Cancer incidence among paraquat exposed applicators in the agricultural health study: prospective cohort study.
Paraquat (1,1'-dimethyl-4, 4'-bipyridinium dichloride) is a nonselective herbicide that is extremely toxic after acute exposure. It was once widely used in North America and is still used in some countries, including the United States. Although there is little firm evidence that paraquat is a carcinogen, previous studies have suggested a potential relationship with some cancers. This prospective cohort study was performed to evaluate the association between lifetime paraquat exposure and cancer incidence among licensed pesticide applicators with 9.1 years of median follow-up. The lifetime ever-use of paraquat was evaluated in 56,224 subjects at baseline and exposure-response relationship was evaluated in 24,667 subjects (44%) who provided detailed information on total life-time paraquat exposure in a second questionnaire. Among the total subjects, the risk for non-Hodgkin's lymphoma (NHL) in the exposed group was marginally elevated (Relative risk [RR], 1.47; 95% confidence interval [CI], 0.97-2.23) compared to the non-exposed group. However, among the 24,667 applicators who supplied total life-time exposure days, the highest tertile of lifetime exposure-days (LE) and intensity-weighted lifetime exposure-days (IWLE) was not significantly associated with NHL risk (RR, 1.57; 95%CI, 0.57-4.23 for LE; RR, 1.42; 95%CI, 0.40-4.71 for IWLE, respectively) and there was no significant exposure-response trend (p-trend > 0.1). There was some suggestion of a possible link between paraquat exposure and NHL risk in humans, but the inconsistency in exposure level trend suggests that this could be a chance finding.
Park
Sue K
SK
Department of Preventive Medicine, Seoul National University College of Medicine, Seoul, Republic of Korea. suepark@snu.ac.kr
Kang
Daehee
D
Beane-Freeman
Laura
L
Blair
Aaron
A
Hoppin
Jane A
JA
Sandler
Dale P
DP
Lynch
Charles F
CF
Knott
Charles
C
Gwak
Jin
J
Alavanja
Michael
M
D000328:Adult; D000382:Agricultural Workers' Diseases / Q000139:chemically induced / Q000453:epidemiology*; D005260:Female; D006540:Herbicides / Q000633:toxicity*; D006801:Humans; D015994:Incidence; D007484:Iowa / Q000453:epidemiology; D008228:Lymphoma, Non-Hodgkin / Q000139:chemically induced / Q000453:epidemiology*; D008297:Male; D008875:Middle Aged; D009657:North Carolina / Q000453:epidemiology; D010269:Paraquat / Q000633:toxicity*; D011446:Prospective Studies; D012306:Risk
D006540:Herbicides; D010269:Paraquat