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

MALATHION 150
3. HEALTH EFFECTS
studies in which subjects were exposed during the manufacture of the material or during application (as
applicators or bystanders), situations that involve inhalation and dermal exposure and generally unknown
exposure levels. Furthermore, few inhalation and dermal studies provided information specifically for
malathion. A single study of controlled inhalation exposure to malathion was available. The oral
database is much more limited and consists mainly of case reports of accidental or intentional ingestion of
high amounts of malathion formulations. This provided a considerable amount of data on acute systemic
and neurological effects, less intermediate data, and no chronic data. No information was located
regarding reproductive, developmental, or cancer effects in humans following oral exposure to malathion.
In animals, the studies available for review provided information on systemic, immunologic, neurologic,
reproductive, developmental, genotoxic, and cancer effects following oral administration of malathion. It
should be mentioned, however, that information on many systemic end points was lacking from the oral
studies. No studies were available on chronic systemic effects by the inhalation and dermal routes of
exposure, regarding reproductive, developmental, genotoxic, or cancer following inhalation exposure, and
regarding genotoxic and cancer effects after dermal exposure.
3.12.2 Identification of Data Needs
Acute-Duration Exposure. Limited acute inhalation data specific for malathion were provided by
Reeves et al. (1981), Golz (1959), and Albright et al. (1983). Reeves et al. (1981) reported the case of a
12-year-old girl who died from aplastic anemia 6 months after exposure to malathion. Golz (1959)
conducted a controlled inhalation study in volunteers and reported nasal and eye irritation within 5–
10 minutes of exposure to 85 mg/m 3 of a malathion aerosol; no effects were reported at 21 mg/m 3 .
Albright et al. (1983) described the case of a 65-year-old man who developed transient renal insufficiency
with massive proteinuria 3 weeks after spraying intensively with malathion. Only one study was
available with acute inhalation data in animals. In this study, four out of six rabbits died 24 hours after a
6-hour exposure to 128 mg/m 3 of malathion aerosol generated from a formulation containing 6%
malathion and a fuel oil mixture (Weeks et al. 1977). However, there were no deaths among rabbits
exposed to 123 mg/m 3 generated from a 95% pure malathion formulation, an exposure concentration that
induced a 38% inhibition of RBC cholinesterase activity. An exposure concentration of 65 mg/m 3 was a
NOAEL and was used to derive an acute inhalation MRL. Acute oral data in humans come almost
exclusively from case reports of accidental or intentional ingestion of high amounts of malathion
formulations. Many cases resulted in deaths following ingestion of estimated doses of malathion between
350 and 2,000 mg/kg (Faragó 1967; Jušić and Milić 1978; Morgade and Barquet 1982; Namba et al.