Evaluation of Costs and Benefits OF A lower arsenic MCL

Abstract

The US Environmental Protection Agency (USEPA) recently proposed that the maximum contaminant level (MCL) for arsenic be revised from 50 to 10 μg/L. This change will have significant economic consequences for water systems. Will the benefits of the revised MCL justify the expense? According to Frost et al, the revised arsenic MCL will result in high costs for uncertain benefits. To support their theory, they examined the cancer health risk studies that were used to support the proposed revision and evaluated the quality of this evidence as well as its cost‐effectiveness. They maintain that the science supporting the proposed new arsenic MCL is fraught with uncertainties. For instance, the arsenic MCL revision is partly based on an extrapolation of arsenic‐related cancer risks from studies in Taiwan to US populations. However, the authors discovered that no US epidemiological studies have found adverse health effects in people who consumed US water supplies that contained arsenic. The authors used estimates of the cost of compliance developed by USEPA and the AWWA Research Foundation and USEPA's estimated reductions in arsenic‐related cancer mortality to calculate the marginal cost per year‐of‐life gained for different MCL options. These costs were then compared with acceptable costs for other public health and medical treatment interventions. Even assuming USEPA's projected benefits and costs, Frost et al maintain that the cost per year of life gained from the proposed regulation is much higher than acceptable costs per year of life gained from medical interventions or other public health programs. With their findings in mind, the authors hope that the drinking water industry will take a more aggressive approach to evaluating the health effects science for new proposed regulations and that their article will initiate a discussion of acceptable costs per unit of benefit for future regulations. Frost and colleagues also hope that the industry, led by AWWA and/or other organizations, will confront USEPA to reform the process used to justify new regulations.