Moving towards transformational WASH – Authors' reply
Authors: Amy J Pickering, Benjamin F Arnold, Andrew J Prendergast, Clair Null, Peter J Winch, Sammy M Njenga, Mahbubur Rahman, Robert Ntozini, Jade Benjamin-Chung, Christine P Stewart, John M Colford, Stephen Luby, Jean H Humphrey
Journal: The Lancet Global Health (2019)

We agree with Karen Levy and Joseph Eisenberg that observational studies of water, sanitation, and hygiene (WASH) interventions with carefully designed counterfactuals can play a valuable role in generating evidence on effectiveness, particularly in urban settings. Randomised controlled trials for community-level WASH infrastructure interventions are not always feasible in urban settings, because of the political and logistical constraints of defining treatment and control groups; strong observational designs could help fill the gap.1Ercumen A Arnold BF Kumpel E et al.Upgrading a piped water supply from intermittent to continuous delivery and association with waterborne illness: a matched cohort study in urban India.PLoS Med. 2015; 12e1001892Crossref PubMed Scopus (43) Google Scholar With increasing urbanisation in Asia and Africa, WASH intervention studies in low-income urban communities will be crucial for informing strategies to meet Sustainable Development Goal (SDG) target 6.1: to achieve universal and equitable access to safe and affordable drinking water for all. We also appreciate the comments about our paper by Josh Kearns, who draws attention to the important issue of human exposure to environmental chemical contamination in low-income communities. The WASH Benefits trials and the Sanitation, Hygiene, Infant Nutrition Efficacy (SHINE) trial delivered interventions designed to minimise children's exposure to faecal contamination in the domestic environment, an objective motivated by the hypothesis that enteropathogen infections could contribute to growth faltering in children in low-resource settings. The trial sites in Kenya, Bangladesh, and Zimbabwe are rural settings unlikely to be affected by large-scale industrial pollution, and the Bangladesh site excluded areas with a large amount of arsenic in drinking water. Although the presence of chemical contaminants from pesticides, fertilisers, and small-scale mining in the study areas is possible, we believe the evidence from the trials does not support chemical contamination being the main explanation for the failure of the WASH interventions to improve child growth. First, we observed growth improvements in the nutrition intervention groups in all three trial sites. Second, household faecal contamination and enteropathogen infections remained pervasive in all three trial sites, indicating that the WASH interventions did not comprehensively interrupt faecal-oral transmission routes. We agree that WASH interventions should consider chemical contaminants. The monitoring guidelines for SDG target 6.1 define safely managed drinking water as "free of faecal and priority chemical contamination". The guidelines list arsenic and fluoride as chemical priorities at the global scale, noting that other priority chemicals vary by country. Additional evidence is needed to inform the selection of other priority chemicals to be targeted by WASH interventions in low-income settings. Measurement of chemical contaminant profiles in drinking water, food, and household soil in rural and urban communities would be valuable, as would epidemiological studies to improve understanding of the effect of specific chemical exposures on child health. Although different treatment methods are often required to address chemical and microbial contaminants in domestic water supplies, one opportunity for synergy might be developing strategies to reduce child exposure to contaminated soil in low-income households—an active area of research within our group and others. Household soil has been highlighted as an important source of animal faeces and enteric pathogens,2Ngure FM Humphrey JH Mbuya MNN et al.Formative research on hygiene behaviors and geophagy among infants and young children and implications of exposure to fecal bacteria.Am J Trop Med Hyg. 2013; 89: 709-716Crossref PubMed Scopus (126) Google Scholar and can also contain heavy metals such as lead, cadmium, nickel, and arsenic.3Forsyth JE Islam MS Parvez SM et al.Prevalence of elevated blood lead levels among pregnant women and sources of lead exposure in rural Bangladesh: a case control study.Environ Res. 2018; 166: 1-9Crossref PubMed Scopus (17) Google Scholar Elevated blood concentrations of lead in children have been associated with the amount of lead in soil in Kenya4Etiang NA Arvelo W Galgalo T et al.Environmental assessment and blood lead levels of children in Owino Uhuru and Bangladesh settlements in Kenya.J Health Pollut. 2018; 8180605Crossref PubMed Scopus (5) Google Scholar and with geophagy (soil eating) in Bangladesh.5Kaiser R Henderson AK Daley WR et al.Blood lead levels of primary school children in Dhaka, Bangladesh.Environ Health Perspect. 2001; 109: 563-566Crossref PubMed Scopus (75) Google Scholar Innovative interventions to prevent children ingesting household soil would have the potential to protect children from both microbial and chemical exposures. AJPi, BFA, CN, MR, and CPS report grants and other support from the Bill & Melinda Gates Foundation, during this study. JMC received salary support and University of California, Berkeley, received the prime award funding for the conduct of the WASH Benefits trials in Bangladesh and Kenya. JHH reports grants from the Bill & Melinda Gates Foundation, the Department for International Development (UK Government), and Swiss Agency for Development and Cooperation, and personal fees from Nestle Nutrition Foundation, outside the submitted work. All other authors declare no competing interests. Moving towards transformational WASHAs noted by the Lancet Commission on pollution and health,1 the anthropogenic release of chemicals from industry and agriculture and the breakdown of consumer waste constitutes a major threat to water and global public health. Chemical pollution is severe and increasing in developing countries, where chemical substances are produced, used, and disposed of in an unregulated manner. The global public health consequences of pollution are similar to or greater than those of widespread infectious diseases, such as HIV/AIDS, tuberculosis, and malaria. Full-Text PDF Open AccessMoving towards transformational WASHThe observational reanalysis by Amy Pickering and colleagues (August, 2019)1 of controls in the WASH Benefits trials and the Sanitation, Hygiene, Infant Nutrition Efficacy (SHINE) trial is a compelling reminder that observational studies are susceptible to confounding bias. However, we should not discount the value of observational studies in global health research, because ethical and logistical issues often limit the feasibility of randomised control trials (RCTs) and observational studies are a requisite precursor to trials. Full-Text PDF Open Access