Genotoxic Effects in Workers Exposed to Benzene: With Special Reference to Exposure Biomarkers and Confounding Factors.

Abstract

The aim of the study was to establish a correlation between biomarkers of exposure and cytogenetic test results in workers occupationally exposed to benzene and toluene, with special reference to confounding factors influencing the outcome of the cytogenetic test. The incidence of structural chromosome aberrations and sister chromatid exchanges was studied in the peripheral blood lymphocytes cell genome of 49 female shoe-makers, mean age 38 years, mean length of occupational exposure 17 years and in a group of 27 well-matched controls. Workers were exposed to concentrations of benzene up to 15 ppm and of toluene up to 50 ppm. The presence of benzene and toluene in the workers' blood samples, and the presence of phenol in pre-and post-shift urine were considered proof of occupational exposure. Chromosomal aberration analysis revealed a significant increase in dicentric incidence in the exposed group compared to the controls (P=0.004). However, significant correlation between cytogenetic test results and the exposure biomarkers was not established.On the contrary, correlation between the cytogenetic test results and data on confounding factors (e.g. age and alcohol consumption), was marked. The major point raised by this study is the influence of confounding factors on the cytogenetic test outcome. This imposes the need for caution in the interpretation of cytogenetic test results, and ultimately in the estimation of individual genotoxicity risk related to low level benzene exposure.

The Nature of Chromosomal Aberrations Detected in Humans Exposed to Benzene

“…Increased SCEs were found in the first group, but not the second (Karacic et al, 1995). Four recent reports found no increase in SCEs in benzene-exposed workers compared with controls (Bogadi-Sare et al, 1997;Carere et al, 1995;Carere et al, 1998a;Xu et al, 1998). Therefore, based on the conflicting results from these studies, the effect of benzene exposure on SCE induction remains unclear.…”

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

“…Page 19 of 31 peripheral blood lymphocytes, bone marrow and sperms of people chronically exposed to benzene has become evident through different studies , Andreoli et al, 1997, Bogadi-Sare et al, 1997, Kasuba et al, 2000, Zhang et al, 2002, Morimoto, 1983. Zhang et al (2011) has reported dose-dependent chromosomal aneuploidies (monosomy & trisomy) in the peripheral blood lymphocytes of 47 workers exposed to benzene .…”

Dysregulation of markers of oxidative stress and DNA damage among nail technicians despite low exposure to volatile organic compounds

“…Nevertheless, interest in the oxidative damage caused by these solvents' toxic effects have only is relatively new, and thus the amount of evidence concerning their possible genotoxic and carcinogenic potential is scarce and still under discussion. Even though these substances are considered to be neither carcinogenic nor genotoxic to humans (IARC class 3 carcinogens, ie, not classifiable as to their carcinogenicity to humans), there is a growing amount of evidence suggesting increased (i) levels of markers of oxidative stress (10)(11)(12), (ii) rate of chromosomal aberrations or sister chromatid exchange (12)(13)(14), and (iii) incidence of various cancers among workers occupationally exposed to toluene or xylene [even at occupational exposures far below the respective occupational limits (15)(16)(17)(18)(19)(20)(21)]. Although precise mechanisms underlying the effects of toluene and xylene remain unknown, the role of oxidative stress, oxidative DNA damage and dysregulated cellular antioxidant levels have been implicated (22)(23)(24).…”