title: Cancer incidence among pesticide applicators exposed to dicamba in the agricultural health study.
abstract: BACKGROUND
  Dicamba is an herbicide commonly applied to crops in the United States and abroad. We evaluated cancer incidence among pesticide applicators exposed to dicamba in the Agricultural Health Study, a prospective cohort of licensed pesticide applicators in North Carolina and Iowa.
  
  
  METHODS
  Detailed pesticide exposure information was obtained through a self-administered questionnaire completed from 1993 to 1997. Cancer incidence was followed through 31 December 2002 by linkage to state cancer registries. We used Poisson regression to estimate rate ratios and 95% confidence intervals for cancer subtypes by tertiles of dicamba exposure. Two dicamba exposure metrics were used: lifetime exposure days and intensity-weighted lifetime exposure days (lifetime days x intensity score).
  
  
  RESULTS
  A total of 41,969 applicators were included in the analysis, and 22,036 (52.5%) reported ever using dicamba. Exposure was not associated with overall cancer incidence nor were there strong associations with any specific type of cancer. When the reference group comprised low-exposed applicators, we observed a positive trend in risk between lifetime exposure days and lung cancer (p = 0.02), but none of the individual point estimates was significantly elevated. We also observed significant trends of increasing risk for colon cancer for both lifetime exposure days and intensity-weighted lifetime days, although these results are largely due to elevated risk at the highest exposure level. There was no apparent risk for non-Hodgkin lymphoma.
  
  
  CONCLUSIONS
  Although associations between exposure and lung and colon cancer were observed, we did not find clear evidence for an association between dicamba exposure and cancer risk.
authors.affiliation: Division of Cancer Epidemiology and Genetics, National Cancer Institute, National Institutes of Health, Department of Health and Human Services, Bethesda, Maryland 20852, USA.
authors.forename: Claudine
authors.initials: C
authors.lastname: Samanic
authors.forename: Jennifer
authors.initials: J
authors.lastname: Rusiecki
authors.forename: Mustafa
authors.initials: M
authors.lastname: Dosemeci
authors.forename: Lifang
authors.initials: L
authors.lastname: Hou
authors.forename: Jane A
authors.initials: JA
authors.lastname: Hoppin
authors.forename: Dale P
authors.initials: DP
authors.lastname: Sandler
authors.forename: Jay
authors.initials: J
authors.lastname: Lubin
authors.forename: Aaron
authors.initials: A
authors.lastname: Blair
authors.forename: Michael C R
authors.initials: MC
authors.lastname: Alavanja
mesh_terms: D000328:Adult; D000382:Agricultural Workers' Diseases / Q000453:epidemiology*; D003996:Dicamba / Q000633:toxicity*; D006801:Humans; D015994:Incidence; D008875:Middle Aged; D009369:Neoplasms / Q000139:chemically induced / Q000145:classification / Q000453:epidemiology*; D009657:North Carolina / Q000453:epidemiology; D010575:Pesticides / Q000633:toxicity*; D012042:Registries
chemical_list: D010575:Pesticides; D003996:Dicamba