Overview

Diazinon, first synthesized in 1953, is a nonsystemic organophosphate insecticide used to control cockroaches, silverfish, ants, and fleas in non-food buildings (ABCbirds.org). It is also used to control pest insects in soil, on ornamental plants, and on fruit and vegetable field crops (ATSDR); however, diazinon products for residential use were taken off the market in 2005.

In 1988, the US Environmental Protection Agency prohibited the use of diazinon on golf courses and sod farms due to decimation of bird flocks that congregated in these areas. As of December 31, 2004, it is unlawful to sell diazinon used in residential indoor and outdoor applications. It is still legal for consumers to use diazinon products, provided that the product was purchased before the ban, and that they follow all label directions and precautions.

Chemical Description

Diazinon is a systemic organophosphate insecticide. Pure diazinon is a clear, colorless oil, which is formulated into the more stable, technical diazinon. Technical diazinon, roughly 90% pure, is an amber to brown liquid with a boiling point around 83 degrees Celsius. Diazinon has a low water solubility of 40 ppm at 20°C (EPA).

In soil, diazinon has a half-life of 5 to 20 days within the top six inches of soil (EPA RED).

Uses

Diazinon is used extensively throughout the Unites States as an insecticide to neutralize cockroaches, silverfish, ants, and fleas in non-food buildings. It is also used to control pest insects in soil, on ornamental plants, and on fruit and vegetable field crops (ATSDR). Before the ban on residential products, it was used in home gardens to control sucking and leaf insects, and in dog collars to ward off fleas (EXTOXNET). When diazinon was in heavy residential usage, around 4% of all calls to local [poison] control centers were related to diazinon exposure, although only a small number of those cases required serious medical attention (EPA).

Prior to the year 2000, diazinon was a very widely used household insecticide. It is estimated that up to 70% of all residential lawn and garden insecticides that were used contained diazinon (EPA RED).

Health Effects

Like all organophosphate insecticides, diazinon is a cholinesterase inhibitor, and the symptoms of exposure depend on the dosage, duration of exposure, and route of exposure (EXTOXNET). In humans, Diazinon is known to overstimulate the nervous system, which may result in nausea, dizziness, and confusion. At extremely high levels of exposure, it can cause respiratory paralysis and death (EPA RED). Other symptoms associated with diazinon poisoning include weakness, headaches, tightness in the chest, blurred vision, nonreactive pinpoint pupils, salivation, sweating, vomiting, diarrhea, abdominal cramps, and slurred speech (EXTOXNET).

Diazinon is listed as a developmental toxin in the EPA's Toxics Release Inventory (PANNA). According to the ATSDR, there is no evidence of negative effects on health due to long term exposure to diazinon, nor is it believed to cause cancer. Trace amounts of diazinon have been found in some foods, but the levels are far below those which would cause harm to consumers (ATSDR).
 

Environmental Effects

Due to heavy use, diazinon is ubiquitous in the environment. The United States Geological Survey National Stream Water Quality Network found diazinon in all major U.S. river systems sampled, including the Rio Grande, Mississippi, Columbia, and Colorado at levels that exceeded the safety limit for aquatic organisms (ABCbirds.org).

This presence is a major concern because diazinon is highly toxic to a wide range of wildlife. In 1988, the Environmental Protection Agency (EPA) stated that diazinon application to open areas is a "widespread and continuous hazard" to birds because of its acute toxicity to the animals (EXTOXNET). The EPA has documented more than 200 cases of avian deaths - often with several hundred bird deaths per case - that occurred throughout the US at various times of the year. Lethal effects were found to occur in birds "at residue levels well below those measured in the field."

Diazinon is very harmful to beneficial insects; it is also toxic to mammals when absorbed through the skin, even more so when inhaled. It is also highly toxic to freshwater fish (EPA RED). However, "diazinon does not significantly bioaccumulate in aquatic organisms" (ATSDR).

Precautions

Avoid. Do not use residentially. If one lives near a commercial farm that uses diazinon, take extra precautions to reduce exposure and wash regularly. Information on pesticide spray drift is available from resources including Pesticide Action Network North America (PANNA) and EPA.

Regulation

In December of 2002, sale of all indoor residential diazinon products was outlawed, and the ban on outdoor residential products followed in December of 2004. A buyback program was then implemented to help remove household diazinon products from the retail market.

The use of diazinon for commercial agriculture is still legal. However, due to concerns over occupational exposure, several safety regulations were adopted including the elimination of aerial applications, elimination of granular diazinon formulations, and specific re-entry intervals after application (EPA RED).

Alternatives

See External Links below for websites providing information on alternatives to diazinon.

External Links

• Pesticide Action Network (PAN) - Diazinon
  
  
• Environmental Working Group - Diazinon
  
  
• ATSDR ToxFAQs - Diazinon
  
  
• ATSDR Toxicological Profile - Diazinon
  
  
• Scorecard - Diazinon
  
  
• Alternatives from Environmental Working Group
  
  
• Alternative to Diazinon From BugsAway.com
  
  
• Alternatives from Do My Own Pest Control
  
  

References

ABCbirds.org. Diazinon. Accessed 5-08-07.

Agency for Toxic Substances and Disease Registry. Toxicolocial Profile for Diazinon. (September 2008) Accessed 7-06-10.

United States Environmental Protection Agency: Office of Pesticide Programs. Reregistration Eligibility Decision for Diazinon. (July, 2006) Accessed 7-03-10.

United States Environmental Protection Agency. Diazinon. (December, 2000). Accessed 5-08-07.

Extension Toxicology Network. Pesticide Information Profile - Diazinon. (1996). Accessed 5-08-07.

Pesticide Action Network North America. Diazinon. Accessed 7-09-10.