Chlorination disinfection byproducts in water and their association with adverse reproductive outcomes: a review

Abstract

Objectives and methods-Chlorination has been the major disinfectant process for domestic drinking water for many years. Concern about the potential health eVects of the byproducts of chlorination has prompted the investigation of the possible association between exposure to these byproducts and incidence of human cancer, and more recently, with adverse reproductive outcomes. This paper evaluates both the toxicological and epidemiological data involving chlorination disinfection byproducts (DBPs) and adverse reproductive outcomes, and makes recommendations for future research. Results and conclusions-Relatively few toxicological and epidemiological studies have been carried out examining the eVects of DBPs on reproductive health outcomes. The main outcomes of interest so far have been low birth weight, preterm delivery, spontaneous abortions, stillbirth, and birth defects-in particular central nervous system, major cardiac defects, oral cleft, and respiratory, and neural tube defects. Various toxicological and epidemiological studies point towards an association between trihalomethanes (THMs), one of the main DBPs and marker for total DBP load, and (low) birth weight, although the evidence is not conclusive. Administered doses in toxicological studies have been high and even though epidemiological studies have mostly shown excess risks, these were often not significant and the assessment of exposure was often limited. Some studies have shown associations for DBPs and other outcomes such as spontaneous abortions, stillbirth and birth defects, and although the evidence for these associations is weaker it is gaining weight. There is no evidence for an association between THMs and preterm delivery. The main limitation of most studies so far has been the relatively crude methodology, in particular for assessment of exposure. Recommendations-Large, well designed epidemiological studies focusing on well defined end points taking into account relevant confounders and with particular emphasis on exposure characterisation are ideally needed to confirm or refute these preliminary findings. In practice, these studies may be impracticable, partly due to the cost involved, but this is an issue that can be put right-for example, by use of subsets of the population in the design of exposure models. The studies should also reflect diVerences of culture and water treatment in diVerent parts of the world. To identify the specific components that may be of aetiological concern and hence to fit the most appropriate exposure model with which to investigate human exposure to chlorinated DBPs, further detailed toxicological assessments of the mixture of byproducts commonly found in drinking water are also needed. (Occup Environ Med 2000;57:73-85)

Inter- and intra-ethnic variation in water intake, contact, and source estimates among Tucson residents: Implications for exposure analysis

“…However, there is a growing body of literature suggesting that the quality of bottled water is suspect ( Allen et al, 1991;Fayad et al, 1997;Lalumandier, 2000;McSwane et al, 1994;Natural Resources Defense Council, 1999;Page et al, 1993 ). Other studies raise concerns about the health effects of chlorinated tap water, particularly in the area of reproductive outcomes (Kallen and Robert, 2000; Magnus et al, 1999;Nieuwenhuijsen et al, 2000;Swan and Waller, 1998;Swan et al, 1988 ). It remains unclear if either bottled or tap water is less likely to pose a risk to the public.…”

“…It remains unclear if either bottled or tap water is less likely to pose a risk to the public. Toxicological and exposure studies are stymied by the fact that bottled water is widely distributed, not source specific, and inconsistently regulated ( Nieuwenhuijsen et al, 2000;U.S. EPA, 2000 ).…”

Predictors of use and consumption of public drinking water among pregnant women

“…Exposure to disinfection by-products (DBPs) has been associated with an increased risk of bladder cancer (Villanueva et al, 2004), and, while there might also be an association with adverse reproductive outcomes, the nature of this potential effect remains unclear (Nieuwenhuijsen et al, 2000a;Graves et al, 2001;Bove et al, 2002). Many of the epidemiological studies have relied on approximate measures of DBP exposure, such as concentration in the study subject's municipal water source, potentially resulting in substantial exposure misclassification.…”

Modelling exposure to disinfection by-products in drinking water for an epidemiological study of adverse birth outcomes

“…However, chlorine reacts with natural organic matter and bromide present in the raw water to form a wide range of compounds known as disinfection by-products (DBPs). There has been concern over the potential health effects of these DBPs (Cantor 1994;Nieuwenhuijsen et al 2000a) and we are currently conducting an epidemiological study of DBPs and adverse birth outcomes in the UK (Toledano, 2004). As an index of exposure to DBPs in this study, we use the concentration of trihalomethanes (THMs) in the water supply.…”