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The Effect Occupational Exposure to Ionizing Radiation on the DNA Damage in Peripheral Blood Leukocytes of Nuclear Medicine Personnel: Małgorzata M. DOBRZYŃSKA, et al. Department of Radiation Hygiene and Radiobiology, National Institute of Public Health – National Institute of Hygiene, Poland— Objectives The aim of this study was estimation of DNA strand breaks in leukocytes of peripheral blood of staff in a nuclear medicine department. Methods The exposed group consisted of 46 volunteers and the control group consisted of 40 volunteers. Samples consisting of 1 ml whole blood were collected by venepuncture. DNA damage in leukocytes was detected by alkaline comet assay. Results There was no correlation between the effective dose measured by individual dosimeters and DNA damage and no differences between sexes. The mean level of damage to DNA in people exposed to ionizing radiation was significantly elevated compared with control individuals. The highest value for mean comet tail moment was noted in leukocytes of PET/CT and scintigraphy technicians (1.28 vs. 0.30 for control, p=0.013). The levels of DNA damage in leukocytes of workers in category B (effective dose may exceed 1 mSv/year) were significantly enhanced. The DNA migration of leukocytes in exposed smokers and nonsmokers was similar. In the control group the damage to DNA of leukocytes in smokers was markedly but not significantly higher compared with nonsmokers. Conclusions Occupational exposure to ionizing radiation leads to enhanced levels of reversible DNA damage in leukocytes of nuclear medicine employees. The level of DNA damage depends on the kind of work. Cigarette smoking is related to the increase in DNA damage in unexposed individuals but not in nuclear medicine workers. Radiation seems to be a stronger inducer of DNA damage than smoking. Although most of the DNA damage detected by comet assay is repaired, further improvement of radiation safety should be taken under consideration.

Bisphenol A (BPA) is employed in the manufacturing of epoxy, polyester-styrene, and polycarbonate resins, which are used for the production of baby and water bottles and reusable containers, food and beverage packing, dental fillings and sealants. The study was designed to examine the effects of 8-week exposure (a full cycle of spermatogenesis) to BPA alone and in a combination with X-irradiation on the reproductive organs and germ cells of adult and pubescent male mice. Pzh:Sfis male mice were exposed to BPA (5, 10, and 20 mg/kg) or X-rays (0.05 Gy) or to a combination of both (0.05 Gy + 5 mg/kg bw BPA). The following parameters were examined: sperm count, sperm motility, sperm morphology, and DNA damage in male gametes. Both BPA and X-rays alone diminished sperm quality. BPA exposure significantly reduced sperm count in pubescent males compared to adult mice, with degenerative changes detected in seminiferous epithelium. This may suggest a higher susceptibility of germ cells of younger males to BPA action. Combined BPA with X-ray treatment enhanced the harmful effect induced by BPA alone in male germ cells of adult males, whereas low-dose irradiation showed sometimes protective or additive effects in pubescent mice.

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Many studies suggest that exogenous antioxidants may protect cells against DNA damage caused with ionizing radiation. One of the most powerful antioxidants is lycopene (LYC), a carotenoid derived from tomatoes. The aim of this study was to investigate, using the comet assay, whether LYC can act as protectors/modifiers and prevent DNA damage induced in human blood lymphocytes, as well as to mitigate the effects of radiation exposure. In this project, LYC, dissolved in DMSO at a concentration of 10, 20 or 40 μM/ml of cell suspension, was added to the isolated lymphocytes from human blood at appropriate intervals before or after the X-irradiation at doses of 0.5, 1 and 2 Gy. Cell viability in all groups was maintained at above 70%. The results showed the decrease of DNA damage in cells treated with various concentrations of LYC directly and 1 h before exposure to X-rays compared to the control group exposed to irradiation alone. Contrary results were observed in cells exposed to LYC immediately after exposure to ionizing radiation. The studies confirmed the protective effect of LYC against DNA damage induced by ionizing radiation, but after irradiation the carotenoid did not stimulate of DNA repair and cannot act as modifier. However, supplementation with LYC, especially at lower doses, may be useful in protection from radiation-induced oxidative damage.

Humans are exposed to phthalates continuously throughout life. The aim of this study was to evaluate the genotoxic effects induced in male mice following 8 weeks of subchronic exposure to di-n-butyl phthalate (DBP) during their puberty and to investigate the possibility of transmission of mutations to subsequent generations via the sperm. Pzh:Sfis outbred male mice aged 4.5 weeks were exposed to DBP by gavage for 8 weeks, 3 days per week to doses of 1/16 LD50 or 1/4 LD50 each time. Six to seven males from each dosage group were sacrificed at 4, 8 and 12 weeks after the start of exposure for examination of sperm count and quality. Immediately after the end of exposure, the remaining males were caged for 1 week with two unexposed females each. Group of females were sacrificed 1 day before expected parturition, whilst other females were allowed to deliver and rear litters. F1 generation males at 8-9 weeks of age were caged with females from the same group, but from a different litter, for examination of prenatal development of the F2 generation. The remaining F1 generation males were sacrificed at the same age to check the sperm count and quality. Our results confirmed the toxic effects of DBP on the reproductive organs and germ cells of pubertally exposed males. The changes induced in male gametes might be transmitted to the next generation via the sperm. The most important effects were induced in the F1 generation. Exposure of F0 males to DBP induced skeletal malformations in surviving foetuses, caused significant mortality in postnatal life and a disturbance in the sex ratio (superior survival of females in F1), as well as increased frequency of DNA damage in the germ cells of F1 males. The present study did not confirm higher sensitivity to DBP of pubescent males compared to adult males, but the effects induced in the F1 generation differed from that after exposure of adult F0 males.