toxicological profile for malathion - Agency for Toxic Substances and ...

MALATHION 177
6. POTENTIAL FOR HUMAN EXPOSURE
ingestion of water or food-borne residues. Also at increased risk of exposure are persons utilizing
malathion for extensive home and garden use, particularly if they consume contaminated, unwashed
backyard produce. Those likely to receive the highest levels of exposure are those who are involved in
the production, formulation, handling, and application of malathion, as well as farm workers who enter
treated fields prior to the passage of the appropriate restricted entry intervals. Dermal contact appears to
be the major route of exposure, while ingestion may also be an important route of exposure. Inhalation
has not been shown to be a significant route of exposure to malathion.
6.2 RELEASES TO THE ENVIRONMENT
Malathion has been released to the environment mainly as a result of its use as an insecticide on food and
feed crops, noncrop agricultural use, home and garden use, and public health use (for medfly and
mosquito control). It is also released as a result of USDA special program usage such as the USDA Boll
Weevil Eradication Program, which accounts for approximately 90% of malathion agricultural crop usage
(EPA 2000a). Additionally, malathion is used as a pharmaceutical for humans. It is applied in the
environment mainly by aerial, ground spraying, or fogging equipment, but is also used in bait type
formulations (i.e., applied to food baits). The annual use of malathion in 1994 was reported to be
3,377,681 pounds, of which 782,434 pounds were used in the state of California (Wilson et al. 1997).
There are no known natural sources of the compound. Malathion has been identified in at least 21 of the
1,623 hazardous waste sites on the NPL (HazDat 2003).
According to recent Toxics Release Inventory (TRI) data, malathion was discharged to air from four
processing sites and to water from one processing site in the United States in 2000; no releases to soil
were reported for that year (TRI00 2002). The TRI data should be used with caution because only certain
types of facilities are required to report. This is not an exhaustive list.
6.2.1 Air
As a result of its use as an insecticide on cotton, sod/turf, ornamentals, berries, fruit trees, vegetables, and
other crops; its use in regional pest eradication programs, including public health use for medfly
quarantine and mosquito abatement; its noncrop agricultural site use; and its outdoor home and garden
use, malathion is released directly to the atmosphere during application. It is applied primarily by