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Today, EPA announced an agreement to phase-out diazinon, one of the most widely used pesticides in the United States, for indoor uses, beginning in March 2001, and for all lawn, garden and turf uses by December 2003.

"The Clinton-Gore Administration continues to aggressively target for elimination those pesticides that pose the greatest risk to human health and the environment, and especially those posing the greatest risk to children," said Carol M. Browner, EPA Administrator. "The action we are taking today is another major step toward ensuring that all Americans can enjoy greater safety from exposure to harmful pesticides."

"Today's action will significantly eliminate the vast majority of organophosphate insecticide products in and around the home, and by implementing this phase-out, it will help encourage consumers to move to safer pest control practice," said Browner.

Diazinon is the most widely used pesticide by homeowners on lawns, and is one of the most widely used pesticide ingredients for application around the home and in gardens. It is used to control insects and grub worms. The agreement reached today with the manufacturers, Syngenta and Makhteshim Agan, will eliminate 75 percent of the use which amounts to more than 11 million pounds of the pesticide used annually.

EPA is taking this action under the Food Quality Protection Act, which President Clinton signed into law in 1996 after the Administration helped lead the way for the new, tougher national pesticide law. Since then, EPA has targeted a large group of older, riskier pesticides called organophosphates for review because they pose the greatest potential risk to children. In August of 1999, for example, EPA announced action against methyl parathion and azinphos methyl to protect children from pesticide residues in food. The Agency reached an agreement to halt by December 2000 the manufacture of chlorpyrifos, or Dursban, for nearly all residential uses. Diazinon - used in homes, and on lawns and gardens - is the latest organophosphate to be phased out. Specifically, the terms of the agreement implement the following phase-out schedules:

  • For the indoor household use, the registration will be canceled on March 2001, and all retail sales will stop by December 2002.

  • For all lawn, garden and turf uses, manufacturing stops in June 2003; all sales and distribution to retailers ends in August 2003. Further, the company will implement a product recovery program in 2004 to complete the phase out of the product.

  • Additionally, as part of the phase out, for all lawn, garden, and turf uses, the agreement ratchets down the manufacturing amounts. Specifically, for 2002, there will be a 25 percent decrease in production; and for 2003, there will be a 50 percent decrease in production.

  • Also, the agreement begins the process to cancel around 20 different uses on food crops.

Organophosphates can affect the nervous system. The effects from diazinon vary depending on the dose, but symptoms from over-exposure can include nausea, headaches, vomiting, diarrhea, and general weakness. Today's action also represents an important step for the environment. Diazinon's use on turf poses a risk to birds, and it is one of the most commonly found pesticides in air, rain, and drinking and surface water.

It is legal to purchase and use diazinon products according to label directions and precautions. Consumers should take special care to always read and follow the label directions and precautions. If consumers choose to discontinue use, they should contact their state or local hazardous waste disposal program or the local solid waste collection service for information on proper disposal.

Diazinon Summary

December 5, 2000


Over 13 million lbs of diazinon are applied annually. Use is on a variety of agricultural corps and livestock (about 20% of usage), on turf and for residential control of various insects indoors and outdoors (about 80% of usage). For non-ag use, the largest share is in homeowner outdoor insect control for turf and gardens (39%). Other large usage is in lawn care operators (19%) and pest control operators (11%). Indoor homeowner use is also registered. California, Texas and Florida are states with the most significant usage. Diazinon is about 1% of the Pest Control Operator (PCO) market for indoor insecticides.


Diazinon is registered as dust, granules, wettable powders, seed dressings, emulsifiable solutions, impregnated materials, encapsulated materials, concentrates and ready-to- use solutions.


Diazinon endpoints are based on plasma, red blood cell and/or brain cholinesterase inhibition for all exposure routes and durations. Because route specific toxicity studies are available, dermal and inhalation absorption factors are not necessary. For inhalation, the standard uncertainty factor of 100 was applied with an extra 3X uncertainty factor due to the lack of a NOAEL in a rat 21-day inhalation study. Therefore, for inhalation exposures of all durations, an MOE of 300 is acceptable. For dermal short-term exposure, the target MOE of 100 is acceptable. For intermediate- and long-term dermal exposure, a 3X safety factor was added to account for the extrapolation from a 21-day dermal exposure to a longer term exposure. For intermediate- and long-term dermal exposure, a target MOE of 300 is acceptable.

Food Risks:

Acute and chronic dietary risk from food are acceptable (highest sub-population is 63% for acute and 22% for chronic (children 1-6 years old).

Water Risks:

Diazinon parent is moderately mobile and persistent. Based on monitoring data, there is no risk concern for either groundwater or surface derived drinking water exposure for chronic or acute. Modeling data indicate a possible concern for infants and children age 1-6 (acute), and children 1-6 and females age 13+ (chronic) from surface derived drinking water only. Water estimates do not include metabolites, since toxicity and monitoring data for these are lacking.

Residential Risks:

The Agency has concerns for potential childrens' exposures in the home. Potential routes of exposure for children may include inhalation of vapors and airborne particles and dermal contact.

Occupational Risks:

Occupational "handler" exposure to diazinon can occur during mixing, loading and application activities. Postapplication exposure may occur during scouting, irrigation, cultivation, harvesting and handling seeds. The majority of occupational risk estimates for handlers exposed to diazinon exceed the Agency's level of concern, even with personal protective equipment (PPE) and/or engineering controls. The majority of postapplication exposures exceed EPA's level of concern at the currently established restricted entry interval (REI) of 24 hours.

Ecological Risks:

Diazinon is highly toxic to birds, mammals, honey bees and other beneficial insects. It is also very highly toxic to freshwater fish and invertebrates following acute exposure. The endangered species levels of concern are exceeded for terrestrial wildlife, aquatic life and terrestrial plants.


Diazinon is one of the leading causes of acute insecticide poisoning for humans and wildlife. For humans, the rate of incidents is not high relative to its large volume of usage. The majority of incidents occur in the home. It also is one of the top causes of bird kill incidents.

"Serious problems cannot be dealt with at the level of thinking that created them."
 Albert Einstein
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