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

MALATHION 193
6. POTENTIAL FOR HUMAN EXPOSURE
agricultural purposes within the 40-km zone near the river, was detected at all 10 sampling times during
the 10-day study; the highest levels of detection corresponded with the major metropolitan areas near or
along the sampling route. The maximum concentration (0.25 ng/m 3 detection limit) of malathion was
4.6 ng/m 3 (near New Orleans, Louisiana), with a range of 0.14–4.6 ng/m 3 ; the median concentration was
0.23 ng/m 3 (Majewski et al. 1998).
A review of published data was conducted to determine the presence of pesticides in atmospheric fog in
both agricultural and nonagricultural areas of the United States (Rice 1996). The presence of malathion
has been reported most frequently in the San Joaquin Valley of California during the dormant spraying
season (January–February) when dense fog events occur frequently in the California’s Central Valley.
Reported concentrations of malathion plus malaoxon (in a 1:0.9 ratio) in atmospheric fog over
agricultural areas have ranged from 0.07 to 8.7 µg/L, with the maximum concentration observed in
Monterey, California in January 1985; concentrations of 0.14–0.30 and 0.90–3.0 µg/L have been reported
for malathion and malaoxon, respectively, for nonagricultural areas of Monterey, California.
Concentrations of