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Objectives: High mammographic breast density (MBD) is one of the strongest breast cancer risk factors. The results of some epidemiological studies suggest that one of the lifestyle factors likely altering breast density is cigarette smoking. The aim of this study was to assess the association between active smoking, considering in detail the duration and intensity of smoking, and MBD among Polish women.Material and Methods: A cross-sectional study included 467 women aged 40-60 years who underwent screening mammography in Łódź, Poland. Volumetric mammographic density, fibroglandular tissue volume and non-fibroglandular tissue volume were determined based on the analysis of mammographic image (in the "for processing" format) using Volpara Imaging Software. Current and lifetime intensity of cigarette smoking was assessed based on the data from interviews. Linear and logistic regressions were fitted with estimated MBD parameters as the outcomes, and life-long smoking duration and intensity as the determinants, adjusted for major confounders.Results: The former smokers had a significantly lower volumetric mammographic density compared to the non-smokers in the crude analysis (p = 0.022). However, the associations became insignificant after adjustments for important confounding factors. The analyses adjusted for important confounders revealed an inverse statistically significant association between the number of pack-years and volumetric mammographic density among the current smokers (p = 0.048).Conclusions: The observed result is consistent with the majority of previous studies that analyzed the associations between mammographic density and life-long smoking duration. Int J Occup Med Environ Health. 2021;34(6):805-15. [ABSTRACT FROM AUTHOR]

Investigating the methylation status of the circadian genes may contribute to a better understanding of the shift work-related circadian disruption in individuals exposed to artificial light at night. In the present study, we determined the methylation status of the circadian genes associated with a shift work pattern among nurses and midwives participating in a cross-sectional study in Lodz, Poland. Quantitative methylation polymerase chain reaction assays were used to assess promoter CpG methylation inPER1, PER2, PER3, CRY1, CRY2, BMAL1, CLOCK, andNPAS2in genomic DNA from whole blood of 347 women having a rotating-shift work schedule and 363 women working days only. The percentage of methylated reference (PMR) was assessed using fluorescent probes forPER1, PER2, PER3, CRY1, andNPAS2, and the percentage of gene methylation, as the methylation index (MI), using two sets of primers forBMAL1, CLOCK, andCRY2. We tested the possible association between current and lifetime rotating night-shift work characteristics and circadian gene methylation by using proportional odds regression model with blood DNA methylation, categorized into tertiles, and adjusted for age, current smoking status, folate intake and blood collection time. The findings indicated that CpG methylation inPER2promoter was significantly decreased (P < 0.004) among nurses and midwives currently working rotating shifts, as compared with day-working nurses and midwives. The lower percentage ofPER2methylation was associated with a higher monthly frequency of current night duties (2–7 night shifts, and eight or more night shifts per month) (P = 0.012) and was associated at borderline significance (P = 0.092) with the lifetime duration of shift work (>10 ≤ 20 years and >20 ≤ 43 years of rotating-shift work) among nurses and midwives (N = 710). Moreover, women with a longer lifetime duration of shift work presented a lower status ofPER1methylation (P = 0.040) than did the women with up to 10 years of rotating-shift work. Long lifetime duration of shift work (> 10 years) among current rotating night-shift workers (N =  347) was associated withBMAL1hypomethylation (P = 0.013). Among eight of the investigated circadian genes, onlyPER1, PER2, andBMAL1showed differential methylation attributable to the rotating-shift work of nurses and midwives. The findings on blood-based DNA methylation in the circadian genes may provide a better insight into the mechanistic principles underlying the possible health effects of night-shift work but these should be verified in further studies recruiting larger populations of shift workers. [ABSTRACT FROM AUTHOR]

The aim of the study was to evaluate the association between environmental exposure to nonpersistent insecticides and semen quality (concentration, motility, morphology, computer-aided semen analysis [CASA] parameters, and sperm DNA damage). Urine samples (n = 315) collected from men who attended the infertility clinic with normal semen concentration of 15 to 300 mln/ml and age under 45 years were analyzed for two metabolites (1-naphthol [1N] and 3,5,6-trichloro-2-pyridinol [TCPY]) of nonpersistent insecticides. Participants provided semen, blood, and saliva samples; additionally, men filled a detailed questionnaire. The results identified that urinary TCPY concentration was significantly associated with a decrease in motility; also there was a positive association between TCPY and DNA fragmentation index (DFI). 1N concentration was negatively associated with a percentage of sperm with normal morphology and positively with one of the CASA parameters (curvilinear velocity [VCL]). The results suggest that environmental exposure to nonpersistent insecticides may have an impact on semen quality parameters and sperm DNA damage. [ABSTRACT FROM AUTHOR]