From a chemical point of view, Nitrate (NO3 –) is a polyatomic ion, that is, a chemical species made up of several atoms (one nitrogen and three oxygen) with a negative electrical charge.
Its presence in aquifers is almost entirely due to the use of nitrogen fertilisers, synthetic chemical compounds widely used in agriculture.
In fact, nitrogen that is not metabolised by plants penetrates the groundwater and accumulates in the water in the form of nitrate.
Nitrate in itself would not be dangerous to human health, however once taken into the human body, part of it is transformed into a much more harmful species: nitrite (NO2 –).
The greatest health risk from excess nitrate is Methaemoglobinaemia, a disease that impairs the functioning of red blood cells due to oxidation of the haemoglobin within them. In addition, nitrates and nitrites inhibit the proper functioning of the thyroid gland.
Some authors argue that the onset of stomach cancer may be related to excessive nitrate intake.
For this reason, Legislative Decree 31/1 sets the maximum threshold for nitrate concentration in water intended for human consumption at 50 mg/l.