Abstract
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.
Highlights
The use of disinfectants in drinking water to control microbial pathogens (e.g., E. coli and Cryptosporidium) is widely considered one of the greatest advances in public health in the 20th century [1], these disinfectants react with natural organic matter and halide salts in the treatment process and form undesirable disinfectant byproducts (DBPs)
We evaluated the short-term exposure variability of individual regulated DBPs to determine their influence on aggregated THM and haloacetic acids (HAAs) levels
The measured levels of total THMs and HAAs in residential tap water samples were used to summarize the mean concentrations for the entire monitoring period (May–August) by each treatment station for their use in analyzing the central tendency and variability in THMs and HAAs (Table 3)
Summary
The use of disinfectants (e.g., chlorine or chloramine) in drinking water to control microbial pathogens (e.g., E. coli and Cryptosporidium) is widely considered one of the greatest advances in public health in the 20th century [1], these disinfectants react with natural organic matter and halide salts in the treatment process and form undesirable disinfectant byproducts (DBPs). 600 DBPs have been identified and nearly 80 DBPs have been measured in drinking water [2,3,4]. Trihalomethanes (THMs) were the first group of DBPs detected in finished drinking water and have been regulated since 1979 due to their association with elevated chronic cancer risk [5]. In 1998, haloacetic acids (HAAs) were regulated as the second group of DBPs due to their frequent occurrence in the disinfected water supply [6]. Public Health 2017, 14, 548; doi:10.3390/ijerph14050548 www.mdpi.com/journal/ijerph
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