September 19, 2000

Arsenic Drinking Water Standards

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National Primary Drinking Water Regulations: Arsenic Rule

Stated Purpose:

"The proposed arsenic standard is intended to protect consumers against the effects of long-term, chronic exposure to arsenic in drinking water."

Summary of RSP Comment:

Regulation of arsenic in drinking water presents the most compelling case to date for EPA to use its authority to rely on benefit-cost analysis, granted in the 1996 Amendments to the Safe Drinking Water Act. Unfortunately, EPA does not embrace its new mandate enthusiastically. It continues to constrain its decisions in setting drinking water standards with internally-imposed levels of "acceptable risk," and has proposed to set such standards at levels that its own analysis reveals will impose net costs on users of drinking water systems.

EPA has used its benefit-cost analysis in a narrow way -- to reject the "technically feasible" level of 3 micrograms per liter (ug/L) in favor of a slightly less stringent level of 5 ug/L (down from the current level of 50 ug/L). However, its analysis reveals that the selected level is likely to impose more costs than benefits on water systems and (ultimately) their consumers. In fact, EPA's own cost and benefit estimates suggest that all the levels it examined in developing the proposal (ranging from 3 ug/L to 20 ug/L) impose costs greater than benefits.

More robust estimates of benefits and costs reveal an even greater disparity between costs and benefits. After correcting for significant flaws in EPA's benefit and cost estimates, it appears that achieving the proposed standard of 5 ug/L would impose net costs (over and above benefits) of over $1.4 billion per year.

Though arsenic poses acute risks at high doses, it is a naturally occurring substance for which health risks have not been observed at the much lower levels found in U.S. drinking water systems. EPA should reexamine the incremental costs and benefits of achieving different standards, and based on the results of such analysis, it should set drinking water standards that make users of drinking water systems better off, as required by the Safe Drinking Water Act.