title: Genotoxicity in workers exposed to methyl bromide.
abstract: To address the genotoxicity of in vivo methyl bromide (CAS 74-83-9) exposure in humans, we collected blood and oropharyngeal cells as part of a cross-sectional morbidity study of methyl bromide-exposed fumigation workers and their referents. Micronuclei were measured in lymphocytes and oropharyngeal cells, and hypoxanthine-guanine phosphoribosyl transferase gene (hprt) mutations were measured in lymphocytes. A total of 32 workers and 28 referents provided specimens. Among current non-smokers, mean hprt variant frequencies (Vfs) were found to be elevated among workers compared to referents (geometric mean: workers=4.49x10(-6), referents=2.96x10-(6); two-sided p=0.22); this difference was more pronounced among workers with 4 h or more of recent methyl bromide exposure compared to referents (geometric mean: workers=6.56x10(-6), referents=2.96x10(-6); two-sided p=0.06). Mean oropharyngeal cell micronuclei were higher among workers compared to referents (mean: workers=2.00, referents=1.31; two-sided p=0.08); the results were similar when workers with 4 h or more of recent methyl bromide exposure were compared to referents (mean: workers=2.07, referents=1.31; two-sided p=0.13). No consistent differences between workers and referents were observed for frequencies of kinetochore-negative lymphocyte micronuclei, or kinetochore-positive lymphocyte micronuclei. The study was limited by a sample size sufficient only for detecting relatively large differences, absence of a reliable method to measure the intensity of workplace methyl bromide exposures, and relatively infrequent methyl bromide exposure (e.g., the median length of exposure to methyl bromide during the 2 weeks preceding the survey was 4 h). In conclusion, our findings provide some evidence that methyl bromide exposure may be associated with genotoxic effects in lymphocytes and oropharyngeal cells. Further study on the genotoxicity of methyl bromide exposure in humans is warranted.
authors.affiliation: Division of Surveillance, Hazard, Evaluations and Field Studies, National Institute for Occupational Safety and Health, Centers for Disease Control and Prevention, 4676 Columbia Parkway, R-21, Cincinnati, OH 45226, USA. jac6@cdc.gov
authors.forename: G M
authors.initials: GM
authors.lastname: Calvert
authors.forename: G
authors.initials: G
authors.lastname: Talaska
authors.forename: C A
authors.initials: CA
authors.lastname: Mueller
authors.forename: M M
authors.initials: MM
authors.lastname: Ammenheuser
authors.forename: W W
authors.initials: WW
authors.lastname: Au
authors.forename: J M
authors.initials: JM
authors.lastname: Fajen
authors.forename: L E
authors.initials: LE
authors.lastname: Fleming
authors.forename: T
authors.initials: T
authors.lastname: Briggle
authors.forename: E
authors.initials: E
authors.lastname: Ward
mesh_terms: D000328:Adult; D000368:Aged; D002869:Chromosome Aberrations; D006801:Humans; D006842:Hydrocarbons, Brominated / Q000009:adverse effects*; D007041:Hypoxanthine Phosphoribosyltransferase / Q000235:genetics; D019570:Inhalation Exposure / Q000009:adverse effects*; D008214:Lymphocytes / Q000187:drug effects* / Q000201:enzymology / Q000648:ultrastructure; D008297:Male; D015162:Micronucleus Tests; D008875:Middle Aged; D009154:Mutation; D016273:Occupational Exposure / Q000009:adverse effects*; D009960:Oropharynx / Q000187:drug effects* / Q000648:ultrastructure; D010575:Pesticides / Q000009:adverse effects*; D012044:Regression Analysis
chemical_list: D006842:Hydrocarbons, Brominated; D010575:Pesticides; C005218:methyl bromide; D007041:Hypoxanthine Phosphoribosyltransferase