radon has generally remained, despite numerous and sometimes costly public education efforts. Though the evaluation of many of these programs has not been rigorous, on the basis of the reported results, the committee concludes that an education and outreach program would be insufficient to provide a scientifically sound basis for claiming equivalent health-risk reductions and that an active program of mitigation of homes would be needed to demonstrate health-risk reduction.

Furthermore, the mitigation of indoor-air radon concentrations in a small number of homes means risk reduction among only a few people who had high initial risk, rather than uniform risk reduction for a whole population served by the water utility. This approach raises questions of equity among the various groups that are being exposed to various levels of risk associated with radon. Equity issues would also result if the airborne-radon risks in one community were traded for the risks in another without a resulting identical or improved public health effect and a commensurate economic benefit to both communities. Non-economic considerations could play a large role in the evaluation of multimedia mitigation programs and might be the deciding factors in whether to undertake such a program. In any planning process, a careful program of public education, utilizing experts in risk communication, will be essential to give the public an adequate perspective of the tradeoffs in risks being proposed and of the health and economic costs and benefits that will be produced by the various alternatives.

EPA and the state agencies responsible for water quality will continue to be faced with the problem of the health risks associated with the presence of radon in drinking water. The increment in indoor radon that emanates from the water will generally be small compared with the average concentration of radon already present in the dwellings from other sources. Thus, except in situations where concentrations of radon in water are very high, the reduction of radon in water will generally not make a substantial reduction in the total radon-related health risks to occupants of dwellings served by the water supply. However, the risks associated with the waterborne radon are large in comparison with other regulated contaminants in drinking water. Using mitigation of airborne radon to achieve equivalent or greater health-risk reductions therefore makes good sense from a public-health perspective. However, there are concerns that the equity issues associated with the multimedia approach and other related issues will become important in obtaining agreement by all of the stakeholders. This issue will require each public water supply and the regulatory agency overseeing it to study the circumstances carefully before deciding to implement a multimedia mitigation program in lieu of water treatment.

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