Cytogenetic monitoring of nuclear workers occupationally exposed to ionising radiation

Chromosome aberration (CA) analysis using Giemsa techniques was performed in blood lymphocytes of 84 nuclear workers with cumulative doses of 1-632 mSv during employment periods of 1-25 y. The control group comprised 82 healthy male donors. An estimated CA frequency in the total radiation-exposed group was significantly higher when compared with the controls (2.27 vs. 1.76 CA/100 cells, p < 0.05). CA analyses revealed no significant differences between workers with external gamma radiation exposure and the controls (1.60 vs. 1.76 CA/100 cells, p > 0.05). However, significant increase in the total CA frequency was determined in workers with additional internal exposure (2.54 CA/100 cells, p < 0.05) and those with registered neutron doses (2.95 CA/100 cells, p < 0.01). No correlation was found between CA frequency and occupational exposure dose. Borderline significant correlation was found between duration of employment and total CA (r = 0.218, p = 0.046, Fig. 2) and chromosome-type aberration (r = 0.265, p = 0.015) frequency.

Evaluation of the biological activity of naturally occurring 5,8-dihydroxycoumarin

5,8-Dihydroxycoumarin (5,8-DHC) was isolated from aerial parts of sweet grass (Hierochloë odorata L.) and screened for antioxidant and genotoxic activities. A clear linear dependency of radical scavenging capacity in DPPH^• and ABTS^•+ assays was determined. 5,8-DHC was very efficient in retarding rapeseed oil oxidation (Oxipress test). TPC (total phenols content) and FRAP (the ability to reduce ferric ion to ferrous ion) assays revealed a somewhat lower antioxidant capacity of 5,8-DHC as compared with gallic acid. Genotoxic activity was tested using different genetic end-points: chromosome aberrations (CAs) and micronuclei (MN) in Wistar rat bone marrow in vivo, CAs and sister chromatid exchanges (SCEs) in human lymphocytes in vitro, and somatic mutations and recombination in Drosophila melanogaster wing cells in vivo. 5,8-DHC did not increase frequency of CAs in rat bone marrow cells, but induced a significant increase of MN. It was slightly mutagenic in the Drosophila melanogaster assay after 120 h of treatment, but not after 48 h of treatment. 5,8-DHC induced both CAs and SCEs in vitro in human lymphocytes in a clear dose-dependent manner. Thus, 5,8-DHC may be classified as weakly genotoxic both in vivo and in vitro.

Biomonitoring study of dry cleaning workers using cytogenetic tests and the comet assay

Perchloroethylene (PCE) is the main solvent used in the dry cleaning industry worldwide. The aim of the present work was to evaluate the genotoxic potential of occupational exposure to PCE in dry cleaning workers. The study was carried out in 59 volunteers (30 workers, 29 controls). The genotoxic effect was evaluated by analyzing chromosome aberrations (CAs), and micronuclei (MN) and DNA damage (assessed by the comet assay) in peripheral blood lymphocytes. Environmental monitoring of exposure was carried out on personal breathing zone air samples collected during two consecutive working days by measuring the concentration of PCE air levels. The mean PCE concentration in workplace air of dry cleaning workers was 31.40 mg/m(3). There were no significant differences in CA frequency between dry cleaning workers and the controls, but analysis showed a significant association of CA frequency with employment duration and frequency of exposure to PCE. The MN frequency and DNA damage detected by alkaline comet assay were significantly increased in dry cleaning workers compared to the controls. The results suggest that (a) chronic occupational exposure to dry cleaning solvents below permissible occupational exposure limit of 70 mg/m(3) (i.e., ~10.3 ppm) may lead to an increased risk of genetic damage among dry cleaning workers, and (b) CA, MN tests, and comet assay are useful to monitor populations exposed to low doses of PCE.