Evaluation of DNA damage and DNA repair capacity in occupationally lead-exposed workers

Abstract

Occupational lead (Pb) exposure remains a significant concern for workers in Turkey. Health hazards of Pb exposure have been investigated in various test systems, but results regarding its potential genotoxic effects on exposed populations are contradictory. In this study, a control group and an exposed group were studied, each consisting of 25 male subjects. Blood lead levels (BLLs) were estimated by graphite furnace atomic absorption spectrometry. Genotoxic effects of Pb exposure were studied in leukocytes by comet and challenge assays. The effect of Pb exposure to DNA repair capacity was evaluated following in vitro hydrogen peroxide exposure. Pb-exposed workers had significantly higher BLLs than the control group ( p < 0.01). DNA damage in exposed workers had a significantly higher percentage of DNA in tail than the control group ( p < 0.05). In the challenge assay, it was found that the mean DNA% repair capacity was significantly decreased in Pb-exposed workers ( p < 0.01). The results indicated that occupational Pb exposure is associated with DNA damage and causes decrease in DNA% repair capacity, indicating a potential health concern for occupationally Pb-exposed populations.

Oxidative DNA damage and oxidative stress in lead-exposed workers

“…Consistent results were shown in other studies on industry workers. [18][19][20][21][22][23][24] The analysis of the confounding factors in the above-mentioned studies is not conclusive. In this study, to evaluate the role of confounders, a multivariate regression analysis and comparisons between subgroups of smokers and nonsmokers and subgroups of subjects divided on the basis of the median age, years of work, and BMI were performed.…”

“…The results of the other studies are difficult to compare because of the completely different demographic and epidemiological characteristics of the examined populations, the different study protocols, and the complexity of the involved pathophysiological mechanisms. [17][18][19][20][21] Additively, associations between lead exposure and DNA damage may be modified by gene polymorphisms. For instance, it has been shown that workers, who had the ALAD1-1 genotype, were more susceptible to the DNA damage development than those carrying the ALAD1-2 genotype.…”

“…Consistent results were shown in other studies on industry workers. 18 –24…”

“…The cytogenetic tests detect cumulative damage, whereas the comet assay provides information on a type of damage that could be easily repaired and reflects recent exposures. The divergent results of cytogenetic tests might be a result of the interference between lead and the DNA repair system which was postulated in a study of Jannuzzi and Alpertunga, 20 who showed decreased DNA repair capacity due to lead toxicity. However, the consistency of the data obtained in studies using a comet assay might result from the stronger relationship between DNA damage, which these assays detect, and PbB, which reflects rather short-term exposure and is commonly measured in these studies.…”

Oxidative damage of DNA in subjects occupationally exposed to lead

“…19 Occupational exposure to Pb is associated with decreased repair capacity of DNA. 28 The increase in comet parameters observed at higher Pb concentrations due to prolonged exposure can be associated with less efficient and more error-prone mechanisms of repair of DNA.…”