The effect of the Environmental Protection Agency maximum contaminant level on arsenic exposure in the USA from 2003 to 2014: an analysis of the National Health and Nutrition Examination Survey (NHANES)

Abstract

BackgroundThe current US Environmental Protection Agency (EPA) maximum contaminant level (MCL) for arsenic in public water systems (10 µg/L) took effect in 2006. Arsenic is not federally regulated in private wells. The impact of the 2006 MCL on arsenic exposure in the US, as confirmed through biomarkers, is presently unknown. We evaluated national trends in water arsenic exposure in the US, hypothesizing that urinary arsenic levels would decrease over time among participants using public water systems but not among those using well water. We further estimated the expected number of avoided lung, bladder, and skin cancer cases.MethodsWe evaluated 14,127 participants in the National Health and Nutrition Examination Survey (NHANES) 2003–2014 with urinary dimethylarsinate (DMA) and total arsenic available. To isolate water exposure, we expanded a residual-based method to remove tobacco and dietary contributions of arsenic. We applied EPA risk assessment approaches to estimate the expected annual number of avoided cancer cases comparing arsenic exposure in 2013–2014 vs. 2003–2004.FindingsAmong public water users, fully adjusted geometric means (GMs) of DMA decreased from 3.01 µg/L in 2003–2004 to 2.49 µg/L in 2013–2014 (17% reduction; 95% confidence interval 10%, 24%; p-trend<0.01); no change was observed among well water users (p-trend= 0.35). Assuming these estimated exposure reductions will remain similar across a lifetime, we estimate a reduction of 200 to 900 lung and bladder cancer cases per year depending on the approach used.InterpretationThe decline in urinary arsenic among public water but not private well users in NHANES 2003–2014 indicates that the implementation of the current MCL has reduced arsenic exposure in the US population. Our study supports prior work showing that well water users are inadequately protected against drinking water arsenic, and confirms the critical role of federal drinking water regulations in reducing toxic exposures and protecting human health.FundingThis work was supported by the National Institute of Environmental Health Sciences (1R01ES025216, R01ES021367, 5P30ES009089 and P42ES010349). A. E. Nigra was supported by 5T32ES007322.

Positive Association of Cardiovascular Disease (CVD) with Chronic Exposure to Drinking Water Arsenic (As) at Concentrations below the WHO Provisional Guideline Value: A Systematic Review and Meta-analysis

“…Originating from either geological or anthropogenic activities, arsenic (As) has been widely recognized since the 1950s as one of the most serious human carcinogens [1,2]. Ubiquitously present in the environment [3][4][5], exposure to As can take place via ingestion (oral), dermal contact, inhalation, and even parenteral routes [6], and can lead to a wide range of carcinogenic and non-carcinogenic end-points [7,8]. Long-term As exposure is known to result in lung, bladder, liver, skin and kidney cancers [9].…”

US Water Pollution Regulation over the Past Half Century: Burning Waters to Crystal Springs?

“…This analysis does not have a control group, though it does find an abrupt change in a time series. Nigra et al (2017) show that urinary arsenic concentrations in a national sample of 14,000 Americans had similar trends before the year 2008 for Americans who drank water from public systems versus for Americans who drank well water. After 2008, arsenic concentrations fell for individuals using public water systems but did not change for individuals drinking well water, which did not face new regulations.…”

Underutilized and Under Threat: Environmental Policy as a Tool to Address Diabetes Risk

“…While arsenic policy changed for public water, it did not change for well water where the arsenic MCL is not enforced. Following the adoption of the lower MCL for arsenic, public water users experienced a 17% reduction in dimethylarsinate (DMA) levels, the main metabolite of inorganic arsenic in humans, following the change in MCL, while levels among private well users were unchanged; this indicates both inadequate protection where arsenic MCLs were not enforced and reductions in exposure for those under the new MCL [43••, 44••]. Importantly, the MCLs and treatment technique requirements under the Safe Drinking Water Act allow available technology and economic costs to be considered along with risks to public health when determining targets and remediation techniques.…”