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

MALATHION 99
3. HEALTH EFFECTS
of 200 mg/kg/day induced an increase in relative weight (Dikshith et al. 1987). Since body weight data
were not provided, the significance of the changes in testes weight is unknown. There were no gross or
microscopical alterations in the testes. Another intermediate-duration study did not observe significant
changes in weight or gross or microscopical alterations in the ovaries, testes, or epididymis from rabbits
applied up to 1,000 mg/kg/day on the skin for 6 hours/day, 5 days/weeks for 3 weeks (Moreno 1989).
Only the latter study is listed in Table 3-3 since few details were provided in the former.
3.2.3.6 Developmental Effects
No relevant information was located regarding developmental effects of malathion in humans after
dermal exposure with the exception of a report discussing a possible link between a mother’s use of a hair
lotion containing 0.5% malathion during the 11 th and 12 th weeks of pregnancy and the birth of a severely
malformed child who died shortly after birth (Lindhout and Hageman 1987). The child’s condition
resembled amyoplasia congenita in which skeletal muscle is almost completely replaced by fatty tissue.
Although no causal link can be established, the mother and father were healthy and had two other children
who were healthy.
No studies were located regarding developmental effects in animals following dermal exposure to
malathion.
3.2.3.7 Cancer
No studies were located regarding cancer in humans or animals following dermal exposure to malathion.
3.3 GENOTOXICITY
Many in vivo and in vitro studies in humans and animals have investigated the genotoxic effects of
malathion, and evidence suggests that technical-grade malathion has the potential to be a genotoxic agent.
Most studies (many with positive results) have used technical or commercial grades of malathion rather
than the purified form. This, plus positive genotoxicity results of studies on malaoxon, suggests the
possibility that impurities in commercial formulations might be the active genotoxicity agents (Flessel et