Documents Olsen, Jørn 6 results

"In 2007, the International Agency for Research on Cancer classified shift work involving circadian disruption as probably carcinogenic to humans (group 2A), primarily based on experimental and epidemiologic evidence for breast cancer. In order to examine options for evidence-based preventive actions, 16 researchers in basic, epidemiological and applied sciences convened at a workshop in Copenhagen 26-27 October 2011. This paper summarizes the evidence from epidemiological and experimental studies and presents possible recommendations for prevention of the effects of night work on breast cancer. Among those studies that quantified duration of shift work, there were statistically significant elevations in risk only after about 20 years working night shift. It is unclear from these studies whether or not there is a modest but real elevated risk for shorter durations. Hence, restriction of the total number of years working night shift could be one future preventive recommendation for shift workers. The diurnal secretion of melatonin by the pineal gland with peak in secretory activity during the night is a good biochemical marker of the circadian rhythm. Disruption of the diurnal melatonin secretion pattern can be diminished by restricting the number of consecutive night shifts. Reddish light and reduced light intensity during work at night could potentially help diminish the inhibitory activity of light with strong intensity on the melatonin secretion, but further mechanistic insight is needed before definite recommendations can be made. Earlier or more intensive mammography screening among female night shift worker is not recommended because the harm-benefit ratio in this age group may not be beneficial. Preventive effects of melatonin supplementation on breast cancer risk have not been clearly documented, but may be a promising avenue if a lack of side effects can be shown even after long-term ingestion. Women with previous or current breast cancer should be advised not to work night shifts because of strong experimental evidence demonstrating accelerated tumor growth by suppression of melatonin secretion. Work during the night is widespread worldwide. To provide additional evidence-based recommendations on prevention of diseases related to night shift work, large studies on the impact of various shift schedules and type of light on circadian rhythms need to be conducted in real work environments."

"The etiology of male breast cancer (MBC) is largely unknown but a causal role of exposure to organic solvents has been suggested. Previous studies on occupational risk factors of breast cancer were often restricted to women who are frequently exposed to lower levels and at a lower frequency than men. We investigated the association between MBC and occupational exposure to petroleum and oxygenated and chlorinated solvents in a multicenter case-control study of rare cancers in Europe."

"Welding may involve hazards to the male reproductive system, but previous studies of semen quality have produced inconsistent results. We studied the effects of welding on markers of semen quality in a Danish nationwide sample of 430 first-time pregnancy planners without earlier reproductive experience. Couples were recruited among members of the union of metal workers and three other trade unions and were followed from termination of birth control until pregnancy for a maximum of six menstrual cycles. The males provided semen samples in each cycle. Median sperm density for welders was 56 x 10(6)/mL (52.5 x 10(6)/mL and 50.0 x 10(6)/mL in two reference groups). No statistically significant differences attributable to welding were found in proportions of morphologically normal sperm, sperm motility assessed by computer-aided sperm analysis, or sex hormones (testosterone, follicle-stimulating hormone, and luteinizing hormone). These negative findings may not apply to populations with high-level exposure to welding fume or to welders exposed to other putative hazards, e.g., heat."

"This book is an introductory text for those people who need to know more about the scientific principles behind the study of the causes of disease occurrence. As most people spend a large part of their lives at work, and as some people may be at risk of being exposed to harmful substances at high levels, workers protection should have a high priority. Studies in the workplace can help to identify causes of occupational diseases, and the outcome of such investigations should be applied when the effects of protective action are evaluated. In searching for occupational causes of diseases, epidemiological principles should be used, even at the factory level. Applying strict logical principles to the collection of data concerning workers' experience with ill-health ensures that a useful insight is gained into the causes of disease, and that data are obtained in a format suitable for subsequent larger scale studies."

"During the past decades conclusive evidence has accumulated that alkylating antineoplastic drugs (ADs) can cause cancer, most notably acute non-lymphocytic leukaemia, and that most ADs are reprotoxic. Studies on health workers handling ADs have shown significantly increased risks for miscarriages (two studies) and malformations (two studies). The present study monitored the risk for cancer and adverse reproductive outcome among Danish nurses handling ADs. No increased risks were found for miscarriages, malformations, low birth weight, or preterm birth among the offspring of nurses handling ADs during pregnancy. The sex ratio was normal. The relative risk (RR) for leukaemia was significantly increased (10.65) but based on only two cases, one of acute myeloblastic and one of chronic myeloid leukaemia. From the available exposure data occupational exposures to ADs were apparently higher in the studies that have reported increased risks for miscarriages and malformations than in the present one. Regarding reproductive outcome the study gives some confidence that the safety measures which were implemented in the oncology departments around 1980 can protect the health personnel against adverse effects of ADs on reproduction. As the study is as yet the only negative one in a well protected setting, it should be followed up by other studies of well protected health personnel handling ADs. The findings concerning the leukaemia risk, although based on small numbers, encourage larger studies."