Information on Malathion

On November 8, 2012 Health Canada’s Pest Management Regulatory Agency (PMRA) released a summary of their decision to grant continued registration of insect control products containing Malathion. The PMRA has made it clear that as long as malathion is used with care and due caution for a strictly defined range of purposes, it will not pose unacceptable risks to human health or the environment. Toxicology studies cited by the PMRA in their summary show that in laboratory settings adverse health effects become apparent in animals at doses more than 100-times higher, and often much higher, than levels to which humans are normally exposed when malathion products are used according to label directions.

Malathion operates by attacking the nervous system. In mosquitos and other small insects relatively small does are enough to cause their nervous system to cease operating. Overexposure in animals and humans may produce a variety of symptoms including (but not limited to) nausea, dizziness, sweating, incoordination, vomiting, abdominal cramps, and diarrhea. Young animals have shown to be more sensitive to some effects of malathion.

The PMRA has declared that “residential risks from the use of malathion on vegetable gardens, ornamentals, and in mosquito abatement programs are not of concern.” They have specifically allowed malathion to be used in residential areas where bystanders could potentially be exposed by inhalation or by residues left on turf.

The tests, studies, and evidence the PMRA has utilized in rendering their decision has included the use of malathion around the most sensitive members of a community, including nursing mothers and children. However, to minimize exposure, the Town of Cardston still suggests that you stay inside with the windows shut and A/C off until the malathion fog has dissipated after being spread near your residence if you have severe allergies or breathing issues, are pregnant, are nursing, or have very small children.



The first three stages—egg, larva, and pupa—are largely aquatic. These stages typically last five to 14 days, depending on the species and the ambient temperature.... Bloodsucking mosquitoes, depending on species, gender, and weather conditions, have potential adult lifespans ranging from as short as a week to as long as several months. (Wikipedia, Mosquito)