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

MALATHION 30
3. HEALTH EFFECTS
Respiratory Effects. In a controlled-exposure study, 16 male volunteers (4/exposure level) were
exposed to aerosol bombs that contained 0 (control), 5, or 20% malathion 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 . By adjusting the
application rate of the 20% formation, the highest exposure groups were formed.The malathion in the
formulation was 95% pure. There were no signs of toxicity during the study, with the exception of
complaints of nasal irritation in men exposed to the highest concentration during the first 5–10 minutes of
each exposure. One study of 85 subjects who worked in the production of six organophosphate pesticides
(malathion was one of them) for periods ranging from 0.1 to 29 years found a higher frequency of upper
respiratory tract infections in workers than in 67 controls (Hermanowicz and Kossman 1984) (see also
information under Immunological Effects). Also, those exposed for 11–29 years had more respiratory
infections than individuals exposed for 0.1–2 years. Before and during the study, total air concentrations
of organophosphates remained below admissible limits. Exposure to chlorinated solvents also occurred
during pesticide production and may have contributed to the effects observed. The role of malathion, if
any, cannot be ascertained. Additional information was found in a study of self-reported symptoms in
22 seamen who may have been exposed to a single cloud of malathion that escaped from a nearby
overheated tank (Markowitz et al. 1986). Compared with a group of controls, the seamen reported
significantly more problems with sore throat, stuffy nose, and laryngitis when contacted 12 days
following the incident. It should be noted, however, that there was no evidence of actual exposure to the
chemical.
Following aerial application of malathion in Santa Clara County, California, in 1981, a survey was
conducted to assess the acute health effects of the application (Kahn et al. 1992). The study included
three indirect assessments that focused on the utilization of acute care services and two surveys to assess
self-reported symptoms. The results showed no significant increase in the number of visits for the broad
category, respiratory, to hospital emergency departments during the application period compared with the
prespray period or the corresponding period the previous year. Furthermore, there was no significant
increase in the number of asthma-related visits to a university medical school in the area, although the
numbers in the study may have been too small to provide definite conclusions. The results of the surveys
to assess self-reported symptoms revealed no detectable increase in acute morbidity or in
organophosphate-compatible symptomatology, but again, the sample size may have been too small for
marginal increases in the prevalence of various symptoms to be detected.