title: Methyl bromide exposure and cancer risk in the Agricultural Health Study.
abstract: OBJECTIVE
  Methyl bromide is a genotoxic soil fumigant with high acute toxicity, but unknown human carcinogenicity. Although many countries have reduced methyl bromide use because of its ozone depleting properties, some uses remain in the United States and other countries, warranting further investigation of human health effects.
  
  
  METHODS
  We used Poisson regression to calculate rate ratios (RR) and 95 % confidence intervals (CI) for associations between methyl bromide use and all cancers combined, as well as 12 specific sites, among 53,588 Agricultural Health Study pesticide applicators with follow-up from 1993 to 2007. We also evaluated interactions with a family history for four common cancers (prostate, lung, colon, and lymphohematopoietic). We categorized methyl bromide exposure based on lifetime days applied weighted by an intensity score.
  
  
  RESULTS
  A total of 7,814 applicators (14.6 %) used methyl bromide, predominantly before enrollment. Based on 15 exposed cases, stomach cancer risk increased monotonically with increasing methyl bromide use (RR = 1.42; 95 % CI, 0.51-3.95 and RR = 3.13; 95 % CI, 1.25-7.80 for low and high use compared with no use; p                            (trend) = 0.02). No other sites displayed a significant monotonic pattern. Although we previously observed an association with prostate cancer (follow-up through 1999), the association did not persist with longer follow-up. We observed a nonsignificant elevated risk of prostate cancer with methyl bromide use among those with a family history of prostate cancer, but the interaction with a family history did not achieve statistical significance.
  
  
  CONCLUSIONS
  Our results provide little evidence of methyl bromide associations with cancer risk for most sites examined; however, we observed a significant exposure-dependent increase in stomach cancer risk. Small numbers of exposed cases and declining methyl bromide use might have influenced our findings. Further study is needed in more recently exposed populations to expand on these results.
authors.affiliation: Occupational and Environmental Epidemiology Branch, Division of Cancer Epidemiology and Genetics, National Cancer Institute, National Institutes of Health, 6120 Executive Blvd., Bethesda, MD 20892-7240, USA. barrykh@mail.nih.gov
authors.forename: Kathryn Hughes
authors.initials: KH
authors.lastname: Barry
authors.forename: Stella
authors.initials: S
authors.lastname: Koutros
authors.forename: Jay H
authors.initials: JH
authors.lastname: Lubin
authors.forename: Joseph B
authors.initials: JB
authors.lastname: Coble
authors.forename: Francesco
authors.initials: F
authors.lastname: Barone-Adesi
authors.forename: Laura E
authors.initials: LE
authors.lastname: Beane Freeman
authors.forename: Dale P
authors.initials: DP
authors.lastname: Sandler
authors.forename: Jane A
authors.initials: JA
authors.lastname: Hoppin
authors.forename: Xiaomei
authors.initials: X
authors.lastname: Ma
authors.forename: Tongzhang
authors.initials: T
authors.lastname: Zheng
authors.forename: Michael C R
authors.initials: MC
authors.lastname: Alavanja
mesh_terms: D000382:Agricultural Workers' Diseases / Q000139:chemically induced* / Q000453:epidemiology; D000383:Agriculture; D015331:Cohort Studies; D016001:Confidence Intervals; D005260:Female; D005500:Follow-Up Studies; D006540:Herbicides / Q000506:poisoning; D006801:Humans; D006842:Hydrocarbons, Brominated / Q000506:poisoning*; D007484:Iowa / Q000453:epidemiology; D008297:Male; D008875:Middle Aged; D009657:North Carolina / Q000453:epidemiology; D016273:Occupational Exposure / Q000009:adverse effects* / Q000706:statistics & numerical data; D016012:Poisson Distribution; D012307:Risk Factors; D013274:Stomach Neoplasms / Q000139:chemically induced* / Q000453:epidemiology; D011795:Surveys and Questionnaires
chemical_list: D006540:Herbicides; D006842:Hydrocarbons, Brominated; C005218:methyl bromide