Benefits and costs of the IESWTR

Like the Stage 1 Disinfectants/Disinfection By-products Rule, the Interim E nhanced Surface Water Treatment Rule (IESWTR) grew out of the negotiated ru lemaking the US Environmental Protection Agency convened in 1992-93 under t he Federal Advisory Committee Act (FACA). The rulemaking sought to develop a consensus approach to simultaneously addressing potential health risks po sed by disinfection by-products (DBPs) and waterborne pathogens. Even thoug h the process was complicated by (1) the possibility of malting inadvertent risk-risk tradeoffs between protection from DBPs and protection from patho gens and (2) uncertainties affecting the assessment of both risks, the regu latory-negotiations committee was able to devise a well-balanced, staged ap proach to regulation. A second FACA committee finalized the approach in 199 6-97. This article summarizes the microbial side of the benefit-cost analys is and the explicit uncertainty analysis that was used to inform the shareh olders and the negotiators.