Nitrates are a class of compounds that contain nitrogen. They can occur naturally in air, water, and soil, and living things need them to survive. Nitrates are used for industrial purposes to make fertilizers, ammunition, and explosives. They are also used to preserve food, most commonly in the process of curing meat. Many vegetables we eat are naturally rich in nitrates as well.

When nitrate-containing fertilizers are used on crops or yards, the nitrates can easily migrate into surface water and groundwater. This means that people who work with these fertilizers or live near where they are applied could be exposed to nitrates in their drinking water. For most of the population, nitrate exposure happens through the food we eat. The amount of nitrates consumed in a normal diet is generally considered safe, and much of the nitrates our bodies ingest or make naturally are excreted every day. However, people may be exposed to high levels of nitrates by eating lots of foods rich in nitrates such as spinach, lettuce, cured meat, processed meat, fish, and beer.

Once consumed, the body can convert nitrates into similar compounds called nitrites. High levels of nitrites can decrease the blood’s ability to carry oxygen to our cells. This can cause dizziness, headaches, cramps, vomiting, decreased blood pressure, increased heart rate, and death. Infants seem to be more sensitive to the health effects of nitrite exposure than adults.

Once nitrates get converted into nitrites in the body, they can be further converted into compounds called nitrosamines, which are known to cause cancer. For this reason, the International Agency for Research on Cancer has determined that ingesting nitrates probably causes cancer in humans. Because nitrates occur in nature and are made naturally by our bodies, it can be hard to know our exposure risk from dietary and industrial sources. This makes it particularly important for the federal government to regulate nitrates from sources such as fertilizers and food preservation in order to keep people safe from the adverse health effects of exposure.