Science / Medicine : Allergy Symptoms Tied to Malathion Exposure

Exposure to low doses of malathion can affect the immune system and cause a response that mimics allergic reactions, USC immunologist Kathleen Rogers reported last week in the journal Agents and Actions. Doses as low as 1/700th of what is considered toxic to animals provoked allergy-like responses in laboratory mice, she and her colleagues reported.

“The alterations in immune-cell function that we observed lend credence to reports of rashes and other allergic reactions reported by some California residents following aerial malathion spraying,” said the study’s principal investigator, Kathleen Rodgers. Malathion has been sprayed over selected areas of Los Angeles to combat the Mediterranean fruit fly. The practice has sparked protest from residents and environmentalists.

In the USC experiments, laboratory mice were given malathion doses ranging from 900 milligrams per kilogram of body weight to 1/4 milligram per kilogram of weight. Malathion doses as low as 1 milligram caused significant elevations of immune function.

The effects observed were not likely to be life-threatening or to persist beyond a few days in a healthy population, animal or human, Rodgers said. But people or animals with immune problems may be sensitive.