Study calls for five-fold reduction of arsenic limit in US Drinking Water

The U.S. EPA should reduce the allowable level of arsenic in drinking water supplies from 50 micrograms/litre to 10 micrograms/litre as soon as possible, says a new report by a committee of the National Research Council (NRC).

Arsenic has long been identified as a toxicant, and in drinking water it has been associated with skin cancer and other disorders. But recent studies suggest that drinking water with high levels of arsenic also can lead to bladder and lung cancer, which are more likely to be fatal.

“New information on arsenic exposure and cancer indicate that EPA’s current standard for acceptable levels of arsenic in drinking water does not sufficiently protect public health,” said committee chair Robert Goyer, professor emeritus of pathology, University of Western Ontario (retired), Chapel Hill, N.C. “Although additional research on arsenic is needed, available data indicate that EPA should set a new standard to ensure that amounts of arsenic in U.S. drinking water supplies are at levels that minimize potential health risks.”

The American Water Works Association (AWWA) has called on the U.S. Environmental Protection Agency (USEPA) to base its proposal to revise the current standard for arsenic levels in drinking water on a National NRC study.

“We believe that public health must be at the forefront of all criteria in establishing new drinking water standards,” said Jack Hoffbuhr, executive director for AWWA. “Although it did not take into account the costs of reducing arsenic levels, today’s study is a major first step in using a sound scientific review process to determine the effect that low-levels of arsenic have on public health”

Utility costs to lower arsenic levels could reach $1 billion a year, according to a 1997 study commissioned by AWWA. The study showed that up to 2,200 of the 56,000 U.S. water supply systems would be affected if the allowable level of arsenic were lowered from 50 parts per billion (ppb) to 10 ppb.

Inorganic arsenic, the form most likely to cause cancer, is a naturally occurring element in the Earth’s crust. Arsenic is released into ground water that travels through underground rocks and soil. Water from wells often has higher concentrations of arsenic than does surface water such as lakes and streams. Arsenic also can be found in plants, fish, and shellfish.

Serious health problems associated with very high levels of arsenic in drinking water have surfaced recently in India and Bangladesh. In the United States, water supplies rarely contain levels of arsenic above EPA’s current maximum allowable amount of 50 micrograms of arsenic per litre of water. The standard was developed decades ago, and remained in place after EPA performed an assessment of skin cancer risks in 1988. However, the EPA assessment did not include risks for lung and bladder cancer.

New data and more precise models for estimating risk suggest that the likelihood of developing cancer from drinking water that contains the maximum allowable amount of arsenic greatly increases when lung and bladder cancers are included. For example, studies examining males who daily consume water that contains 50 micrograms of arsenic per litre show that they have about a 1 in 1,000 risk of developing bladder cancer, far exceeding EPA’s goal of limiting cancer risks to 1 in 10,000. Moreover, the committee found that the choice of models used to estimate risks posed by arsenic in drinking water can significantly affect risk estimates.

Congress has required EPA to propose a new maximum allowable amount for arsenic in drinking water by January 2000, and to finalize the new standard by 2001. To help inform the agency’s decision, the Research Council was asked to evaluate the latest information on the health effects of arsenic in drinking water and EPA’s methods for assessing cancer risks. The Research Council committee was not charged with examining water treatment technologies or the economic impact of changing the standard.

The report can be purchased from National Academy Press, or read online by following the link below

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