Residential exposure to radon and levels of histone γH2AX and DNA damage in peripheral blood lymphocytes of residents of Kowary city regions (Poland)

INTRODUCTION

Radon-induced biological effects have been studied mainly through epidemiological investigations, and well-controlled in vitro and in vivo experiments. To provide data explaining radon exposure-induced harmful effects in natural environment, exposure assessment under these conditions is needed. The objective of the study was to examine the level of genetic damage assessed with biomarkers of DNA single- and double-strand breaks (SSBs and DSBs) in peripheral blood mononuclear cells obtained from individuals continuously exposed to Rn in homes. Naturally elevated Rn concentrations in homes can be found in the South of Poland, in Kowary city.

METHODS

Measurements of expression of phosphorylated histone γH2AX was used as a marker of DNA double strand breaks. To detect DNA single and double-strand breaks and alkali labile sites, the alkaline comet assay was used. Oxidative damage of DNA was evaluated by formamidopyrimidyne (FPG)-modified comet assay. The blood was collected from 94 volunteers living in Kowary. Subjects were grouped according to their status of living in radon concentration ≥100 Bq/m³ (n = 67), and <100 Bq/m³ (n = 27).

RESULTS

The statistically significant differences in levels of DNA damage in peripheral lymphocytes assessed with comet assay were found to be associated with levels of radon exposure in indoor air (p = 0.034). DNA damage in the comet assay was significantly correlated with DNA damage assessed with γH2AX staining.

CONCLUSIONS

Results of the present study indicate the suitability of alkaline comet assay for the detection of DNA damage in peripheral blood lymphocytes of people environmentally exposed to radon.

[Assessment of hearing impairment in workers exposed to mixtures of organic solvents in the paint and lacquer industry]

Clinical and experimental studies indicate a possible harmful effect of chemicals, especially organic solvents, on the hearing system. In combined exposure to noise and solvents, very common in industry, it is most likely that a synergetic action of these factors enhances the traumatising effect of exposure to noise. The aim of this study was to assess the incidence and the risk of hearing impairment in 117 paint and lacquer factory workers exposed to a mixture of organic solvents. An analysis of organic solvent mixtures reveals that xylene and ethyl acetate are their major components whose concentrations depend on individual workposts. The control group consisted of 76 workers exposed to noise exceeding, Threshold Limit Value and 125 healthy subjects exposed neither to noise nor to solvents in their occupational setting. Pure tone audiometry revealed the highest hearing thresholds in workers exposed to solvents, lower thresholds in those exposed to noise, and the lowest ones in the non-exposed individuals. Hearing loss was found in 30% of workers exposed to organic solvents, in 20% of noise-exposed subjects, and in only 6% of non-exposed subjects. The comparison of relative risk values also indicated significantly enhanced probability of hearing impairment in workers of the paint and lacquer factory (9.6; 3.2-25.6), which is even more strongly pronounced than in the group of subjects exposed to noise (4.2; 1.2-13.2). An analysis of hearing impairment risk in particular frequencies suggests that organic solvents may damage the inner ear in much greater extent than noise. The results of the study show that exposure to organic solvents may create a significant risk of hearing impairment. Therefore, further steps should be taken to include the exposed population into effective preventive programmes.