Previous research updated the mortality experience of North American synthetic rubber industry workers during the period 1944-1998, determined if leukemia and other cancers were associated with several employment factors and carried out Poisson regression analysis to examine exposure-response associations between estimated exposure to 1,3-butadiene (BD) or other chemicals and cancer. The present study used Cox regression procedures to examine further the exposure-response relationship between several unlagged and lagged, continuous, time-dependent BD exposure indices (BD parts per million (ppm)-years, the total number of exposures to BD concentrations >100 ppm ("peaks") and average intensity of BD) and leukemia, lymphoid neoplasms and myeloid neoplasms. All three BD exposure indices were associated positively with leukemia. Using continuous, untransformed BD ppm-years the regression coefficient (beta) from an analysis that controlled only for age was 2.9 x 10(-4) (p
This study documents the radiation doses received by all in-room personnel of three cardiac catheterization laboratories where more than 15,000 cardiac procedures have been performed over a 5-y period. It is shown that all in-room personnel was exposed to a body dose equivalent well below any regulatory limits. However, some workers may have exceeded the occupational 150 mSv y-1 recommended limit for the lens of the eye. The physicians-in-training and the staff physicians are the two groups more likely to reach this limit. It is also demonstrated that a low correlation exists between the annual number of procedures and the annual head dose equivalent of a physician, but more variation is likely to originate from his/her working attitude and techniques. The mean dose equivalent at the collar level of the physicians is estimated to be 0.04 +/- 0.02 mSv per procedure.
In the result of the analysis of irradiation doses of 36,895 servicemen who have participated in liquidation of the Chernobyl APC disaster consequences it was found out that the average radiation dose was 12.1 cSv in 1986, 8.4 cSv in 1987, and in 1988-90 it didn't exceed 5 cSv. The irradiation received by these servicemen has depended on the time of their arrival to the zone of the disaster, the maximum permissible doses of radiation established at that period, the character of their activities and the place of their work, utilization of protection means. A conclusion was made that irradiation dose itself could be considered only as a general guide reference, because it didn't take into consideration internal irradiation and beta-irradiation of skin. That's why it is necessary to continue the further monitoring over the health status of liquidators independently of the doses of irradiation which were fixed in their histories.
OBJECTIVES: This study attempts to demonstrate a calculation of the occupational lung cancer burden using economically active men in Sweden as an example. METHODS: Estimates were calculated using Swedish register data on occupation in 1970, lung cancer incidence in 1971-1989, smoking frequencies in 1963, and the formula I = RI0F + I0(1-F), where I is the overall incidence, R is the relative risk associated with a factor (here smoking), F is the fraction of persons at risk (smokers), and I0 is the incidence among those not at risk (nonsmokers). RESULTS: Farmers, gardeners, forestry workers, and fishermen had the lowest lung cancer risk (42.1 per 100,000 person-years) and a smoking frequency of 44.7%. Their I0 was 12.6 or 8.4 per 100,000 person-years, taking R for smoking as 6 or 10, respectively. From these I0 estimates, the expected rates for white- and blue-collar workers (smoking frequencies 52.7 and 57.7%, respectively) were 45.8 and 49.1 per 100,000 person-years, as compared with the 22% and 57% higher observed rates, respectively. Weighing these excesses proportionally according to the sizes of the three occupational categories gave, respectively for R equal to 6 and 10, occupation-related excesses of 39% and 32% and population-attributable risks of 28% and 24%. CONCLUSIONS: About one-fourth of the lung cancers that occur among economically active Swedish men seem to have been related to occupation. This figure agrees with estimates made by other methods in Nordic countries. Due to interaction, the population-attributable risk from smoking is still high, 73% and 83% at relative risk values of 6 and 10, respectively.
Prior studies have suggested that military service may be associated with the development of amyotrophic lateral sclerosis (ALS). We conducted a population-based case-control study in Denmark to assess whether occupation in the Danish military is associated with an increased risk of developing ALS.
There were 3,650 incident cases of ALS recorded in the Danish National Patient Registry between 1982 and 2009. Each case was matched to 100 age- and sex-matched population controls alive and free of ALS on the date of the case diagnosis. Comprehensive occupational history was obtained from the Danish Pension Fund database, which began in 1964.
2.4% (n = 8,922) of controls had a history of employment in the military before the index date. Military employees overall had an elevated rate of ALS (odds ratio [OR] = 1.3; 95% confidence interval [CI]: 1.1, 1.6). A 10-year increase in years employed by the military was associated with an OR of 1.2 (95% CI: 1.0, 1.4), and all quartiles of time employed were elevated. There was little suggestion of a pattern across calendar year of first employment, but there was some evidence that increasing age at first employment was associated with increased ALS rates. Rates were highest in the decade immediately following the end of employment (OR = 1.6; 95% CI: 1.2, 2.2).
In this large population-based case-control study, employment by the military is associated with increased rates of ALS. These findings are consistent with earlier findings that military service or employment may entail exposure to risk factors for ALS.
Studies of radiation-associated risks among workers chronically exposed to low doses of radiation are important, both to estimate risks directly and to assess the adequacy of extrapolations of risk estimates from high-dose studies. This paper presents results based on a cohort of 45,468 nuclear power industry workers from the Canadian National Dose Registry monitored for more than 1 year for chronic low-dose whole-body ionizing radiation exposures sometime between 1957 and 1994 (mean duration of monitoring = 7.4 years, mean cumulative equivalent dose = 13.5 mSv). The excess relative risks for leukemia [excluding chronic lymphocytic leukemia (CLL)] and for all solid cancers were 52.5 [95% confidence interval (CI): 0.205, 291] and 2.80 (95% CI: -0.038, 7.13) per sievert, respectively, both associations having P values close to 0.05. Relative risks by dose categories increased monotonically for leukemia excluding CLL but were less consistent for all solid cancers combined. Although the point estimates are higher than those found in other studies of whole-body irradiation, the difference could well be due to chance. Further follow-up of this cohort or the combination of results from multiple worker studies will produce more stable estimates and thus complement the risk estimates from higher-dose studies.
When conducting large scale epidemiologic studies, it is a challenge to obtain quantitative exposure estimates, which do not rely on self-report where estimates may be influenced by symptoms and knowledge of disease status. In this study we developed a job exposure matrix (JEM) for use in population studies of the work-relatedness of hip and knee osteoarthritis.
Based on all 2227 occupational titles in the Danish version of the International Standard Classification of Occupations (D-ISCO 88), we constructed 121 job groups comprising occupational titles with expected homogeneous exposure patterns in addition to a minimally exposed job group, which was not included in the JEM. The job groups were allocated the mean value of five experts' ratings of daily duration (hours/day) of standing/walking, kneeling/squatting, and whole-body vibration as well as total load lifted (kg/day), and frequency of lifting loads weighing =20 kg (times/day). Weighted kappa statistics were used to evaluate inter-rater agreement on rankings of the job groups for four of these exposures (whole-body vibration could not be evaluated due to few exposed job groups). Two external experts checked the face validity of the rankings of the mean values.
A JEM was constructed and English ISCO codes were provided where possible. The experts' ratings showed fair to moderate agreement with respect to rankings of the job groups (mean weighted kappa values between 0.36 and 0.49). The external experts agreed on 586 of the 605 rankings.
The Lower Body JEM based on experts' ratings was established. Experts agreed on rankings of the job groups, and rankings based on mean values were in accordance with the opinion of external experts.
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This study investigates the relationship between personal dosemeter (PD) reading, effective dose and dose to the lens of the eye for interventional cardiologists in Norway. Doses were recorded with thermoluminescence dosemeters (TLD-100) for 14 cardiologists, and the effective doses were estimated using the Niklason algorithm. The procedures performed were coronary angiography and percutaneous coronary intervention, and all the hospitals (eight) in Norway, which are performing these procedures, were included in the study. Effective dose per unit dose-area product varied by a factor of 5, and effective dose relative to PD reading varied between 4 and 39%. Eye lens doses ranged from 39 to 138% of the dosemeter reading. On the basis of an estimated annual workload of 900 procedures, the annual effective doses ranged from 1 to 11 mSv. The estimated annual doses to the unprotected eye ranged from 9 to 210 mSv. According to the ICRP dose limits, the results indicate that the eye could be the limiting organ.
Large quantities of man-made vitreous fibers (MMVF) are handled in the Swedish prefabricated wooden house industry. The present study is part of a program to investigate mortality, cancer incidence, and current as well as previous exposure to MMVF among workers in the Swedish prefabricated wooden house industry. Since measurements of historical fiber exposure levels are lacking, these were calculated by the application of a matrix of multipliers to recently measured MMVF levels. The multipliers represented changes over time in production rate, technical properties of the fibers, manual handling vs. automation, and ventilation control. The multipliers were based on a similar matrix, developed for the MMVF-manufacturing industry, which was modified to reflect the conditions in the wooden house industry. The model was developed for the highest-exposed job title in the study, insulators. One hundred and twenty samples of airborne fiber were taken in 11 plants to reflect current exposure levels. The highest mean fiber exposure level for insulators was assessed as 0.18 f/ml (geometric mean), which occurred during the mid-1970s, compared to 0.10 f/ml at the end of the 1980s and the early 1960s. Changes in production rate, improved ventilation control, and the surface area of the total amount of MMVF sheets handled per insulator were the most important variables of the model. No increased risk of lung cancer was found in the present industry.