Long-term effects of exposure to high levels of nitrates in drinking water include shorter height, says World Bank study
The use of nitrogen-based fertilizers in agriculture and rapid urbanization have meant that the state of ground and surface water has significantly deteriorated. Exposure to polluted water during childhood significantly damages health and economic well-being, according to a World Bank study in which researchers Esha Zaveri and others measure the effects of childhood exposure to nitrogen-polluted water in India, Vietnam and African nations.
For India, the authors combine district-level data from the National Family Health Survey (2015-16) with water quality data from monitoring stations across 375 rivers in India (between 1963-2017). Using upstream and downstream river flows to ascertain the direction in which pollutants flow, the researchers track pollution exposure at the district-level for women between their births and the age of three. They find that women exposed to nitrate pollution exceeding safe limits (10mg/l) during their early childhood were shorter (by 2.2 cm) than women not exposed to it. For the more polluted downstream districts, where faecal matter accompanies upstream nitrates, the effects are worse, with the height difference increasing to 3 cm. This stunted development can have economic costs. Using World Bank assumptions on the economic returns of height, the study estimates a 1.7% loss in earning potential for shorter people because of pollution exposure. The link between pollution, height and well-being is also found to hold true for Vietnam and Africa, where stunting in infant years is a direct outcome of exposure to pollution.
In India, the study finds the damaging health effects persist even when pollution levels are below the government’s prescribed safety limits for Indian rivers. Consequently, the authors urge policymakers to rethink the safety standards of drinking water in India.