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

MALATHION 38
3. HEALTH EFFECTS
more likely (CI=1.1, 17.9) to have NHL than those who did not use organophosphates. In 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, a total of four deaths due to
NHL were observed, three were male lawn applicators, and two of them were employed for 3 or more
years (SMR=7.11, 95% CI=1.78, 28.42) (Zahm 1997). However, malathion was not among the pesticides
known to be in use at the branch when the subject was employed as applicator. No significant increase in
NHL was observed in a study of 1,860 men and 589 women pesticide users from Iceland (Zhong and
Rafnsson 1996), but women showed elevated risks of lymphatic and haematopoietic tissue cancer
(standardized incidence ratio [SIR]=5.56, CI=1.12-16.23) compared with the general population.
McDuffie et al. (2001) examined the association between specific pesticide exposure and NHL in a
Canadian multicenter population-based incident, case-control study (517 cases, 1,506 controls) among
men in a diversity of occupations. Detailed information regarding their exposure history was obtained by
telephone interview from 119 cases and 301 controls who indicated pesticide exposure of ≥10 hours/year.
An additional randomly selected 60 cases and 155 controls who indicated exposure of 10 hours/year were
interviewed by telephone. Exposure to the chemical classes carbamates and organophosphates, but not
organochlorines, was significantly associated with NHL. In multivariate analyses, malathion was the only
individual organophosphate exposure (seven organophosphate pesticides were included in the analysis)
significantly associated with NHL (OR=.83, 95% CI=1.31–2.55). Among the study limitations discussed
by the authors are the potential for recall bias and for misclassification of pesticide exposure and the lessthan-optimal
response rates.
A population-based case-control study of 578 white men with leukemia and 1,245 controls living in Iowa
and Minnesota found slight, but significant elevations in risk for all leukemia (OR=1.2, 95% CI=1.0–1.5)
and chronic lymphocytic leukemia (OR=1.4, 95% CI=1.1–1.9) for farmers compared to nonfarmers
(Brown et al. 1990). Also, risk for all leukemia was significantly elevated for use of the organophosphate
family on animals (OR=1.5, 95% CI=1.0–2.1), but not on crops. Risk of leukemia for mixing, handling,
or applying malathion ever or at least 20 years prior to the interview was not significantly elevated, but
the risk of leukemia for use of malathion as an animal insecticide for $10 days/year was significantly
elevated (OR=3.2, 95% CI=1.0–10.0). A similar study of 173 white men with multiple myeloma and
650 controls from Iowa found a slight nonsignificantly increased risk for multiple myeloma among
farmers, the OR for malathion was 1.9 (95% CI=0.8–4.6) (Brown et al. 1993a). However, failure to use
protective equipment was not associated with increased risk.