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

MALATHION 94
3. HEALTH EFFECTS
Endocrine Effects. No studies were located regarding endocrine effects in humans following dermal
exposure to malathion. No significant alteration in the weight of the adrenals was reported in guinea pigs
applied 400 mg/kg/day malathion (98% pure) in acetone on a 36 cm 2 area of the skin for 30 days
(Dikshith et al. 1987). No gross or microscopical lesions were observed in endocrine glands from rabbits
treated dermally with up to 1,000 mg/kg/day malathion (94% pure) for 3 weeks (Moreno 1989).
Dermal Effects. A few cases of dermal injury from assumed skin contact with malathion have been
found in the literature. Baker et al. (1978) observed burns and skin rashes in an unspecified number of
workers spraying malathion in Pakistan. As noted above, the daily dermal exposure was estimated to
have been 330 mg of malathion. However, a survey of residents from an urban area in California who
underwent aerial spraying with malathion found no significant increase in dermatologic problems (skin
rash) that would require the utilization of health care services or in the prevalence of self-reported dermal
symptoms (Kahn et al. 1992). In an absorption study in 31 healthy volunteers, it was found that
application of an aqueous dose of malathion of 2.5 mg/cm 2 to the volar surface of the arm caused a
marked and long-lasting erythema which, according to the investigators, could have been due to
malathion-induced accumulation of acetylcholine within the tissue space in quantities enough to cause
visible erythema (Boutsiouki et al. 2001).
Mild dermatitis was reported in mice following a brief whole-body submersion in a dip preparation
containing 8% malathion (Relford et al. 1989); submersion in a 2% solution induced no significant
effects. Hyperkeratosis of the epidermal layer of the skin was reported in guinea pigs following repeated
applications of 200 mg/kg/day of malathion (98% pure) in acetone in a 30-day study (Dikshith et al.
1987). Also in an intermediate-duration study, repeated application of up to 1,000 mg/kg/day of
malathion (94% pure) to the skin of rabbits resulted in no gross or microscopical alterations of the skin
(Moreno 1989).
Ocular Effects. In a controlled-exposure study, 16 male volunteers (4/exposure level) were exposed
to aerosol bombs that contained 0 (control), 5, or 20% actual malathion (95% pure) for 1 hour,
2 times/day for 42 days (Golz 1959). The actual exposure concentrations were 0, 5.3, 21, or 85 mg/m 3 .
There were no signs of toxicity during the study with the exception of occasional conjunctival irritation.
A study of residents from an urban area in California found no significant increase in the number of visits
to health care services for ocular problems or in the prevalence of self-reported ocular symptoms after
aerial spraying of the area with malathion (Kahn et al. 1992). Kamel et al. (2000) used cross-sectional
data from self-administered questionnaires completed by licensed pesticide applicators from Iowa and