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

MALATHION 201
6. POTENTIAL FOR HUMAN EXPOSURE
Several researchers have found that worker exposure to malathion for a variety of activities (e.g.,
application operations, harvesting, field observation, formulating operations) using various formulation
types (e.g., spray, dust, aerosol) is greater via the dermal route than through inhalation (Culver et al.
1956; Culver et al. 1956; Durham and Wolfe 1962; Jegier 1964; Lin and Hee 1998; Wolfe et al. 1978,
1967). Based on data reported in the literature, Santodonato et al. (1985) reported mean dermal exposures
during malathion spraying of 2–67 mg/hour, and mean airborne concentrations of 0.6–6 mg/m 3 , indicating
a lower potential for exposure via inhalation relative to the dermal route. In a review of worker exposure
data, Durham and Wolfe (1962) reported that exposure rates for workers applying malathion as an aerosol
(liquid sprays) were 6.6 mg/70-kg man/hour via the dermal route and 0.3 mg/70-kg man/hour via
inhalation.
In a study of the persistence of pesticides on the hands of occupationally exposed workers, malathion was
found to persist on the hands of three of eight farmers occupationally exposed to malathion; it was also
found to persist for at least 7 days on the hands of a home gardener who grew fruits and vegetables treated
with the compound, which was applied by the gardener without the use of protective gloves (Kazen et al.
1974). In the study, malathion was not detected on the hands of three nonoccupationally exposed
workers.
In a study of occupational exposure to flea control products, including malathion, among pet handlers in
California, Ames et al. (1989) found that not only the workers who applied the products, but also others
(nonapplicators) who worked at the facilities where the products were used, were exposed to the
chemicals. Of the 200 workers considered to be nonoccupationally exposed based on their duties, 31 of
the workers reported that they were exposed to malathion in the workplace.
In a study of malathion permeation through the gloves of workers exposed to the compound, Lin and Hee
(1998) reported that the highest potential for exposure was associated with worker dermal contact with
pure and technical-grade malathion and the emulsifiable concentrate formulations; these formulations
generally contain 30–91% (w:w) malathion. Dermal exposure to malathion varied with the type of
protective gloves worn by the workers in the study, with greater protection provided by Viton and Silver
Shield gloves, and the least protection provided by nitrile gloves; for the first two types of gloves,
exposure following permeation through the gloves was