Methyl Parathion
Why in News?
Rotterdam Convention’s Chemical Review Committee (CRC) at its 22nd meeting in Rome (Italy) adopted guidance urging tighter global control of methyl parathion, an extremely toxic organophosphorus (OP) insecticide.
What is Methyl Parathion?
- Chemical Group: It is a highly toxic, persistent organophosphorus (OP) insecticide and acaricide first introduced commercially in 1949.
- Primary Use: Used worldwide in agriculture as a foliar spray to control chewing and sucking insects.
- Target Crops: Primarily recommended for cotton, paddy, wheat, pulses (like green gram), and oilseeds (like mustard). However, unauthorized or illegal use on vegetables, spices, and residential spaces remains a significant issue.
Mechanism of Action & Toxicity
- Neurotoxicity: It functions as a potent acetylcholinesterase (AChE) inhibitor. It blocks essential enzymes, leading to the overstimulation of muscle and nerve fibers in both pests and humans.
- Absorption: It is highly dangerous because it is readily and rapidly absorbed through all routes of exposure, including oral ingestion, skin contact (dermal), and inhalation.
Health and Environmental Hazards
- Human Health Risks: Exposure causes acute cholinergic overstimulation. Symptoms include behavioural changes, respiratory depression, dizziness, uncontrollable twitching, convulsions, coma, and death. Long-term exposure is linked to cognitive dysfunction and central nervous system damage.
- Impact on Wildlife: It is a non-selective pesticide that is highly lethal to beneficial species, particularly honey bees.
- Environmental Persistence: It is retained longer in soil than in air or water. Microbial degradation is its primary route of breakdown in nature.
Regulatory Status
- Due to its extreme toxicity—especially to children and field workers—many regulatory bodies like the US Environmental Protection Agency (EPA) have previously cancelled or severely restricted its use on food crops.
- The latest push by the Rotterdam Convention's Chemical Review Committee marks a major step toward establishing binding international trade barriers to limit its global distribution.
