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OBJECTIVES: Firefighters are exposed to a variety of known and suspected carcinogens through their work. However, the association with cancer risk has limited evidence. We examined cancer incidence among firefighters in the newly established Norwegian Fire Departments Cohort restricted to sites with established associations with carcinogens encountered during firefighting. This included sites within the respiratory, urinary, and lympho-hematopoietic systems, and the skin and all sites combined. METHODS: Male firefighters (N=3881) in the cohort were linked to the Cancer Registry of Norway for incident cancer cases occurring during the period 1960–2018. We calculated standardized incidence ratios (SIR) with rates for the national male population as reference, and stratified SIR analyses by period of first employment, duration of employment, and time since first employment. RESULTS: Elevated risk was seen for all sites combined (SIR 1.15, 95% confidence interval 1.07–1.23). Elevated risk of urinary tract cancer was observed among firefighters who began working before 1950, and with observation ≥40 years since first employment. Risk of mesothelioma and laryngeal cancer were elevated with ≥40 years since first employment and with ≥30 years employment duration. CONCLUSIONS: The observed associations between firefighting and urinary tract cancer, laryngeal cancer, and mesothelioma have been observed in some studies previously, and our results suggest the observed elevated risks are related to carcinogenic occupational exposures. Differences in risk by period of employment potentially reflect changes in exposures from improved quality and use of personal protective equipment.

OBJECTIVES: We provide a brief introduction to the objectives, data, methods and results of the World Health Organization (WHO)/International Labor Organization (ILO) Joint Estimates of the Work-related Burden of Disease and Injury (WHO/ILO Joint Estimates), which estimated the burden attributable to 19 selected occupational risk factors. METHODS: The WHO/ILO Joint Estimates were produced within the global Comparative Risk Assessment framework, which attributes the burden of one specific health outcome (ie, disease/injury) to a specific occupational risk factor. For 39 established occupational risk factor-health outcome pairs, estimates are produced using population attributable fractions (PAF) from recent burden of disease estimates. For two additional pairs, PAF are calculated from new databases of exposure and risk ratios produced in WHO/ILO systematic reviews. Attributable disease burdens were estimated by applying the PAF to total disease burdens. RESULTS: Globally in 2016, it is estimated that 1.88 [95% uncertainty range (UR) 1.84–1.92] million deaths and 89.72 (95% UR 88.61–90.83) million disability-adjusted life years were attributable to the 19 selected occupational risk factors and their health outcomes. A disproportionately large work-related burden of disease is observed in the WHO African Region (for disability-adjusted life years), South-East Asia Region, and Western Pacific Region (for deaths), males and older age groups. CONCLUSIONS: The WHO/ILO Joint Estimates can be used for global monitoring of exposure to occupational risk factors and work-related burden of disease and to identify, plan, cost, implement and evaluate policies, programs and actions to prevent exposure to occupational risk factors and their associated burden.

OBJECTIVE: Birth cohorts collect valuable and under-utilized information on employment and health of parents before and during pregnancy, at birth, and sometimes after birth. In this discussion paper, we examine how these data could be exploited to study the complex relationships and interactions between parenthood, work, and health among parents themselves. METHODS: Using a web-based database of birth cohorts, we summarize information on maternal employment and health conditions and other potentially related variables in cohorts spread throughout Europe. This provided information on what data are available and could be used in future studies, and what was missing if specific questions are to be addressed, exploiting the opportunity to explore work–health associations across heterogenous geographical and social contexts. RESULTS: We highlight the many potentialities provided by birth cohorts and identify gaps that need to be addressed to adopt a life-course approach and investigate topics specific to the peri-pregnancy period, such as psychosocial aspects. We address the technical difficulties implied by data harmonization and the ethical challenges related to the repurposing of data, and provide scientific, ecological and economic arguments in favor of improving the value of data already available as a result of a serious investment in human and material resources. CONCLUSIONS: There is a hidden treasure in birth cohorts that deserves to be brought out to study the relationships between employment and health among working parents in a time when the boundaries between work and life are being stretched more than ever before.

Knowing the public health impact of occupational hazards is important for prioritization of preventive and mitigating measures and in monitoring how well they succeed. Information is needed on attributable morbidity and mortality, both globally and by national/regional jurisdiction. The best method of estimating population burdens will vary according to the nature of the hazard. One important consideration is whether health effects can be ascribed to work with confidence in the individual. Such attribution is straightforward where a disease occurs only as a consequence of occupational exposure (eg, coal workers’ pneumoconiosis, byssinosis). Alternatively, a link to occupation can sometimes be established through clinical investigation. For example, allergic contact dermatitis may confidently be attributed to work where it is associated with demonstrable sensitization to an agent encountered only in the workplace; and the role of work in an acute injury or poisoning may be clear from its circumstances and timing. Even where a disorder is not occupational in origin, it may be made worse by exposures in the workplace to an extent that can be determined in the individual case. For example, exacerbation of pre-existing asthma by occupational inhalation of irritants may be apparent from serial measurements of lung function when an employee is at, and away from, work. In such circumstances, public health burden can be estimated by aggregating data on individual cases, either across the population as a whole, or in a representative subsample. Possible sources of information include routine surveillance schemes such as the Health and Occupation Research (THOR) Network (1), data on claims for industrial injuries compensation (provided they are sufficiently accurate and complete), and ad hoc surveys in representative samples of the population. Where a disease has material fatality (eg, silicosis), counts of deaths may provide a good measure of attributable mortality. More commonly, occupational disorders are not specific to work, and there is no reliable way of determining occupational contribution in the individual case. The hazard may increase the probability and/or the average severity of a disease. For example, asbestos makes development of lung cancer more likely, while coal mine dust causes chronic obstructive pulmonary disease (COPD) through incremental loss of lung function. Either way, the need is to determine how much morbidity or mortality would be eliminated across the population, if the relevant occupational exposure were removed. To this end, epidemiological data comparing health outcomes in people according to their exposure must be combined with information on the prevalence and distribution of exposure in the population for which an estimate is sought. This is the approach underpinning the WHO/ILO analysis that is reported in Pega et al’s paper (2). Estimates of relative risk for paired combinations of occupational risk factor and disease were collated with data on the population prevalence of exposure to calculate population attributable fractions (PAF) (3), which then were multiplied by estimates of the total population impact of the disease (in terms of deaths and disability-adjusted life-years) to derive burdens attributable to occupation (2). The analysis was necessarily restricted to combinations of risk factor and disease for which there was judged to be adequate evidence, but it also has other important limitations, not all of which are acknowledged and discussed. Some of the assumed hazards are questionable. For example, occupational exposure to formaldehyde is estimated to account for some 350–400 deaths per year from leukemia. Although the International Agency for Research on Cancer has classified formaldehyde as a human carcinogen (4), that decision was controversial, and the systematic review and meta-analysis from which the relative risk was derived concluded that “on balance, these data do not provide consistent support for a relationship between formaldehyde exposure and leukemia risk” (5). Similarly, doubts have been cast on the assumed hazard of ischemic heart disease from long working hours, at least among people of higher socioeconomic status (6). A second problem lies in the ambiguous specification of some risk factors. The analysis attributes large numbers of deaths from COPD to occupational exposure to “particulate matter, gases and fumes” (2). It is unclear, however, what exactly is implied by that term. The many and varied particulates, gases and fumes that people encounter through their work differ widely in their toxicity. If the mix of such pollutants differed between the studies that were used to estimate the prevalence of exposure, and those used to estimate relative risk, then major bias is possible. Even where risk factors are specified more precisely (eg, sulfuric acid), there are challenging complexities in the characterization and classification of exposure. Impacts at an individual level, whether on risk of disease or its severity, can vary enormously according to the timing, duration and intensity of exposures. An earlier report suggests that for many occupational carcinogens, exposures were classed to three levels (background/low/high) (7). However, within such broad categories, there may be substantial heterogeneity of risk. In the WHO/ILO analysis, many of the risk estimates for occupational carcinogens come from industrial cohort studies, which have tended to focus on working populations known or expected to have relatively high intensity and duration of exposure (making any risks more readily detectable). In contrast, data on the prevalence of exposure derive from studies that aimed to ascertain the full extent of exposure in the population, even if only at a modest level. Within a broad exposure category, a meta-estimate of risk from published cohort studies may not be applicable to the distribution of exposures within that category in the general population, and such incompatibility could in some cases cause population burden to be seriously overestimated. Another challenge when extrapolating risk estimates from samples to populations is the potential for effect modification. The burden of back and neck pain was assessed in relation to “occupational exposure to ergonomic factors” (2), defined as “proportion of the population who are exposed to ergonomic risk factors for low back pain at work or through their occupation” (3). However, it is unclear how well the calculation allowed for major variation between countries in the individual risk of musculoskeletal pain and disability from specified occupational activities (8, 9). One way round these problems is to estimate population burden more directly, using the same study to provide information both on the distribution of exposure in the population and the effects of that exposure. For example, a national analysis of mortality by occupation has been used to estimate excess deaths from COPD among coal miners in England and Wales (10). While such analyses have other important limitations (for example, mortality as recorded on death certificates is an imperfect marker for disease, and full account cannot be taken of changes in occupation over a lifetime), the risk estimates that they generate are an average for exposure as it occurs in the population as a whole. In this respect, provided the ascertainment of exposure is reasonably sensitive (specificity is less critical), estimates of population burden will be less prone to bias. Given the many sources of uncertainty in the WHO/ILO analysis, only some of which have been highlighted here, it is surprising that such tight 95% uncertainty ranges are reported. For example, the uncertainty in thousands of deaths globally in 2017 from occupational exposure to formaldehyde is reported as 1 to 1, and that for lung cancer from occupational exposure to diesel exhaust as 16 to 20 (3). This is a concern because findings published under the auspices of authoritative international bodies such as WHO and ILO are liable to be accepted by many without question. As occupational health researchers and practitioners, we are naturally disposed to champion the importance of health protection in the workplace, but that enthusiasm should not compromise scientific rigor. Findings that appear to support our case must be scrutinized with the same care as those that call it into question. When estimating population burdens of disease from occupational hazards, we should aim if possible to triangulate between different analytical approaches and sources of data, carefully considering and acknowledging sources of uncertainty. The potential for error will often be greatest for exposures that are relatively prevalent in the working population (eg, long working hours), for which small differences in excess relative risk can translate into substantial differences in estimated burdens of disease at population level. References 1. Carder M, Hussey L, Money A, et al. The Health and Occupation Research Network: an evolving surveillance system. Safety and Health at Work 2017;8:231-6. https://doi.org/10.1016/j.shaw.2016.12.003 2. Pega F, Hamzaoui H, Náfrádi B, Momen NC. Global, regional and national burden of disease attributable to 19 selected occupational risk factors for 183 countries, 2000-2016: A systematic analysis from the WHO/ILO Joint Estimates of the Work-related Burden of Disease and Injury. Scand J Work Environ Health. 2022;48(2):158168. https://doi.org/10.5271/sjweh.4001 3. GBD 2017 Risk Factor Collaborators. Global, regional, and national comparative risk assessment of 84 behavioural, environmental and occupational, and metabolic risks or clusters of risks for 195 countries and territories, 1990-2017: a systematic analysis for the Global Burden of Disease Study 2017. Lancet 2018;392:1923-4. https://doi.org/10.1016/S0140-6736(18)32225-6 4. International Agency for Research on Cancer. Chemical agents and related occupations. IARC Monographs on the Evaluation of Carcinogenic Risks to Humans; Volume 100F:401-435. Lyon, France 2012. https://publications.iarc.fr/123 (accessed 30.11.21). 5. Collins JJ, Lineker GA. A review and meta-analysis of formaldehyde and leukemia. Reg Toxicol Pharmacol 2004;40:81-89. https://doi.org/10.1016/j.yrtph.2004.04.006 6. Kivimäki M, Virtana M, Nyberg ST, Batty GD. The WHO/ILO report on long working hours and ischaemic heart disease - conclusions are not supported by the evidence. Environment International 2020;144:106048. https://doi.org/10.1016/j.envint.2020.106048 7. Concha-Barrientos M, Nelson D I, Driscoll T, et al. Chapter 21. Selected occupational risk factors. In Ezzati M, Lopez AD, Rogers A, Murray CJL, editors. Comparative quantification of health risks: global and regional burden of disease attributable to selected major risk factors. Geneva: World Health Organization; 2004. 8. Coggon D, Ntani G, Palmer KT, et al. Disabling musculoskeletal pain in working populations: Is it the job, the person or the culture? Pain. 2013;154:856-63. 9. Coggon D, Ntani G, Palmer KT, et al. Drivers of international variation in prevalence of disabling low back pain: Findings from the CUPID Study. Eur J Pain. 2019;23:35-45. https://doi.org/10.1002/ejp.1255 10. Coggon D, Harris EC, Brown T, Rice S, Palmer KT. Work-related mortality in England and Wales1979-2000. Occup Environ Med. 2010;67:816-22. https://doi.org/10.1136/oem.2009.052670

Objectives Firefighters are exposed to a variety of known and suspected carcinogens through their work. However, the association with cancer risk has limited evidence. We examined cancer incidence among firefighters in the newly established Norwegian Fire Departments Cohort restricted to sites with established associations with carcinogens encountered during firefighting. This included sites within the respiratory, urinary, and lymphohematopoietic systems, and the skin and all sites combined. Methods Male firefighters (N=3881) in the cohort were linked to the Cancer Registry of Norway for incident cancer cases occurring during the period 1960–2018. We calculated standardized incidence ratios (SIR) with rates for the national male population as reference, and stratified SIR analyses by period of first employment, duration of employment, and time since first employment. Results Elevated risk was seen for all sites combined (SIR 1.15, 95% confidence interval 1.07–1.23). Elevated risk of urinary tract cancer was observed among firefighters who began working before 1950, and with observation ≥40 years since first employment. Risk of mesothelioma and laryngeal cancer were elevated with ≥40 years since first employment and with ≥30 years employment duration. Conclusions The observed associations between firefighting and urinary tract cancer, laryngeal cancer, and mesothelioma have been observed in some studies previously, and our results suggest the observed elevated risks are related to carcinogenic occupational exposures. Differences in risk by period of employment potentially reflect changes in exposures from improved quality and use of personal protective equipment. [ABSTRACT FROM AUTHOR]

Objectives We provide a brief introduction to the objectives, data, methods and results of the World Health Organization (WHO)/International Labor Organization (ILO) Joint Estimates of the Work-related Burden of Disease and Injury (WHO/ILO Joint Estimates), which estimated the burden attributable to 19 selected occupational risk factors. Methods The WHO/ILO Joint Estimates were produced within the global Comparative Risk Assessment framework, which attributes the burden of one specific health outcome (ie, disease/injury) to a specific occupational risk factor. For 39 established occupational risk factor-health outcome pairs, estimates are produced using population attributable fractions (PAF) from recent burden of disease estimates. For two additional pairs, PAF are calculated from new databases of exposure and risk ratios produced in WHO/ILO systematic reviews. Attributable disease burdens were estimated by applying the PAF to total disease burdens. Results Globally in 2016, it is estimated that 1.88 [95% uncertainty range (UR) 1.84-1.92] million deaths and 89.72 (95% UR 88.61-90.83) million disability-adjusted life years were attributable to the 19 selected occupational risk factors and their health outcomes. A disproportionately large work-related burden of disease is observed in the WHO African Region (for disability-adjusted life years), South-East Asia Region, and Western Pacific Region (for deaths), males and older age groups. Conclusions The WHO/ILO Joint Estimates can be used for global monitoring of exposure to occupational risk factors and work-related burden of disease and to identify, plan, cost, implement and evaluate policies, programs and actions to prevent exposure to occupational risk factors and their associated burden. [ABSTRACT FROM AUTHOR]

An editorial is presented on public health impact of occupational hazards. Topics include exacerbation of pre-existing asthma by occupational inhalation of irritants being apparent from serial measurements of lung function; and asbestos making development of lung cancer while coal mine dust causing chronic obstructive pulmonary disease (COPD) through incremental loss of lung function.

Job-exposure matrices (JEM) are a common method for exposure assessment in occupational epidemiology. The first JEM were described in the early 1980s (1, 2) and have been used in a wide range of settings ever since. A recent review on methods for retrospective exposure assessment in the general population revealed that more than a quarter of the studies on cancer applied a JEM (3). Where JEM originally assigned exposures at a qualitative or semi-quantitative level based on expert ratings, quantitative exposure estimates can also be derived when measurements are used to calibrate these ratings (4-6). A JEM typically consists of job and exposure axes. The major advantage of JEM is that job histories can be translated into specific exposures in a systematic and unbiased way. It is basically a computerized linkage of exposure estimates to job codes, and, as such, JEM represent a highly efficient and reproducible methodology. This way, a standardized exposure assessment within and between studies can be guaranteed, and any misclassification is expected to be non-differential with respect to the health outcome. Once developed, a JEM is relatively easy to apply and less costly than case-by-case expert assessment. These benefits make JEM a particularly useful instrument for exposure assessment in large-scale, general population studies. Such studies (eg, based on register data) permit collection of full occupational histories and enable the study of rare diseases or subtypes. Subjects have typically worked in a wide variety of occupations and industries. Detailed exposure information, which can more easily be collected in industry-based cohorts, is often not available. For register-based cohorts, collected occupational histories are also typically limited to the basic information of job titles and industries. Using JEM, exposures can be assessed for many agents and stressors, based solely on job titles. The DOC*X project is a good example of the use of register data in occupational epidemiology (7). The large number of subjects – the full working population of Denmark for several decades – offers unique opportunities for studying new associations between a variety of exposures and various health outcomes. Individual data from several databases, including health and labour registries, were linked by a personal identifier. For each cohort member, job title and industry have been annually registered and coded (7). Subsequently, the project has been linking a series of JEM to this nationwide cohort to assess several kinds of occupational exposures. A couple of these efforts have been published in this issue of the Scandinavian Journal of Work, Environment and Health to assess the association between physical activities at work and acute myocardial infarction (8) and the risk of work-related hand eczema in relation to wet work (9). It is impossible to go back to all individuals in this cohort to collect detailed information on their occupations: firstly because part of the cohort has died over the years but also due to practical reasons given the large numbers. So, by applying JEM, the Danes make the best use of the information available in their registry data. The ease of using a JEM, by simply assigning exposures based on job titles, also has a flipside. By design, a JEM allocates the same exposure estimates to all workers with the same job title. This aspect represents the main drawback since it is well-recognized that there can be substantial inter-individual variability (10). In other words, a JEM completely dismisses exposure heterogeneity between workers in similar jobs, as has also been acknowledged by the authors of the DOC*X studies (8, 9). Heterogeneity between workers may be larger for some types of exposures than others, particularly when exposures are largely determined by specific tasks. To illustrate, when assessing welding fumes, job title alone does not provide information on different tasks and circumstances that influence the level and frequency of exposure to welding fumes (11). For exposures related to tasks like welding, decreasing or pesticide application – but also exposures such as shift work or certain psychosocial working conditions – exposure assessment based on job title alone may not be sufficient. Thus, researchers need to critically evaluate for each given exposure, if that exposure can be reasonably assessed on the job group level or if further assessment on the workplace, work unit or individual-worker level is needed. A large part of heterogeneity is determined by the workers’ behavior (12). Although this is virtually impossible to take into account in a JEM, some of the exposure heterogeneity may be accounted for by adding more detail, ie, by expanding the number of axes of the JEM. For example, an industry-axis, a time dimension, or region-, sex- and age-specific estimates may help explain part of the exposure heterogeneity. Importantly, this type of information is also typically available in the large studies where the JEM are being applied to. The JEM for wet work used by Lund et al (9) provided sex-specific estimates. A similar effort has been described for mechanical and psychosocial work exposures in Norway (13). In addition to within-job (ie, between-worker) variability, exposures may have large temporal (ie, within-worker) variability. Levels can vary from day-to-day or over the course of the work day, the variability of which is not captured in a JEM. When studying acute health effects, for example, short-term high exposures may be more relevant than the annual average or cumulative levels and a JEM may not provide the appropriate assessment. Many different JEM, in all forms and shapes, have been developed over the last 40 years. Due to the lack of a gold standard, JEM cannot be truly validated. Several studies, however, have described the performance of JEM (14–16). For asbestos, for instance, poor agreement between different JEM has been reported, indicating variable performance (14). Exposure assessment methods can also be evaluated using known associations with health outcomes. Using lung cancer case–control data, comparisons with other methods showed that a JEM for asbestos could outperform self-reported exposure (16) and perform as well as case-by-case expert assessment in a multicenter study (15). Yet, as indicated above, the performance of a JEM will depend on the exposure and effect of interest. Improvement in the use of JEM could be achieved by harmonizing existing JEM. A harmonized JEM, which provides a standardized exposure assessment across regions and time periods, would be highly valuable for pooled analyses. Such large-scale analyses will offer unique opportunities to study exposure–disease associations that have been understudied until now due to lack of statistical power. JEM will be invaluable instruments to such (exploratory) exercises. Derivation of exposure–response relations requires quantification of exposure. Development of more quantitative JEM, as first described for the multinational SYNERGY project on lung cancer (4) and the Shanghai Women’s Health Study (6), may further increase the impact of occupational studies. However, a quantitative JEM will still have the same limitation of assuming homogeneity within jobs and large amounts of (measurement) data are needed to develop a quantitative JEM. Data mining techniques could be explored to make better use. The coding of job titles is another major challenge related to the use of JEM. Manual coding of each individual’s job history in large epidemiological studies is a very time-consuming task. As a result, many of these studies are not used to their full potential for occupational health outcomes. Further improvement could therefore be achieved by systems that automatically translate free text into occupational codes, increasing the efficiency and feasibility of investigating occupational risk factors (using JEM) in large-scale epidemiological studies. Efforts in developing automatic coding in the US have shown agreements with manual coding of around 50% (17, 18). Automated coding systems would not be applicable to most registry data, however, since job information is only available as a code. For pooling these registry data with other data, or for application of another JEM, crosswalks between systems can be the solution. In addition to differences between human coders, crosswalks may also introduce disagreement between codes and actual jobs, possibly leading to further misclassification of exposure. Interestingly, within DOC*X it was shown that errors in job coding had limited effect on the exposure assessment of wood dust, lifting, standing/walking, arm elevation, and noise (19). Previous studies also reported that the effects of disagreements in job coding generally diminish in the exposure assessment stage (12, 20). Specificity is crucial when the prevalence of occupational exposure is low, which is often the case in the general population because possible associations may otherwise be severely underestimated. When exposures are more prevalent, sensitivity becomes more important (12). Since the performance of a JEM is also determined by the between-worker (ie, within job) and between-job variance, the level of detail of the job classification plays an important role. Occupational classification systems have primarily been developed from a social-economic perspective. These systems, either international or national coding schemes, are therefore not necessarily reflecting exposure categories in the best way. Developing new or adjusted coding systems for exposure assessment may help moving the occupational health field forward. Several research initiatives are currently working on such improvements in the use of JEM, including the Network on the Coordination and Harmonisation of European Occupational Cohorts (OMEGA-NET, omeganetcohorts.eu) and the Exposome Project for Health and Occupational Research (EPHOR, www.ephor-project.eu). In conclusion, a JEM can be a very handy tool for exposure assessment in occupational epidemiology, particularly in large-scale studies with limited occupational information. When selecting the most suitable exposure assessment method, however, researchers should always remain critical. Know when a JEM has added value and recognize its limitations. References 1. Hoar SK, Morrison AS, Cole P, Silverman DT. An occupation and exposure linkage system for the study of occupational carcinogenesis. J Occup Med. 1980;22(11):722-6. 2. Pannett B, Coggon D, Acheson ED. A job-exposure matrix for use in population based studies in England and Wales. Br J Ind Med. 1985;42(11):777-83. https://doi.org/10.1136/oem.42.11.777 3. Ge CB, Friesen MC, Kromhout H, Peters S, Rothman N, Lan Q, et al. Use and Reliability of Exposure Assessment Methods in Occupational Case-Control Studies in the General Population: Past, Present, and Future. Ann Work Expo Health. 2018;62(9):1047-63. https://doi.org/10.1093/annweh/wxy080 4. Peters S, Vermeulen R, Portengen L, Olsson A, Kendzia B, Vincent R, et al. Modelling of occupational respirable crystalline silica exposure for quantitative exposure assessment in community-based case-control studies. J Environ Monit. 2011;13(11):3262-8. https://doi.org/10.1039/c1em10628g 5. Peters S, Vermeulen R, Portengen L, Olsson A, Kendzia B, Vincent R, et al. SYN-JEM: A Quantitative Job-Exposure Matrix for Five Lung Carcinogens. Ann Occup Hyg. 2016;60(7):795-811. https://doi.org/10.1093/annhyg/mew034 6. Friesen MC, Coble JB, Lu W, Shu XO, Ji BT, Xue S, et al. Combining a job-exposure matrix with exposure measurements to assess occupational exposure to benzene in a population cohort in shanghai, china. Ann Occup Hyg. 2012;56(1):80-91. https://doi.org/10.1136/oemed-2011-100382.81 7. Flachs EM, Petersen SEB, Kolstad HA, Schlunssen V, Svendsen SW, Hansen J, et al. Cohort Profile: DOC*X: a nationwide Danish occupational cohort with eXposure data - an open research resource. Int J Epidemiol. 2019;48(5):1413-k. https://doi.org/10.1093/ije/dyz110 8. Bonde JPE, Flachs EM, Madsen IE, Petersen SB, Andersen JH, Hansen J, et al. Acute myocardial infarction in relation to physical activities at work: a nationwide follow-up study based on job-exposure matrices. Scand J Work Environ Health. 2019. https://doi.org/10.5271/sjweh.3863 9. Lund T, Petersen SB, Flachs EM, Ebbehoj NE, Bonde JP, Agner T. Risk of work-related hand eczema in relation to wet work exposure. Scand J Work Environ Health. 2020. https://doi.org/10.5271/sjweh.3876 10. Kromhout H, Symanski E, Rappaport SM. A comprehensive evaluation of within- and between-worker components of occupational exposure to chemical agents. Ann Occup Hyg. 1993;37(3):253-70. 11. IARC Working Group. Volume 118: Welding, Indium Tin Oxide, Molybdenum Trioxide.: IARC Monogr Eval Carcinog Risks Hum; 2018. 12. Kromhout H, Vermeulen R. Application of job-exposure matrices in studies of the general population. Some clues to their performance. European Respiratory Review. 2001;11:80-90. 13. Hanvold TN, Sterud T, Kristensen P, Mehlum IS. Mechanical and psychosocial work exposures: the construction and evaluation of a gender-specific job exposure matrix (JEM). Scand J Work Environ Health. 2019;45(3):239-47. https://doi.org/10.5271/sjweh.3774 14. Offermans NS, Vermeulen R, Burdorf A, Peters S, Goldbohm RA, Koeman T, et al. Comparison of expert and job-exposure matrix-based retrospective exposure assessment of occupational carcinogens in The Netherlands Cohort Study. Occup Environ Med. 2012;69(10):745-51. https://doi.org/10.1136/oemed-2011-100556 15. Peters S, Vermeulen R, Cassidy A, Mannetje A, van Tongeren M, Boffetta P, et al. Comparison of exposure assessment methods for occupational carcinogens in a multi-centre lung cancer case-control study. Occup Environ Med. 2011;68(2):148-53. https://doi.org/10.1136/oem.2010.055608 16. Hardt JS, Vermeulen R, Peters S, Kromhout H, McLaughlin JR, Demers PA. A comparison of exposure assessment approaches: lung cancer and occupational asbestos exposure in a population-based case-control study. Occup Environ Med. 2014;71(4):282-8. https://doi.org/10.1136/oemed-2013-101735 17. Russ DE, Ho KY, Colt JS, Armenti KR, Baris D, Chow WH, et al. Computer-based coding of free-text job descriptions to efficiently identify occupations in epidemiological studies. Occup Environ Med. 2016;73(6):417-24. https://doi.org/10.1136/oemed-2015-103152 18. Burstyn I, Slutsky A, Lee DG, Singer AB, An Y, Michael YL. Beyond crosswalks: reliability of exposure assessment following automated coding of free-text job descriptions for occupational epidemiology. Ann Occup Hyg. 2014;58(4):482-92. 19. Petersen SB, Flachs EM, Svendsen SW, Marott JL, Budtz-Jorgensen E, Hansen J, et al. Influence of errors in job codes on job exposure matrix-based exposure assessment in the register-based occupational cohort DOC*X. Scand J Work Environ Health. 2019. https://doi.org/10.5271/sjweh.3857 20. Koeman T, Offermans NS, Christopher-de Vries Y, Slottje P, Van Den Brandt PA, Goldbohm RA, et al. JEMs and incompatible occupational coding systems: effect of manual and automatic recoding of job codes on exposure assignment. Ann Occup Hyg. 2013;57(1):107-14.

OBJECTIVE: The aim of this study was to investigate cross-sectional and prospective associations between heavy occupational lifting and hypertension. METHODS: Data from the third, fourth and fifth examinations of the Copenhagen City Heart Study were included. Multivariable logistic regression models were applied to adjust for sex, age, body mass index (BMI), smoking, education, self-rated cardiorespiratory fitness, vital exhaustion and baseline blood pressure, and were used to estimate (i) the cross-sectional association between heavy occupational lifting and hypertension, defined as using anti-hypertensives or having a systolic blood pressure (SBP) ≥140 mmHg or diastolic blood pressure (DBP) ≥90 mmHg, and (ii) the prospective association between heavy occupational lifting and risk of becoming a systolic blood pressure case, defined as an above median change (from baseline to follow-up) and/or a shift from no use of anti-hypertensives at baseline to use of anti-hypertensives at a ten-year follow-up. RESULTS: Both cross-sectional [odds ratio (OR) 1.06, 95% confidence interval (CI) 0.94–1.20] and prospective (OR 1.10, 95% CI 0.92–1.31) analysis indicated no relations. Explorative prospective analyses suggested linear associations between heavy occupational lifting and systolic blood pressure among participants using anti-hypertensives. Exposure to heavy occupational lifting tended to increase the incidence of hypertension (OR 1.30, 95% CI 0.97–1.73) among participants ≥50 years. CONCLUSIONS: No associations were seen among the general population. Positive associations were seen among users of anti-hypertensives and participants ≥50 years, indicating these groups as vulnerable to increases in blood pressure when exposed to occupational lifting.

Objective Birth cohorts collect valuable and under-utilized information on employment and health of parents before and during pregnancy, at birth, and sometimes after birth. In this discussion paper, we examine how these data could be exploited to study the complex relationships and interactions between parenthood, work, and health among parents themselves. Methods Using a web-based database of birth cohorts, we summarize information on maternal employment and health conditions and other potentially related variables in cohorts spread throughout Europe. This provided information on what data are available and could be used in future studies, and what was missing if specific questions are to be addressed, exploiting the opportunity to explore work-health associations across heterogenous geographical and social contexts. Results We highlight the many potentialities provided by birth cohorts and identify gaps that need to be addressed to adopt a life-course approach and investigate topics specific to the peri-pregnancy period, such as psychosocial aspects. We address the technical difficulties implied by data harmonization and the ethical challenges related to the repurposing of data, and provide scientific, ecological and economic arguments in favor of improving the value of data already available as a result of a serious investment in human and material resources. Conclusions There is a hidden treasure in birth cohorts that deserves to be brought out to study the relationships between employment and health among working parents in a time when the boundaries between work and life are being stretched more than ever before. [ABSTRACT FROM AUTHOR]

Objective The aim of this study was to investigate cross-sectional and prospective associations between heavy occupational lifting and hypertension. Methods Data from the third, fourth and fifth examinations of the Copenhagen City Heart Study were included. Multivariable logistic regression models were applied to adjust for sex, age, body mass index (BMI), smoking, education, self-rated cardiorespiratory fitness, vital exhaustion and baseline blood pressure, and were used to estimate (i) the cross-sectional association between heavy occupational lifting and hypertension, defined as using anti-hypertensives or having a systolic blood pressure (SBP) =140 mmHg or diastolic blood pressure (DBP) =90 mmHg, and (ii) the prospective association between heavy occupational lifting and risk of becoming a systolic blood pressure case, defined as an above median change (from baseline to follow-up) and/or a shift from no use of anti-hypertensives at baseline to use of anti-hypertensives at a ten-year follow-up. Results Both cross-sectional [odds ratio (OR) 1.06, 95% confidence interval (CI) 0.94-1.20] and prospective (OR 1.10, 95% CI 0.92-1.31) analysis indicated no relations. Explorative prospective analyses suggested linear associations between heavy occupational lifting and systolic blood pressure among participants using antihypertensives. Exposure to heavy occupational lifting tended to increase the incidence of hypertension (OR 1.30, 95% CI 0.97-1.73) among participants =50 years. Conclusions No associations were seen among the general population. Positive associations were seen among users of anti-hypertensives and participants =50 years, indicating these groups as vulnerable to increases in blood pressure when exposed to occupational lifting. [ABSTRACT FROM AUTHOR]

OBJECTIVES: No study so far has combined register-based socioeconomic information with self-reported information on health, demographics, work characteristics, and the social environment. The aim of this study was to investigate whether socioeconomic, health, demographic, work characteristics and social environmental characteristics independently predict working beyond retirement. METHODS: Questionnaire data from the Study on Transitions in Employment, Ability and Motivation were linked to data from Statistics Netherlands. A prediction model was built consisting of the following blocks: socioeconomic, health, demographic, work characteristics and the social environment. First, univariate analyses were performed (P02 days/week, higher body height, and working in healthcare predicted working beyond retirement. If respondents had a permanent contract or worked in handcraft, or had a partner that did not like them to work until the official retirement age, they were less likely to work beyond retirement. CONCLUSION: Health, work characteristics and social environment predicted working beyond retirement, but register-based socioeconomic and demographic characteristics did not independently predict working beyond retirement. This study shows that working beyond retirement is multifactorial.

OBJECTIVES: The objective of this paper is to show the benefits of using a 2-phase case–control (2PCC) design in identifying dose–response relationships between cumulative occupational exposure as assessed by experts and lung cancer incidence in an actual study. METHODS: A population-based case–control study including 246 cases and 531 controls was conducted in an area with high lung cancer rates in Northeast France. Detailed occupational and personal risk factors were obtained in face-to-face interviews. Cumulative expert-based exposure scores were obtained from a subset of 215 cases and 269 controls stratified on smoking and a prior algorithmic exposure score for asbestos, crystalline silica, and polycyclic aromatic hydrocarbons (PAH) in the framework of a 2PCC design. This subset deliberately under-sampled large strata among controls but not among cases. Logistic regression models adapted to 2PCC studies were applied and corresponding computations of attributable fractions and their confidence intervals developed. RESULTS: Based on this 2PCC design, statistically significant dose–response relationships were obtained for asbestos, crystalline silica, PAH, and diesel motor exhaust. Simulations within this study showed that 2PCC studies were always more powerful than random samples. CONCLUSION: The 2PCC design may be the design of choice when resources allow only a limited number of subjects with a full expert-based exposure assessment.

OBJECTIVES: Water-based soluble and synthetic metalworking fluids (MWF) used in auto manufacturing may be contaminated by endotoxin from Gram-negative bacteria, a possible anticarcinogen via increased immuno­surveillance. The effectiveness of biocide, generally added to limit bacterial growth is unknown. We investigated whether an inverse relationship between lung cancer and synthetic MWF and biocide – as surrogates of endotoxin exposure – persisted in an extended follow-up of autoworkers. METHODS: A nested case–control analysis was performed within a retrospective cohort study of 46 399 auto manufacturing workers. Follow-up began in 1941 and was extended from 1985–1995. Mortality rate ratios (MRR) were estimated in Cox regression models for lung cancer as discrete and smoothed functions of cumulative exposure to synthetic MWF (mg/m^3 per year) and years exposed to biocide with both synthetic and soluble MWF. The analysis was also restricted to the subcohort hired on or after 1941 and stratified by follow-up period. RESULTS: The splines suggested a non-linear inverse exposure–response for lung cancer mortality with increasing endotoxin exposure. Overall, the greatest reduction in mortality was observed among those with the highest exposure [MRR 0.63, 95% confidence interval (95% CI) 0.39–0.98] at the 99^th percentile of exposure (15.8 mg/m^3 per year). Evidence for an inverse effect was limited to the earlier follow-up period. Effect modification by biocide was marginally significant (P=0.07); the protective effect of synthetic MWF was observed only for those who were co-exposed. CONCLUSIONS: The protective effect of synthetic MWF against lung cancer mortality persisted through the extended period of follow-up, although attenuated, and was observed only among workers with co-exposure to biocide and synthetic MWF.

OBJECTIVE: The literature on psychosocial job factors and musculoskeletal pain is inconclusive in part due to insufficient control for confounding by biomechanical factors. The aim of this study was to investigate prospectively the independent effects of effort–reward imbalance (ERI) at work on regional musculoskeletal pain of the neck and upper extremities of call center operators after controlling for (i) duration of computer use both at work and at home, (ii) ergonomic workstation design, (iii) physical activities during leisure time, and (iv) other individual worker characteristics. METHODS: This was a one-year prospective study among 165 call center operators who participated in a randomized ergonomic intervention trial that has been described previously. Over an approximate four-week period, we measured ERI and 28 potential confounders via a questionnaire at baseline. Regional upper-body pain and computer use was measured by weekly surveys for up to 12 months following the implementation of ergonomic interventions. Regional pain change scores were calculated as the difference between average weekly pain scores pre- and post intervention. RESULTS: A significant relationship was found between high average ERI ratios and one-year increases in right upper-extremity pain after adjustment for pre-intervention regional mean pain score, current and past physical workload, ergonomic workstation design, and anthropometric, sociodemographic, and behavioral risk factors. No significant associations were found with change in neck–shoulder or left upper-extremity pain. CONCLUSIONS: This study suggests that ERI predicts regional upper-extremity pain in ­computer operators working ≥20 hours per week. Control for physical workload and ergonomic workstation design was essential for identifying ERI as a risk factor.

Objectives The objective of this paper is to show the benefits of using a 2-phase case-control (2PCC) design in identifying dose-response relationships between cumulative occupational exposure as assessed by experts and lung cancer incidence in an actual study. Methods A population-based case-control study including 246 cases and 531 controls was conducted in an area with high lung cancer rates in Northeast France. Detailed occupational and personal risk factors were obtained in face-to-face interviews. Cumulative expert-based exposure scores were obtained from a subset of 215 cases and 269 controls stratified on smoking and a prior algorithmic exposure score for asbestos, crystalline silica, and polycyclic aromatic hydrocarbons (PAH) in the framework of a 2PCC design. This subset deliberately under-sampled large strata among controls but not among cases. Logistic regression models adapted to 2PCC studies were applied and corresponding computations of attributable fractions and their confidence intervals developed. Results Based on this 2PCC design, statistically significant dose-response relationships were obtained for asbestos, crystalline silica, PAH, and diesel motor exhaust. Simulations within this study showed that 2PCC studies were always more powerful than random samples. Conclusion The 2PCC design may be the design of choice when resources allow only a limited number of subjects with a full expert-based exposure assessment. [ABSTRACT FROM AUTHOR]

Objectives Water-based soluble and synthetic metalworking fluids (MWF) used in auto manufacturing may be contaminated by endotoxin from Gram-negative bacteria, a possible anticarcinogen via increased immuno- surveillance. The effectiveness of biocide, generally added to limit bacterial growth is unknown. We investigated whether an inverse relationship between lung cancer and synthetic MWF and biocide - as surrogates of endotoxin exposure - persisted in an extended follow-up of autoworkers. Methods A nested case-control analysis was performed within a retrospective cohort study of 46 399 auto manufacturing workers. Follow-up began in 1941 and was extended from 1985-1995. Mortality rate ratios (MRR) were estimated in Cox regression models for lung cancer as discrete and smoothed functions of cumulative exposure to synthetic MWF (mg/m3 per year) and years exposed to biocide with both synthetic and soluble MWF. The analysis was also restricted to the subcohort hired on or after 1941 and stratified by follow-up period. Results The splines suggested a non-linear inverse exposure-response for lung cancer mortality with increasing endotoxin exposure. Overall, the greatest reduction in mortality was observed among those with the highest exposure [MRR 0.63, 95% confidence interval (95% CI) 0.39-0.98] at the 99th percentile of exposure (15.8 mg/m3 per year). Evidence for an inverse effect was limited to the earlier follow-up period. Effect modification by biocide was marginally significant (P=0.07); the protective effect of synthetic MWF was observed only for those who were co-exposed. Conclusions The protective effect of synthetic MWF against lung cancer mortality persisted through the extended period of follow-up, although attenuated, and was observed only among workers with co-exposure to biocide and synthetic MWF. [ABSTRACT FROM AUTHOR]

Objective The literature on psychosocial job factors and musculoskeletal pain is inconclusive in part due to insufficient control for confounding by biomechanical factors. The aim of this study was to investigate prospectively the independent effects of effort-reward imbalance (ERI) at work on regional musculoskeletal pain of the neck and upper extremities of call center operators after controlling for (i) duration of computer use both at work and at home, (ii) ergonomic workstation design, (iii) physical activities during leisure time, and (iv) other individual worker characteristics. Methods This was a one-year prospective study among 165 call center operators who participated in a randomized ergonomic intervention trial that has been described previously. Over an approximate four-week period, we measured ERI and 28 potential confounders via a questionnaire at baseline. Regional upper-body pain and computer use was measured by weekly surveys for up to 12 months following the implementation of ergonomic interventions. Regional pain change scores were calculated as the difference between average weekly pain scores pre- and post intervention. Results A significant relationship was found between high average ERI ratios and one-year increases in right upper-extremity pain after adjustment for pre-intervention regional mean pain score, current and past physical workload, ergonomic workstation design, and anthropometric, sociodemographic, and behavioral risk factors. No significant associations were found with change in neck-shoulder or left upper-extremity pain. Conclusions This study suggests that ERI predicts regional upper-extremity pain in computer operators working ≥20 hours per week. Control for physical workload and ergonomic workstation design was essential for identifying ERI as a risk factor. [ABSTRACT FROM AUTHOR]

The article presents a study on the exposure to iron and welding fumes and the risk of lung cancer. The research assessed the condition of a group of economically active Finnish men who participated in the national census in 1970. The participants' lung cancer cases were evaluated using Multivariate Poisson regressions. Results showed that occupational exposure to iron and welding fumes was related to the increase in lung cancer risk.

The article provides a study to estimate the risk of incident stroke according to job levels and examines the risk of incident stroke in the working population in Sweden. A cohort study of nearly 3 million working people was performed followed by 13-year follow up for incident stroke. It is concluded that the risk of incident stroke was higher in low job-control occupations and that the risk of intracerebral hemorrhage was more prone for the women.