To account for use of hearing protection devices (HPDs) in retrospective noise exposure assessment, adjust noise exposure estimates accordingly, and validate the adjusted estimates.
A previous study in the same working population showed a stronger relation for noise and acute myocardial infarction among those who did not wear HPD. Because accurate noise exposure assessment is complicated by the use of HPD, we previously developed a multilevel model of the likelihood of HPD use for British Columbia (Canada) lumber mill workers. Historical estimates of noise exposure can be adjusted according to models predictions and a reduction in misclassifying workers, exposure is expected.
Work history and exposure information were obtained for 13,147 lumber mill workers followed from 1909 until 1998. Audiometric data for the cohort, including hearing threshold levels at several pure tone frequencies, were obtained from the local regulatory agency for the period from 1978 to 2003. Following the modeling of HPD use, noise estimates were adjusted according to models predictions and attenuation factors based on existing research and standards. Adjusted and unadjusted noise metrics were compared by investigating their ability to predict noise-induced hearing loss.
We showed a 4-fold increase in the noise exposure and hearing loss slope, after adjusting for HPD use, while controlling for gender, age, race, as well as medical and non-occupational confounding variables.
While the relative difference before and after adjustment for use of HPD is considerable, we observed a subtle absolute magnitude of the effect. Using noise-induced hearing loss as a 'gold standard' for testing the assessment of retrospective noise exposure estimates should continue to be investigated.
To investigate the feasibility of routine monitoring for workplace antineoplastic agent contamination in the Alberta Cancer Board (ACB) pharmacy practice environment.
The ACB in the Canadian province of Alberta, which includes two public tertiary centres and 17 associated community satellite sites based around the province in existing hospitals.
Obtained organizational support and input prior to launching the feasibility study (Phase I). Samples were analysed for a common cytotoxic agent - cyclophosphamide. Surfaces chosen were within the biological safety cabinets, workplace counter tops and on external surfaces of vials provided by manufacturers. Blank samples and known contaminated controls were included in Phase I to reconfirm the methodology in a previously published study. Feasibility aspects of logistics and financial expenses were examined. A second phase (Phase II) was completed to test other areas of the pharmacy and vials, with blank samples included to reconfirm previously mentioned methodology.
The results determined that the samples tested were below acceptable detection limits with the exception of the known contaminated sample (Phase I) and exterior surfaces of vials (Phase II).
This project has increased staff awareness of the sources for antineoplastic agent workplace contamination. Some practice changes were instituted during the project itself. Logistics and expenses were realistic for routine monitoring to be adopted.
Welder exposure to metals in various industrial sectors is poorly characterized. We had the opportunity to carry out an exploratory study to characterize manganese exposure in welding operations in a recently established Quebec factory that assembled accessories for heavy excavation machinery. Ten workers were sampled for total manganese for at least two consecutive days out of three followed by two consecutive days for respirable manganese (with a size selective sampler with a median cut-off of 4 microns), during a typical week in the summer of 1998. Parts being welded were characterized as large or small. Small parts were those being welded on tables during subassembly. Workers were divided into two groups according to the parts they were welding. Seventy-eight percent of the total manganese exposure levels of welding operations during the assembly of large accessories of heavy excavation machinery exceeded the manganese American Conference of Governmental Industrial Hygienists (ACGIH) threshold limit value (TLV) of 0.20 mg/m3 (GM 0.24 mg/m3, n = 14) while none exceeded the TLV during the assembly of small pieces (GM 0.06 mg/m3, n = 8). Welding operations during the assembly of large heavy excavation machinery accessories may pose a significant health hazard. Considering the importance of task-related variables affecting exposure among workers, further studies are needed to better characterize exposure determinants of welding operations during the assembly of heavy excavation machinery accessories.
To characterize exposures of asphalt workers in Norway and to evaluate exposure control measures.
Representative asphalt paving and mixing operations were monitored in Norway in 1991-92 for exposures to bitumen fume, organic vapor, polycyclic aromatic hydrocarbons (PAHs) and vehicle exhaust (NO2, CO). Linear regression was used to evaluate introduced control measures.
A total of 320 samples of airborne organic matter were gathered (279 from paving). Median personal bitumen fume measurements ranged from 0.03 to 0.15 mg/m3 and were similar in paving and asphalt mixing. According to principal component analysis, there were three independent sets of PAHs: (i) PAHs lighter than 228 g/mol; (ii) 4- to 6-ring PAHs non-detectable in 80-90% of samples; and (iii) naphthalene. Some NO2 (1/49) and CO (12/58) concentrations near paving equipment exceeded 15 min exposure limits, 2 and 25 p.p.m., respectively. Changing sampling methods midway through the study had a significant impact on the measured bitumen fume and organic vapor levels. For pavers, lower application temperatures reduced organic vapor, but not bitumen fume, exposures. Retrofitting a paving machine produced at least a 5-fold reduction in exposure to airborne organic matter. Work in tunnels increased PAH exposures, but general ventilation partially counteracted this effect.
The observed exposure levels indicate that some potentially hazardous exposures may have occurred during paving in Norway. Bitumen fume, organic vapor and PAH exposures can be reduced using appropriate engineering control measures.
The exposure of the combined occupational hazards on the workers of aluminum plants results in the development of the occupational chronic diseases of bronchopulmonary and bone systems and oncopathology. Pathogenetic mechanisms of the toxic exposure of fluorides on the body as well as molecular and cellular structures are presented.
In a cohort study of lumber mill workers' exposure to noise and incidence of heart disease, initial noise estimates were likely overestimated because they did not account for reductions afforded by the use of hearing protection. As such information was seldom available for individual workers, modeling was necessary to predict hearing protection use and derive adjusted noise measures.
To develop a multilevel model of the likelihood of use of hearing protection devices (HPDs) for British Columbia (Canada) lumber mill workers.
The study population included 13,147 workers in 14 sawmills for whom we had information on HPD use. Subjects self-reported their use of hearing protectors during routine hearing tests over their work history period. Separate multilevel logistic regression models with increasing complexity were developed for a subcohort of workers with complete information (n = 1493) and for a subcohort comprised subjects with hearing tests coinciding with their jobs (n = 10 203). The models included random intercepts for worker and for sawmill.
HPD use was associated in both subcohorts with factors such as noise exposure and age. We also showed that specific jobs (such as sawfiling) and departments (planer, in particular) were strongly associated with the use of HPDs. The model illustrates the quantitative importance of including a hierarchical structure which allows for explaining potential sources of outcome variability.
We developed a hierarchical model to predict hearing protection use to enable correction of exposure assessments for use in retrospective epidemiological studies. We showed that this was feasible even in the absence of complete determinant information.
This paper investigates the relation between wood dust exposure in the furniture industry and occupational hygiene variables. During the winter 1997-98 54 factories were visited and 2362 personal, passive inhalable dust samples were obtained; the geometric mean was 0.95 mg/m(3) and the geometric standard deviation was 2.08. In a first measuring round 1685 dust concentrations were obtained. For some of the workers repeated measurements were carried out 1 (351) and 2 weeks (326) after the first measurement. Hygiene variables like job, exhaust ventilation, cleaning procedures, etc., were documented. A multivariate analysis based on mixed effects models was used with hygiene variables being fixed effects and worker, machine, department and factory being random effects. A modified stepwise strategy of model making was adopted taking into account the hierarchically structured variables and making possible the exclusion of non-influential random as well as fixed effects. For woodworking, the following determinants of exposure increase the dust concentration: manual and automatic sanding and use of compressed air with fully automatic and semi-automatic machines and for cleaning of work pieces. Decreased dust exposure resulted from the use of compressed air with manual machines, working at fully automatic or semi-automatic machines, functioning exhaust ventilation, work on the night shift, daily cleaning of rooms, cleaning of work pieces with a brush, vacuum cleaning of machines, supplementary fresh air intake and safety representative elected within the last 2 yr. For handling and assembling, increased exposure results from work at automatic machines and presence of wood dust on the workpieces. Work on the evening shift, supplementary fresh air intake, work in a chair factory and special cleaning staff produced decreased exposure to wood dust. The implications of the results for the prevention of wood dust exposure are discussed.
In this study the data of multiyear investigations of occupational and environmental hazards at different enterprises of the Russian aluminum industry are presented. Basing on these data, we have been elaborated the algorithm and methodological approaches on management of the occupational and ecology-related risks using hygienic safety criteria, risk evaluation technique, epidemiological and economic analysis.
The article deals with materials on radiation hygienic evaluation of radiologic diagnostic departments in various medical institutions of Moscow. The studies covered work of medical staffers in X-ray examination and in contact with short-lived isotope generators. The authors outlined the examination types and stages with maximal radiation danger. Disimetric information obtained during the study helped to calculate values of equivalent, effective doses of radiation for medical personnel and maximal potential doses.