Benjamin F. Arnold, Jade Benjamin-Chung, and John M. Colford Jr are with the Division of Epidemiology, School of Public Health, University of California, Berkeley. Timothy J. Wade is with the US Environmental Protection Agency (EPA), National Health and Environmental Effects Research Laboratory, Research Triangle Park, NC. Kenneth C. Schiff, John F. Griffith, and Stephen B. Weisberg are with the Southern California Coastal Water Research Project, Costa Mesa, CA. Alfred P. Dufour is with the US EPA,...