IntroductionMany molecular epidemiology studies focusing on high prevalent diseases, such as metabolic disorders and cancer, investigate metabolic and hormonal markers. In general, sampling for these markers can occur at any time-point during the day or after an overnight fast. However, environmental factors, such as light exposure and food intake might affect the levels of these markers, since they provide input for the internal time-keeping system. When diurnal variation is larger than the inter-individual variation, time of day should be taken into account. Importantly, heterogeneity in diurnal variation and disturbance of circadian rhythms among a study population might increasingly occur as a result of our increasing 24/7 economy and related variation in exposure to environmental factors (such as light and food).AimThe aim of the present study was to determine whether a set of often used biomarkers shows diurnal variation in a setting resembling large molecular epidemiology studies, i.e., non-fasted and limited control possibilities for other environmental influences.ResultsWe show that markers for which diurnal variation is not an issue are adrenocorticotropic hormone, follicle stimulating hormone, estradiol and high-density lipoprotein. For all other tested markers diurnal variation was observed in at least one gender (cholesterol, cortisol, dehydroepiandrosterone sulfate, free fatty acids, low-density lipoprotein, luteinizing hormone, prolactin, progesterone, testosterone, triglycerides, total triiodothyronine and thyroid-stimulating hormone) or could not reliably be detected (human growth hormone).DiscussionThus, studies investigating these markers should take diurnal variation into account, for which we provide some options. Furthermore, our study indicates the need for investigating diurnal variation (in literature or experimentally) before setting up studies measuring markers in routine and controlled settings, especially since time-of-day likely matters for many more markers than the ones investigated in the present study.

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Aims of this study was to detect cytogenetic damage in mine workers working in a lead-zinc mine, which could be associated with a combined exposure to lead, zinc and cadmium. Methods: This study involved 120 mine workers from the lead-zinc mine in Macedonia, and a control group (30) of local people who had never worked in the mine. The authors used peripheral blood lymphocytes as the target material. The total share of structural chromosome aberration (SCA) were searched out over the 3 years of monitoring. Also they measured the blood level of lead, zinc and cadmium with ISP-AES. Results: The authors concluded increased blood lead level in the exposed group (Mean= O,089mg/l) and in 20% in the control group (Mean=0,066mg/l); increased zinc blood level in the exposed (Mean=1,391mg/l) and in control group (Mean=1,074mg/l); increased cadmium blood level in 62% of the exposed (Mean=0,007mg/l) and in 50% of the control group (Mean=0,006mg/l); Chromosomal aberrations (like dicentric and acentric chromosome) were found to be elevated in 7% of exposed individuals (mine workers) non in the control group. Both chromosome type aberrations in the exposed group were accompanied with anemia, leucocitosis and anisocitosis. Conclusion: The group of exposed people showing increased levels of chromosome abnormalities has a higher risk of developing cancer and other deseasses.

The aim of this study was to evaluate the genotoxicity of ionizing radiation on medical personnel using the micronucleus assay and to determine the human health risk. Paired Student?s t-test shows significant statistical difference between the total number of binucleated (BN) cells with micronuclei within the two groups (exposed and control) (t=6,812; p<0,05). The mean of MN frequencies in the exposed group increased in comparison with the mean of MN frequencies in the control group. The formation of small and large micronuclei indicates that medical personnel who are exposed on radiation in their work place, have a chromosomal instability and a risk of cancer.