Use of the Finnish Information System on Occupational Exposure (FINJEM) in epidemiologic, surveillance, and other applications

Leveraging Administrative Health Databases to Address Health Challenges in Farming Populations: Scoping Review and Bibliometric Analysis (1975-2024)

BACKGROUND

Although agricultural health has gained importance, to date, much of the existing research relies on traditional epidemiological approaches that often face limitations related to sample size, geographic scope, temporal coverage, and the range of health events examined. To address these challenges, a complementary approach involves leveraging and reusing data beyond its original purpose. Administrative health databases (AHDs) are increasingly reused in population-based research and digital public health, especially for populations such as farmers, who face distinct environmental risks.

OBJECTIVE

We aimed to explore the reuse of AHDs in addressing health issues within farming populations by summarizing the current landscape of AHD-based research and identifying key areas of interest, research gaps, and unmet needs.

METHODS

We conducted a scoping review and bibliometric analysis using PubMed and Web of Science. Building upon previous reviews of AHD-based public health research, we conducted a comprehensive literature search using 72 terms related to the farming population and AHDs. To identify research hot spots, directions, and gaps, we used keyword frequency, co-occurrence, and thematic mapping. We also explored the bibliometric profile of the farming exposome by mapping keyword co-occurrences between environmental factors and health outcomes.

RESULTS

Between 1975 and April 2024, 296 publications across 118 journals, predominantly from high-income countries, were identified. Nearly one-third of these publications were associated with well-established cohorts, such as Agriculture and Cancer and Agricultural Health Study. The most frequently used AHDs included disease registers (158/296, 53.4%), electronic health records (124/296, 41.9%), insurance claims (106/296, 35.8%), population registers (95/296, 32.1%), and hospital discharge databases (41/296, 13.9%). Fifty (16.9%) of 296 studies involved >1 million participants. Although a broad range of exposure proxies were used, most studies (254/296, 85.8%) relied on broad proxies, which failed to capture the specifics of farming tasks. Research on the farming exposome remains underexplored, with a predominant focus on the specific external exposome, particularly pesticide exposure. A limited range of health events have been examined, primarily cancer, mortality, and injuries.

CONCLUSIONS

The increasing use of AHDs holds major potential to advance public health research within farming populations. However, substantial research gaps persist, particularly in low-income regions and among underrepresented farming subgroups, such as women, children, and contingent workers. Emerging issues, including exposure to per- and polyfluoroalkyl substances, biological agents, microbiome, microplastics, and climate change, warrant further research. Major gaps also persist in understanding various health conditions, including cardiovascular, reproductive, ocular, sleep-related, age-related, and autoimmune diseases. Addressing these overlooked areas is essential for comprehending the health risks faced by farming communities and guiding public health policies. Within this context, promoting AHD-based research, in conjunction with other digital data sources (eg, mobile health, social health data, and wearables) and artificial intelligence approaches, represents a promising avenue for future exploration.

Development of Korean CARcinogen EXposure: occupation-based exposure matrix

OBJECTIVES

Information systems focusing on occupational carcinogen exposure, whether categorized by industry or occupation, play a pivotal role in the prevention of occupational cancers. Recently, the Korean CARcinogen EXposure (K-CAREX) system was developed to assess carcinogen exposure by industry. However, corresponding information categorized by occupation has yet to be developed. This study aimed to develop an occupation-based exposure matrix for occupational carcinogens as an extension of the K-CAREX framework.

METHODS

The Work Environment Measurement Database (WEMD) and the Special Health Examination Database (SHED) were combined to estimate exposure intensity by occupation. The WEMD supplied exposure levels, whereas the SHED provided occupation information. Additionally, the SHED served as the primary data source for constructing an indicator of exposure prevalence by occupation, utilizing standard occupational classification.

RESULTS

A total of 22 carcinogens were selected for evaluating exposure intensity, and 20 carcinogens were selected for assessing exposure prevalence. Exposure intensity and prevalence were assigned to 156 occupational groups based on these carcinogens. For instance, in terms of welding fume exposure, welders were assigned an exposure intensity rating of 3 and exhibited exposure prevalence of 26%.

CONCLUSIONS

Our findings complement the previously developed K-CAREX, which offered an industry-based exposure matrix. The resultant comprehensive K-CAREX, incorporating both industry- and occupation-based matrices, can be utilized for occupational cancer prevention and epidemiological studies.

An occupational mechanical job exposure index based on five Norwegian nationwide surveys of living conditions on work environment

OBJECTIVES

Nordic register data are not collected for research purposes, and various dimensions of working conditions are typically missing in register-based research. One way to address the issue of missing information on the work environment in register data is to utilize a job exposure matrix (JEM). The purpose of this paper is to document and provide access to a Mechanical Job Exposure Matrix (JEM) and a validated Occupational Mechanical Job Exposure Index based on the constructed JEM, allowing researchers to utilize the index in register-based research. The JEM and the Occupational Mechanical Job Exposure Index were created using data from five nationwide Surveys of Living Conditions on work environment conducted in Norway in 2006, 2009, 2013, 2016, and 2019, encompassing a total of 43,977 respondents. The index can be merged to register data using occupational codes (STYRK-98) and gender, which is information collected by the registries. The ultimate aim of constructing the index was to create a comprehensive measure of mechanical job exposures for use in future analyses of Norwegian register data.

DATA DESCRIPTION

This paper provides the scripts documenting the construction of the Mechanical Job Exposure Matrix (JEM) and the Occupational Mechanical Job Exposure Index, as well as a data file including the matrix and the index. A script for merging the matrix and index to register data is also provided.

Occupational characteristics and disability-free survival after retirement age: an exploratory analysis from the ASPREE study

Background

Certain occupational characteristics have been linked with poor health and reduced longevity. However, the association between occupational characteristics and survival free of disability in a post-retirement age group has not been investigated.

Methods

We investigated outcomes in 12,215 healthy older Australian adults in the Aspirin in Reducing Events in the Elderly (ASPREE) and ASPREE Longitudinal Study of Older Persons (ALSOP) sub-study. The ISCO-88 major occupational groups, settings, and activity levels were assigned based on free-text job descriptions. The Finnish Job Exposure Matrix was used to assign occupational characteristics to the three longest-held jobs. The primary endpoint, disability-free survival, was defined as a composite measure of death, dementia, or persistent physical disability. The endpoint of all-cause mortality was analyzed separately. Because of multiple exploratory analyses, only those associations with a two-sided value of p less than 0.005 were considered statistically significant. Cox proportional hazard models were used to calculate adjusted hazard ratios.

Results

Having worked in an 'elementary' occupation was associated with a reduction in disability-free survival. A specific impact on disability-free survival was observed among those whose work had involved high accident risk and adverse social climate. No significant relationship was identified with those previously exposed to sedentary work, vigorous physical activity, work primarily outdoors, or a range of other occupational characteristics. All-cause mortality was not increased among any of the occupational groups.

Conclusion

This exploratory study found a reduction in disability-free survival among people who worked in 'elementary' occupations, with specific risks associated with occupations involving high accident risks and adverse social climate.

Long working hours, sedentary work, noise, night shifts and risk of ischaemic heart disease

OBJECTIVE

Ischaemic heart disease (IHD) is a leading cause of death in Western countries. The aim of this study was to examine the associations between occupational exposure to loud noise, long working hours, shift work, and sedentary work and IHD.

METHODS

This data linkage study included all New Zealanders employed and aged 20-64 years at the time of the 2013 census, followed up for incident IHD between 2013 and 2018 based on hospitalisation, prescription and death records. Occupation and number of working hours were obtained from the census, and exposure to sedentary work, loud noise and night shift work was assessed using New Zealand job exposure matrices. HRs were calculated for males and females using Cox regression adjusted for age, socioeconomic status, smoking and ethnicity.

RESULTS

From the 8 11 470 males and 7 83 207 females employed at the time of the census, 15 012 male (1.9%) and 5595 female IHD cases (0.7%) were identified. For males, there was a modestly higher risk of IHD for the highest category (>90 dBA) of noise exposure (HR 1.19; 95% CI 1.07 to 1.33), while for females exposure prevalence was too low to calculate an HR. Night shift work was associated with IHD for males (HR 1.10; 95% CI 1.05 to 1.14) and females (HR 1.25; 95% CI 1.17 to 1.34). The population attributable fractions for night shift work were 1.8% and 4.6%, respectively. No clear associations with working long hours and sedentary work were observed.

CONCLUSIONS

This study suggests that occupational exposures to high levels of noise and night shift work might be associated with IHD risk.

Constructing and validating an Occupational Mechanical Job Exposure Index based on five Norwegian nationwide Surveys of Living Conditions on work environment

Background

The overall aim of this study was to examine essential aspects of reliability and validity of a constructed Occupational Mechanical Job Exposure Index for use in analyses of Norwegian register data. 

Methods

We utilized data from the Norwegian nationwide Survey of Living Conditions on work environment in 2006, 2009, 2013, 2016 and 2019. Occupations were classified on a 4-digit level based on the Norwegian version of the International Standard Classification of Occupations (ISCO-88). We constructed a 4-digit correspondence table between the occupational codes used in the 2006 and 2009 surveys (STYRK-98) and the codes used in 2013, 2016 and 2019 (STYRK-08). The mechanical exposures were collected by Statistics Norway using telephone interviews. As for reliability, we examined the agreement between the individual- and the occupational-based mechanical exposures using Cohen’s kappa, sensitivity and specificity measures. Construct, concurrent and predictive validity pertaining to the Occupational Mechanical Job Exposure Index were analysed using both survey data and nationwide register data.

Results

The analysis shows a fair-to-moderate overlap between occupational-based mechanical exposures and the individually reported exposures. Construct validity of the Occupational Mechanical Job Exposure Index, as estimated by a confirmatory factor analysis using the occupational-based mechanical exposures, showed that the 8 exposures formed one underlying factor. When assessing the concurrent value of the Occupational Mechanical Job Exposure Index to the index based on the individual reported exposures, the occupational mechanical index showed lower and reproducible associations with lower back pain for both men and women. For long-term sick leave, the occupational mechanical index showed higher and reproducible associations for both genders. As for predictive validity, the register data analysis shows that the occupational mechanical index was associated with disability and a higher number of long-term sickness benefits periods for both men and women. For men the index also predicted higher mortality.

Conclusion

Our tests of reliability and validity of the Occupational Mechanical Job Exposure Index indicate that the index overall has acceptable statistical properties and will be useful in analyses of Norwegian register data where individual information on these types of exposures is missing.

Job-Exposure Matrix: A Useful Tool for Incorporating Workplace Exposure Data Into Population Health Research and Practice

Workplace exposures to physical, chemical, and psychosocial factors account for a large burden of chronic diseases. Obtaining useful estimates of current and past workplace exposures is challenging, particularly in large general population studies. Job-exposure matrices (JEMs) are a useful tool for exposure assessment, particularly when no individual level exposure data are available. A JEM provides a cross-tabulation of job titles (sometimes combined with industry) and estimated exposures to workers carrying out these jobs during different time periods. The major limitation of JEMs is that they do not account for individual variation in exposures within the same job. This limitation is offset by the advantages of low cost, wide applicability, lack of bias from self-reporting, and the ability to estimate exposures based on job titles when no other exposure data exist. There is growing use of JEMs in research examining the role of workplace exposures in the development of chronic diseases, and interest in their application to public health practice. This paper provides a scoping review of JEM use, some examples of JEMs, and brief guidance for the application of JEMs in epidemiological research. In conclusion, JEMs provide a useful tool for researchers and public health practitioners to estimate occupational exposures in large scale epidemiological studies relevant to many health conditions.

Development of a Job-Exposure Matrix for Ultrafine Particle Exposure: The MatPUF JEM

OBJECTIVE

Ultrafine particles (UFPs) are generated from common work processes and have thus existed for a long time. Far more prevalent than engineered nanoparticles, they share common toxicological characteristics with them. However, there is no existing retrospective assessment tool specific to UFPs, for example, for epidemiological purposes. Thus, we aimed to develop a job-exposure matrix dedicated to UFPs.

METHOD

Fifty-seven work processes were identified as well as the chemical composition of UFPs emitted, following a literature review and the input of an expert panel. These work processes were associated with occupational codes as defined by the ISCO 1968 classification. The probability and frequency of UFP exposure were assessed for each combination of occupational code and process. Summarized probabilities and frequencies were then calculated for all ISCO occupational codes associated with several processes. Variations in exposure over time or across industrial sectors were accounted for in the assessment of each occupational code.

RESULTS

In the ISCO classification, 52.8% of the occupational codes (n = 835) assessed were associated with exposure to UFPs, consisting mainly of carbonaceous, metallic, and mineral families (39.5%, 22 and, 15.8%, respectively). Among them, 42.6% involved very probable exposure, and at a high frequency (regularly or continuously).

CONCLUSION

These results suggest that occupational exposure to UFPs may be extensive at the workplace and could concern a wide variety of workers. Pending the integration of a third parameter assessing the intensity of UFP exposure, the MatPUF JEM already constitutes a promising and easy-to-use tool to study the possible adverse health effects of UFPs at work. It may also guide prevention policies in the occupational environments concerned, including those involving engineered nanoparticles.

Development of Korean CARcinogen EXposure: An Initiative of the Occupational Carcinogen Surveillance System in Korea

OBJECTIVE

To prevent occupational cancers, carcinogen exposure surveillance systems have been developed in many countries. This study aimed to develop a carcinogen exposure database specific to South Korea.

METHODS

Twenty known human carcinogens were selected for this study. The International Standard Classification of Industry was used for a classification scheme of industries. Three nationwide occupational exposure databases, the Work Environment Measurement Database, the Special Health Examination Database, and the Work Environment Condition Survey, were used to calculate reference exposure prevalence estimates by carcinogen and industry. Then, 37 professional industrial hygienists with at least 19 years of field experience provided their own exposure prevalence estimates, after reviewing the abovementioned reference estimates derived from three data sources. The median value of the experts' estimates was used as the final exposure prevalence. Finally, the number of exposed workers was computed by multiplying the final exposure prevalence by the number of workers extracted from the 2010 national census data by carcinogen and industry.

RESULTS

The exposure prevalence and the number of exposed workers were calculated according to 20 carcinogen and 228 minor industrial groups, assuming year 2010 circumstances. The largest population was exposed to welding fumes (326 822 workers), followed by ultraviolet radiation (238 937 workers), ionizing radiation (168 712 workers), and mineral oil mist (146 798 workers).

CONCLUSIONS

Our results provide critical data on carcinogen exposure for the prevention of occupational cancers.

Solvent exposed occupations and risk of Parkinson disease in Finland

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Finnish register-based case-control Parkinson disease (PD) studies are feasible.

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Some occupations with potential for exposure to solvents are associated with PD.

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Chlorinated hydrocarbon solvents in particular might increase PD risk modestly.

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Some occupational co-exposures might enhance PD-solvent associations in PD studies.

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Studies without smoking/education data will underestimate PD-solvent associations.

Introduction

Epidemiologic and toxicology studies suggest that exposure to various solvents, especially chlorinated hydrocarbon solvents, might increase Parkinson disease (PD) risk.

Methods

In a population-based case-control study in Finland, we examined whether occupations with potential for solvent exposures were associated with PD. We identified newly diagnosed cases age 45–84 from a nationwide medication reimbursement register in 1995–2014. From the population register, we randomly selected non-PD controls matched on sex, along with birth and diagnosis years (age). We included 11,757 cases and 23,236 controls with an occupation in the 1990 census, corresponding to age 40–60. We focused on 28 occupations with ≥ 5% probability of solvent exposure according to the Finnish Job Exposure Matrix. We estimated odds ratios (ORs) and 95% confidence intervals (CIs) by logistic regression modeling, adjusting for age, sex, socioeconomic status, and smoking probability.

Results

Similar proportions of cases (5.5%) and controls (5.6%) had an occupation with potential exposure to any solvents. However, all occupations with a point estimate above one, and all significantly or marginally significantly associated with PD (electronic/telecommunications worker [OR = 1.63, 95% CI 1.05–2.50], laboratory assistant [OR = 1.40, 95% CI 0.98–1.99], and machine/engine mechanic [OR = 1.23, 95% CI 0.99–1.52]) entailed potential for exposure to chlorinated hydrocarbon solvents, specifically. Secondary analyses indicated exposure to polycyclic aromatic hydrocarbons and some metals might contribute to the association for mechanics.

Conclusion

PD risk might be slightly increased in occupations with potential exposure to chlorinated hydrocarbon solvents. Confirmation is required in additional studies that adjust for other occupational exposures and smoking.

Lifetime occupational exposure proportion estimation methods: a sensitivity analysis in the general population

OBJECTIVE

To present a sensitivity analysis of the most widely used means of estimating lifetime occupational exposure proportion (LOEP) and their respective impacts on LOEP and population-attributable fraction (PAF) estimates.

METHODS

A French population-based sample with full job history (N = 10,010) was linked with four Matgéné job-exposure matrices: flour, cement, silica and benzene. LOEP and the 95% confidence interval were estimated using four methods: the maximum exposure probability during the career (Proba_max), two methods subdividing careers into job-periods (job-period_M1, job-period_M2) and one into job-years (job-year). To quantify differences between methods, percentages of variation were calculated for proportion values and PAF, and compared with published results for France using cross-sectional proportion multiplied by a factor.

RESULTS

For each agent, LOEP estimated from the maximum probability during the career (Proba_max) was consistently lower than proportion taking account of job-periods or job-years. LOEP on Proba_max for flour, cement, silica and benzene were, respectively, 4.4% 95% CI (4.0-4.7), 4.3% (3.9-4.6), 6.1% (5.7-6.5) and 3.9% (3.6-4.2). Percentage of variation ranged from 0 to 55.8% according to the agent. The number of cancer cases varied by a twofold factor for exposure to silica and lung cancer and by a fourfold factor for exposure to benzene and acute myeloid lymphoma.

CONCLUSIONS

The present study provides a description of several LOEP estimation methods based on exposure assessment over the entire career and describes their impact on PAF. For health monitoring purposes, we recommend to report a range of LOEP with low and high estimates obtained using job-periods (job-period_M1 and job-period_M2).

Occupational exposure to noise in relation to pregnancy-related hypertensive disorders and diabetes

Objectives Exposure to environmental noise has been associated with an increased risk of cardiovascular diseases and diabetes, but evidence for occupational noise is limited and conflicting, especially related to pregnancy outcomes. This study aimed to evaluate the association of occupational noise exposure with hypertensive disorders of pregnancy (HDP) and gestational diabetes. Methods Our population-based cohort study utilized data on 1 109 516 singletons born to working mothers in Sweden between 1994-2014 from the Medical Birth Register and the Longitudinal Integration Database for Health Insurance and Labor Market Studies. Noise exposure came from a job exposure matrix (JEM) in five categories <70, 70-74, 75-80, 80-85, >85 dB(A). Relative risks (RR), adjusted for confounders and other job exposures, were calculated by modified Poisson regressions for the full sample and a subsample of first-time mothers reporting full-time work. Results Exposure to 80-85 dB(A) of noise was associated with an increased risk of all HDP [RR 1.12, 95% confidence interval (CI) 1.05-1.18] and preeclampsia alone (RR 1.14, 95% CI 1.07-1.22) in the full sample. Results were similar for first-pregnancy, full-time workers. Exposure to >85 dB(A) of noise was also associated with an increased risk of gestational diabetes (RR 1.57, 95% CI 1.10-2.24) in the analysis restricted to first-time mothers working full-time. Conclusion In this study, exposure to noise was associated with an increased risk for HDP and gestational diabetes, particularly in first-time mothers who work full-time. Further research is needed to confirm findings and identify the role of hearing protection on this association so prevention policies can be implemented.

Study of Occupational Chromium, Iron, and Nickel Exposure and Amyotrophic Lateral Sclerosis in Denmark

Studies of occupational metal exposures and amyotrophic lateral sclerosis (ALS) have focused primarily on known neurotoxicants, including lead, mercury, selenium, and cadmium. However, these exposures are often co-occurring with other lesser studied metals. We conducted a population-based case-control study with the aim of assessing associations between occupational chromium, iron, and nickel exposures and risk of ALS. We identified ALS cases in Denmark from 1982 through 2013 from the Danish National Patient Registry and matched them to 100 controls based on birth year and sex. Cumulative metal exposures were estimated using job exposure matrices applied to occupational history from the Danish Pension Fund. Although mutually adjusted odds of ALS were higher in men with chromium exposures in the third quartile (aOR = 1.24; 95% CI 0.91, 1.69) and fourth quartile (aOR = 1.19; 95% CI: 0.80, 1.76) compared to those with no exposure, differences did not reach statistical significance. We also observed higher odds of ALS in women with nickel exposures in the third quartile (aOR = 2.21; 95% CI: 1.14, 4.28), but not for the fourth quartile (aOR = 0.61; 95% CI: 0.23, 1.64). Our findings do not suggest associations between occupational exposures to these metals and ALS. However, unavoidable non-differential misclassification from the use of JEMs may have masked truly increased risk.

Sarcoidosis and silica dust exposure among men in Sweden: a case-control study

OBJECTIVE

To determine whether occupational exposure to silica dust is associated with an increased risk of developing sarcoidosis.

DESIGN

Case-control study of all individuals between 20 and 65 years of age diagnosed with sarcoidosis (D86) in Sweden between 2007 and 2016. Controls were matched to cases (2:1) based on age, sex and county at the time of diagnosis. A Job Exposure Matrix was used to estimate the occupational silica exposure of all cases and controls.

SETTING

Medical and occupational data from the National Outpatient Register were used to implement a case-control analysis, while the two controls used for each case were selected from the National Register of the Total Population. Information about occupation and time of employment were collected from the Swedish Occupational Register.

PARTICIPANTS

All men and women aged 20-65 years old who were diagnosed sarcoidosis (D86) from 2007 to 2016 were included and assigned two controls.

MAIN OUTCOMES

Silica dust exposure correlates with an increased risk of developing sarcoidosis in men.

RESULTS

The prevalence of silica exposure at work was statistically significantly higher among male cases than controls (OR 1.27, 95% CI 1.13 to 1.43). For men of an age of 35 years or younger the correlation seems to be stronger (OR 1.48, 95% CI 1.1 to 1.87) than in older men (OR 1.21, 95% CI 1.05 to 1.39). For men older than 35 with exposure to silica the prevalence of sarcoidosis increased with the exposure time, with an OR of 1.44 (95% CI 1.04 to 2.00) for exposure of more than 10 years.

CONCLUSIONS

Occupational exposure to silica dust seems to increase the risk of sarcoidosis among men between 20 and 65 years of age. The risk is higher among exposed men 35 years or younger and older men with longer exposure (>6 years).

Developing a Job Exposure Matrix of Work Organization Hazards in the United States: A Review on Methodological Issues and Research Protocol

Background

Most job exposure matrices (JEMs) have been developed for chemical and physical hazards in the United States (US). In addition, the overall validity of most JEMs of work organization hazards using self-reported data in the literature remains to be further tested due to several methodological weaknesses.

Methods

This paper aims to review important methodological issues with regard to a JEM of work organization hazards using self-report data and to present a research protocol for developing a four-axis (job titles, hazards, sex, and time) JEM of major work organization hazards using the US General Social Survey-Quality of Work-Life (GSS-QWL) data (2002–2018; N = 7,100 workers).

Results

Five methodological weaknesses in existing JEMs of work organization hazards using self-report data were identified: having only two axes (hazard and occupation), using psychometrically weak items and scales, including scales having little interoccupational variability, unresolved optimal minimum numbers of subjects per occupation, and low accessibility. The methodological weaknesses were successfully addressed in the proposed research protocol.

Conclusion

The work organization JEM to be developed will significantly facilitate and strengthen occupational epidemiological studies on work organization hazards and major health outcomes, improve national and occupational surveillance of work organization hazards, and promote interventions for a healthy work environment in the US.

A mixtures approach to solvent exposures and amyotrophic lateral sclerosis: a population-based study in Denmark

Studies of occupational solvent exposures and amyotrophic lateral sclerosis (ALS) have been conflicting. We conducted a population-based case-control study of mixed occupational solvent exposures and ALS. Using the Danish National Patient Registry, we identified ALS cases in Denmark from 1982 to 2013, and matched them to 100 controls based on sex and birth year. We estimated cumulative exposures to solvents (benzene, methylene chloride, toluene, trichloroethylene, perchloroethylene, and 1,1,1-trichloroethane) via job exposure matrices and applied them to occupational history from the Danish Pension Fund. Sex-stratified conditional logistic regression analyses revealed higher adjusted odds of ALS for men with exposure to benzene (aOR = 1.20; 95% CI 1.02, 1.41) and methylene chloride (aOR = 1.23; 95% CI 1.07, 1.42). We used weighted quantile sum regression to explore combined solvent exposures and risk of ALS in exposed subjects and found increased odds of 26 to 28% in all exposure lag periods for every one-unit increase in the mixture index in men. Weights of methylene chloride predominated the mixture index in all lag periods. Our study suggests an increased risk of ALS in men exposed to multiple solvents, with the greatest influence being from methylene chloride. These findings highlight the need to utilize mixtures analysis when considering co-occurring exposures.

Risks of developing ulcerative colitis and Crohn's disease in relation to silica dust exposure in Sweden: a case-control study

OBJECTIVE

To determine whether occupational exposure to silica dust causes an increased risk of developing Crohn's disease (CD) and ulcerative colitis (UC).

DESIGN

Case-control study of CD (K50) and UC (K51) from 2007 through 2016. Controls were matched to cases (2:1) based on age, sex and county at the time of diagnosis. A job exposure matrix was used to estimate the occupational silica exposure of all cases and controls.

SETTING

Medical and occupational data from the National Outpatient Register were used to implement a case-control analysis, while the two controls used for each case were selected from the National Register of the Total Population.

PARTICIPANTS

All men and women aged 20-65 years old who were diagnosed with CD (K50) and UC (K51) during the years of study were included and assigned two controls, resulting in 58 136 cases and 116 272 controls.

MAIN OUTCOMES

Silica dust exposure correlates with an increased risk of developing UC in men and CD in women.

RESULTS

The prevalence of UC was significantly higher in the group exposed to silica dust (OR 1.13, 95% CI 1.06 to 1.21) than in controls, particularly in individuals with over 5 years exposure. When stratified by sex, a significantly increased OR was detected for men (OR 1.33, 95% CI 1.05 to 1.22). This trend was also consistent with longer exposure times. The prevalence of UC was not increased in exposed women. The prevalence of CD was significantly increased among exposed women (OR 1.29, 95% CI 1.01 to 1.65), but not for exposed men.

CONCLUSIONS

Silica dust exposure correlates with an increased risk of developing UC, especially in men, and the risk seems to increase with the duration and degree of exposure. Conversely, silica dust exposure correlates positively with the risk of developing CD in women.

Occupational exposure to asbestos and silica and risk of developing rheumatoid arthritis: findings from a Swedish population-based case-control study

Objective

Airborne agents including cigarette smoke associate with an increased risk of rheumatoid arthritis (RA). We analysed to which extent occupational exposure to asbestos and silica confers an increased risk of developing serologically defined subsets of RA.

Methods

This Swedish population-based case-control study enrolled incident RA cases between 1996 and 2013 (n=11 285), identified through national public authority and quality registers, as well as from the Epidemiological Investigation of Rheumatoid Arthritis (EIRA) Study. Controls (n=1 15 249) were randomly selected from Sweden’s population register and matched on sex, age, index year and county. Occupational histories were obtained from national censuses. Exposure to asbestos and silica was assessed by job-exposure matrices. Logistic regression was used to calculate ORs adjusted for age, sex, county, index year, alcohol use and smoking.

Results

Results showed that male workers exposed to asbestos had higher risk of seropositive RA (OR=1.2, 95% CI 1.0 to 1.4) and seronegative RA (OR=1.2, 95% CI 1.0 to 1.5) compared with unexposed workers. The risk was highest among workers exposed to asbestos from 1970, before a national ban was introduced. Male workers exposed to silica also had higher risk of RA (seropositive RA: OR=1.4, 95% CI 1.2 to 1.6; seronegative RA: OR=1.3, 95% CI 1.0 to 1.5). For the largest subset, seropositive RA, the OR increased with the number of years exposed to silica, up to OR=2.3 (95% CI 1.4 to 3.8, p for trend <0.0001). Women overall had lower ORs than men, but the duration and intensity of their exposure were lower.

Conclusions

In conclusion, we observed an association between asbestos exposure and risk of developing RA and extended previous findings of an association between silica exposure and RA risk, where a dose-response relationship was observed.

Physical demand at work and sick leave due to low back pain: a cross-sectional study

OBJECTIVES

To investigate if self-reported high physical demand at work, objective physical workload using a job exposure matrix (JEM) and fear-avoidance beliefs are associated with reported sick leave in the previous year in persons with low back pain (LBP). Second, to investigate if the effects of fear-avoidance and self-reported high physical demand at work on sick leave are modified by the objective physical workloads.

SETTINGS

Participants were recruited from general practice and by advertisement in a local newspaper.

PARTICIPANTS

305participants with a current period of 2-4 weeks LBP and self-reported difficulty in maintaining physically demanding jobs due to LBP were interviewed, clinically examined and had an MRI at baseline.

MAIN OUTCOME MEASURES

Independent variables were high fear-avoidance, self-reported high physical demand at work and objective measures of physical workloads (JEM). Outcome was self-reported sick leave due to LBP in the previous year. Logistic regression and tests for interaction were used to identify risk factors and modifiers for the association with self-reported sick leave.

RESULTS

Self-reported physically demanding work and high fear-avoidance were significantly associated with prior sick leave due to LBP in the previous year with OR 1.75 95% CI (1.10 to 2.75) and 2.75 95% CI (1.61to 4.84), respectively. No objective physical workloads had significant associations. There was no modifying effect of objective physical workloads on the association between self-reported physical demand at work/high fear-avoidance and sick leave.

CONCLUSIONS

Occupational interventions to reduce sick leave due to LBP may have to focus more on those with high self-reported physical demands and high fear-avoidance, and less on individuals with the objectively highest physical workload.

TRIAL REGISTRATION NUMBER

NCT02015572; Post-results.

Population-based study of amyotrophic lateral sclerosis and occupational lead exposure in Denmark

OBJECTIVES

Previous research has indicated links between lead (Pb) exposure and increased risk of neurodegenerative disorders, including amyotrophic lateral sclerosis (ALS). In this study, we evaluated the association between occupational Pb exposures and ALS.

METHODS

ALS cases were ascertained through the Danish National Patient Registry from 1982 to 2013 and age and sex-matched to 100 controls. Using complete employment history since 1964 from the Danish Pension Fund, cumulative Pb exposure was estimated for each subject via a Danish job exposure matrix. Associations were evaluated using conditional logistic regression analyses and stratified by sex.

RESULTS

For men with >50% probability of exposure, there was an increase in odds of ALS for exposures in the 60th percentile or higher during any time 5 years prior to diagnosis (aOR: 1.35; 95% CI 1.04 to 1.76) and 10 years prior to diagnosis (aOR: 1.33; 95% CI 1.03 to 1.72). No significant associations were observed in women, and there were no linear trends seen for Pb exposures for either sex.

CONCLUSIONS

Our study indicates an association between consistently higher occupational Pb exposures and ALS. These findings support those of previously reported associations between ALS and specific occupations that commonly experience Pb exposure.

Biological monitoring of workers exposed to engineered nanomaterials

As the number of nanomaterial workers increase there is need to consider whether biomonitoring of exposure should be used as a routine risk management tool. Currently, no biomonitoring of nanomaterials is mandated by authoritative or regulatory agencies. However, there is a growing knowledge base to support such biomonitoring, but further research is needed as are investigations of priorities for biomonitoring. That research should be focused on validation of biomarkers of exposure and effect. Some biomarkers of effect are generally nonspecific. These biomarkers need further interpretation before they should be used. Overall biomonitoring of nanomaterial workers may be important to supplement risk assessment and risk management efforts.

Development of and Selected Performance Characteristics of CANJEM, a General Population Job-Exposure Matrix Based on Past Expert Assessments of Exposure

Objectives

We developed a job-exposure matrix called CANJEM using data generated in population-based case-control studies of cancer. This article describes some of the decisions in developing CANJEM, and some of its performance characteristics.

Methods

CANJEM is built from exposure information from 31673 jobs held by study subjects included in our past case-control studies. For each job, experts had evaluated the intensity, frequency, and likelihood of exposure to a predefined list of agents based on jobs histories and descriptions of tasks and workplaces. The creation of CANJEM involved a host of decisions regarding the structure of CANJEM, and operational decisions regarding which parameters to present. The goal was to produce an instrument that would provide great flexibility to the user. In addition to describing these decisions, we conducted analyses to assess how well CANJEM covered the range of occupations found in Canada.

Results

Even at quite a high level of resolution of the occupation classifications and time periods, over 90% of the recent Canadian working population would be covered by CANJEM. Prevalence of exposure of specific agents in specific occupations ranges from 0% to nearly 100%, thereby providing the user with basic information to discriminate exposed from unexposed workers. Furthermore, among exposed workers there is information that can be used to discriminate those with high exposure from those with low exposure.

Conclusions

CANJEM provides good coverage of the Canadian working population and possibly that of several other countries. Available in several occupation classification systems and including 258 agents, CANJEM can be used to support exposure assessment efforts in epidemiology and prevention of occupational diseases.

Relationships of Lower Lung Fibrosis, Pleural Disease, and Lung Mass with Occupational, Household, Neighborhood, and Slate Roof-Dense Area Residential Asbestos Exposure

This study aimed to evaluate the relationship between various asbestos exposure routes and asbestos-related disorders (ARDs). The study population comprised 11,186 residents of a metropolitan city who lived near asbestos factories, shipyards, or in slate roof-dense areas. ARDs were determined from chest X-rays indicating lower lung fibrosis (LFF), pleural disease (PD), and lung masses (LMs). Of the subjects, 11.2%, 10.4%, 67.2% and 8.3% were exposed to asbestos via occupational, household, neighborhood, and slate roof routes, respectively. The odds ratio (OR) of PD from household exposure (i.e., living with asbestos-producing workers) was 1.9 (95% confidence interval: 0.9–4.2), and those of LLF and PD from neighborhood exposure, or residing near asbestos factories) for <19 or >20 years, or near a mine, were 4.1 (2.8–5.8) and 4.8 (3.4–6.7), 8.3 (5.5–12.3) and 8.0 (5.5–11.6), and 4.8 (2.7–8.5) and 9.0 (5.6–14.4), respectively. The ORs of LLF, PD, and LM among those residing in slate-dense areas were 5.5 (3.3–9.0), 8.8 (5.6–13.8), and 20.5 (10.4–40.4), respectively. Substantial proportions of citizens residing in industrialized cities have potentially been exposed to asbestos, and various exposure routes are associated with the development of ARDs. Given the limitations of this study, including potential confounders such as socioeconomic status, further research is needed.

Case–control study to assess the association between colorectal cancer and selected occupational agents using INTEROCC job exposure matrix

Background

Colorectal cancer is the third most prevalent cancer in the world and is twice as common in developed countries when compared with low-income and middle-income countries. Few occupational risk factors for colorectal cancer have been identified. This case–control study aimed to assess the association between colorectal cancer and occupational exposure to selected solvents, combustion products, metals, dusts and other agents.

Methods

Cases (n=918) were enrolled from the Western Australian Cancer Registry from June 2005 to August 2007. Controls (n=1021) were randomly selected from the Western Australian electoral roll. We collected lifetime occupational history from cases and controls, in addition to their demographic and lifestyle characteristics. We applied the INTEROCC job exposure matrix to convert the occupational history to occupational exposure for 18 selected agents. Three exposure indices were developed: (1) exposed versus non-exposed; (2) lifetime cumulative exposure; and (3) total duration of exposure. The associations between colorectal cancer and the selected agents were estimated using logistic regression models adjusting for sex and age.

Results

None of the 18 selected agents showed an association with colorectal cancer. No dose–response relationships with lifetime cumulative exposure or duration of exposure were observed.

Conclusion

There was no evidence to suggest that occupational exposure to 18 selected agents increased the risk of colorectal cancer.

New Opportunities in Exposure Assessment of Occupational Epidemiology: Use of Measurements to Aid Exposure Reconstruction in Population-Based Studies

PURPOSE OF REVIEW

Exposure assessment efforts in population-based studies are increasingly incorporating measurements. The published literature was reviewed to identify the measurement sources and the approaches used to incorporate measurements into these efforts.

RECENT FINDINGS

The variety of occupations and industries in these studies made collecting participant-specific measurements impractical. Thus, the starting point was often the compilation of large databases of measurements from inspections, published literature, and other exposure surveys. These measurements usually represented multiple occupations, industries, and worksites, and spanned multiple decades. Measurements were used both qualitatively and quantitatively, dependent on the coverage and quality of the data. Increasingly, statistical models were used to derive job-, industry-, time period-, and other determinant-specific exposure concentrations. Quantitative measurement-based approaches are increasingly replacing expert judgment, which facilitates the development of quantitative exposure-response associations. Evaluations of potential biases in these measurement sources, and their representativeness of typical exposure situations, warrant additional examination.

Parental Occupational Exposure to Organic Solvents and Testicular Germ Cell Tumors in their Offspring: NORD-TEST Study

BACKGROUND

Testicular germ cell tumors (TGCT) were suggested to have a prenatal environmentally related origin. The potential endocrine disrupting properties of certain solvents may interfere with the male genital development in utero.

OBJECTIVES

We aimed to assess the association between maternal and paternal occupational exposures to organic solvents during the prenatal period and TGCT risk in their offspring.

METHODS

This registry-based case control study included TGCT cases aged 14–49 y (n=8,112) diagnosed from 1978 to 2012 in Finland, Norway, and Sweden. Controls (n=26,264) were randomly selected from the central population registries and were individually matched to cases on year and country of birth. Occupational histories of parents prior to the child’s birth were extracted from the national censuses. Job codes were converted into solvent exposure using the Nordic job-Nordic Occupational Cancer Study Job-Exposure Matrix. Conditional logistic regression was used to estimate odds ratios (OR) and 95% confidence intervals (CI).

RESULTS

Overall, no association was found between prenatal maternal exposure to solvents and TGCT risk. In subset analyses using only mothers for whom occupational information was available in the year of or in the year prior to the child’s birth, there was an association with maternal exposure to aromatic hydrocarbon solvents (ARHC) (OR=1.53; CI: 1.08, 2.17), driven by exposure to toluene (OR=1.67; CI: 1.02, 2.73). No association was seen for any paternal occupational exposure to solvents with the exception of exposure to perchloroethylene in Finland (OR=2.42; CI: 1.32, 4.41).

CONCLUSIONS

This study suggests a modest increase in TGCT risk associated with maternal prenatal exposure to ARHC. https://doi.org/10.1289/EHP864.

Estimates of the Number of Workers Exposed to Diesel Engine Exhaust in South Korea from 1993 to 2013

Background

The aim of this study was to estimate the number of workers exposed to diesel engine exhaust (DEE) by industry and year in the Republic of Korea.

Method

The estimates of workers potentially exposed to DEE in the Republic of Korea were calculated by industry on the basis of the carcinogen exposure (CAREX) surveillance system. The data on the labor force employed in DEE exposure industries were obtained from the Census on Establishments conducted by the Korea National Statistical Office from 1993 to 2013. The mean values of prevalence rates adopted by EU15 countries were used as the primary exposure prevalence rates. We also investigated the exposure prevalence rates and exposure characteristics of DEE in 359 workplaces representing 11 industries.

Results

The total number of workers exposed to DEE were estimated as 270,014 in 1993 and 417,034 in 2013 (2.2% of the total labor force). As of 2013, the industry categorized as “Land transport” showed the highest number of workers exposed to DEE with 174,359, followed by “Personal and household services” with 70,298, “Construction” with 45,555, “Wholesale and retail trade and restaurants and hotels” with 44,005, and “Sanitation and similar services” with 12,584. These five industries, with more than 10,000 workers exposed to DEE, accounted for 83% of the total DEE-exposed workers. Comparing primary prevalence rates used for preliminary estimation among 49 industries, “Metal ore mining” had the highest rate at 52.6%, followed by “Other mining” with 50.0%, and “Land transport” with 23.6%.

Conclusion

The DEE prevalence rates we surveyed (1.3–19.8%) were higher than the primary prevalence rates. The most common emission sources of DEE were diesel engine vehicles such as forklifts, trucks, and vans. Our estimated numbers of workers exposed to DEE can be used to identify industries with workers requiring protection from potential exposure to DEE in the Republic of Korea.

A review of job-exposure matrix methodology for application to workers exposed to radiation from internally deposited plutonium or other radioactive materials

Any potential health effects of radiation emitted from radionuclides deposited in the bodies of workers exposed to radioactive materials can be directly investigated through epidemiological studies. However, estimates of radionuclide exposure and consequent tissue-specific doses, particularly for early workers for whom monitoring was relatively crude but exposures tended to be highest, can be uncertain, limiting the accuracy of risk estimates. We review the use of job-exposure matrices (JEMs) in peer-reviewed epidemiological and exposure assessment studies of nuclear industry workers exposed to radioactive materials as a method for addressing gaps in exposure data, and discuss methodology and comparability between studies. We identified nine studies of nuclear worker cohorts in France, Russia, the USA and the UK that had incorporated JEMs in their exposure assessments. All these JEMs were study or cohort-specific, and although broadly comparable methodologies were used in their construction, this is insufficient to enable the transfer of any one JEM to another study. Moreover there was often inadequate detail on whether, or how, JEMs were validated. JEMs have become more detailed and more quantitative, and this trend may eventually enable better comparison across, and the pooling of, studies. We conclude that JEMs have been shown to be a valuable exposure assessment methodology for imputation of missing exposure data for nuclear worker cohorts with data not missing at random. The next step forward for direct comparison or pooled analysis of complete cohorts would be the use of transparent and transferable methods.

Expected number of asbestos-related lung cancers in the Netherlands in the next two decades: a comparison of methods

OBJECTIVES

Exposure to asbestos fibres increases the risk of mesothelioma and lung cancer. Although the vast majority of mesothelioma cases are caused by asbestos exposure, the number of asbestos-related lung cancers is less clear. This number cannot be determined directly as lung cancer causes are not clinically distinguishable but may be estimated using varying modelling methods.

METHODS

We applied three different modelling methods to the Dutch population supplemented with uncertainty ranges (UR) due to uncertainty in model input values. The first method estimated asbestos-related lung cancer cases directly from observed and predicted mesothelioma cases in an age-period-cohort analysis. The second method used evidence on the fraction of lung cancer cases attributable (population attributable risk (PAR)) to asbestos exposure. The third method incorporated risk estimates and population exposure estimates to perform a life table analysis.

RESULTS

The three methods varied substantially in incorporated evidence. Moreover, the estimated number of asbestos-related lung cancer cases in the Netherlands between 2011 and 2030 depended crucially on the actual method applied, as the mesothelioma method predicts 17 500 expected cases (UR 7000-57 000), the PAR method predicts 12 150 cases (UR 6700-19 000), and the life table analysis predicts 6800 cases (UR 6800-33 850).

CONCLUSIONS

The three different methods described resulted in absolute estimates varying by a factor of ∼2.5. These results show that accurate estimation of the impact of asbestos exposure on the lung cancer burden remains a challenge.

Testicular germ cell tumours and parental occupational exposure to pesticides: a register-based case-control study in the Nordic countries (NORD-TEST study)

OBJECTIVES

A potential impact of exposure to endocrine disruptors, including pesticides, during intrauterine life, has been hypothesised in testicular germ cell tumour (TGCT) aetiology, but exposure assessment is challenging. This large-scale registry-based case-control study aimed to investigate the association between parental occupational exposure to pesticides and TGCT risk in their sons.

METHODS

Cases born in 1960 or onwards, aged between 14 and 49 years, and diagnosed between 1978 and 2013 in Denmark, Finland, Norway or Sweden, were identified from the respective nationwide cancer registries. Four controls per case were randomly selected from the general national populations, matched on year of birth. Information on parental occupation was collected through censuses or Pension Fund information and converted into a pesticide exposure index based on the Finnish National Job-Exposure Matrix.

RESULTS

A total of 9569 cases and 32,028 controls were included. No overall associations were found for either maternal or paternal exposures and TGCT risk in their sons, with ORs of 0.83 (95% CI 0.56 to 1.23) and of 1.03 (0.92 to 1.14), respectively. Country-specific estimates and stratification by birth cohorts revealed some heterogeneity. Cryptorchidism, hypospadias and family history of testicular cancer were risk factors but adjustment did not change the main results.

CONCLUSIONS

This is the largest study on prenatal exposure to pesticides and TGCT risk, overall providing no evidence of an association. Limitations to assess individual exposure in registry-based studies might have contributed to the null result.

CAREX Canada: an enhanced model for assessing occupational carcinogen exposure

OBJECTIVES

To estimate the numbers of workers exposed to known and suspected occupational carcinogens in Canada, building on the methods of CARcinogen EXposure (CAREX) projects in the European Union (EU).

METHODS

CAREX Canada consists of estimates of the prevalence and level of exposure to occupational carcinogens. CAREX Canada includes occupational agents evaluated by the International Agency for Research on Cancer as known, probable or possible human carcinogens that were present and feasible to assess in Canadian workplaces. A Canadian Workplace Exposure Database was established to identify the potential for exposure in particular industries and occupations, and to create exposure level estimates among priority agents, where possible. CAREX EU data were reviewed for relevance to the Canadian context and the proportion of workers likely to be exposed by industry and occupation in Canada was assigned using expert assessment and agreement by a minimum of two occupational hygienists. These proportions were used to generate prevalence estimates by linkage with the Census of Population for 2006, and these estimates are available by industry, occupation, sex and province.

RESULTS

CAREX Canada estimated the number of workers exposed to 44 known, probable and suspected carcinogens. Estimates of levels of exposure were further developed for 18 priority agents. Common exposures included night shift work (1.9 million exposed), solar ultraviolet radiation exposure (1.5 million exposed) and diesel engine exhaust (781 000 exposed).

CONCLUSIONS

A substantial proportion of Canadian workers are exposed to known and suspected carcinogens at work.