Properties and Health Effects

Summary
Exposure to diazinon is most significant in people involved in the manufacture and professional application of this pesticide. Exposure to diazinon can result in headache, dizziness, weakness, feeling of anxiety, constriction of the pupils, and blurred vision.

What is diazinon?
Diazinon is the common name of an organophosphorus pesticide used to control pest insects in soil, on ornamental plants, and on fruit and vegetable field crops. It was formerly used as the active ingredient in household and garden products used to control pests such as flies, fleas, and cockroaches. Diazinon is a synthetic chemical, it does not occur naturally in the environment. Pure diazinon is a colorless and practically odorless oil. Preparations used in agriculture and by exterminators contain 85–90% diazinon and appear as a pale to dark brown liquid. Diazinon preparations sold in the past for home and garden use contained 1–5% diazinon in a liquid or as solid granules. Most diazinon used is in liquid form, but it is possible to be exposed to the solid form. Diazinon does not dissolve easily in water and does not burn easily.

What happens to diazinon when it enters the environment?
Most environmental diazinon contamination comes from agricultural and household application to control insects, but it may also enter the environment during the manufacturing process. After diazinon has been applied, it may be found in the soil, surface waters, and on the surface of plants. Diazinon on soil and plant surfaces may be washed into surface waters by rain; diazinon can move through soil and contaminate groundwater. In the environment, diazinon is quickly broken down into a variety of other chemicals. Diazinon is not likely to build up to high or dangerous levels in animal or plant foods that you might eat.

How might I be exposed to diazinon?
People who work in the manufacture and professional application of diazinon are likely to have the most significant exposure to this pesticide. Exposure may occur by contact with contaminated soils or contaminated runoff water or groundwater. Small amounts have been detected in foods, but the levels are far below those that might cause harmful health effects. Although sales of home and garden products containing diazinon ceased in the U.S. in 2004, you may be exposed if you still have such products stored at home and use them.

How can diazinon affect my health?
Most diazinon that is ingested will enter the bloodstream, but very little will enter the bloodstream if there is skin contact with it. Most cases of unintentional diazinon poisoning in people have resulted from short exposures to very high concentrations of the material. These very high levels have occasionally resulted in death. Diazinon affects mainly the nervous system regardless of the route of exposure. Some mild signs and symptoms of poisoning include headache, dizziness, weakness, feelings of anxiety, constriction of the pupils, and blurred vision. More severe symptoms include nausea and vomiting, abdominal cramps, slow pulse, diarrhea, pinpoint pupils, difficulty breathing, coma, and possibly death. These effects also occur in animals exposed to high doses of diazinon. There is no evidence that long-term exposure to low levels of diazinon causes harmful effects in people. Diazinon has not been shown to affect fertility in humans.

How likely is diazinon to cause cancer?
Diazinon has not been shown to cause cancer in humans or in animals. The U.S. Department of Health and Human Services (DHHS), the International Agency for Research on Cancer (IARC) and the U.S. EPA have not classified diazinon as to its carcinogenicity.

How can diazinon affect children?
Diazinon affects the nervous system in children and adults alike. Therefore, children exposed to diazinon will likely experience the same signs and symptoms observed in exposed adults (see above). However, we do not know whether children are more susceptible than adults to diazinon toxicity. There is no evidence that environmental exposure to diazinon causes birth defects or other developmental effects in people. In animals, exposure levels that affected the health of the pregnant mothers caused developmental effects in their newborn babies.

How can families reduce the risks of exposure to diazinon?
Stay away from agricultural areas that have been treated with diazinon. During spraying operations, remain indoors or leave the area for a short time. Agricultural workers and exterminators who come in contact with diazinon should remove contaminated clothing and wash before coming in contact with family members. Always wash fruits and vegetables before consuming them. Make sure that any person who treats your home with pesticides is properly certified.

Is there a medical test to determine whether I have been exposed to diazinon?
The most common test for exposure to diazinon is to determine the level of an enzyme (cholinesterase) in the blood. However, this test indicates only exposure to a pesticide of this type; it does not specifically show exposure to diazinon. In addition, other chemicals and health conditions may alter the levels of this enzyme. There are specific tests to determine the presence of diazinon or its break down products in blood, urine, and body tissues.

Has the federal government made recommendations to protect human health?
The U.S. EPA has determined that exposure to diazinon in drinking water at a concentration of 20 micrograms per
liter (µg/L) for up to 10 days is not expected to cause any harmful effects in a child. The U.s. EPA has determined that lifetime exposure to 1 µg/L diazinon in drinking water is not expected to cause any harmful effects.

References
Agency for Toxic Substances and Disease Registry (ATSDR). 2008. Toxicological Profile for Diazinon. Atlanta, GA: U.S. Department of Health and Human Services, Public Health Service

Updated: September 2008