1. Water Missions International, 1150 Kinzer Street, Building 1605, N. Charleston, SC 29405-1484, USA
2. Department of Environmental Sciences and Engineering, Gillings School of Global Public Health, University of North Carolina, Chapel Hill, NC 27599, USA
3. Division of Environmental Health, School of Public Health, Georgia State University, 140 Decatur St, Atlanta, GA 30302, USA