Assessment of lifetime exposure to trihalomethanes through different routes

Abstract

Objectives: To evaluate lifetime exposure to trihalomethanes (THM) through ingestion, inhalation, and dermal absorption in a hospital based case-control study of bladder cancer conducted between 1998 and 2001 in five areas of Spain. The study base was comprised of subjects living in the catchment areas of the participating hospitals. Methods: Individual information on water related habits was obtained from personal interviews of 1219 cases and 1271 controls: residential and occupational history, drinking water source at each residence and job, amount of water consumption, frequency and duration of showering, bathing, and swimming pool attendance. THM levels, water source history, and year when chlorination started in study areas were ascertained through measurements in drinking water samples and questionnaires to water companies and local authorities. Estimates of THM levels covered 79% of the subjects' person-years of exposure. Results: Current and historical average THM levels in water were correlated. Control subjects reported that drinking water source in the last residence was municipal for 63%, bottled for 22%, private well for 2%, and other sources for 13%. For the time window between age 15 and the time of interview, average residential THM level was 32.2 mg/l. THM exposure through ingestion was 23.7 mg/day on average, and was correlated with the ingestion THM level in the workplace. Overall, 79% usually took showers, 16% usually took baths, and 13% had ever attended a swimming pool. Between 21% and 45% of controls unexposed to THM through ingestion were evaluated as moderately or highly exposed through showering or bathing, and 5-10% were exposed through swimming in pools. Conclusion: The importance of evaluating different routes is underscored by findings from experimental studies showing substantial differences in THM uptake and internal distribution by route.D isinfection by-products (DBP) have been associated with elevated risk of several types of cancer, with evidence most consistent for the urinary bladder. This is particularly true among studies that incorporated a detailed evaluation of exposure to trihalomethanes (THM, the most prevalent group of chlorination by-products) as an index of exposure to DBP. [1][2][3][4] Relative risks in these studies were generally below 2.0, and despite the consistency of the evidence, concerns remain about the validity of these findings, particularly regarding the evaluation of exposure.DBP constitute a complex mixture of hundreds of compounds with heterogeneous physical and chemical properties, different mutagenic and carcinogenic potential, and with temporal and spatial variability. 5 6 Different exposure pathways (ingestion, inhalation, dermal absorption) depend on the type of DBP and the exposure setting, such as drinking the water or beverage made up with water, showering, bathing, swimming in pools, and to a lesser extent other water related activities such as washing dishes, cooking, and washing children. [7][8][9][10] Recent studies show that inhalation ...

Occurrence of Trihalomethanes in Chlorinated Waters from Different Sources Used for Urban Supply

“…The Total THMs concentration was in agreement with drinking water quality standards in 100% of the results [6], being below the European parametric value (100 μg/L), as well as in accordance with the criteria set by WHO based on a fractionation approach. However, regarding other European countries such as Germany, Luxembourg and Sweden regulations, only 69.7% of water samples complied with the limit of 50µg/L.…”

“…Individual exposure to THMs from tap water can occur not only through ingestion, but also by inhalation of indoor air, largely due to volatilization from drinking-water, or 58 Occurrence of Trihalomethanes in Chlorinated Waters from Different Sources Used for Urban Supply dermal exposure during showering or bathing since TTHM through ingestion composed less than 10% of integrated internal dose [5,6].…”

“…Considering health outcomes from lifelong exposure and the limited information about the risks and uncertainties that arise from mixtures effects, efforts are currently made by water suppliers and legislators to maintain the concentrations of THMs as low as reasonably achievable without compromising the effectiveness of disinfection [6,13,14].…”

Risk of Bladder Cancer Associated with Family History of Cancer: Do Low-Penetrance Polymorphisms Account for the Increase in Risk?

“…Furthermore, regular smokers were classified into two groups according to the duration smoked, <20 or z20 years (26). To adjust analyses by environmental shared risk factors among first-degree relatives, we considered exposure to environmental tobacco smoke (ETS) among nonsmokers, which was assessed by asking subjects for the number of persons who smoked around them at every residence and every job held (26) and lifelong average residential trihalomethane levels (Ag/L), as recorded by Villanueva et al (27).…”

DNA methylation levels and long-term trihalomethane exposure in drinking water: an epigenome-wide association study

“…Residential histories and estimated THM levels were merged by zip code and year to estimate average THM levels from age 18 to the time of interview in study subjects, according to previously published methodology. 47 Subjects included in this analysis had THM exposure data covering at least 70% of years from age 18 until the time of interview, with an average (range) of available data of 95.2% (74.1-100) of the years.…”