Evaluation of possible molecular toxicity induced by occupational exposure to lead and concomitant effect of smoking

Environ Sci Pollut Res Int. 2020 Jan;27(1):411-423. doi: 10.1007/s11356-019-06879-0. Epub 2019 Dec 2.


One of the most toxic heavy metals in the environment nowadays is lead (Pb). Even though exposure to lead has been reduced in some developed countries, individuals working in certain occupations are still exposed to lead at dangerous levels. Occupational exposure is of great concern and is also the main cause of lead poisoning. Although experts in various fields have been investigating the toxic effects of lead and its compounds for many years now, the association between chronic lead exposure and geno-toxicity is still an interesting point of research. The study aims to evaluate the possible DNA damage and the oxidative stress status induced by occupational exposure to lead and the role of concomitant smoking. The study was conducted on 60 subjects divided into two groups: an exposed group (40 male workers exposed to lead in their workplaces). This group was further divided into two subgroups; 20 workers were cigarette smokers and the other 20 workers were non-smokers. The other control group consists of 20 healthy males, not exposed to lead and matched by age to the exposed group (10 were smokers and the rest were non-smokers). Venous blood samples were collected from each participant for the determination of the following: blood lead level (BLL), plasma malondialdehyde (MDA) levels, and DNA damage using agarose gel electrophoresis. The exposed workers had significantly higher levels of lead and MDA, as well as a high frequency of DNA fragmentation. Smoking workers showed a greater frequency of DNA fragmentation than non-smokers. A significant relation was revealed between the BLL, as well as the MDA level, and the degree of DNA fragmentation among the lead-exposed workers. The study has shown additional evidence proving the association between Pb exposure and oxidative stress. The results further reinforced the role of cigarette smoking in augmenting such oxidative damage in the Pb-exposed population. However, further studies are recommended to evaluate the effect of cigarette smoking on Pb-exposed workers.

Keywords: DNA damage; DNA fragmentation; Lead; Oxidative stress; Smoking.

MeSH terms

  • Adult
  • Air Pollutants, Occupational / analysis*
  • Air Pollutants, Occupational / toxicity
  • DNA Damage
  • DNA Fragmentation
  • Humans
  • Lead / analysis*
  • Lead / toxicity
  • Leukocytes / drug effects
  • Male
  • Malondialdehyde / metabolism
  • Middle Aged
  • Occupational Exposure / analysis
  • Occupational Exposure / statistics & numerical data*
  • Oxidation-Reduction
  • Oxidative Stress / drug effects
  • Smoking
  • Tobacco Smoking*


  • Air Pollutants, Occupational
  • Lead
  • Malondialdehyde