title: Occupational exposure to benzene and chromosomal structural aberrations in the sperm of Chinese men.
abstract: BACKGROUND
  Benzene is an industrial chemical that causes blood disorders, including acute myeloid leukemia. We previously reported that occupational exposures near the U.S. Occupational Safety and Health Administration permissible exposure limit (8 hr) of 1 ppm was associated with sperm aneuploidy.
  
  
  OBJECTIVE
  We investigated whether occupational exposures near 1 ppm increase the incidence of sperm carrying structural chromosomal aberrations.
  
  
  METHODS
  We applied a sperm fluorescence in situ hybridization assay to measure frequencies of sperm carrying partial chromosomal duplications or deletions of 1cen or 1p36.3 or breaks within 1cen-1q12 among 30 benzene-exposed and 11 unexposed workers in Tianjin, China, as part of the China Benzene and Sperm Study (C-BASS). Exposed workers were categorized into low-, moderate-, and high-exposure groups based on urinary benzene (medians: 2.9, 11.0, and 110.6 µg/L, respectively). Median air benzene concentrations in the three exposure groups were 1.2, 3.7, and 8.4 ppm, respectively.
  
  
  RESULTS
  Adjusted incidence rate ratios (IRRs) and 95% confidence intervals (CIs) for all structural aberrations combined were 1.42 (95% CI: 1.10, 1.83), 1.44 (95% CI: 1.12, 1.85), and 1.75 (95% CI: 1.36, 2.24) and for deletion of 1p36.3 alone were 4.31 (95% CI: 1.18, 15.78), 6.02 (95% CI: 1.69, 21.39), and 7.88 (95% CI: 2.21, 28.05) for men with low, moderate, and high exposure, respectively, compared with unexposed men. Chromosome breaks were significantly increased in the high-exposure group [IRR 1.49 (95% CI: 1.10, 2.02)].
  
  
  CONCLUSIONS
  Occupational exposures to benzene were associated with increased incidence of chromosomally defective sperm, raising concerns for worker infertility and spontaneous abortions as well as mental retardation and inherited defects in their children. Our sperm findings point to benzene as a possible risk factor for de novo 1p36 deletion syndrome. Because chromosomal aberrations in sperm can arise from defective stem cells/spermatogonia, our findings raise concerns that occupational exposure to benzene may have persistent reproductive effects in formerly exposed workers.
authors.affiliation: Life Sciences Division, Lawrence Berkeley National Laboratory, Berkeley, California, USA.
authors.forename: Francesco
authors.initials: F
authors.lastname: Marchetti
authors.forename: Brenda
authors.initials: B
authors.lastname: Eskenazi
authors.forename: Rosana H
authors.initials: RH
authors.lastname: Weldon
authors.forename: Guilan
authors.initials: G
authors.lastname: Li
authors.forename: Luoping
authors.initials: L
authors.lastname: Zhang
authors.forename: Stephen M
authors.initials: SM
authors.lastname: Rappaport
authors.forename: Thomas E
authors.initials: TE
authors.lastname: Schmid
authors.forename: Caihong
authors.initials: C
authors.lastname: Xing
authors.forename: Elaine
authors.initials: E
authors.lastname: Kurtovich
authors.forename: Andrew J
authors.initials: AJ
authors.lastname: Wyrobek
mesh_terms: D000328:Adult; D001554:Benzene / Q000032:analysis / Q000592:standards / Q000633:toxicity*; D002681:China; D002869:Chromosome Aberrations / Q000139:chemically induced*; D004305:Dose-Response Relationship, Drug; D004785:Environmental Pollutants / Q000592:standards / Q000633:toxicity* / Q000652:urine; D006801:Humans; D017404:In Situ Hybridization, Fluorescence; D008297:Male; D008875:Middle Aged; D016273:Occupational Exposure; D013011:Sorbic Acid / Q000031:analogs & derivatives / Q000032:analysis; D013094:Spermatozoa / Q000187:drug effects*; D055815:Young Adult
chemical_list: D004785:Environmental Pollutants; C005939:muconic acid; D001554:Benzene; D013011:Sorbic Acid
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