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

MALATHION 26
3. HEALTH EFFECTS
single case of apparent acute inhalation exposure, a 12-year-old girl admitted to the hospital died from
aplastic anemia 6 months after exposure to malathion (Reeves et al. 1981). Although aplastic anemia was
diagnosed 2 weeks after a 1-hour exposure to malathion (unspecified formulation or purity), there is no
evidence that anemia occurred as a consequence of exposure to malathion. This case was one of six cases
of children exposed to pesticides described in this brief report and few details are presented. It is
mentioned, however, that the parents of all six children recalled previously using the product in the home.
The second report is a retrospective cohort study that investigated deaths among 32,600 employees of a
lawn care company that used a variety of pesticides, malathion among them, as well as herbicides and
fungicides (Zahm 1997). Among all employees (regardless of duration of employment or type of job
activity), deaths due to bladder cancer were significantly higher than expected for the general population
(standard mortality ratio [SMR]=7.10, 95% confidence interval [CI]=1.43, 20.73), but two of the three
observed deaths had no direct occupational contact with pesticides. Among male applicators employed
for 3 or more years, deaths due to non-Hodgkin’s lymphoma (NHL) were elevated (SMR=7.11, 95%
CI=1.78, 28.42), but malathion was not among the pesticides known to be in use at the branch when the
subjects were employed as applicators (Zahm 1997). More details regarding the NHL cases are presented
under Cancer in Section 3.2.1.7. No other cause of death was significantly elevated among lawn
applicators as a group or among those employed for 3 or more years. This cohort had significantly lower
than expected mortality for all causes of deaths combined, arterioesclerotic heart disease, symptoms and
ill-defined conditions, and accidents.
Very limited information was located regarding death in animals following inhalation exposure to
malathion. Four out of six male New Zealand rabbits died within 24 hours of exposure to 128 mg/m 3
malathion aerosol generated from a formulation containing 6% malathion and a fuel oil mixture (Weeks
et al. 1977). However, no deaths or signs of toxicity were observed in a group of rabbits exposed to
123 mg/m 3 of an aerosol generated from a 95% malathion formulation (Weeks et al. 1977).
3.2.1.2 Systemic Effects
The highest NOAEL and all reliable LOAEL values from each study for systemic effects in each species
and duration category are recorded in Table 3-1 and plotted in Figure 3-1. No studies were located
regarding cardiovascular, musculoskeletal, hepatic, or endocrine effects in humans or in animals
following inhalation exposure to malathion. Dermal and ocular effects reported in studies in humans or
animals that occurred by exposure to the chemical in the air, most likely due to direct contact with the
skin or eyes, are summarized in Section 3.2.3, Dermal Exposure.