Assessing Exposure and Health Consequences of Chemicals in Drinking Water: Current State of Knowledge and Research Needs

Abstract

Background: Safe drinking water is essential for well-being. Although microbiological contamination remains the largest cause of water-related morbidity and mortality globally, chemicals in water supplies may also cause disease, and evidence of the human health consequences is limited or lacking for many of them.Objectives: We aimed to summarize the state of knowledge, identify gaps in understanding, and provide recommendations for epidemiological research relating to chemicals occurring in drinking water.Discussion: Assessing exposure and the health consequences of chemicals in drinking water is challenging. Exposures are typically at low concentrations, measurements in water are frequently insufficient, chemicals are present in mixtures, exposure periods are usually long, multiple exposure routes may be involved, and valid biomarkers reflecting the relevant exposure period are scarce. In addition, the magnitude of the relative risks tends to be small.Conclusions: Research should include well-designed epidemiological studies covering regions with contrasting contaminant levels and sufficient sample size; comprehensive evaluation of contaminant occurrence in combination with bioassays integrating the effect of complex mixtures; sufficient numbers of measurements in water to evaluate geographical and temporal variability; detailed information on personal habits resulting in exposure (e.g., ingestion, showering, swimming, diet); collection of biological samples to measure relevant biomarkers; and advanced statistical models to estimate exposure and relative risks, considering methods to address measurement error. Last, the incorporation of molecular markers of early biological effects and genetic susceptibility is essential to understand the mechanisms of action. There is a particular knowledge gap and need to evaluate human exposure and the risks of a wide range of emerging contaminants.Citation: Villanueva CM, Kogevinas M, Cordier S, Templeton MR, Vermeulen R, Nuckols JR, Nieuwenhuijsen MJ, Levallois P. 2014. Assessing exposure and health consequences of chemicals in drinking water: current state of knowledge and research needs. Environ Health Perspect 122:213–221; http://dx.doi.org/10.1289/ehp.1206229

Biomarkers of chronic fluoride exposure in groundwater in a highly exposed population

“…Globally, drinking water continues to be a primary route of exposure to F − at levels that exceed the optimum F − concentrations to protecting dental decay and many naturally occurring contaminants of major public health concern (Meacher et al, 2002; Villanueva et al, 2014; WHO, 2016). This study demonstrated that many individuals in this region of the world are exposed to unacceptable and harmful levels of drinking water F − ranging up to 15 mg/L.…”

Effect-based trigger values for in vitro bioassays: Reading across from existing water quality guideline values

“…Given the overwhelming number of chemicals present in water (Schwarzenbach et al, 2006;Villanueva et al, 2014), chemical analysis has been complemented for many years by in vitro bioassays which not only give information on the level of effect but also on the type of effect, i.e., the mode of action. Further, bioanalytical tools also integrate the mixture effects of chemicals that act according to the same mode of action in a concentrationadditive manner (Escher and Leusch, 2012).…”

Relevance of Assessment Methods for Fluid Intake

“…data at population level, it is not possible to firmly establish these links, investigate dose-response relationships or develop meaningful public health policies or reference intake values. It is important to emphasize that data from population surveys are also used for water quality and exposure studies (e.g., disinfection by-products) [2] . Currently, there is no consensus regarding the most reliable method to assess total fluid intake (TFI, the sum of water and all other beverages) [3] ; for clarity the term TFI, which does not include water from food, will be used in this article.…”