Successful prevention of organic solvent induced disorders: history and lessons.

In this discussion paper, we describe the history of the science and societal action resulting in the mitigation of neurotoxic disorders from exposure to organic solvents at the workplaces in Sweden. When alkyd paints were introduced in large scale in construction painting in the 1960s and 1970s, Scandinavian unions voiced increasing concern as members reported symptoms like headache and vertigo, supported by participatory studies and case studies. Although acute and chronic neurotoxic effects were established for some specific solvents such as carbon disulphide, this was not the case for those used in the new paints. Union advocacy promoted formal epidemiological studies, providing increasing evidence for chronic neurotoxicity at levels far below current occupational exposure levels. The results were widely disseminated and accepted and led to concerted action with preventive measures, most importantly substitution of the organic solvents in paints for indoor use, but also drastic reductions in occupational exposure limits. The findings also resulted in funding of further research on solvent toxicity and the establishment of expert groups to advice authorities on occupational standards for exposure to chemicals. The substitution strategy was subsequently adopted in many other countries and occupational exposure limits were lowered, although several years or even decades later. While the societal context in Sweden was unique in many ways, we conclude that there are lessons to be learned from this preventive success when addressing current challenges.

Initiatives Addressing Precarious Employment and Its Effects on Workers' Health and Well-Being: A Systematic Review.

The prevalence of precarious employment has increased in recent decades and aspects such as employment insecurity and income inadequacy have intensified during the COVID-19 pandemic. The purpose of this systematic review was to identify, appraise, and synthesise existing evidence pertaining to implemented initiatives addressing precarious employment that have evaluated and reported health and well-being outcomes. We used the PRISMA framework to guide this review and identified 11 relevant initiatives through searches in PubMed, Scopus, Web of Science, and three sources of grey literature. We found very few evaluated interventions addressing precarious employment and its impact on the health and well-being of workers globally. Ten out of 11 initiatives were not purposefully designed to address precarious employment in general, nor specific dimensions of it. Seven out of 11 initiatives evaluated outcomes related to the occupational health and safety of precariously employed workers and six out of 11 evaluated worker health and well-being outcomes. Most initiatives showed the potential to improve the health of workers, although the evaluation component was often described with less detail than the initiative itself. Given the heterogeneity of the 11 initiatives regarding study design, sample size, implementation, evaluation, economic and political contexts, and target population, we found insufficient evidence to compare outcomes across types of initiatives, generalize findings, or make specific recommendations for the adoption of initiatives.

Initiatives addressing precarious employment and its effects on workers' health and well-being: a protocol for a systematic review.

BACKGROUND: Precarious employment is a significant determinant of population health and health inequities and has complex public health consequences both for a given nation and internationally. Precarious employment is conceptualized as a multi-dimensional construct including but not limited to employment insecurity, income inadequacy, and lack of rights and protection in the employment relation, which could affect both informal and formal workers. The purpose of this review is to identify, appraise, and synthesize existing research on the effectiveness of initiatives aiming to or having the potential to eliminate, reduce, or mitigate workers' exposure to precarious employment conditions and its effects on the health and well-being of workers and their families. METHODS: The electronic databases searched (from January 2000 onwards) are Scopus, Web of Science Core Collection, and PubMed, along with three institutional databases as sources of grey literature. We will include any study (e.g. quantitative, qualitative, or mixed-methods design) evaluating the effects of initiatives that aim to or have the potential to address workers' exposure to precarious employment or its effects on the health and well-being of workers and their families, whether or not such initiatives were designed specifically to address precarious employment. The primary outcomes will be changes in (i) the prevalence of precarious employment and workers' exposure to precarious employment and (ii) the health and well-being of precariously employed workers and their families. No secondary outcomes will be included. Given the large body of evidence screened, the initial screening of each study will be done by one reviewer, after implementing several strategies to ensure decision-making consistency across reviewers. The screening of full-text articles, data extraction, and critical appraisal will be done independently by two reviewers. Potential conflicts will be resolved through discussion. Established checklists will be used to assess a study's methodological quality or bias. A narrative synthesis will be employed to describe and summarize the included studies' characteristics and findings and to explore relationships both within and between the included studies. DISCUSSION: We expect that this review's findings will provide stakeholders interested in tackling precarious employment and its harmful health effects with evidence on effectiveness of solutions that have been implemented to inform considerations for adaptation of these to their unique contexts. In addition, the review will increase our understanding of existing research gaps and enable us to make recommendations to address them. Our work aligns with the sustainable development agenda to protect workers, promote decent work and economic growth, eliminate poverty, and reduce inequalities. SYSTEMATIC REVIEW REGISTRATION: PROSPERO CRD42020187544 .

COVID-19 and Precarious Employment: Consequences of the Evolving Crisis.

The world of work is facing an ongoing pandemic and an economic downturn with severe effects worldwide. Workers trapped in precarious employment (PE), both formal and informal, are among those most affected by the COVID-19 pandemic. Here we call attention to at least 5 critical ways that the consequences of the crisis among workers in PE will be felt globally: (a) PE will increase, (b) workers in PE will become more precarious, (c) workers in PE will face unemployment without being officially laid off, (d) workers in PE will be exposed to serious stressors and dramatic life changes that may lead to a rise in diseases of despair, and (e) PE might be a factor in deterring the control of or in generating new COVID-19 outbreaks. We conclude that what we really need is a new social contract, where the work of all workers is recognized and protected with adequate job contracts, employment security, and social protection in a new economy, both during and after the COVID-19 crisis.

Preventing kidney injury among sugarcane workers: promising evidence from enhanced workplace interventions.

OBJECTIVES: To assess if improvement of working conditions related to heat stress was associated with improved kidney health outcomes among sugarcane harvest workers in Chichigalpa, Nicaragua, a region heavily affected by the epidemic of chronic kidney disease of non-traditional origin. METHODS: Based on our findings during the 2017-2018 harvest (harvest 1), recommendations that enhanced the rest schedule and improved access to hydration and shade were given before the 2018-2019 harvest (harvest 2). Actual work conditions during harvest 2 were then observed. Serum creatinine (SCr) was measured before and at end-harvest, and cross-harvest changes in estimated glomerular filtration rate (eGFR) and incident kidney injury (IKI, ie, SCr increase by ≥0.30 mg/dL or ≥1.5 times the baseline value) were compared between harvest 1 and harvest 2 for three jobs with different physical workloads using regression modelling. Workers who left during harvest were contacted at home, to address the healthy worker selection effect. RESULTS: In burned cane cutters, mean cross-harvest eGFR decreased 6 mL/min/1.73 m2 (95% CI 2 to 9 mL/min/1.73 m2) less and IKI was 70% (95% CI 90% to 50%) lower in harvest 2 as compared with harvest 1 data. No such improvements were seen among seed cutters groups with less successful intervention implementation. CONCLUSION: Kidney injury risk was again elevated in workers with strenuous jobs. The results support further efforts to prevent kidney injury among sugarcane workers, and other heat-stressed workers, by improving access to water, rest and shade. The distinction between design and implementation of such interventions should be recognised.

Chronic kidney disease of non-traditional origin in Mesoamerica: a disease primarily driven by occupational heat stress.

The death toll of the epidemic of chronic kidney disease of nontraditional origin (CKDnt) in Mesoamerica runs into the tens of thousands, affecting mostly young men. There is no consensus on the etiology. Anecdotal evidence from the 1990s pointed to work in sugarcane; pesticides and heat stress were suspected. Subsequent population-based surveys supported an occupational origin with overall high male-female ratios in high-risk lowlands, but small sex differences within occupational categories, and low prevalence in non-workers. CKDnt was reported in sugarcane and other high-intensity agriculture, and in non-agricultural occupations with heavy manual labor in hot environments, but not among subsistence farmers. Recent studies with stronger designs have shown cross-shift changes in kidney function and hydration biomarkers and cross-harvest kidney function declines related to heat and workload. The implementation of a water-rest-shade intervention midharvest in El Salvador appeared to halt declining kidney function among cane cutters. In Nicaragua a water-rest-shade program appeared sufficient to prevent kidney damage among cane workers with low-moderate workload but not among cutters with heaviest workload. Studies on pesticides and infectious risk factors have been largely negative. Non-occupational risk factors do not explain the observed epidemiologic patterns. In conclusion, work is the main driver of the CKDnt epidemic in Mesoamerica, with occupational heat stress being the single uniting factor shown to lead to kidney dysfunction in affected populations. Sugarcane cutters with extreme heat stress could be viewed as a sentinel occupational population. Occupational heat stress prevention is critical, even more so in view of climate change.

La mortalidad por la epidemia de enfermedad renal crónica de origen no tradicional (ERCnt) en Mesoamérica asciende a decenas de miles de personas, principalmente hombres jóvenes. No existe consenso sobre su etiología. En la década de 1990, informes anecdóticos apuntaban como factor de riesgo al trabajo en plantaciones de caña de azúcar; se consideró como posibles causantes a los plaguicidas y el estrés térmico. Estudios de prevalencia de base poblacional subsiguientes apoyaron un origen ocupacional, con una proporción elevada de hombres respecto de las mujeres en las tierras bajas donde el riesgo era elevado, pero con pequeñas diferencias de sexo dentro de las categorías ocupacionales y baja prevalencia en el ámbito no laboral. Se reportó ERCnt en los trabajadores de la caña de azúcar y otros cultivos con alta exigencia física y en ocupaciones no agrícolas que implican trabajo manual intenso en ambientes calurosos, pero no entre los agricultores de subsistencia. Estudios recientes con diseños más sólidos han demostrado cambios en la función renal y en los biomarcadores de hidratación en el curso de los turnos laborales, y disminución de la función renal relacionada con el calor y la carga de trabajo en el curso de la cosecha. La implementación de una intervención basada en la provisión de agua, descanso y sombra a mitad de la cosecha en El Salvador detuvo la disminución de la función renal en los cortadores de caña. En Nicaragua, un programa de provisión de agua, descanso y sombra evitó la lesión renal en los trabajadores de la caña con una carga de trabajo baja y moderada, pero no entre los cortadores, quienes tienen la mayor carga de trabajo. Los estudios sobre plaguicidas y factores de riesgo infecciosos han sido en gran medida negativos. Los factores de riesgo no ocupacionales no explican los patrones epidemiológicos observados. En conclusión, el trabajo es el principal desencadenante de la epidemia de ERCnt en Mesoamérica, y el estrés térmico ocupacional es el único factor que consistentemente conduce a la disfunción renal en las poblaciones afectadas. Los cortadores que trabajan en los ingenios azucareros y están expuestos a un estrés térmico extremo podrían ser considerados una población ocupacional centinela. La prevención del estrés térmico ocupacional es crítica, más aún si se consideran los efectos del cambio climático.

A mortalidade devida à epidemia de doença renal crônica de origem não tradicional (DRCnt) na Mesoamérica atinge dezenas de milhares de pessoas, principalmente homens jovens. Não há consenso sobre a sua etiologia. Na década de 1990, informações empíricas apontavam o trabalho em plantações de cana de açúcar como um fator de risco; pesticidas e estresse térmico também eram considerados causas possíveis. As pesquisas populacionais subsequentes sustentam uma origem ocupacional da doença, com uma elevada proporção de homens quando comparados à de mulheres, em areas de baixa altitude, onde o risco da doença é mais elevado, mas com pequenas diferenças de gênero quando se consideram as categorias ocupacionais e baixa prevalência no ambiente não-ocupacional. A DRCnt foi identificada em trabalhadores agrícolas da cana de açúcar e de outras culturas que exigem trabalho físico de alta intensidade e em ocupações não agrícolas envolvendo um trabalho manual intenso em ambientes quentes, mas não entre os agricultores de subsistência. Estudos recentes com desenhos mais robustos demonstraram mudanças na função renal e nos biomarcadores de hidratação ao longo dos turnos de trabalho, e diminuição da função renal relacionada à exposição ao calor e à carga de trabalho ao longo da colheita. A implementação de uma intervenção de água-descanso-sombra durante a colheita em El Salvador interrompeu o declínio da função renal em cortadores de cana. Na Nicarágua, intervenções água-descanso-sombra parecem ter sido suficientes para evitar lesões renais em trabalhadores canavieiros com cargas de trabalho baixa e moderada, mas não entre os cortadores de cana que têm carga de trabalho mais pesada. Estudos sobre exposição a pesticidas e a fatores de risco de origem infecciosa têm sido largamente negativos. Os fatores de risco não-ocupacionais não explicam os padrões epidemiológicos observados. Em conclusão, ocupação é o principal desencadeador da epidemia de DRCnt na Mesoamérica, e o estresse térmico ocupacional é o único fator comprovado que leva à disfunção renal nas populações afetadas. Os cortadores de cana que trabalham em engenhos de açúcar e expostos a um estresse térmico extremo podem ser considerados uma população ocupacional sentinela. A prevenção do estresse térmico ocupacional é crítica, especialmente considerando os efeitos das mudanças climáticas.

Workload and cross-harvest kidney injury in a Nicaraguan sugarcane worker cohort.

OBJECTIVES: To examine the association between workload and kidney injury in a fieldworker cohort with different levels of physically demanding work over a sugarcane harvest, and to assess whether the existing heat prevention efforts at a leading occupational safety and health programme are sufficient to mitigate kidney injury. METHODS: Biological and questionnaire data were collected before (n=545) and at the end (n=427) of harvest among field support staff (low workload), drip irrigation workers (moderate), seed cutters (high) and burned sugarcane cutters (very high). Dropouts were contacted (87%) and reported the reason for leaving work. Cross-harvest incident kidney injury (IKI) was defined as serum creatinine increase ≥0.30 mg/dL or ≥1.5 times the baseline value, or among dropouts reporting kidney injury leading to leaving work. RESULTS: Mean cross-harvest estimated glomerular filtration rate change was significantly associated with workload, increasing from 0 mL/min/1.73 m2 in the low-moderate category to -5 mL/min/1.73 m2 in the high and -9 mL/min/1.73 m2 in the very high workload group. A similar pattern occurred with IKI, where low-moderate workload had 2% compared with 27% in the very high workload category. A healthy worker selection effect was detected, with 32% of dropouts reporting kidney injury. Fever and C reactive protein elevation were associated with kidney injury. CONCLUSIONS: Workers considered to have the highest workload had more cross-harvest kidney damage than workers with less workload. Work practices preventing heat stress should be strengthened and their role in preventing kidney damage examined further. Future occupational studies on chronic kidney disease of unknown aetiology should account for a healthy worker effect by pursuing those lost to follow-up.

Intervention to diminish dehydration and kidney damage among sugarcane workers.

Objective The aim of this study was to assess the potential to reduce kidney function damage during the implementation of a water, rest, shade (WRS) and efficiency intervention program among sugarcane workers. Methods A WRS intervention program adapted from the US Occupational Safety and Health Administration (OSHA) coupled with an efficiency program began two months into the 5-month harvest. One of the two groups of workers studied was provided with portable water reservoirs, mobile shaded tents, and scheduled rest periods. Health data (anthropometric and questionnaires), blood, and urine were collected at baseline and at three subsequent times over the course of the harvest. Daily wet bulb globe temperatures (WBGT) were recorded. Results Across a working day there were changes in biomarkers indicating dehydration (urine osmolality) and serum albumin and reduced estimated glomerular filtration rate (eGFR). Cross-shift eGFR decrease was present in both groups; -10.5 mL/min/1.73m2 [95% confidence interval (95% CI) -11.8- -9.1], but smaller for the intervention group after receiving the program. Decreased eGFR over the 5-month harvest was seen in both groups: in the one receiving the intervention -3.4 mL/min/1.73m 2(95% CI -5.5- -1.3) and in the other -5.3 (95% CI -7.9- -2.7). The decrease appeared to halt after the introduction of the intervention in the group receiving the program. Conclusion A WRS and efficiency intervention program was successfully introduced for workers in sugarcane fields and appears to reduce the impact of heat stress on acute and over-harvest biomarkers of kidney function. Further research is needed to determine whether biomarker changes predict reduced risk of chronic kidney disease in this type of work.

A systematic review including meta-analysis of work environment and burnout symptoms.

BACKGROUND: Practitioners and decision makers in the medical and insurance systems need knowledge on the relationship between work exposures and burnout. Many burnout studies - original as well as reviews - restricted their analyses to emotional exhaustion or did not report results on cynicism, personal accomplishment or global burnout. To meet this need we carried out this review and meta-analyses with the aim to provide systematically graded evidence for associations between working conditions and near-future development of burnout symptoms. METHODS: A wide range of work exposure factors was screened. Inclusion criteria were: 1) Study performed in Europe, North America, Australia and New Zealand 1990-2013. 2) Prospective or comparable case control design. 3) Assessments of exposure (work) and outcome at baseline and at least once again during follow up 1-5 years later. Twenty-five articles met the predefined relevance and quality criteria. The GRADE-system with its 4-grade evidence scale was used. RESULTS: Most of the 25 studies focused emotional exhaustion, fewer cynicism and still fewer personal accomplishment. Moderately strong evidence (grade 3) was concluded for the association between job control and reduced emotional exhaustion and between low workplace support and increased emotional exhaustion. Limited evidence (grade 2) was found for the associations between workplace justice, demands, high work load, low reward, low supervisor support, low co-worker support, job insecurity and change in emotional exhaustion. Cynicism was associated with most of these work factors. Reduced personal accomplishment was only associated with low reward. There were few prospective studies with sufficient quality on adverse chemical, biological and physical factors and burnout. CONCLUSION: While high levels of job support and workplace justice were protective for emotional exhaustion, high demands, low job control, high work load, low reward and job insecurity increased the risk for developing exhaustion. Our approach with a wide range of work exposure factors analysed in relation to the separate dimensions of burnout expanded the knowledge of associations, evidence as well as research needs. The potential of organizational interventions is illustrated by the findings that burnout symptoms are strongly influenced by structural factors such as job demands, support and the possibility to exert control.

A systematic review including meta-analysis of work environment and depressive symptoms.

BACKGROUND: Depressive symptoms are potential outcomes of poorly functioning work environments. Such symptoms are frequent and cause considerable suffering for the employees as well as financial loss for the employers. Accordingly good prospective studies of psychosocial working conditions and depressive symptoms are valuable. Scientific reviews of such studies have pointed at methodological difficulties but still established a few job risk factors. Those reviews were published some years ago. There is need for an updated systematic review using the GRADE system. In addition, gender related questions have been insufficiently reviewed. METHOD: Inclusion criteria for the studies published 1990 to June 2013: 1. European and English speaking countries. 2. Quantified results describing the relationship between exposure (psychosocial or physical/chemical) and outcome (standardized questionnaire assessment of depressive symptoms or interview-based clinical depression). 3. Prospective or comparable case-control design with at least 100 participants. 4. Assessments of exposure (working conditions) and outcome at baseline and outcome (depressive symptoms) once again after follow-up 1-5 years later. 5. Adjustment for age and adjustment or stratification for gender. Studies filling inclusion criteria were subjected to assessment of 1.) relevance and 2.) quality using predefined criteria. Systematic review of the evidence was made using the GRADE system. When applicable, meta-analysis of the magnitude of associations was made. Consistency of findings was examined for a number of possible confounders and publication bias was discussed. RESULTS: Fifty-nine articles of high or medium high scientific quality were included. Moderately strong evidence (grade three out of four) was found for job strain (high psychological demands and low decision latitude), low decision latitude and bullying having significant impact on development of depressive symptoms. Limited evidence (grade two) was shown for psychological demands, effort reward imbalance, low support, unfavorable social climate, lack of work justice, conflicts, limited skill discretion, job insecurity and long working hours. There was no differential gender effect of adverse job conditions on depressive symptoms CONCLUSION: There is substantial empirical evidence that employees, both men and women, who report lack of decision latitude, job strain and bullying, will experience increasing depressive symptoms over time. These conditions are amenable to organizational interventions.

Mesoamerican nephropathy: geographical distribution and time trends of chronic kidney disease mortality between 1970 and 2012 in Costa Rica.

OBJECTIVES: Mesoamerican nephropathy is an epidemic of chronic kidney disease (CKD) unrelated to traditional causes, mostly observed in sugarcane workers. We analysed CKD mortality in Costa Rica to explore when and where the epidemic emerged, sex and age patterns, and relationship with altitude, climate and sugarcane production. METHODS: SMRs for CKD deaths (1970-2012) among population aged ≥20 were computed for 7 provinces and 81 counties over 4 time periods. Time trends were assessed with age-standardised mortality rates. We qualitatively examined relations between mortality and data on altitude, climate and sugarcane production. RESULTS: During 1970-2012, age-adjusted mortality rates in the Guanacaste province increased among men from 4.4 to 38.5 per 100,000 vs. 3.6-8.4 in the rest of Costa Rica, and among women from 2.3 to 10.7 per 100,000 vs. 2.6-5.0 in the rest of Costa Rica. A significant moderate excess mortality was observed among men in Guanacaste already in the mid-1970s, steeply increasing thereafter; a similar female excess mortality appeared a decade later, remaining stable. Male age-specific rates were high in Guanacaste for age categories ≥30, and since the late 1990s also for age range 20-29. The male spatiotemporal patterns roughly followed sugarcane expansion in hot, dry lowlands with manual harvesting. CONCLUSIONS: Excess CKD mortality occurs primarily in Guanacaste lowlands and was already present 4 decades ago. The increasing rates among Guanacaste men in hot, dry lowland counties with sugarcane are consistent with an occupational component. Stable moderate increases among women, and among men in counties without sugarcane, suggest coexisting environmental risk factors.

Myocardial infarction and occupational exposure to motor exhaust: a population-based case-control study in Sweden.

There is a well-established association between particulate urban air pollution and cardiovascular disease, but few studies have investigated the risk associated with occupational exposure to particles from motor exhaust. This study investigated the risk of myocardial infarction (MI) after occupational exposure to motor exhaust, using elemental carbon (EC) as a marker of exposure. A population-based case-control study of first-time non-lethal MI was conducted among Swedish citizens in ages 45-70 living in Stockholm County 1992-1994, including 1,643 cases and 2,235 controls. Working histories and data on potential confounders were collected by questionnaire and medical examination. The exposure to EC was assessed through a job-exposure matrix. Odds ratios (ORs) and corresponding 95% confidence intervals (CIs) were estimated by unconditional logistic regression. We investigated various exposure metrics: intensity, cumulative exposure and years since exposure. There was an exposure-response relation between the highest average exposure intensity during the work history and the risk of MI when adjusting for smoking and alcohol drinking (p for trend 0.034), with an OR of 1.30 (95% CI 0.99-1.71) in the highest tertile of exposure compared to the unexposed. An exposure-response pattern was observed in the analysis of years since exposure cessation among formerly exposed. Additional adjustments for markers of the metabolic syndrome reduced ORs and trends to non-significant levels, although this might be an over-adjustment since the metabolic syndrome may be part of the causal pathway. Occupational exposure to motor exhaust was associated with a moderately increased risk of MI.

Resolving the enigma of the mesoamerican nephropathy: a research workshop summary.

The First International Research Workshop on Mesoamerican Nephropathy (MeN) met in Costa Rica in November 2012 to discuss how to establish the extent and degree of MeN, examine relevant causal hypotheses, and focus efforts to control or eliminate the disease burden. MeN describes a devastating epidemic of chronic kidney disease of unknown origin predominantly observed among young male sugarcane cutters. The cause of MeN remains uncertain; however, the strongest hypothesis pursued to date is repeated episodes of occupational heat stress and water and solute loss, probably in combination with other potential risk factor(s), such as nonsteroidal anti-inflammatory drug and other nephrotoxic medication use, inorganic arsenic, leptospirosis, or pesticides. At the research workshop, clinical and epidemiologic case definitions were proposed in order to facilitate both public health and research efforts. Recommendations emanating from the workshop included measuring workload, heat, and water and solute loss among workers; quantifying nephrotoxic agents in drinking water and food; using biomarkers of early kidney injury to explore potential causes of MeN; and characterizing social and working conditions together with methods for valid data collection of exposures and personal risk factors. Advantages and disadvantages of different population study designs were detailed. To elucidate the etiology of MeN, multicountry studies with prospective cohort design, preferably integrating an ecosystem health approach, were considered the most promising. In addition, genetic, experimental, and mechanistic methods and designs were addressed, specifically the need for kidney biopsy analysis, studies in animal models, advances in biomarkers, genetic and epigenetic studies, a common registry and repository of biological and demographic data and/or specimens, and other areas of potential chronic kidney disease experimental research. Finally, in order to improve international collaboration on MeN, workshop participants agreed to establish a research consortium to link these Mesoamerican efforts to other efforts worldwide.

Incidence of myocardial infarction in Swedish chimney sweeps 1991-2005: a prospective cohort study.

OBJECTIVES: Previous studies of chimney sweeps have shown an excess mortality from cardiovascular diseases, although the extent of confounding from tobacco smoking is uncertain. The present study used referents of similar socioeconomic background as the chimney sweeps in order to reduce confounding, included both lethal and surviving cases of myocardial infarction, and investigated dose-response in terms of duration of employment. METHODS: A cohort of 4436 male chimney sweeps was identified from nationwide trade union records from 1918 to 2006. Myocardial infarctions during 1991-2005 were identified from the Swedish nationwide register of first-time myocardial infarctions. Standardised incidence ratios (SIRs) were estimated using skilled manual workers in the service sector in Sweden to calculate expected numbers. RESULTS: There was a strong and statistically significant excess of myocardial infarction among the chimney sweeps, SIR 1.39 (95% CI 1.24 to 1.55). The excess was observed among both short- and long-term employed. CONCLUSIONS: While the excess of myocardial infarction among the short-term employed may be due to tobacco and, possibly, alcohol use, it is likely that the excess noted among the long-term employed was caused by the high exposure to combustion products, particles or metals still occurring among chimney sweeps. Preventive measures to reduce hazardous occupational exposures as well as smoking and alcohol use among chimney sweeps are urgently needed.