## 3 Results  
The general characteristics and lifestyle habits were not found to be different when comparing the exposed workers and controls (Table 2). In exposed workers the effective whole body dose of IR in the last year (median: 0.27 mSv; range \(<\) 0.01-2.46 mSv) and the cumulative dose over the entire working life (median: 5.31 mSv; range: 0.20-54.43 mSv) were generally very low, both significantly different among the workers divided by the type of job (Table 3). All the genotypes studied were found to be balanced according to the Hardy-Weinberg equation. No significant differences were found between exposed workers and controls, as regards the frequencies of the polymorphisms studied, except for polymorphism Arg280 His of _XRCC1_ with the Arg/Arg genotype, that was significantly more frequent in the exposed workers (97.5%) than the controls (75%) (\(p\) = 0.007) (Table 4). The frequency of total CAs and spontaneous chromosomal breaks was significantly higher in the exposed workers than the controls (\(p\) < 0.05 and \(p\) < 0.01, respectively), while the frequency of chromatid breaks and spontaneous MN, of all the BLM-induced DNA damage biomarkers, and the three Comet assay parameters, did not seem different between the two groups (Table 5). The simultaneous influence of occupational exposure and sex, and of cigarette smoking, on the spontaneous and BLM-induced DNA damage biomarkers was verified in exposed workers and controls by two-way analysis of variance. For this purpose, the subjects were subdivided into males versus females, and smokers versus nonsmokers + ex-smokers. No relation was found between occupational exposure, sex, and cigarette smoking and spontaneous and BLM-induced DNA damage biomarkers, except for spontaneous chromosomal breaks, that appeared to be associated with occupational exposure (\(p\) < 0.05), and for TI and TI Endo III, that showed significantly higher values in females (\(p\) < 0.01 for both comparisons; Table 6). Study was made of the correlation between biomarkers of spontaneous and BLM-induced genotoxicity and the general characteristics and lifestyle habits, respectively, and, only in the exposed workers, the effective whole body dose of IR in the last year and the cumulative one, in all subjects considered as a single group and then in exposed workers and controls separately. As regards the biomarkers of spontaneous genotoxicity, there was a positive correlation only between the frequency of MN and age (r = 0.24, \(p\) < 0.05) in all the subjects considered as a single group. For BLM-induced genotoxicity biomarkers, in all subjects considered as a single group there was a significant negative correlation between the number of cigarettes smoked daily and the frequency of total chromatid breaks (r = \(-\)0.44, \(p\) < 0.05), the frequency of metaphases with chromatid breaks (r = \(-\)0.48, \(p\) < 0.05) and the frequency of chromatid breaks per cell (r = \(-\)0.44, \(p\) < 0.05), while for the frequency of metaphases with chromatid breaks only a negative correlation was observed also in the exposed workers (r = \(-\)0.65, \(p\) < 0.05). To verify the influence of polymorphisms of DNA repair and detoxification enzymes on the frequency of spontaneous and BLM-induced DNA damage biomarkers, exposed workers and controls were subdivided into wild-type and carriers of allelic variants in hetero and homozygous for the enzymes _XRCC1_, _XRCC3_, _XPD_, _BLHX_, _GSTM1_, and _GSTT1_. In particular, for the gene _XRCC1_, the overall presence of allelic variants for the three polymorphisms studied, namely Arg194 Trp, Arg280 His, and Arg399 Gln was analyzed, subdividing the subjects, both exposed workers and controls, into those who presented no allelic variant for any of the genetic polymorphisms of _XRCC1_ (wild-type), versus subjects that presented at least one.