# 8. Conclusion

Recent studies have focused attention on the loss of human lives and immediate birth outcomes as a result of water pollution. In a departure from previous studies, this paper underscores the long‐lasting health damages, and decreased economic capability that survivors of water pollution endure. We find a statistically significant negative effect of early‐life exposure to nitrogen pollution on women’s height in India, with supporting evidence of a decrease in child height in Vietnam, and infant HAZ scores and increased incidence of stunting in Africa. These results are robust to several checks for confounding factors. By demonstrating the long‐term effects of nitrogen pollution, our results draw attention to the critical role that local environmental spillovers play for population health outcomes and highlight the need for closer policy attention to nitrogen pollution.

The policy relevance of our results is underscored by the fact that health effects also emerge at levels well below prescribed limits, raising questions about what constitutes safe standards for nitrates in water. Emerging evidence from epidemiological studies has also found relationships between nitrate ingestion and cancer, thyroid disease, and adverse pregnancy outcomes, such as neural tube defects, at concentrations below regulatory limits (Temkin et al., forthcoming; Ward et al. 2018). Even as far back as 1977, a report by the U.S. National Academy of Sciences warned that “there is little margin of safety” in the 10 mg/L safety limit for nitrates (National Research Council 1977). More research and assessments across even more geographies and populations are needed to make definitive claims. It is possible that future research will uncover even more health effects as more data become available to link <mark>exposures that began decades ago to diseases that develop today.</mark> However, the body of evidence so far suggests that there still remains a great deal of uncertainty surrounding drinking water standards for nitrates set by environmental agencies. The magnitude of people impacted by nitrate contaminated water is, therefore, likely to be much larger than presently thought.

This work also speaks to the consequentiality of fertilizer subsidies in developing countries that are tipped in the favor of nitrogen fertilizer use. In India, a system of domestic price controls by way of large subsidies has significantly distorted market prices for nitrogen fertilizer compared to other nutrients, resulting in an inefficient balance of fertilizer application (Gulati and Banerjee 2015). By 2015, subsidy costs amounted to $11.6 billion per year in India, roughly five times more than what was recorded 15 years earlier (Gulati and Banerjee 2015). This is exemplified by the wide gap between global and Indian domestic nitrogen prices ‐‐‐world prices were almost four times higher than regulated Indian prices in 2014 (Huang, Gulati, and Gregory 2017). In recent years the government has made efforts to improve nitrogen use efficiency in agriculture and has mandated urea manufacturers to produce neem‐coated urea. Since neem acts as a nitrification inhibitor, it allows a more gradual release of nitrogen into the soil, thereby 14