When Does Nitrate Become a Risk for Humans?

Abstract

Is nitrate harmful to humans? Are the current limits for nitrate concentration in drinking water justified by science? There is substantial disagreement among scientists over the interpretation of evidence on the issue. There are two main health issues: the linkage between nitrate and (i) infant methaemoglobinaemia, also known as blue baby syndrome, and (ii) cancers of the digestive tract. The evidence for nitrate as a cause of these serious diseases remains controversial. On one hand there is evidence that shows there is no clear association between nitrate in drinking water and the two main health issues with which it has been linked, and there is even evidence emerging of a possible benefit of nitrate in cardiovascular health. There is also evidence of nitrate intake giving protection against infections such as gastroenteritis. Some scientists suggest that there is sufficient evidence for increasing the permitted concentration of nitrate in drinking water without increasing risks to human health. However, subgroups within a population may be more susceptible than others to the adverse health effects of nitrate. Moreover, individuals with increased rates of endogenous formation of carcinogenic N‐nitroso compounds are likely to be susceptible to the development of cancers in the digestive system. Given the lack of consensus, there is an urgent need for a comprehensive, independent study to determine whether the current nitrate limit for drinking water is scientifically justified or whether it could safely be raised.

Mineral-Based Slow Release Fertilizers: A Review

“…In a soil, nitrogen from fertilizers is likely to be transformed to nitrate which is highly mobile via runoff or leaching. The high concentration of nitrate in groundwater or drinking water may cause the "Blue Baby Syndrome" mainly in infants preventing red blood cells from carrying sufficient oxygen (Powlson et al, 2008). Therefore, the efficient use of fertilizers to meet the demand for macronutrients (nitrogen, phosphorus, and potassium) is of great importance and a key in the productivity of agriculture and protection of environment and health.…”

Nitrate, sulphate and chloride contents in public drinking water supplies in Sicily, Italy

“…The high rates of nitrogen fertilization, particularly on permeable soils with shallow water tables, result in the concentration of nitrate in groundwater being significantly higher than background levels in many agricultural areas. How nitrate influences human health is strongly debated (Powlson et al 2008). The maximum admissible concentration (MAC) in most countries is within the range of 45-50 mg/l.…”

On the fate of anthropogenic nitrogen

“…Some environmental effects are obvious, including the expanding summertime hypoxic zone in the Gulf of Mexico (4) and rising concentrations of nitrous oxide in Earth's atmosphere (5). Other consequences, such as the health impacts of nitrate in drinking water are less clear (6).…”