SINGLE-STRAND BREAKS IN DEOXYRIBONUCLEIC-ACID IN FIRE FIGHTERS ACCIDENTALLY EXPOSED TO O-NITROANISOLE AND OTHER CHEMICALS

Objectives The aim of the study was to detect single-strand breaks in deoxyribonucleic acid (DNA) in mononuclear blood cells of fire fighter s exposed to o-nitroanisole and other substances released into the env ironment during an accident in a chemical plant. Methods The level of DNA single-strand breaks in mononuclear blood cells was detected by al kaline elution. The results were compared for 16 fire fighters who wor ked in a contaminated area for about 8 h and two reference groups (one of fire fighters who had not worked in the contaminated area, group I , and one of persons without any apparent occupational exposure to gen otoxic substances, group II). Results The mean normalized elution rate (nER) 19 d after the accident was slightly but statistically signific antly (P < 0.05) higher for the exposed fire fighters [mean 1.48 +/- 9 5% confidence interval (95% CI) 0.21] than for reference group I (mean 1.21 +/- 95% CI 0.21) or reference group II (mean 1.17 +/- 95% CI 0.1 8). No statistically significant difference was found between referenc e groups I and II. Another analysis was performed three months after t he first. The level of DNA single-strand breaks (mean nER 1.21 +/- 95% CI 0.11) was no longer increased in comparison with the levels of the reference groups. Conclusions DNA single-strand breaks were increased in fire fighters exposed to o-nitroanisole and other substances. In c omparison with the extent of DNA strand breaks found in other occupati onal groups the increase was only moderate. The observed decrease in D NA single-strand breaks to the reference level in exposed fire fighter s three months later suggests a DNA repair mechanism for DNA single-st rand breaks caused by o-nitroanisole.