In a new World Bank report that looks at the impact of water pollution worldwide, one aspect covered is the long-term impact of nitrate exposure experienced during infancy. While short-term exposure to nitrates has almost negligible effect on adult height, cumulative exposure over the first three years of life has considerable impact.
An infant girl who has been exposed to nitrate levels above the safety threshold in the first three years experiences a 1-2 cm decrease in her adult height, the report found. Given that female adult height in India has increased by approximately 4 cm over the last century, a 1-2 cm loss means that nitrate exposure in infancy can wipe out almost half of this gain in height.
Nitrate pollution is caused by the overuse of nitrogenous fertilisers which, while boosting yields, can be harmful if they leach into water or air. In India, the Green Revolution of the 1960s kick-started the use of synthetic fertilisers, the report notes.
The data set used was taken from over 1,330 monitoring stations from 1963-2017. The birth years of the sample range was from 1966-1999, “a period when the effect of the Green Revolution was already in force yet nitrogen fertilisers were increasing in use.”
The report also found (using data from the Central Groundwater Board of India) that nitrate levels in groundwater aquifers exceeded permissible levels in more than 50 per cent of the districts across 19 states.
The report broadly covers two types of pollutants — the well known ones such as faecal contaminants and the new pollutants that include plastic, nutrients and pharmaceuticals.