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Arsenic exposure in U.S. drinking water declines following new EPA regulations


New research found that arsenic exposure in drinking water was significantly reduced among Americans using public water systems following the Environmental Protection Agency (EPA) regulation on maximum levels of arsenic.

The study, conducted at Columbia University’s Mailman School of Public Health, shows that compliance with the regulation led to a decline of 17% in levels of urinary arsenic, equivalent to an estimated reduction of over 200 cases of lung and bladder disease every year. However, there were no improvements in arsenic exposure rates among users of private wells, which are not federally regulated and provide water to roughly 45.5 million Americans.

According to Columbia University, this is the first study to evaluate the impact of the 2006 implementation of the maximum contaminant level on reducing arsenic exposure at the individual level or by using biomarker data.

Arsenic is an established carcinogen and naturally occurs in drinking water across the U.S. and Canada. In 2006, public water systems were required to meet the new EPA 10 μg/L regulatory limit for the maximum arsenic level in drinking water, down from 50 μg/L. In the southwest states, many cities’ public water supplies come from water sources with naturally high levels of arsenic, including Los Angeles, Albuquerque, Scottsdale and Tucson.

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According to Health Canada, the primary source of arsenic exposure for most Canadians is food, followed by drinking water, soil and air. Under Health Canada’s Guidelines for Canadian Drinking Water Quality, the maximum acceptable concentration for arsenic in drinking water is 0.010 mg/L (10 µg/L).

The Columbia University researchers compared data from 14,127 participants in the National Health and Nutrition Examination Survey (NHANES) between 2003 and 2014 who tested for dimethylarsinate (DMA) – the main metabolite of inorganic arsenic in humans. They adjusted for other sources of arsenic such as diet and smoking. Arsenic was measured in spot urine samples collected during the examination in a one-third random subsample of participants six years of age or older.

Among public water users, approximately 70% of participants, arsenic levels decreased from 3.01 μg/L in 2003-2004 to 2.49 μg/L in 2013-2014, or by 17%.

“The 17% reduction in water arsenic exposure for public water users represents a significant exposure reduction when applied at the population level,” said Ana Navas-Acien, MD, PhD, professor of Environmental Health Sciences at the Mailman School, and co-author.

The decrease was only observed after 2009-2010, consistent with the regulatory compliance process under the Safe Drinking Water Act, which required time for testing, and time to address the problem by changing the source or installing water treatment.

The authors estimate that the reduction in exposure to arsenic is equivalent to a reduction of 200 cases of lung and bladder cancer per year, but could be as many as 900 cases. There was no change recorded among well water users. It has been estimated that 1.7 million Americans are at risk of exposure to arsenic above the maximum contaminant level, >10 μg/L and 3.8 million to arsenic > 5 μg/L in household well water.

“To date, no state government requires homeowners to install treatment systems to reduce arsenic if test results for arsenic exceed these contaminant levels. Continuing efforts for additional state and federal initiatives are critical to help families sample, test, and address arsenic exposure from unregulated private wells,” added Navas-Acien.

To read the original news release, visit: www.mailman.columbia.edu

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