Terry R. Hunt

EPA's Phaseout of Diazinon

In December 2000, the Environmental Protection Agency (EPA) announced that, pursuant to an agreement with manufacturers of diazinon, all residential uses of diazinon, one of the most widely used pesticides in the United States, would be phased out. As of March 2001, the registration of diazinon for indoor use was cancelled, and retail sales for indoor use ended December 31, 2002. Manufacturing of residential diazinon products ended as of December 2003. As of December 31, 2004, it will be illegal to sell outdoor, non-agricultural diazinon products in the United States.

Diazinon is sold by several different companies under a wide variety of brand names. In September 2004, the EPA issued a notice to remind retailers of the December 31st stop-sale date and that diazinon manufacturers are offering to buy back product still unsold at retail. Consumers may continue to use diazinon remaining in their homes after December 31st according to product labeling and precautions. The EPA has warned that consumers should not dispose of product they do not wish to retain in sinks, toilets, storm drains, or any body of water; rather, they should contact local solid waste authorities for directions on how to dispose of unused diazinon products.

Diazinon is an organophosphate insecticide that is relatively persistent, which means that it does not readily break down in to non-harmful byproducts. People may be exposed to diazinon by eating food that is treated with the insecticide, by touching treated lawns or other surfaces, by breathing the air near treatment sites, or by applying the insecticide. When the phaseout was announced, some 11 million pounds of diazinon were used annually for residential purposes.

Exposure to diazinon causes a wide variety of symptoms and in high enough concentrations can cause seizures, coma, and death. Signs of early or mild exposure include headache, nausea, vomiting, dizziness, muscle weakness, lethargy and drowsiness, and anxiety. Moderate exposure can cause respiratory difficulties, cardiac problems, circulatory problems, memory loss, poor concentration, confusion, and vision problems. In addition, diazinon poses a significant hazard to wildlife, particularly birds and fish.

People at the highest risk for diazinon poisoning are children who play in diazinon-treated areas and those who work in the manufacture of diazinon or that apply it. Between 1993 and 1996, 11,808 unintentional residential diazinon exposures were reported to poison control centers, and an EPA statistician concluded that diazinon was one of the leading causes of acute reactions to pesticide use reported as poisoning incidents. Diazinon is the most frequently detected insecticide in the United States Geological Survey's National Ambient Water Quality Assessment program and has been found at levels in drinking water that exceed EPA-established safe levels.