Determinants of inhalable dust exposure in the European carbon black manufacturing industry

A large study to investigate the respiratory health effects of occupational exposure to carbon black in the European carbon black manufacturing industry commenced in 1987. During the study, a large amount of personal occupational exposure data was collected. This article describes the empirical models used to study the determinants of inhalable dust exposure, using data from 16 factories collected in the third and last cross-sectional phase of this study. Information on activities during the measurements was collected using short job category-specific questionnaires. In addition, questionnaires were completed by factory representatives on the implementation of control measures and changes in production process since the first cross-sectional phase. Mixed effects analyses of variance models were used to identify determinants of exposure, while taking into account the within- and between-worker (random) variance components. The results of these models show that, for any job category, factory is a strong predictor of exposure in this industry. These differences could not be explained entirely by factors such as age of the factory or the control measures implemented since the first phase of the study. Surprisingly, implementation of local exhaust ventilation systems had an effect that was counterintuitive; for example, in warehouses where local exhaust ventilation systems had been implemented, higher dust exposure levels were found compared to those where such control measures had not been installed since the first cross-sectional survey. Season appeared to have some effect on exposure for some job titles, with generally relatively low exposures being found in the summer. Finally, a number of activities were identified that caused higher levels of dust exposure, most notably "changing of filters" and "clean-up of carbon black spills."     

A retrospective assessment of occupational exposure to elemental carbon in the U.S. trucking industry

Background: Despite considerable epidemiologic evidence about the health effects of chronic exposure to vehicle exhaust, efforts at defining the extent of risk have been limited by the lack of historical exposure measurements suitable for use in epidemiologic studies and for risk assessment.Objectives: We sought to reconstruct exposure to elemental carbon (EC), a marker of diesel and other vehicle exhaust exposure, in a large national cohort of U.S. trucking industry workers.Methods: We identified the predictors of measured exposures based on a statistical model and used this information to extrapolate exposures across the cohort nationally. These estimates were adjusted for changes in work-related conditions over time based on a previous exposure assessment of this industry, and for changes in background levels based on a trend analysis of historical air pollution data, to derive monthly estimates of EC exposure for each job and trucking terminal combination between 1971 and 2000.Results: Occupational exposure to EC declined substantially over time, and we found significant variability in estimated exposures both within and across job groups, trucking terminals, and regions of the United States. Average estimated EC exposures during a typical work shift ranged from < 1 μg/m³ in the lowest exposed category in the 1990s to > 40 μg/m³ for workers in the highest exposed jobs in the 1970s.Conclusions: Our results provide a framework for understanding changes over time in exposure to EC in the U.S. trucking industry. Our assessment should minimize exposure misclassification by capturing variation among terminals and across U.S. regions, and changes over time.     

A historical job-exposure matrix for occupational exposure to diesel exhaust using elemental carbon as an indicator of exposure

Abstract

Any study of the long-term health effects of diesel exhaust exposure requires past exposure to be assessed. Few historical measurements of occupational exposure to elemental carbon (EC) are available, so past exposure must be assessed using models and judgments based on indirect data. A job-exposure matrix (JEM) for historical occupational exposure to diesel exhaust based on EC is presented. Past exposure to EC in occupations with a high exposure to diesel exhaust was assessed using an eight-step process. The assessments were based on technical specific data and NO₂-exposure data, and a current EC-exposure measurement program. Finally, group assessment was carried out by consensus. Temporal variations in exposure were assessed for different groups. The matrix was constructed to assess annual average EC exposure for 72 occupations between 1950 and 2004. EC exposure between 1950 and 2004 varied between 1 and 247?µg/m³, for farmers in 2000 and miners in 1975 respectively, and was generally highest in the 1970s. The JEM allows lifetime diesel exhaust exposure intensity in 72 occupations to be assessed and used in epidemiological studies.     

地质勘探工人历年接触矽尘的评价

目的对接触矽尘的地质勘探工人的接尘水平进行定量评价.方法收集9个省地质矿产勘查局所属队(厂、矿)50年代以来各工种历年的矽尘监测资料30000个,还收集历史的和近期的其他矽尘监测资料,以及1627个研究对象的工作史.利用上述资料按队(厂、矿)、工种和年段建立了矽尘接触水平,并用呼吸性矽尘量、全肺的矽尘量和总粉尘中矽尘含量估算矽尘的接触量.结果呼吸性粉尘接触浓度平均值是3mg/m3;总粉尘浓度平均值是14mg/m3,早年是29mg/m3,近年是3mg/m3;粉尘中游离二氧化硅含量平均值是(28.0±8.2)%.结合每个研究对象的工作史和矽尘接触水平分别计算出不同的矽尘接触指数.结论这种大规模矽尘接触评价方法对历年接触矽尘的估算可为剂量-反应关系评价提供依据.     

Occupational exposure to carbon black in its manufacture.

Carbon black is manufactured by the vapour phase pyrolysis of heavy aromatic hydrocarbon feedstocks. Its manufacture is worldwide and the majority of its production is for use in the rubber industry especially tyre manufacture. Its carbonaceous nature has led many to investigate the occurrence of exposure-related medical conditions. To quantify any such relationships, it is necessary to assess exposure accurately. As part of such an epidemiological investigation survey involving the measurement both of respirable and of total inhalable carbon black was undertaken in 18 plants in seven European countries between mid-1987 and mid-1989. A total of 1298 respirable samples (SIMPEDS cyclone) and 1317 total inhalable samples (IOM head) were taken and deemed of sufficient quality for inclusion in the study. The distributions of the time-weighted average values were assessed and found to be best described by a log-normal distribution, and so exposure is characterized by geometric means and standard deviations. The data are presented in terms of 13 separate job titles for both dust fractions and shows a wide variation between job titles, with the highest mean exposure experienced by the site cleaners, and 30% of the samples taken from the warehouse packers being in excess of the relevant countries' occupational exposure limits for total inhalable dust. The quality and extent of this data allows both for comparison with exposure standards and for generation of occupational exposure indices, which will be presented in another paper (Gardiner et al., in preparation).     

Applicability of homogeneous exposure groups for exposure assessment in the chemical industry

The purpose of the study was to assess occupational exposure to chemicals, by taking the aspects presented in European standard EN 689 into account, especially with respect to homogeneous exposure groups and their suitability as the basis for exposure assessment. In addition, dermal exposure to chemicals was assessed when appropriate. The industries studied included a plywood factory, a paint factory and a sewage treatment plant of an oil refinery. The workers were classified into homogeneous exposure groups by the persons in charge of occupational health issues in the respective workplaces. The concentrations of the contaminants were measured in workplace air by breathing-zone and stationary sampling, and these approaches were compared. Dermal exposure was measured when applicable. The homogeneity of the grouping was tested with analysis of variance whenever possible. The tasks studied in plywood manufacturing fulfilled the criteria of homogeneous exposure groups for both respiratory and dermal exposure. The group of operators in the sewage treatment plant was highly homogeneous. The complicated organization of the tasks made the use of homogeneous exposure groups (HEG) unsuitable at the paint factory. These findings show that reliable exposure assessment cannot be achieved with a formal standard; instead, comprehensive occupational hygiene evaluation is needed. It should also have a great importance when exposure models are developed. Received: 27 December 1999 / Accepted: 6 May 2000     

A novel strategy for retrospective exposure assessment in the Norwegian silicon carbide industry

The objective was to construct a retrospective job-exposure matrix (JEM) for the Norwegian silicon carbide industry. More than 3300 historical total dust measurements were available (1967-2005); however, there were few measurements of other agents. Total dust measurements were therefore used as the basis for the JEM, and a novel method was developed to estimate exposure to other agents. Multiple linear regression models were developed to describe historical exposure to total dust. Exposure estimates were extrapolated backward to periods without exposure data by adjustments for process and work-hour related changes. An exposure assessment study was performed where total dust was sampled in parallel with fibers or respirable dust. The respirable dust was analyzed for the content of quartz, cristobalite, and silicon carbide. Mixed-effect models were developed to estimate the exposure to these agents from total dust exposure, plant, and job group. Exposure to asbestos and polycyclic aromatic hydrocarbons was assigned qualitatively. Multiple linear regression models of total dust described historical exposure best in the furnace department (R(2) (adj) = 0.49-0.74). Models in the other departments explained less variance (R(2) (adj) = 0.12-0.32). Exposure determinants and total dust explained a substantial proportion of the between- (70-100%) and within-worker (8.0-54%) variance in the mixed-effect models. The relative bias between available historical measurements and the estimated exposure to dust components varied between -39% (fiber) and 40% (quartz). However, corrections were not considered necessary due to limitations in the historical data. The component-specific metrices were sufficiently different from each other (r(Pearson) < 0.7), with the exception of total and respirable dust (r(Pearson) = 0.84) and total dust and cristobalite (r(Pearson) = 0.72), and will enable component-specific epidemiologic analyses in the future. Improved and less correlated estimates of exposure levels for the different components in the dust were obtained with the updated exposure assessment. Due to limitations in the measurement data, assumptions had to be made, especially in the period before 1967. [Supplementary materials are available for this article. Go to the publisher's online edition of Journal of Occupational and Environmental Hygiene for the following free supplemental resource: a file containing tables outlining multiple linear regression models for prediction of total dust exposure in the processing departments of Norwegian SiC producing plants, evaluation of the predictive abilities of the reduced total dust models, and mixed models for pedicting exposure to fibers and respirable quartz, cristobalite, non-fibrous silicon carbide and respirable dust from total dust exposure.].     

Retrospective exposure assessment for benzene in the Australian petroleum industry

An excess of lympho-haematopoietic (LH) cancers has been identified in the Australian petroleum industry through the Health Watch surveillance programme. A nested case-control study is being conducted to investigate this excess. This paper describes the methods used to provide quantitative estimates of benzene exposure for each of the subjects in the case-control study. Job histories were compiled for each subject from interviews and company employment records. Site visits and telephone interviews were used to identify the tasks included in each job title. Details about the tasks such as their frequency, the technology in use and about changes that had taken place over the years were also gathered. Exposure dated back to the late 1940s for a few subjects. Collaborating petroleum companies provided recent benzene exposure monitoring data. These were used to generate Base Estimates of exposure for each task, augmented with data from the literature where necessary. Past exposures were estimated from the Base Estimates by means of an exposure algorithm. The modifying effects of technological changes and changes to the product were used in the algorithm.The algorithm was then computed to give, for each job, for each subject, an estimate of average benzene exposure in ppm in the workplace atmosphere (Workplace Estimate). This value was multiplied by the years for which the job was held and these values summed to give an estimate of Cumulative Estimate of benzene in ppm-years. The occupational hygienists performing the exposure assessment did so without knowledge of the case or control status of subjects.Overall exposures to benzene in the Australian petroleum industry were low, and virtually all activities and jobs were below a time-weighted average of 5 ppm. Exposures in terminals were generally higher than at refineries. Exposures in upstream areas were extremely low. Estimates of Cumulative Estimate to benzene ranged from 0.005 to 50.9 ppm-years.     

Occupational exposure to carbon monoxide and sulphur dioxide during the manufacture of carbon black.

The manufacture of carbon black is known to generate carbon monoxide and sulphur dioxide in the 'production gas' and the pyrolysis products of the 'production gas', respectively. Adverse health effects have been reported as associated with both contaminants (coronary heart disease with carbon monoxide and respiratory morbidity with sulphur dioxide). A major cross-sectional and longitudinal respiratory morbidity study is being conducted to assess the effects of exposure to carbon black on lung function, on chest X-rays and on responses to a questionnaire. The questionnaire includes questions on respiratory and cardiovascular symptoms, so that information regarding confounding exposure is essential. The working population of 18 manufacturing plants in seven European Countries was split into 13 job title numbers (1-13) which were then amalgamated into five job categories (A-E), with an appropriate (statistically) number of samples taken from each plant-job category. In total, 1322 carbon monoxide samples and 1301 sulphur dioxide samples were taken, using actively pumped longterm colorimetric tubes. In the majority of cases, more than half of the samples in each plant-job category were either zero or trace, thereby preventing the accurate estimation of the average exposure. The highest median carbon monoxide concentration was from the amalgamated data from all 18 plants in job number 9 (furnace operators), the highest median sulphur dioxide concentration was only 'trace'. The large number of zero and trace values also precluded the generation of current and retrospective exposure indices.     

Trends in levels of inhalable dust exposure, exceedance and overexposure in the European carbon black manufacturing industry

In an attempt to investigate the relationship between exposure to carbon black and respiratory morbidity, a study of the complete carbon black manufacturing industry in Western Europe was commissioned. As part of this study, a large number of personal inhalable (n=8015) dust exposure measurements was taken during three phases of data collection between 1987 and 1995. Repeated measurements on the same worker were taken in the last two phases, which enabled the estimation of the within- and between-worker components of variance. Simultaneously, the fixed effects of phase and factory were estimated using mixed-effects analysis of variance. The results show that the personal inhalable dust exposure has reduced significantly since the first phase of the study. In addition, the interaction term between phase and factory was significant in most job categories, confirming that the reduction of exposure was not equal across all factories.When all factories were considered together, the probability that the mean exposure of a randomly selected worker (overexposure) or the probability that the exposure on a randomly selected day for a randomly selected worker (exceedance) was higher than 3.5mg m(-3), was 10% or less for all job categories in the last phase. However, when the factories were considered separately, it appeared that the probability of overexposure or exceedance was in excess of 10% for the job categories 'Fitter/Welder', 'Warehouseman' and 'Site crew' for a number of factories. Therefore, even though exposure levels of inhalable dust have dropped considerably across the whole carbon black manufacturing industry in Western Europe, further reductions in exposure levels are required in these areas to make sure that the probability of overexposure and exceedance falls below a level of 10%.     

Retrospective exposure assessment to airborne asbestos among power industry workers

Background  

A method of individually assessing former exposure to asbestos fibres is a precondition of risk-differentiated health surveillance. The main aims of our study were to assess former levels of airborne asbestos exposure in the power industry in Germany and to propose a basic strategy for health surveillance and the early detection of asbestos related diseases.     

Biological assessment of exposure to antimony and lead in the glass-producing industry

Summary The oxide of trivalent antimony is used in the glass-producing industry as a refining agent and as a glass colouring. The batch contains up to 2% Sb₂O₃, a substance which has shown carcinogenic properties in animal experiments. The internal levels of antimony and lead in blood (SbB and PbB) as well as the excretion with the urine (SbU and PbU) were determined by hydrid and electrothermal atomic absorption (HY-AAS and ET-AAS), respectively. In addition, measurements of airborne Sb₂O₃-concentrations were performed. The 109 volunteers were employed in four different fields: melting area, batch bunker, glass-washing area, and transport/maintenance. Differences between the concentrations of antimony and lead in blood and urine with respect to the fields of activity were evaluated statistically. The highest values of airborne Sb₂O₃ with up to 840 g/m³ (TWA), were detected in the batch bunker. Correspondingly, significantly enhanced SbU-values from 1.5 to 15.7 g/l (median: 5.0 g/l were found in specimens collected from the batch mixers. In the same group, the lead excretion (PbU) with values from 9 to 110 g/l (median: 43 g/l) was also found to be the highest. Due to the fast renal excretion of antimony, the determination of SbU is useful for biological monitoring.     

Current and historical individual data about exposure of workers in the rayon industry to carbon disulfide and their validity in calculating the cumulative dose

Introduction

The objective of the study was to investigate how exposure to carbon disulfide (CS₂) in a rayon-manufacturing plant has changed within two decades and whether it is possible to calculate valid data for the individual cumulative exposure.

Methods

The data for CS₂ concentration in air and biological exposure monitoring (2-thio-1,3-thiaxolidine-4-carboxylic acid (TTCA) in urine) from two cross-sectional studies, performed in 1992 (n = 362) and 2009 (n = 212) in a German rayon-manufacturing plant, were compared to data obtained from company-internal measurements between the studies.

Results

Using the data from the cross-sectional studies and company-internal data, cumulative external exposure and the cumulative internal exposure were calculated for each worker. External and internal CS₂ exposure of the employees decreased from 1992 (medians 4.0 ppm and 1.63 mgTTCA/g creatinine) to 2009 (medians 2.5 ppm and 0.86 mg/g). However, company-internal CS₂ data do not show a straight trend for this period. The annual medians of the company-internal measurement of external exposure to CS₂ have varied between 2.7 and 8.4 ppm, in which median values exceeded 5 ppm generally since 2000. The annual medians for the company-internal biomonitoring assessment ranged between 1.2 and 2.8 mg/g creatinine. The cumulative CS₂ exposure ranged from 8.5 to 869.5 ppm years for external exposure and between 1.30 and 176.2 mg/g creatinine years for the internal exposure. Significant correlations were found between the current air pollution and the internal exposure in 2009 but also between the cumulative external and internal CS₂ exposure.

Conclusions

Current exposure data, usually collected in cross-sectional studies, rarely allow a reliable statement on the cumulative dose, because of higher exposure in the past and of fluctuating courses of exposure. On the other hand, company-internal exposure data may be affected by non-representative measurement strategies. Some verification of the reliability of cumulative exposure data may be possible by testing the correlation between cumulative exposure data of external assessment and biological monitoring.     

A translational science approach to community-based participatory research using methodological triangulation

Journal of Public Health - To advance the science of translational research and triangulation through a case study of community-based participatory research (CBPR) study on children’s...     

Expert assessment of exposure to carcinogens in Norway's offshore petroleum industry

This study presents and evaluates an expert group's assessment of exposure to carcinogens for defined job categories in Norway's offshore petroleum industry, 1970-2005, to provide exposure information for a planned cohort study on cancer. Three university and five industry experts in occupational hygiene individually assessed the likelihood of exposure to 1836 combinations of carcinogens (n=17), job categories (n=27) and time periods (n=4). In subsequent plenary discussions, the experts agreed on exposed combinations. Agreement between the individual and the panel assessments was calculated by Cohen's kappa index. Using the panel assessment as reference, sensitivity and specificity were estimated. The eight experts assessed 63% of the 1836 combinations in plenary, resulting in 265 (14%) convened exposed combinations. Chlorinated hydrocarbons, benzene and inhalation of mineral oils had the highest number of exposed job categories (n=14, 9 and 10, respectively). The job categories classified as exposed to the highest numbers of carcinogens were the mechanics (n=10), derrick workers (n=6) and process technicians (n=5). The agreement between the experts' individual assessments and the panel assessment was kappa=0.53-0.74. The sensitivity was 0.55-0.86 and specificity 0.91-0.97. For these parameters, there were no apparent differences between the university experts and the industry experts. The resulting 265 of 1836 possible exposure combinations convened as "exposed" by expert assessment is presented in this study. The experts' individual ratings highly agreed with the succeeding panel assessment. Correlation was found between years of experience of the raters and agreement with the panel. The university experts and the industry experts' assessments had no apparent differences. Further validation of the exposure assessment is suggested, such as by new sampling data or observational studies.     

A practical approach to exposure assessment programs in the private sector: a partial validation study of a qualitative chemical exposure assessment model

Utilizing a computer-based exposure assessment program, a United States-based chemical company was able to predict which chemicals and tasks presented the greatest probability of exposure in the workplace. The data generated by the model also enabled the company to prioritize these tasks for quantitative exposure monitoring. The assessment program addressed potential chemical exposure to workers in a cost-effective way. This assessment program reduced a facility's cost of complying with the Occupational Safety and Health Administration (OSHA) standard by about 90 percent. Overall, the program reduced the company's cost by about $700,000 when compared to traditional methods used for achieving compliance with these regulations. In addition, by utilizing a computer-based approach, a facility did streamline its chemical exposure assessment process. A comparative evaluation study was conducted in conjunction with a graduate research project. The purpose of the study was to compare the company's qualitative exposure assessment model with several other exposure assessment models. The project compared hazard rankings calculated from three exposure assessment models with actual exposure data for three work scenarios. Overall, the models appeared to be predictive of measured exposures. Therefore, they can be useful tools to help make decisions on which exposures have the highest potential to cause occupational illness to employees and therefore require additional monitoring and follow-up.     

Personal sampling for inhalable aerosol exposures of carbon black manufacturing industry workers

The study was concerned with the measurement of inhalable aerosol exposures in the carbon black production industry. The primary goal of the study was to determine the extent to which inhalable aerosol exposure, as measured by the Institute of Occupational Medicine (IOM) personal inhalable sampling head, compared to "total" aerosol exposure, as measured by traditional methodology. A secondary objective was the evaluation of another inhalable aerosol sampler for carbon black aerosol measurement. In addition, an exploratory evaluation of the applicability of the National Institute for Occupational Safety and Health (NIOSH) analytical method (Method 5040) for the determination of carbon black, measured as elemental carbon, was conducted. A field study was carried out in a number of North American carbon black production plants using three samplers: the 2 Lpm IOM sampler as a reference sampler for the inhalable fraction, the 2 Lpm closed-face 37-mm plastic cassette that has been used for many years for total aerosol, and the 3.5 Lpm GSP sampler that has recently been identified by some as a possible candidate for inhalable aerosol. No such studies have previously been reported for the carbon black industry. Further, there have been no reports of the GSP performance in direct comparison to a reference instrument like the IOM sampler. The results showed that inhalable aerosol exposures for workers in carbon black production and packing areas were higher than the corresponding total aerosol exposures by a factor of nearly three, implying the presence of significantly coarser aerosol than previously thought based simply on knowledge of the carbon black production process. The fact that the aerosols collected in portions of the process comprised high proportions of non-elemental carbon particulate was thought likely to be responsible, underlining the need to consider whether gravimetric assessment for such exposure is the most appropriate metric. In addition, and somewhat surprisingly, the GSP sampler emerged clearly as a good alternative to the IOM sampler for collecting inhalable aerosol in carbon black industry workplaces like those studied (although this conclusion cannot yet be extended to other workplaces).