Methyl bromide exposure and cancer risk in the Agricultural Health Study
- 414 Downloads
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.
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.
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; ptrend = 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.
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.
KeywordsMethyl bromide Fumigant Pesticide Cancer
This research was supported by the Intramural Research Program of the National Cancer Institute, Division of Cancer Epidemiology and Genetics (Z01CP010119), and National Institute of Environmental Health Sciences (Z01ES049030), National Institutes of Health. Additionally, support for K.H.B. was provided by National Cancer Institute grant T32 CA105666.
Conflict of interest
The authors declare that they have no conflict of interest.
- 1.US Environmental Protection Agency (2009) Amended reregistration eligibility decision for methyl bromide (soil and non-food structural uses). http://www.regulations.gov/#!documentDetail;D=EPA-HQ-OPP-2005-0123-0716. Accessed 2 Dec 2010
- 2.Agency for Toxic Substances and Disease Registry (1992) Toxicological profile for bromomethane. http://www.atsdr.cdc.gov/toxprofiles/tp27.pdf. Accessed 6 Mar 2012
- 3.US Environmental Protection Agency (2011) The phaseout of methyl bromide. http://www.epa.gov/ozone/mbr/. Accessed 3 Jan 2011
- 4.Kegley SE, Hill BR, Orme S et al (2010) Methyl bromide—registration, import consent and bans. PAN pesticide database. Pesticide Action Network, North America, San Francisco, CA. http://www.pesticideinfo.org/Detail_ChemReg.jsp?Rec_Id=PC32864. Accessed 7 Jan 2011
- 5.US Environmental Protection Agency (2010) Other regulatory information. http://www.epa.gov/ozone/mbr/otherreginfo.html. Accessed 5 Jan 2011
- 6.NIOSH (1984) Current Intelligence Bulletin 43: monohalomethanes; methyl chloride, methyl bromide, methyl iodide; evidence of carcinogenicity. National Institute for Occupational Safety and Health, Cincinnati. DHHS publication no. 84–117Google Scholar
- 7.IARC (1999) Re-evaluation of some organic chemicals, hydrazine and hydrogen peroxide. IARC monographs on the evaluation of carcinogenic risks to humans, vol 71. Lyon, FranceGoogle Scholar
- 18.Heltshe SL, Lubin JH, Koutros S et al (2012) Using multiple imputation to assign pesticide use for non-responders in the follow-up questionnaire in the Agricultural Health Study. J Expo Sci Environ Epidemiol (in press)Google Scholar
- 19.Koutros S, Beane Freeman LE, Lubin JH et al (2012) Risk of total and aggressive prostate cancer and pesticide use in the Agricultural Health Study. Am J Epidemiol (in press)Google Scholar