Final answer:
The EPA regulates nitrates and nitrites in food as they can limit blood's oxygen transport ability, potentially leading to methemoglobinemia. Excessive use of these chemicals in fertilizers also contributes to environmental problems like eutrophication.
Step-by-step explanation:
The EPA regulates the presence of nitrates and nitrites in food because they interact with the blood and limit its ability to transport oxygen. Specifically, nitrates can be converted in the body to nitrites, which then react with hemoglobin to form methemoglobin. Methemoglobin cannot effectively release oxygen to body tissues, a condition known as methemoglobinemia. This condition can cause symptoms such as shortness of breath and blue skin, and is especially dangerous for infants.
Moreover, the presence of excessive nitrates and nitrites from human activities, such as the use of artificial fertilizers or the combustion of fossil fuels, can lead to environmental issues such as eutrophication. This process, enhanced by high nutrient loads, results in the overgrowth of algae in water bodies, depleting dissolved oxygen and creating hypoxic 'dead zones' that are inhospitable to aquatic life.