In Bangladesh, contamination of drinking water with arsenic is widespread and health effects from arsenic exposure during pregnancy, childhood, and adult life have been widely studied in recent years. Much less attention has been paid to other drinking water contaminants, although some studies of the neurotoxic and reproductive effects of manganese have been reported. Information on well water contaminants was systematically collected in 1998–2000 by the Government of Bangladesh, together with the British Geological Survey (BGS), which analyzed water from 3,534 tube-wells from 61 of the 64 districts in Bangladesh [1
]. In addition to arsenic and manganese, 18 other constituents were measured, including zinc. Zinc was of interest for three reasons. First, zinc deficiency has long been a concern for fetal health and a considerable number of trials have been conducted of the effects of zinc supplementation in pregnancy. A trial in Bangladesh did not show beneficial effects of supplementation [2
], but a Cochrane review of 17 randomised controlled trials found a reduced number of preterm births in mothers receiving zinc (typically 20–30 mg/day) [3
]. The second reason for interest in zinc arose from the use of zinc supplementation as treatment to reduce the duration and severity of diarrhoea once symptoms had appeared [4
]. Infant mortality in Bangladesh, as elsewhere in the developing world, has historically reflected high rates of diarrhoea. Following a worldwide trend deaths from diarrhoea have been reduced in Bangladesh in recent years [5
]. In Bangladesh this may reflect the increased access to relatively bacteria free water from tube wells as well as use of oral rehydration salts (ORS) and, most recently, zinc supplementation in diarrhoeal treatment. Third, there have been a significant number of trials (37 in the most recent meta-analysis) in which zinc supplementation has been used as an attempt to prevent rather that treat diarrhoea [6
]. While a great deal of heterogeneity in results was found, it appeared that trials in Asia had been effective in preventing incident diarrhoea: none had looked at deaths specifically from diarrhoea. As part of our ongoing work with Gonoshasthaya Kendra (GK), an NGO with responsibility for health care of some 600 villages, information on infant mortality was available for villages in all Divisions of Bangladesh except Khulna and Sylhet. This information, initially analysed for the relationship of infant mortality to arsenic and manganese in well water [7
], has been used in the present report to examine whether higher levels of zinc in drinking water were associated with a reduction in infant mortality, overall or from diarrhoea.