Malathion is an insecticide that is used primarily on crops to control insects. Malathion brakes down quickly when exposed to the elements like soil, water, and sunlight. Normally people are not exposed to this insecticide unless they are in the vicinity of the area that is being sprayed. Then the risk will be the spray that is in the air, or on surfaces that have been touched. (http://www.atsdr.cdc.gov)
Malathion affects how the brain and the nervous system work and exposure to excessive amounts can cause difficulty breathing, tightness of chest, cramps, vomiting, diarrhea, blurred vision, headaches, dizziness, los of consciousness, and death. However if treatment is administered quickly Malathion has no long term affects; while low level exposure has few, or no health problems. Since Malathion is an insecticide it needs to be spayed at dusk to reduce the harm factor of the animals, and other insects. (http://www.atsdr.cdc.gov)
Dose-response
The EPA lists the safe doses of the insecticide Malathion to be 0.1 milligrams of Malathion per liter of drinking water, 0.1 to 135 PPM for certain types of food, and 15 milligrams per meter of work area at an 8 hour work day for a 40 hour work week. Exposures to amount les than these amounts may cause skin irritation, irritate asthma patients, or act as a lung irritant. In high doses Malathion may cause difficulty breathing, tightness of chest, cramps, vomiting, diarrhea, blurred vision, headaches, dizziness, los of consciousness, and death. (http://www.atsdr.cdc.gov)
Exposure
The risk of spraying the Malathion for mosquito control in the center of the town at the low concentrations associated with mosquito spraying will be kept to a minimum by giving ample notice to the public and by spraying for the mosquitoes at dusk. The maximum amount of the active ingredient Malathion is 8 ounces to an acre, and the marsh, and river banks can be sprayed once a year
References: Retrieved may 26, 2008 from http://www.atsdr.cdc.gov/tfacts154.html