Fish do not appear to take in and store methyl parathion from the water. Most people are not exposed to methyl parathion. Exposure is most likely for those people living or working near or on a farm where methyl parathion is sprayed on crops. Farm workers, pesticide sprayers, or people in factories that make methyl parathion may also be exposed to it. Methyl parathion has been detected at very low levels in food.
Methyl parathion is a poisonous chemical that affects the central nervous system.
Exposure to very high levels for a short time in the air or water may cause loss of consciousness, dizziness, confusion, headaches, difficulty breathing, chest tightness, blurred vision, sweating, and even death. Changes in mental state may last several months after exposure to high levels of methyl parathion has ended. It is not known whether exposure to low levels affects people's health. Animal studies have shown effects on the central nervous system, decreased heart rate and blood pressure, and a reduced ability of the animals to fight infection from long-term ingestion exposure to methyl parathion. The International Agency for Research on Cancer has determined that methyl parathion is not classifiable as to its carcinogenicity to humans.