Historical Asbestos Measurements in Denmark-A National Database

Objectives: Due to the long lag-time for health outcomes, historical asbestos exposure measurements are valuable to support assessments of associated occupational health effects, and also to assess time trends and effects of preventive measures. Methods: Different sources of stored data were collated, assessed and refined to create a harmonized database on historical asbestos fibre concentrations measured in specific work tasks and different industries. The final database contains 9236 asbestos measurements from Danish workplaces collected from 1971 to 1997. Results: The geometric mean of asbestos concentrations in different occupations and tasks ranged from 0.003 to 35 fibres cm⁻³. Highest concentrations were registered during handling of asbestos products in the construction services during the period 1981–1997. Although all the measured asbestos exposures without the use of respiratory equipment by the worker in the period of 1971–1997 exceeded the current 8-h time-weighted average exposure limit of 0.1 fibres cm⁻³, the majority of samples collected in the earlier period of 1971 to 1980 did not exceed the exposure limit of 2 fibres cm⁻³, which was in place at the time. All exposure data obtained from 1980 and onwards were found to be one seventh of the mean fibre concentrations in the previous measurement period. The impact of time shows a clear exponentially decreasing trend-line. Conclusions: Despite limitations in coverage of different occupations and tasks associated with the inventoried historical asbestos measurements, the data are helpful to identify specific work scenarios within an industry, where relatively high asbestos exposure levels may still occur or have occurred from 1971 to 1997.

Reconstruction of the Korean Asbestos Job Exposure Matrix

Background

A job-exposure matrix (JEM) is an important surrogate indicator to evaluate past exposure levels. Although a Korean asbestos JEM has been constructed previously, this JEM includes only a few industrial and occupational groups. This study aimed to reconstruct the JEM by integrating the latest organized data to improve its utility.

Methods

We used recent Korean standard industry and occupation codes and extracted 36 articles from a systematic literature review to initiate the reconstruction of the previous Korean asbestos JEM. The resulting data consisted of 141 combinations of industrial and occupational groups. Data from the Netherlands's JEM were also reviewed and categorized into 70 industrial and 117 occupational groups by matching with the Korean data. We also utilized Germany's data, which consisted of 10 industrial and 14 occupational groups.

Results

The reconstructed Korean asbestos JEM had 141 combinations of industries and occupations. The time periods are from the 1980s to the 2000s in 10-year intervals. Most of the data were distributed between the 1990s and the 2000s. Occupations with high exposure to asbestos included knitting and weaving machine operators, automobile mechanics or assemblers, ship mechanics or assemblers, mineral ore and stone products processing mechanics, and metal casting machine operators or mold makers.

Conclusions

The reconstructed Korean asbestos JEM has expanded the type and duration of the occupational groups of the previous JEM and can serve as an important reference tool for evaluating asbestos exposure and designing compensation and prevention policies in Korea.

Compensation for Asbestos-Related Diseases in Japan: Utilization of Standard Classifications of Industry and Occupations

Background:

Asbestos-related diseases (ARD) are occupational hazards with high mortality rates. To identify asbestos exposure by previous occupation is the main issue for ARD compensation for workers. This study aimed to identify risk groups by applying standard classifications of industries and occupations to a national database of compensated ARD victims in Japan.

Methods:

We identified occupations that carry a risk of asbestos exposure according to the International Standard Industrial Classification of All Economic Activities (ISIC). ARD compensation data from Japan between 2006 and 2013 were retrieved. Each compensated worker was classified by job section and group according to the ISIC code. Risk ratios for compensation were calculated according to the percentage of workers compensated because of ARD in each ISIC category.

Results:

In total, there were 6,916 workers with ARD who received compensation in Japan between 2008 and 2013. ISIC classification section F (construction) had the highest compensated risk ratio of 6.3. Section C (manufacturing) and section F (construction) had the largest number of compensated workers (2,868 and 3,463, respectively). In the manufacturing section C, 9 out of 13 divisions had a risk ratio of more than 1. For ISIC divisions in the construction section, construction of buildings (division 41) had the highest number of workers registering claims (2,504).

Conclusion:

ISIC classification of occupations that are at risk of developing ARD can be used to identify the actual risk of workers’ compensation at the national level.

A case of laryngeal cancer induced by exposure to asbestos in a construction site supervisor

Background

Construction site supervisors are exposed to many chemicals, dusts, and metals including asbestos. Asbestos is a hazardous chemical that is carcinogenic. Laryngeal cancer is not a rare disease in Korea. The most common causes of this disease are tobacco and alcohol, and representative occupational cause is asbestos. However, up to now, no case of laryngeal cancer induced by asbestos has been reported in Korea. In this study, we report such a case in a construction site supervisor.

Case presentation

A 60-year-old man who had been experiencing hoarseness for 2 months was diagnosed with laryngeal cancer. The pathologic diagnosis was squamous cell carcinoma in situ, based on examination of a biopsy specimen obtained by resection of the lesion. The patient had been exposed to asbestos for 38 years at construction sites where he worked until diagnosed with laryngeal cancer. He had been exposed to asbestos when demolishing buildings and inspecting materials.

Conclusion

The patient in this case worked with construction materials including asbestos and supervised construction for 38 years, and was thus exposed to asbestos at construction sites. Much of the asbestos was highly concentrated especially during demolition processes. We therefore consider the laryngeal cancer of this patient to be a work-related disease.

Impact of aggregating exposure information from cases and controls when building a population-based job-exposure matrix from past expert evaluations

OBJECTIVES

To assess whether the inclusion of data from cases would bias a job-exposure matrix (JEM), we evaluated whether exposures were systematically different between cases and controls from a large historical case-control study.

METHODS

Data included 10 381 jobs assessed for occupational exposure to 294 agents within a lung cancer case-control study. For each sex, 1 JEM was developed from case jobs, and 1 from control jobs: with occupation (four-digit occupational codes), time period (1945-1959, 1960-1984, 1985-1995) and agent axes. We estimated concordance in exposure status (defined as probability of exposure threshold ≥5%) and exposure metrics of probability and intensity of exposure, between the 2 JEMs.

RESULTS

Of all hypothetical occupation-period-agent combinations, most had no or few observations. Among males there were 8136 common cells (24-occupational codes, 3-periods, 226-agents), containing sufficient observations for comparison with 92% concordance in exposure status; discordance was equally likely to be towards cases or controls. Females had 1710 common cells (9-occupational codes, 3-periods, 114-agents) with 93% concordance in exposure status; discordant cells were more likely to reflect greater exposure among cases. Among concordantly exposed cells, probability and intensity of exposures were highly correlated between the case JEM and control JEM (Kendall τ>0.50), and absolute differences were small (median difference in probability <1.5%, median ratio in intensity=1.00) for both sexes.

CONCLUSIONS

Agreement between the case JEM and control JEM was high, suggesting that aggregating the case and control information in our study into a single JEM is justifiable given the benefits of increased sample size.

Development and validation of a physical and psychosocial job-exposure matrix in older and retired workers

OBJECTIVES

A general population job-exposure matrix (GPJEM) including physical and psychosocial demands as well as psychosocial resources applicable to older and retired workers was developed. Its validity was evaluated by examining associations of physical demands and iso-strain (combination of high psychosocial demands and low resources) with health.

METHODS

Physical and psychosocial work exposures reported by 55-64 year olds were derived from the Netherlands Working Conditions Survey and linked to the Netherlands Standard Classification of Occupations 1992. A GPJEM with low, moderate, and high probability of exposure to demands and resources was developed. To examine associations with health, two groups of the Longitudinal Aging Study Amsterdam were selected: current (i.e. at the time of the interview, 55-64 years) and former workers (55-84 years). Linear and logistic regression models were applied.

RESULTS

Use of force and work in uncomfortable positions were significantly associated with functional limitations and self-perceived health (SPH), but not hip or knee osteoarthritis (OA), in current and former workers. A moderate probability of repetitive movements was associated with functional limitations in former workers. A high probability of repetitive movements was associated with functional limitations in current and former workers as well as with SPH and hip and knee OA in former workers. Respondents formerly exposed to iso-strain had significantly higher diastolic blood pressure and more often hypertension. No such associations were found in current workers. No association was found with cardiovascular disease.

CONCLUSIONS

The results suggest that our GPJEM accurately classifies jobs according to physical demands and, although less clearly, iso-strain.

Occupational toxicology of asbestos-related malignancies

INTRODUCTION

Asbestos is banned in most Western countries but related malignancies are still of clinical concern because of their long latencies. This review identifies and addresses some controversial occupational and clinical aspects of asbestos-related malignancies.

METHODS

Papers published in English from 1980 to 2009 were retrieved from PubMed. A total of 307 original articles were identified and 159 were included.

ASSESSMENT OF EXPOSURE

The retrospective assessment of exposure is usually performed by using questionnaires and job exposure matrices and by careful collection of medical history. In this way crucial information about manufacturing processes and specific jobs can be obtained. In addition, fibers and asbestos bodies are counted in lung tissue, broncho-alveolar lavage, and sputum, but different techniques and interlaboratory variability hamper the interpretation of reported measurements. SCREENING FOR MALIGNANCIES: The effectiveness of low-dose chest CT screening in exposed workers is debatable. Several biomarkers have also been considered to screen individuals at risk for lung cancer and mesothelioma but reliable signatures are still missing. ATTRIBUTION OF LUNG CANCER: Exposures correlating with lung cancer are high and in the same range where asbestosis occurs. However, the unresolved question is whether the presence of fibrosis is a requirement for the attribution of lung cancer to asbestos. The etiology of lung cancer is difficult to define in cases of low-level asbestos exposure and concurrent smoking habits. MESOTHELIOMA: The diagnosis of malignant mesothelioma may also be difficult, because of procedures in sampling, fixation, and processing, and uses of immunohistochemical probes.

CONCLUSIONS

Assessment of exposure is crucial and requires accurate medical and occupational histories. Quantitative analysis of asbestos body burden is better performed in digested lung tissues by counting asbestos bodies by light microscopy and/or uncoated fibers by transmission electron microscopy. The benefits of screenings for asbestos-related malignancies are equivocal. The attribution of lung cancer to asbestos exposure is difficult in a clinical setting because of the need to assess asbestos body burden and the fact that virtually all these patients are also tobacco smokers or former smokers. Given the premise that asbestosis is necessary to causally link lung cancer to asbestos, it follows that the assessment of both lung fibrosis and asbestos body burden is necessary.

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.

Methods

Between March 2002 and the end of 2006, we conducted a retrospective questionnaire based survey of occupational tasks and exposures with airborne asbestos fibres in a cohort of 8632 formerly asbestos exposed power industry workers. The data on exposure and occupation were entered into a specially designed computer programme, based on ambient monitoring of airborne asbestos fibre concentrations. The cumulative asbestos exposure was expressed as the product of the eight-hour time weighted average and the total duration of exposure in fibre years (fibres/cubic centimetre-years).

Results

Data of 7775 (90% of the total) participants working in installations for power generation, power distribution or gas supply could be evaluated. The power generation group (n = 5284) had a mean age of 56 years, were exposed for 20 years and had an average cumulative asbestos exposure of 42 fibre years. The occupational group of "metalworkers" (n = 1600) had the highest mean value of 79 fibre years. The corresponding results for the power distribution group (n = 2491) were a mean age of 45 years, a mean exposure duration of 12 years and an average cumulative asbestos exposure of only 2.5 fibre years. The gas supply workers (n = 512) had a mean age of 54 years and a mean duration of exposure of 15 years.

Conclusions

While the surveyed cohort as a whole was heavily exposed to asbestos dust, the power distribution group had a mean cumulative exposure of only 6% of that found in the power generation group. Based on the presented data, risk-differentiated disease surveillance focusing on metalworkers and electricians from the power generating industry seems justified. That combined with a sensitive examination technique would allow detecting asbestos related diseases early and efficiently.

Lessons from ecological and spatial studies in relation to occupational lung disease

PURPOSE OF REVIEW

The majority of epidemiological research into occupational lung disease has been advanced by the study of individuals, typically in a workplace setting. This review examines how recent advances in ecological and spatial study methodology and in the information held in routine databases could be used to enhance occupational health studies.

RECENT FINDINGS

Ecological studies often use routinely collected data, and this is becoming much more extensive and better validated with potential for increasing use in occupational health research. Improvements in computing power and statistical and geographical information systems methodology have led to more sophisticated mapping techniques and greater use of spatial information when investigating lung diseases usually related to occupational exposures. Ecological study methodology is experiencing a radical overhaul with supplementation of group-level data with information from small-scale individual-level studies. This hybrid design can be used to reduce bias and increase power and is directly applicable to the enhancement of aggregate information from job exposure matrices.

SUMMARY

Studies of occupational lung disease can be enhanced by incorporating methodological innovations from ecological and spatial studies.