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

MALATHION 96
3. HEALTH EFFECTS
Other Effects. Hyperglycemia and glucosuria were found in four children with severe malathion
intoxication following application to the hair of a solution containing 50% malathion in xylene (Ramu et
al. 1973). Since the hyperglycemia was accompanied with hyperinsulinemia, Ramu et al. (1973)
suggested that it may have not been mediated by release of catecholamines, which are known to inhibit
insulin secretion.
3.2.3.3 Immunological and Lymphoreticular Effects
Laboratory studies conducted by Milby and Epstein (1964) in 87 volunteers showed that a single
exposure to 10% malathion (95% pure) induced contact sensitization in almost half of the subjects, and
that 0.1 and 0.01% concentrations of 99.3% malathion were able to evoke positive responses in
previously sensitized individuals. Field experiments conducted with occupationally exposed subjects
showed that only about 3% reacted to a 1% malathion patch test (Milby and Epstein 1964). The field
study results, however, showed that three of the four positive reactions in mosquito workers were in a
district that used malathion dissolved in diesel oil, which was subsequently found to cause irritation.
Cases of possible immediate and delayed type hypersensitivity reactions to malathion or to a corn syrup
bait were investigated among 10 subjects who had developed dermatitis within a week of exposure to
aerial application of malathion in Southern California (Schanker et al. 1992). The authors found one case
of possible immediate IgE reaction to malathion bait and another case of irritant reaction to malathion and
to the bait, but there were no cases of delayed type hypersensitivity. Schanker et al. (1992) noted that due
to the low participation rate in the study, no specific conclusions regarding the rate of sensitivity in the
population could be drawn.
Three studies were located that provided information on immunological effects of malathion in animals
following dermal exposure. One of them examined the effect of acute administration of malathion on
serum levels of histamine in Sprague-Dawley rats and C57BL/6N mice (Rodgers and Xiong 1997b).
Doses from 2 to 2,000 mg/kg of malathion (>99% pure) in dimethyl sulfoxide (DMSO) were applied once
to the shaved skin under an occlusive bandage. Both in rats and mice, treatment with malathion produced
a dose-related increase in serum histamine levels, which was maximum 4 hours after dosing. Eight hours
after dosing, histamine levels had returned to near control levels. The investigators (Rodgers and Xiong
1997b) suggested that signs such as lacrimation, rashes, and irritation of mucous membranes that may
have reported by individual exposed to malathion may be of systemic origin rather than the result of
localized action. A study in BALB/c mice sensitized with two daily applications of malathion (25 µL at
17.8 or 177.6 mg/mL) to the shaved abdomen showed no delayed-type hypersensitivity when challenged