Nitrate can be converted into carcinogenic substances in the body. Scientists found that people whose drinking water had high nitrate concentrations had a higher risk of colon cancer than people with less nitrate pollution in their drinking water. The nitrate values, which increased the risk of colon cancer, were well below the limit prescribed in Germany.

The concentrations of nitrate in the drinking water that 1.7 million adults were exposed to could be determined fairly accurately. High nitrate concentrations in drinking water increased the risk of colon cancer (source DGP)

The main reason for excessive nitrate levels in the soil is the large amounts of manure that livestock farms apply to agricultural land. (Slurry is animal excrement, i.e. faeces and urine, which result from the factory farming of pigs and cattle). It is reported as fertilization, but corresponds more to disposal. The EU has repeatedly threatened lawsuits. The state of Schleswig-Holstein has started to map areas with high nitrate concentrations.

Slurry may contain residues of veterinary medicines and feed additives. Especially in intensive livestock farming, in which antibiotics are used on a large scale, the animals excrete a large part of the substances in the faeces and urine unchanged.