1. Department
of Civil and Environmental Engineering, Stanford University, Stanford, California 94305, United States
2. Division
of Epidemiology, University of California, Berkeley, Berkeley, California 94720, United States
3. Office of Research & Development, U.S. Environmental Protection Agency, Cincinnati, Ohio 45268, United States
4. International Center for Diarrheal Diseases Research, Bangladesh, Dhaka 1000, Bangladesh
5. The World Bank, Washington, D.C. 20433, United States
6. Woods
Institute
for the Environment, Stanford University, Stanford, California 94305, United States