Effects of Low Intensity Pulsed Ultrasound Stimulation on the Temporal Dynamics of Irradiated Bone Tissue Healing: A Histomorphometric Study in Rabbits.

The present study evaluated the influence of Low-Intensity Pulsed Ultrasound (LIPUS) on the regeneration processes of non-critical-size bone defects in irradiated and non-irradiated rabbit tibias. Bone defects were surgically created on both tibiae of six rabbits. The control group had no additional treatment. In one intervention group, one tibia was irradiated with 15 Gy in a single dose. A second group was treated with LIPUS, and a third with a combination of both treatments. The control samples showed 83.10% ± 17.79% of bone repair after 9 weeks, while the irradiated bone had regenerated significantly less during the same period (66.42% ± 29.36%). The LIPUS treatment on irradiated bones performed a 79.21% ± 21.07% bone fill and could not significantly improve the response compared to the non-treated irradiated specimens. However, LIPUS treatment on non-irradiated bone showed bone formations beyond the size defect (115.91% ± 33.69%), which was a highly significant increase when compared to the control group or any irradiated group. The application of ultrasound to healthy bone produced highly significant and enhanced bone formations with 36.70% more regenerated bone when compared to the same application on irradiated bone. LIPUS vibration stimuli may be considered as a promising complementary treatment approach in non-irradiated bone regeneration procedures to shorten the treatment and enhance bone healing. In irradiated bones, the effect of ultrasound application is less clear, and further studies are needed to refine the dynamics of the present results.

Cohort study of occupational cosmic radiation dose and cancer mortality in German aircrew, 1960-2014.

OBJECTIVES: To determine cancer mortality compared with the general population and to examine dose-response relationships between cumulative occupational radiation dose and specific cancer outcomes in the German aircrew cohort. METHODS: For a cohort of 26 846 aircrew personnel, standardised mortality ratios (SMR) were calculated. Dose-response analyses were carried out using Poisson regression to assess dose-related cancer risks for the period 1960-2014. Exposure assessment comprises recently available dose register data for all cohort members and newly estimated retrospective cabin crew doses for 1960-2003. RESULTS: SMR for all-cause, specific cancer groups and most individual cancers were reduced in all aircrew groups. The only increases were seen for brain cancer in pilots (n=23, SMR 2.01, 95% CI 1.15 to 3.28) and for malignant melanoma (n=10, SMR 1.88, 95% CI 0.78 to 3.85). Breast cancer mortality among female cabin crew was similar to the general population (n=71, SMR 1.06, 95% CI 0.77 to 1.44). Overall median cumulative effective dose was 34.2 mSv (max: 116 mSv) for 1960-2014. No dose-response associations were seen in any of the models. For brain cancer, relative risks were elevated across dose categories. An indicative negative trend with increasing dose category was seen for large intestine cancer in female cabin crew (n=23). CONCLUSIONS: There was no evidence for significant dose-response patterns for the considered cancer types. Interpretation of results remains difficult as cumulative dose is closely related to age. Future work should focus on investigating radiation jointly with other risk factors that may contribute to risks for specific cancers among aircrew.

Second follow-up of a German cohort on childhood cancer incidence after exposure to postnatal diagnostic x-ray.

Studies on children exposed to ionising radiation by computed tomography (CT) indicate an increased risk of leukemia and central nervous system (CNS) tumors. Evidence of the risks associated with diagnostic x-ray examinations, the most frequent examination in pediatric radiology, in which the radiation dose is up to 750 times lower compared to CT examinations, is less clear. This study presents results of the second follow-up for the risk of childhood cancer in a cohort of children (<15 years) with diagnostic x-ray exposure at a large German hospital during 1976-2003 followed for additional 10 years until 2016. With a latency period of 6 months, 92 998 children contributed 794 549 person-years. The median effective dose was 7 µSv. Hundred incident cancer cases were identified: 35 leukemia, 13 lymphomas, 12 CNS tumors, 15 blastomas, 15 sarcomas and 10 other solid tumors, consisting of six germ cells tumors, three thyroid cancers and one adrenocortical carcinoma. For all cancer cases combined the standardised incidence ratio (SIR) was 1.14 (95% confidence interval (CI) 0.93-1.39), for leukemia 1.15 (95% CI 0.63-1.61), for lymphomas 1.03 (95% CI 0.55-1.76), for CNS tumors 0.65 (95% CI 0.34-1.14), for blastomas 1.77 (95% CI 0.91-2.91), for sarcomas 1.28 (95% CI 0.71-2.11) and for other solid tumors 2.38 (95% CI 1.14-4.38). Dose-response analysis using Poisson regression revealed no significant trend for dose groups. Results did not differ substantially with a latency period of 2 years for all cancer entities and 5 years for solid tumors in sensitivity analyses. Overall, the null results of the first follow-up were confirmed. Although an association between radiation exposure and a risk for certain solid tumors like thyroid cancer is known, the significantly increased SIR in the group of other solid tumors must be critically interpreted in the context of the small number of cases and the very low doses of radiation exposure in this group.

Ionising radiation and lens opacities in interventional physicians: results of a German pilot study.

We assessed the feasibility of an epidemiological study on the risk of radiation-related lens opacities among interventional physicians in Germany. In a regional multi-centre pilot study associated with a European project, we tested the recruitment strategy, a European questionnaire on work history for the latter dosimetry calculation and the endpoint assessment. 263 interventional physicians and 129 non-exposed colleagues were invited. Questionnaires assessed eligibility criteria, risk factors for cataract, and work history relating to occupational exposure to ionising radiation, including details on type and amount of procedures performed, radiation sources, and use of protective equipment. Eye examinations included regular inspection by an ophthalmologist, digital slit lamp images graded according to the lens opacities classification system, and Scheimpflug camera measurements. 46 interventional (17.5%) and 30 non-exposed physicians (23.3%) agreed to participate, of which 42 and 19, respectively, met the inclusion criteria. Table shields and ceiling suspended shields were used as protective equipment by 85% and 78% of the interventional cardiologists, respectively. However, 68% of them never used lead glasses. More, although minor, opacifications were diagnosed among the 17 interventional cardiologists participating in the eye examinations than among the 18 non-exposed (59% versus 28%), mainly nuclear cataracts in interventional cardiologists and cortical cataracts in the non-exposed. Opacification scores calculated from Scheimpflug measurements were higher among the interventional cardiologists, especially in the left eye (56% versus 28%). Challenges of the approach studied include the dissuading time investment related to pupil dilatation for the eye examinations, the reliance on a retrospective work history questionnaire to gather exposure-relevant information for dose reconstructions and its length, resulting in a low participation rate. Dosimetry data are bound to get better when the prospective lens dose monitoring as foreseen by 2013 European Directives is implemented and doses are recorded.

Mortality from cancer and other causes in commercial airline crews: a joint analysis of cohorts from 10 countries.

BACKGROUND: Commercial airline crew is one of the occupational groups with the highest exposures to ionising radiation. Crew members are also exposed to other physical risk factors and subject to potential disruption of circadian rhythms. METHODS: This study analyses mortality in a pooled cohort of 93 771 crew members from 10 countries. The cohort was followed for a mean of 21.7 years (2.0 million person-years), during which 5508 deaths occurred. RESULTS: The overall mortality was strongly reduced in male cockpit (SMR 0.56) and female cabin crews (SMR 0.73). The mortality from radiation-related cancers was also reduced in male cockpit crew (SMR 0.73), but not in female or male cabin crews (SMR 1.01 and 1.00, respectively). The mortality from female breast cancer (SMR 1.06), leukaemia and brain cancer was similar to that of the general population. The mortality from malignant melanoma was elevated, and significantly so in male cockpit crew (SMR 1.57). The mortality from cardiovascular diseases was strongly reduced (SMR 0.46). On the other hand, the mortality from aircraft accidents was exceedingly high (SMR 33.9), as was that from AIDS in male cabin crew (SMR 14.0). CONCLUSIONS: This large study with highly complete follow-up shows a reduced overall mortality in male cockpit and female cabin crews, an increased mortality of aircraft accidents and an increased mortality in malignant skin melanoma in cockpit crew. Further analysis after longer follow-up is recommended.

Mortality risk in a historical cohort of nuclear power plant workers in Germany: results from a second follow-up.

Possible health effects of low and protracted doses of ionizing radiation are relevant for persons who are exposed to an occupational context like nuclear industry workers. A historical cohort study was therefore conducted to examine mortality risks following occupational radiation exposure among 4,844 German nuclear power plant workers. This cohort included workers from ten nuclear power plants with an observational period from 1991 until 1997. The results of an enlarged cohort with 8,972 workers from all 17 nuclear power plants in West Germany are now available. During the extended follow-up period from 1991 to 2008, a total of 310 deaths among men were observed. The standardized mortality ratio (SMR) from all causes of deaths was estimated at 0.50 [95 % confidence interval (CI) 0.45-0.56]. A total of 126 deaths due to cancer occurred (SMR = 0.65; 95 % CI 0.51-0.82) and seven deaths due to leukemia (SMR = 1.23; 95 % CI 0.42-2.84). Overall, a reduced mortality compared to the general population of West Germany was observed indicating a healthy worker effect. In the dose-response analysis, no statistically significant risk due to ionizing radiation was seen. The hazard ratio (HR/mSv) for leukemia excluding chronic lymphocytic leukemia was estimated at 1.004 (95 % CI 0.997-1.011). In conclusion, the cohort is small and made up of young workers, most of whom were still employed at the end of the observational period in 2008. Results of the external analysis are difficult to interpret as influenced by a healthy worker effect. In the internal analysis, no excess of risk due to radiation was detected.

Testicular cancer and viral infections: a systematic literature review and meta-analysis.

In 1984, Newell and coworkers were the first to suggest that testicular cancer might have a viral etiology since it showed similar characteristics to Hodgkin's lymphoma. A systematic literature review and meta-analysis was conducted to investigate a possible association between viral infections (EBV, CMV, Parvovirus B19, HPV, and HIV) and testicular cancer. Articles published from 1985 through June 2010 were located from MEDLINE and EMBASE databases, 21 articles were finally included in the review. For infection with EBV, CMV, Parvovirus B19, and HIV the pooled OR were 4.80 (95% CI 0.98-23.54), 1.85 (95% CI 0.92-3.70), 2.86 (95% CI 0.35-23.17), and 1.79 (95% CI 1.45-2.21) respectively. No pooling was possible for HPV infection studies due to small numbers. The results support a possible association, but more epidemiological studies with better viral identification and localization methods are needed to verify these findings.

Occupational exposure to low doses of ionizing radiation and cataract development: a systematic literature review and perspectives on future studies.

Ionizing radiation is a well-known but little understood risk factor for lens opacities. Until recently, cataract development was considered to be a deterministic effect occurring at lens doses exceeding a threshold of 5-8 Gy. Substantial uncertainty about the level and the existence of a threshold subsists. The International Commission on Radiation Protection recently revised it to 0.5 Gy. Based on a systematic literature review of epidemiological studies on exposure to low levels of ionizing radiation and the occurrence of lens opacities, a list of criteria for new epidemiological studies was compiled, and a list of potential study populations was reviewed. Among 24 publications finally identified, six report analyses of acute exposures in atomic bomb survivors and Chernobyl liquidators, and the others report analyses of protracted exposures in occupationally, medically or accidentally exposed populations. Three studies investigated a dose threshold: in atomic bomb survivors, the best estimates were 1 Sv (95 % CI <0-0.8 Sv) regarding lensectomies; in survivors exposed as children, 0.6 Sv (90 % CI <0.0-1.2 Sv) for cortical cataract prevalence and 0.7 Sv (90 % CI 0.0-2.8 Sv) for posterior subcapsular cataract; and in Chernobyl liquidators, 0.34 Sv (95 % CI 0.19-0.68 Sv) for stage 1 cataract. Current studies are heterogeneous and inconclusive regarding the dose-response relationship. Protracted exposures and high lens doses occur in several occupational groups, for instance, in physicians performing fluoroscopy-guided interventional procedures, and in accidentally exposed populations. New studies with a good retrospective exposure assessment are feasible and should be initiated.

Effects of Minocycline Hydrochloride as an Adjuvant Therapy for a Guided Bone Augmentation Procedure in The Rat Calvarium.

This in vivo study reports the influence of minocycline-HCl administration on extra-skeletal bone generation in a Guided Bone Augmentation model, utilizing titanium caps placed on the intact as well as perforated calvaria of rats. The test group was administered 0.5 mg/mL minocycline-HCl with the drinking water, and the amount of bone tissue in the caps was quantified at three time points (4, 8 and 16 weeks). A continuously increased tissue fill was observed in all groups over time. The administration of minocycline-HCl as well as perforation of the calvaria increased this effect, especially with regard to mineralization. The strongest tissue augmentation, with 1.8 times that of the untreated control group, and, at the same time, the most mineralized tissue (2.3× over untreated control), was produced in the combination of both treatments, indicating that systemic administration of minocycline-HCl has an accelerating and enhancing effect on vertical bone augmentation.

Epidemiological investigations of aircrew: an occupational group with low-level cosmic radiation exposure.

Aircrew and passengers are exposed to low-level cosmic ionising radiation. Annual effective doses for flight crew have been estimated to be in the order of 2-5 mSv and can attain 75 mSv at career end. Epidemiological studies in this occupational group have been conducted over the last 15-20 years, usually with a focus on radiation-associated cancer. These studies are summarised in this note. Overall cancer risk was not elevated in most studies and subpopulations analysed, while malignant melanoma, other skin cancers and breast cancer in female aircrew have shown elevated incidence, with lesser risk elevations in terms of mortality. In some studies, including the large German cohort, brain cancer risk appears elevated. Cardiovascular mortality risks were generally very low. Dose information for pilots was usually derived from calculation procedures based on routine licence information, types of aircraft and routes/hours flown, but not on direct measurements. However, dose estimates have shown high validity when compared with measured values. No clear-cut dose-response patterns pointing to a higher risk for those with higher cumulative doses were found. Studies on other health outcomes have shown mixed results. Overall, aircrew are a highly selected group with many specific characteristics and exposures that might also influence cancers or other health outcomes. Radiation-associated health effects have not been clearly established in the studies available so far.

Childhood cancer risk from conventional radiographic examinations for selected referral criteria: results from a large cohort study.

OBJECTIVE: Little is known about the long-term effects of exposure to diagnostic ionizing radiation in childhood. Current estimates are made with models derived mainly from studies of atomic bomb survivors, a population that differs from today's patients in many respects. MATERIALS AND METHODS: We analyzed the cancer incidence among children who underwent diagnostic x-ray exposures between 1976 and 2003 in a large German university hospital. We reconstructed individual radiation doses for each examination and sorted results by groups of referral criteria for all cancers combined, solid tumors, and leukemia and lymphoma combined. RESULTS: A total of 68 incidence cancer cases between 1980 and 2006 were identified in a 78,527-patient cohort in the German childhood cancer registry: 28 leukemia, nine lymphoma, six tumors of the CNS, and 25 other tumors. The standardized incidence ratio for all cancers was 0.97 (95% CI, 0.75-1.23). Dose-response relations were analyzed by multivariable Poisson regression. Although the cancer incidence risk differed by initial referral criterion for radiographic examination, a positive dose-response relation was observed in five patients with endocrine or metabolic disease. CONCLUSION: Overall, we observed no increase in cancer risk among children and youths with very low radiation doses from diagnostic radiation, which is compatible with model calculations. The growing use of CT warrants further studies to assess associated cancer risk. Our work is an early contribution of epidemiologic data for quantifying these risks among young patients.

The effect of risky alcohol use and smoking on suicide risk: findings from the German MONICA/KORA-Augsburg Cohort Study.

BACKGROUND: Smoking and heavy alcohol use predicts suicidal behaviour. Whether the simultaneous presentation of both conditions induces an amplified effect on risk prediction has not been investigated so far. METHODS: In a community-based cohort study, a total of 12,888 subjects (6,456 men, 6,432 women; age range of 25-74 years at assessment) from three independent population-based cross-sectional MONICA surveys (conducted in 1984/85, 1989/90, and 1994/95), representative for the Southern German population, was followed up until 31 December 2002. Standardized mortality ratios (SMR) for deaths from suicide using German population rates were calculated for smoking and high alcohol consumption. RESULTS: After a mean follow-up time of 12.0 (SD 4.4) years and 154,275 person-years at risk, a total of 1,449 persons had died from all causes and 38 of them from suicide. Compared to the general population, mortality from suicide was increased for risky alcohol consumption (SMR = 2.37; 95% CI 1.14-4.37) and for smoking (SMR = 2.30; 95% CI 1.36-3.63). A substantial increase in suicide mortality (SMR = 4.80; 95% CI 2.07-9.46) was observed for smokers with risky alcohol consumption. CONCLUSIONS: The approximately fourfold increased relative risk for completed suicide in subjects with smoking and risky alcohol consumption indicates a synergistic effect which deserves an increased alertness.

Cancer mortality among German aircrew: second follow-up.

Aircrew members are exposed to cosmic radiation and other specific occupational factors. In a previous analysis of a large cohort of German aircrew, no increase in cancer mortality or dose-related effects was observed. In the present study, the follow-up of this cohort of 6,017 cockpit and 20,757 cabin crew members was extended by 6 years to 2003. Among male cockpit crew, the resulting all-cancer standardized mortality ratio (SMR) (n = 127) is 0.6 (95% CI 0.5-0.8), while for brain tumors it is 2.1 (95% CI 1.0-3.9). The cancer risk is significantly raised (RR = 2.2, 95% CI 1.2-4.1) among cockpit crew members employed 30 years or more compared to those employed less than 10 years. Among both female and male cabin crew, the all-cancer SMR and that for most individual cancers are close to 1. The SMR for breast cancer among female crew is 1.2 (95% CI 0.8-1.8). Non-Hodgkin's Lymphoma among male cabin crew is increased (SMR 4.2; 95% CI 1.3-10.8). However, cancers associated with radiation exposure are not raised in the cohort. It is concluded that among cockpit crew cancer mortality is low, particularly for lung cancer. The positive trend of all cancer with duration of employment persists. The increased brain cancer SMR among cockpit crew requires replication in other cohorts. For cabin crew, cancer mortality is generally close to population rates. Cosmic radiation dose estimates will allow more detailed assessments, as will a pooling of updated aircrew studies currently in planning.

Testicular cancer risk associated with occupational radiation exposure: a systematic literature review.

Testicular cancer is a rare disease, affecting mainly young men aged 15-49. There have been some recent reports that it might be associated with radiation exposure. We have systematically reviewed this topic. English-language articles published between 1990 and 2008 studying the relationship between occupational radiation exposure and testicular cancer were included. Risk of bias was assessed using a modified version of the EPHPP checklist. For ionising radiation we subdivided study populations into occupational groups. No pooled analysis was performed due to the heterogeneity of studies. Seven case-control and 30 cohort studies were included in the review. For radiation workers, one incidence study showed a significant increase and four showed no effect. Eight mortality studies did not indicate an effect while four showed a non-significant increase. Incidence among persons with military exposure was not increased in two studies and non-significantly increased in another two. Among aircrew studies, one showed no effect against five with slight increases. Medical exposure studies showed no increases. For EMF exposure, three studies showed no effect, two reported a significant and four a non-significant increase in incidence. Overall, there was very limited evidence for associations between occupational ionising radiation and testicular cancer, while there were some positive associations for EMF. Testicular cancer mortality is generally low and was not associated with radiation. New incidence studies are recommended to investigate the association between radiation exposure and testicular cancer where exposure is better specified and individually estimated.

A cohort study of childhood cancer incidence after postnatal diagnostic X-ray exposure.

Ionizing radiation is an established cause of cancer, yet little is known about the health effects of doses from diagnostic examinations in children. The risk of childhood cancer was studied in a cohort of 92.957 children who had been examined with diagnostic X rays in a large German hospital during 1976-2003. Radiation doses were reconstructed using the individual dose area product and other exposure parameters, together with conversion coefficients developed specifically for the medical devices and standards used at the radiology department. Newly diagnosed cancers occurring between 1980 and 2006 were determined through record linkage to the German Childhood Cancer Registry. The median radiation dose was 7 microSv. Eight-seven incident cases were found in the cohort: 33 leukemia, 13 lymphoma, 10 central nervous system tumors, and 31 other tumors. The standardized incidence ratio (SIR) for all cancers was 0.99 (95% CI: 0.79-1.22). No trend in the incidence of total cancer, leukemia or solid tumors with increasing radiation dose was observed in the SIR analysis or in the multivariate Poisson regression. Risk did not differ significantly in girls and boys. Overall, while no increase in cancer risk with diagnostic radiation was observed, the results are compatible with a broad range of risk estimates.

Season of death and birth predict patterns of mortality in Burkina Faso.

BACKGROUND: Mortality in developing countries has multiple causes. Some of these causes are linked to climatic conditions that differ over the year. Data on season-specific mortality are sparse. METHODS: We analysed longitudinal data from a population of approximately 35,000 individuals in Burkina Faso. During the observation period 1993-2001, a total number of 4,098 deaths were recorded. The effect of season on mortality was investigated separately by age group as (i) date of death and (ii) date of birth. For (i), age-specific death rates by month of death were calculated. The relative effect of each month was assessed using the floating relative risk method and modelled continuously. For (ii), age-specific death rates by month of birth were calculated and the mean date of birth among deaths and survivors was compared. RESULTS: Overall mortality was found to be consistently higher during the dry season (November to May). The pattern was seen in all age groups except in infants where a peak was seen around the end of the rainy season. In infants we found a strong association between high mortality and being born during the time period September to February. No effect was seen for the other age groups. CONCLUSIONS: The observed excess mortality in young children at or around the end of the rainy season can be explained by the effects of infectious diseases and, in particular, malaria during this time period. In contrast, the excess mortality seen in older children and adults during the early dry season remains largely unexplained although specific infectious diseases such as meningitis and pneumonia are possible main causes. The association between high infant mortality and being born at around the end of the rainy season is probably explained by most of the malaria deaths in areas of high transmission intensity occurring in the second half of infancy.

Pattern of cause-specific childhood mortality in a malaria endemic area of Burkina Faso.

BACKGROUND: Reliable mortality data are a prerequisite for planning health interventions, yet such data are often not available in developing countries, particularly in sub-Saharan Africa (SSA). Demographic surveillance systems (DSS) implementing the verbal autopsy (VA) method are the only possibility to observe cause-specific mortality of a population on a longitudinal basis in many countries. METHODS: This paper reports all-cause and cause-specific mortality rates in children under the age of five years from 1999 until 2003 in a malaria holoendemic area of north-western Burkina Faso. The DSS of the Nouna Health Research Centre, in which VA data were analysed, covers a rural population of about 30,000 (41 villages) and an urban population of about 25,000 (Nouna town). RESULTS: A total of 1,544 deaths were analysed, 87 (6%), 225 (14%), 317 (21%) and 915 (59%) of which occurred in the periods < 1 month, 1-5 months, 6-11 months and 1-4 years respectively. All cause mortality rates of children under five years were higher in the rural than the urban area (34 vs 24 per 1,000 person-years) and in the rainy than the dry season (35 vs 29 per 1,000 person-years). Malaria was the most frequent diagnosis (42%) with peak mortality rates in infants aged 6-11 months. CONCLUSION: Malaria is the most important cause of death in this remote area of SSA, even considering the low specificity of malaria diagnosis in young children. Strengthening the existing malaria control tools is of prime importance to reduce the high childhood mortality in the endemic areas of SSA.

Risk factors for childhood mortality in sub-Saharan Africa. A comparison of data from a Demographic and Health Survey and from a Demographic Surveillance System.

OBJECTS: In a comparative analysis, the effect of risk factors for childhood mortality in Burkina Faso, sub-Saharan Africa, were computed from Demographic and Health Survey (DHS) and Demographic Surveillance System (DSS), two very different sources. While most analyses so far determined levels of risk factors, this analysis focuses on the effects of those risk factors. METHODS: Mortality levels are often calculated by strata of risk factor levels separately for each factor. In this publication, their effect was modelled jointly by survival analysis, using all-cause childhood mortality as outcome variable. All live births in rural Burkina Faso in the period of 1994-1998 recorded by the DHS survey Burkina Faso 1998-1999 (5018 births) and the Demographic Surveillance System based in Nouna, western Burkina Faso (6196 births) were included. RESULTS: A simultaneous estimation of hazard rate ratios by a Cox regression model yielded similar estimates for the DHS and DSS data, in line with previous findings based on the Nouna DSS alone. Although DHS surveys do not include children whose mothers had died, ignoring the strong risk factor "death of the mother" does not strongly affect DHS-based results. CONCLUSIONS: Despite the different nature of survey (DHS) and longitudinal (DSS) data, these findings demonstrate that, despite some limitations, results derived from DHS surveys are broadly comparable to DSS data. Both are valuable tools for assessing the importance of risk factors for childhood mortality in sub-Saharan Africa, and they could be combined for better predictions.

Shift Work and Prostate Cancer Incidence in Industrial Workers: A Historical Cohort Study in a German Chemical Company.

BACKGROUND: There is inconsistent evidence for a possible carcinogenic effect of shift work. In particular, little is known about the putative association of shift work with prostate cancer. METHOD: We studied a cohort of 27,828 male industrial production workers residing in the German federal state of Rhineland-Palatinate who worked for at least one year in a chemical company in the period 1995-2005. We obtained data on shift work and potential confounders including age, occupational task, and duration of employment from personnel files and from the records of the occupational health service. New cases of cancer in the period 2000-2009 were ascertained from the state cancer registry. Differences in risk between shift workers and daytime workers were analyzed with Cox regression, stratified by stage of cancer, and adjusted for potential confounding effects. RESULTS: There were 146 new cases of prostate cancer in 12,609 rotating shift workers and 191 in 15,219 daytime workers. The median year of birth was 1960 in the first group and 1959 in the second. The shift workers did not have an elevated hazard ratio for prostate cancer in comparison to the daytime workers (HR = 0.93, 95% confidence interval [CI] 0.73-1.18). Some differences were seen depending on tumor stage. Both groups of workers had a higher incidence of prostate carcinoma than the general population (standardized incidence rate [SIR] = 1.44, 95% CI 1.22-1.70 for daytime workers; SIR = 1.51, 95% CI 1.30-1.74 for shift workers). CONCLUSION: In this well-documented, large-scale cohort study, the incidence of prostate cancer among shift workers did not differ from that among daytime workers. In the authors' opinion, further follow-up of this relatively young cohort is required.

A retrospective cohort study of shift work and risk of incident cancer among German male chemical workers.

OBJECTIVE: Human evidence of carcinogenicity concerning shift work is inconsistent. This industry-based cohort study aimed to examine the relationship between working in a rotating shift and cancer incidence. METHODS: The cohort consisted of male production workers (12 609 shift and 15 219 day), employed in a large chemical industry for at least one year between 1995-2005, and residing in the German federal state of Rhineland-Palatinate. Incident cancer cases from 2000-2009 were identified through record linkage with the cancer registry of Rhineland-Palatinate. Information on exposure to shift work and potential confounders, including age, smoking status, job level, and employment duration, was extracted from the personnel and health records. Cox proportional hazard models were used to estimate hazard ratios (HR) with 95% confidence interval (95% CI) adjusted for potential confounders. RESULTS: Between 2000-2009, 518 and 555 cancer cases (excluding non-melanoma skin cancer) occurred among shift and day work employees, respectively. Compared to "never shift work", shift workers experienced an increased risk of cancers neither at all-sites (HR 1.04, 95% CI 0.89-1.21) nor for prostate cancer in particular (HR 0.93, 95% CI 0.71-1.21). The risks of leukemia and esophagus cancer were increased if smoking was not taken into account, albeit based on small numbers. However, adjusting for smoking changed the HR and the risk diminished. CONCLUSIONS: Our analyses do not provide evidence for a carcinogenic effect of the shift system under study.