Benzene Exposure Near the U.S. Permissible Limit Is Associated with Sperm Aneuploidy

Abstract

BackgroundBenzene is a common industrial chemical known to induce leukemia and other blood disorders, as well as aneuploidy, in both human blood cells and sperm at exposures > 10 ppm. Recent reports have identified health effects at exposure levels < 1 ppm, the permissible exposure limit (PEL; 8 hr) set by the U.S. Occupational Safety and Health Administration.ObjectiveWe investigated whether occupational exposures to benzene near 1 ppm induce aneuploidy in sperm.MethodsWe used multicolor fluorescence in situ hybridization to measure the incidence of sperm with numerical abnormalities of chromosomes X, Y, and 21 among 33 benzene-exposed men and 33 unexposed men from Chinese factories. Individual exposures were assessed using personal air monitoring and urinary concentrations of benzene and trans,trans-muconic acid (E,E-MA). Air benzene concentrations were not detectable in unexposed men; in exposed men, concentrations ranged from below the detection limit to 24 ppm (median, 2.9 ppm), with 27% of exposed men (n = 9) having concentrations of ≤ 1 ppm. Exposed men were categorized into low and high groups based on urinary E,E-MA (median concentrations of 1.9 and 14.4 mg/L, respectively; median air benzene of 1 and 7.7 ppm, respectively), and aneuploidy frequencies were compared with those of unexposed men.ResultsSperm aneuploidy increased across low- and high-exposed groups for disomy X [incidence rate ratio (IRR) = 2.0; 95% confidence interval (CI), 1.1–3.4; and IRR = 2.8; 95% CI, 1.5–4.9, respectively], and for overall hyperhaploidy for the three chromosomes investigated (IRR = 1.6; 95% CI, 1.0–2.4; and IRR = 2.3; 95% CI, 1.5–3.6, respectively). We also found elevated disomy X and hyperhaploidy in the nine men exposed to ≤ 1 ppm benzene compared with unexposed men (IRR = 1.8; 95% CI, 1.1–3.0; and IRR = 2.0; 95% CI, 1.1–3.9, respectively).ConclusionsBenzene appeared to increase the frequencies of aneuploid sperm for chromosomes associated with chromosomal abnormality syndromes in human offspring, even in men whose air benzene exposure was at or below the U.S. permissible exposure limit.

Current understandings and perspectives on non-cancer health effects of benzene: A global concern

“…A vital factor in male fertility is normal morphology of sperms on which benzene at concentration below U.S. Occupational Safety and Health Administration (OSHA) permissible limits has been reported to possess toxic effects (Xing et al, 2010). Katukam et al (2012) have published a prospective cohort study of 160 workers exposed to A C C E P T E D M A N U S C R I P T…”

Developmental and reproductive effects of chemicals associated with unconventional oil and natural gas operations

“…Toluene metabolites may have the ability to directly target the male reproductive organs by initiating oxidative stress mechanisms resulting in damage to the DNA in the testis (88). Chromosomal abnormalities in sperm have also been associated with benzene exposure (89,90). Formaldehyde has been associated with decreased sperm count, motility, viability and morphology in mice (91).…”

Environmental Hazard in the Aetiology of Somatic and Germ Cell Aneuploidy

“…In China, the national occupational exposure limit is about twice as high as the US one, and recent studies indicate that in some Chinese factories workers are exposed to concentrations exceeding the limit [Wang et al, 2006]. Recently, a study has been published investigating sperm aneuploidy in a cohort of workers from Chinese factories [Xing et al, 2010]. Exposed men were categorised into low-(median air concentration of 1 ppm) and high-exposure (median air concentration of 7.7 ppm) groups.…”