Older children and adults are able to withstand much higher levels of nitrates with no risk of methemoglobinemia , because their stronger stomach acid content kills the bacteria. There have been some indications of a potential link between high nitrates in drinking water and gastrointestinal cancer. However, this association is controversial. There have been reports of abnormally high levels of gastic cancer in areas with high nitrate levels in the drinking water. As yet, however, there is no conclusive proof of a link between the two.
Livestock are also susceptible to nitrate poisoning, especially cattle.
Lowered milk production and aborted calves are two signs of the disease. In general, through, livestock can withstand much higher nitrate levels than humans. Sources and health risks of coliform bacteria in water Coliform bacteria are microscopic, generally harmless organisms that live in the intestinal tract of many warm-blooded animals. They are excreted along with feces and may eventually make their way into ground water. Coliform bacteria are not directly disease-causing, but they are often found with other, more dangerous strains of bacteria like shigella and salmonella.