China

This study deals with the evaluation of water quality of the Three Gorges Reservoir (TGR) in order to assess its suitability as a raw water source for drinking water production. Therefore, water samples from (1) surface water, (2) tap water, and (3) wastewater treatment plant effluents were taken randomly by 2011-2012 in the area of the TGR and were analyzed for seven different organic contaminant groups (207 substances in total), applying nine different analytical methods. In the three sampled water sources, typical contaminant patterns were found, i.e., pesticides and polycyclic aromatic hydrocarbons (PAH) in surface water with concentrations of 0.020-3.5 μg/L and 0.004-0.12 μg/L, disinfection by-products in tap water with concentrations of 0.050-79 μg/L, and pharmaceuticals in wastewater treatment plant effluents with concentrations of 0.020-0.76 μg/L, respectively. The most frequently detected organic compounds in surface water (45 positives out of 57 samples) were the pyridine pesticides clopyralid and picloram. The concentrations might indicate that they are used on a regular basis and in conjunction in the area of the TGR. Three- and four-ring PAH were ubiquitously distributed, while the poorly soluble five- and six-ring members, perfluorinated compounds, polychlorinated biphenyls, and polybrominated diphenyl ethers, were below the detection limit. In general, the detected concentrations in TGR are in the same range or even lower compared to surface waters in western industrialized countries, although contaminant loads can still be high due to a high discharge. With the exception of the two pesticides, clopyralid and picloram, concentrations of the investigated organic pollutants in TGR meet the limits of the Chinese Standards for Drinking Water Quality GB 5749 (Ministry of Health of China and Standardization Administration of China 2006) and the European Union (EU) Council Directive 98/83/EC on the quality of water intended for human consumption (The Council of the European Union 1998), or rather, the EU Directive on environmental quality standards in the field of water policy (The European Parliament and The Council of the European Union 2008). Therefore, the suggested use of surface water from TGR for drinking water purposes is a valid option. Current treatment methods, however, do not seem to be efficient since organic pollutants were detected in significant concentrations in purified tap water.