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

MALATHION 37
3. HEALTH EFFECTS
and controls. In a subgroup of 14 individuals exposed to malathion, regression analysis showed no
significant associations with outcomes after adjusting for confounding factors.
Two additional studies investigated a broader set of pesticides. Lin et al. (1994) studied the association
between exposures to a variety of pesticides and limb reduction defects (a generally well-reported birth
defect) from a register of congenital anomalies among live births in New York State. In the full sample
and in a subgroup of individuals exposed to insecticides, no significant associations were observed,
although odds ratios for risk of limb reduction defect plus one additional malformation were consistently
higher than those for limb reduction defects only. Rupa et al. (1991b) found significantly reduced
numbers of live births and significantly increased neonatal deaths and congenital defects in
pregnancies/offspring of males exposed to pesticides compared with offspring of unexposed males. The
possible role of malathion cannot be ascertained in these two studies.
No studies were located regarding developmental effects in animals following inhalation exposure to
malathion.
3.2.1.7 Cancer
Several studies provide information on exposure to pesticides, including malathion, and cancer. The
overall evidence from human studies is insufficient to draw any conclusions regarding the association
between exposure to malathion and cancer. In general, the magnitude of the excesses is small, exposure
assessment is unreliable, and people are seldom exposed to a single pesticide.
The possible association between pesticide exposure and non-Hodgkin’s lymphoma (NHL) has been
investigated in several studies. In a study of 622 white men with newly diagnosed NHL in Iowa and
Minnesota and 1,245 population-based controls, the prevalence of NHL in individuals who handled
malathion as a crop insecticide prior to 1965 was significantly higher than in nonfarmers (OR=2.9,
CI=1.1, 7.4) (Cantor et al. 1992). The prevalence was also significantly higher in workers who used
malathion as an animal insecticide than in nonfarmers (OR=1.8, CI=1.0, 3.3). Zahm et al. (1993)
presented data on agricultural exposures among women from a population-based case-control study of
NHL in eastern Nebraska. A total of 119 women diagnosed with NHL and 471 controls reported ever
having lived or worked on a farm. No individual insecticide was associated with a significant risk of
NHL among women, but there was a nonsignificant increase for malathion (OR=1.9; 9 cases, 18 controls)
and for several other insecticides. Women who had personally handled organophosphates were 4.5 times