Sister Chromatid Exchange and Oxidative DNA Damage in Paving Workers exposed to PAHs

Paving workers are exposed during road paving to several polycyclic aromatic hydrocarbons (PAHs) contained in asphalt fumes. In this study early genotoxic and oxidative effects of exposure to bitumen fumes were evaluated in 19 paving workers and 22 controls. Environmental and biological monitoring of exposure was carried out, measuring, on personal air samples from exposed workers collected during three working days, the concentration of 14 PAHs and urinary OH-pyrene at the end of each of the three working days. Genotoxic effect was evaluated analysing sister chromatid exchange (SCE) frequency and direct-oxidative DNA damage by formamido-pyrimidine-glycosylase (Fpg)-modified comet assay on lymphocytes. Tail moment values from Fpg-enzyme treated cells (TMenz) and from untreated cells (TM) were used as parameters of direct and oxidative DNA damage, respectively. For each subject, the TMenz/TM ratio >2.0 was used to indicate the presence of oxidative damage. DNA damage was also evaluated analysing comet percentage. Personal air samples showed low level of total PAHs (2.843 microg m(-3)) with prevalence of 2-3 ring PAHs (2.693 microg m(-3)). Urinary OH-pyrene after work-shift of the three working days was significantly higher than that found at the beginning of the working week. SCE analysis did not show any difference between two groups while an oxidative DNA damage was found in 37% of exposed with respect to the absence in controls. Comet percentage was significantly higher (P = 0.000 ANOVA) in the exposed than in controls. The results demonstrate the high sensitivity of comet assay to assess early oxidative effects induced by exposure to bitumen fumes at low doses and confirm the suitability of urinary OH-pyrene as a biomarker of PAH exposure. In conclusion the study suggests the use of Fpg-modified comet test as a biomarker of early genotoxic effects and that of urinary OH-pyrene as a biomarker of PAH exposure to furnish indications in terms of characterization, prevention and management of risk in occupational exposure to mixtures of potentially carcinogenic substances.

[Study of genotoxic and oxidative effects induced by PAH exposure in paving workers]

Paving workers are exposed during road paving to several PAHs contained in asphalt fumes. We aimed to evaluate early genotoxic and oxidative effects in 19 paving workers and 22 controls. We analysed sister chromatide exchange (SCE) frequency as marker of genotoxicity. Moreover we assessed oxidative DNA damage by Fpg-modified comet assay on lymphocytes calculating tail moment values from fpg-enzyme treated cells (TMenz) and from untreated cells (TM). For each subject the TMenz/TM ratio higher than 2.0 was used to indicate the presence of oxidative damage. We also evaluated DNA damage analysing comet percentage. SCE analysis didn't show any difference between exposed and control groups. We found oxidative DNA damage in 37% of exposed in respect to the absence in controls. Comet percentage was significantly higher in the exposed than in controls. The results demonstrate the high sensitivity of comet assay to assess early oxidative effects induced by exposure to PAH mixtures at low doses and suggest the use of this biomarker in the characterization, prevention and management of risk induced by occupational exposure to mixtures of potentially carcinogenic substances.

Evaluation of oxidative damage and inhibition of DNA repair in an in vitro study of nickel exposure

It has been suggested that Nickel is involved in oxidative damage and inhibition of DNA repair. We studied the effects of NiSO4 on oxidative stress and DNA repair in Jurkat cells to elucidate its mechanism of action. Cells were treated with H2O2 and ROS generation (by flow cytometry), and oxidative DNA damage (as tail moment by Fpg-enzyme comet test), were evaluated immediately and after 4 and 24 h of DNA damage recovery occurred in presence or absence of NiSO4 (0.017 and 0.17 microM) to clarify possible interactions of Ni with DNA repair processes. Moreover, cells were exposed to the same doses of NiSO4 for 4 and 24 hours to evaluate its direct oxidative effect. The results of the comet test showed high tail moment immediately after oxidative burst with a decreasing after 4 h of DNA recovery, and a slight increase after 24 h of recovery. The decreases were more limited for cells treated with NiSO4 0.17 microM indicating an inhibition of oxidative DNA damage repair by this substance. An induction of ROS was observed after 4 h of incubation with higher dose of NiSO4. Cells treated with H2O2 showed the highest level of ROS after 4 h of recovery in presence of NiSO4 0.17 microM that remained at elevated levels also after 24 h of recovery suggesting a synergistic action of Ni with H2O2 in the reduction of cellular anti-oxidative defence activities.

[Study of the genotoxic effects of exposure to cosmic radiation in flight personnel using cytogenetic and molecular techniques]

BACKGROUND

The ever-increasing use of air travel suggests the need to study health risks in flight personnel, by means of correct exposure assessment and evaluation of genotoxic effects.

OBJECTIVES

After taking into consideration occupational risk and possible confounding factors, we studied 48 pilots and flight technicians engaged on long-haul flights together with a control group of 48 ground staff, with the aim of evaluating genotoxic effects of cosmic radiation exposure. On 36/48 subjects we also evaluated the presence of DNA damage (single and double strand breaks).

METHODS

Traditional cytogenetics, the micronucleus test and FISH analysis, were used to study chromosome aberrations, micronuclei and translocations. The Comet test was used to analyze direct DNA damage (single and double strand breaks).

RESULTS

Our findings indicated a significant increase in gaps and breaks and a significant increase of frequency ratio for translocations in pilots compared to controls, but revealed a non-significant difference in unstable aberrations and micronuclei. The Comet test did not show any significant increase of DNA damage in flight personnel with respect to ground staff.

CONCLUSIONS

The possibility of a correlation between translocations and cancer risk emphasizes the need to adopt preventive measures for air flight personnel.