Occupational inhalable agents constitute major risk factors for rheumatoid arthritis, particularly in the context of genetic predisposition and smoking.

OBJECTIVES: To assess the effects of occupational inhalable exposures on rheumatoid arthritis (RA) development and their interactions with smoking and RA-risk genes, stratifying by presence of anticitrullinated protein antibodies (ACPA). METHODS: Data came from the Swedish Epidemiological Investigation of RA, consisting of 4033 incident RA cases and 6485 matched controls. Occupational histories were retrieved, combining with a Swedish national job-exposure matrix, to estimate exposure to 32 inhalable agents. Genetic data were used to define Genetic Risk Score (GRS) or carrying any copy of human leucocyte antigen class II shared epitope (HLA-SE) alleles. Associations were identified with unconditional logistical regression models. Attributable proportion due to interaction was estimated to evaluate presence of interaction. RESULTS: Exposure to any occupational inhalable agents was associated with increased risk for ACPA-positive RA (OR 1.25, 95% CI 1.12 to 1.38). The risk increased as number of exposed agents increased (Ptrend<0.001) or duration of exposure elongated (Ptrend<0.001). When jointly considering exposure to any occupational inhalable agents, smoking and high GRS, a markedly elevated risk for ACPA-positive RA was observed among the triple-exposed group compared with those not exposed to any (OR 18.22, 95% CI 11.77 to 28.19). Significant interactions were found between occupational inhalable agents and smoking/genetic factors (high GRS or HLA-SE) in ACPA-positive RA. CONCLUSIONS: Occupational inhalable agents could act as important environmental triggers in RA development and interact with smoking and RA-risk genes leading to excessive risk for ACPA-positive RA. Future studies are warranted to assess preventive strategies aimed at reducing occupational hazards and smoking, especially among those who are genetically vulnerable.

Childhood cancer risk in offspring of parents occupationally exposed to dusts: A register-based nested case-control study from Sweden of 5 decades.

BACKGROUND: Some largely inconsistent associations between parental occupational dust exposure and childhood cancer have been reported, with maternal exposures inadequately studied. The authors examined whether maternal or paternal occupational exposure to animal, wood, textile, or paper dust around a child's birth was associated with an increased risk of childhood cancer, both overall and by type (leukemias, lymphomas, central nervous system tumors, and other cancers). METHODS: In this nationwide, register-based, case-control study, children who were diagnosed with cancer from 1960 to 2015 were compared with up to 25 matched controls regarding maternal and paternal occupational dust exposure (9653 cases in maternal analyses and 12,521 cases in paternal analyses). Exposures were assessed using a job-exposure matrix and occupational information from census and register data. By using conditional logistic regression models, adjusted odds ratios (ORs) and 95% confidence intervals (CIs) were estimated. RESULTS: Neither maternal nor paternal occupational exposure to animal, wood, textile, or paper dust was associated with childhood cancer overall, leukemias, or central nervous system tumors. Maternal, but not paternal, wood dust exposure was associated with an increased risk of lymphoma (OR, 1.42; 95% CI, 1.10-1.84), particularly non-Hodgkin lymphoma (OR, 2.03; 95% CI, 1.21-3.40). CONCLUSIONS: The current study did not confirm the associations reported previously but is the first to suggest a link between maternal occupational exposure to wood dust around pregnancy and lymphoma in the offspring.

Occupational exposure to respirable crystalline silica and acute myocardial infarction among men and women in Sweden.

OBJECTIVES: Occupational exposure to respirable crystalline silica (RCS) is common. The study aimed to assess the risk for acute myocardial infarction (AMI) after long-term exposure to RCS and to explore differences in risk between men and women. METHODS: The cohort included all manual workers identified from the Swedish National Census in 1980 using data on job titles and demography altogether from five censuses from 1960 to 1990, in total 605 246 men and 480 607 women. Information on AMI was obtained from nationwide registers from 1992 to 2006. Exposure to RCS was assessed with a job-exposure matrix. HRs and 95% CIs were estimated by Cox regression, adjusted for age, socioeconomic status and urbanisation index. RESULTS: Among manual workers ever exposed to RCS, the adjusted risk of AMI was HR 1.29 (95% CI 1.15 to 1.46) in women, and HR 1.02 (95% CI 1.00 to 1.04) in men. In the highest quartile of cumulative exposure, the risk of AMI was HR 1.66 (95% CI 1.27 to 2.18) for women, and HR 1.06 (95% CI 1.03 to 1.10) for men, respectively. The risk of AMI increased with cumulative exposure to RCS both in women (p=0.001) and in men (p=0.016). An interaction analysis showed that the relative risk from exposure to RCS was statistically significantly lower in men than in women at similar exposure levels. CONCLUSIONS: Occupational exposure to RCS was related to the risk of AMI. Women were more sensitive to exposure to RCS than men.

Occupational exposure to pesticides in mothers and fathers and risk of cancer in the offspring: A register-based case-control study from Sweden (1960-2015).

Maternal and paternal occupational exposure to pesticides was linked to leukemia in the offspring in some previous studies. Risks for other cancers, particularly from maternal exposure, are largely unknown. We examined the association between maternal and paternal exposure to pesticides and childhood cancer in a Swedish register-based case-control study (1960-2015). Cancer cases <20 years old were identified from the Cancer Register (n = 17313) and matched to controls (1:25) on birth year and sex. Employment history of each biological parent around the child's birth was retrieved from six censuses and a nationwide register, and exposure to any of herbicides, insecticides, and fungicides was evaluated using the Swedish job-exposure matrix (SWEJEM) in 9653/172194 mothers and 12521/274434 fathers of cases/controls. Adjusted odds ratios (OR) and 95% confidence intervals (CI) were estimated from conditional logistic regression models for any cancer, leukemia, lymphoma, central nervous system [CNS], and other solid tumors. We found an OR of 1.42 (95% CI 0.78, 2.57; 12 exposed cases) for lymphoma and 1.30 (95% CI 0.88, 1.93; 27 exposed cases) for other solid tumors associated with maternal occupational exposure to pesticides. No associations were observed between maternal exposure and leukemia or CNS tumors, or paternal exposure and any of the cancers examined, except for a potential association between pesticides exposure and myeloid leukemia (OR 1.15 [95% CI 0.73, 1.79; 22 exposed cases]). Although these findings merit further investigation, they indicate that parental exposure to pesticides may lead to higher risks of childhood cancer even in settings of low exposure.

Occupational exposure to particles and biomarkers of cardiovascular disease-during work and after vacation.

OBJECTIVE: Ambient particle matter is a risk factor for cardiovascular disease (CVD). However, little is known about associations between particles in occupational settings and risk of CVD. We investigated associations between occupational dust exposure and biomarkers of CVD, and potential recovery effects after vacation. METHODS: Personal dust exposure measurements (respirable silica, respirable dust < 4 µm, and particles of 0.1-10 µm (PM 0.1-10) were conducted once, and biological sampling were performed twice on non-smoking, male construction workers in Stockholm county, Sweden; during work and immediately after summer vacation. Linear regressions with adjustments for confounders and covariates were performed evaluating associations between occupational dust exposure and biomarkers. Paired t tests were performed evaluating changes before and after vacation. RESULTS: Sixty-five workers participated. Homocysteine concentrations were significantly higher with increasing concentrations (mg/m3) of respirable silica, respirable dust, and PM 0.1-10, and pulse rate with higher levels of respirable dust and dust of PM 0.1-10. Homocysteine levels were also positively correlated to number of years of dust exposure, as were low-density lipoprotein (LDL) levels. A clear recovery effect was present for LDL after vacation, but not for homocysteine. CONCLUSIONS: Occupational dust exposure was associated with some CVD risk markers, even at mean exposure concentrations below the Swedish occupational exposure limits for respirable silica and respirable dust, respectively. Vacation resulted in recovery for some risk markers. However, the change of the homocysteine and LDL levels suggest a long-term effect. Reduction of occupational exposure to dust may decrease the risk of CVD among exposed workers.

Parental occupational exposures in wood-related jobs and risk of testicular germ cell tumours in offspring in NORD-TEST a registry-based case-control study in Finland, Norway, and Sweden.

OBJECTIVE: We assessed the association between parental prenatal exposures in wood-related jobs and risk of testicular germ cell tumours (TGCT) in offspring. METHODS: NORD-TEST, a registry-based case-control study in Sweden, Finland and Norway, included 8112 TGCT cases diagnosed at ages 14-49 years between 1978 and 2012 with no history of prior cancer, and up to four controls matched to each case on year and country of birth. Parents of cases and controls were identified via linkages with the population registries and their occupational information was retrieved from censuses. The Nordic Occupational Cancer Study Job-Exposure Matrix was used to assign occupational exposures to each parent. Logistic regression models were used to estimate odds ratios (OR) and 95% confidence intervals (CI). RESULTS: Maternal wood-related job was not associated with the risk of TGCT in offspring (OR 1.08, CI 0.55-2.14), while paternal wood-related job was associated with a decreased risk of TGCT in offspring (OR 0.85, CI 0.75-0.96). None of the specific wood-related jobs, such as upholsterers, sawyers, or construction carpenters, were significantly associated with a risk of TGCT. Only exception was observed in a sensitivity analysis which showed an increased risk in the small group of sons of fathers working as 'cabinetmakers and joiners' the year before conception (OR of 2.06, CI 1.00-4.25). CONCLUSION: This large-scale NORD-TEST analysis provided no evidence of an association between parental prenatal exposures in wood-related jobs and TGCT in sons.

Occupational exposure to particles and increased risk of developing chronic obstructive pulmonary disease (COPD): A population-based cohort study in Stockholm, Sweden.

OBJECTIVES: Chronic Obstructive Pulmonary Disease (COPD) is a common respiratory disorder. Next to tobacco smoking, occupational exposure is the most important risk factor for COPD in high-income countries. To enable preventative measures, more knowledge is needed on which specific occupational exposures that are related to risk of developing COPD in men and women. METHODS: A population-based cohort was formed from subjects responding to the Stockholm Public Health Surveys in 2002, 2006, and 2010, followed up until 2014. The dataset was linked to a quantitative job exposure matrix via occupational titles from the 1990 nation-wide Population and housing census. We identified COPD among subjects having medication for COPD and/or reporting a physician's diagnosis of COPD. The gender-specific risks to develop COPD from occupational particle-exposure were estimated by proportional hazards regression model, adjusted for age and individual data on tobacco-smoking. RESULTS: Men exposed to respirable crystalline silica (RCS) (HR 1.46, CI 1.13-1.90), gypsum and insulation material (HR 1.56, CI 1.18-2.05), diesel exhaust (HR 1.18, CI 0.99-1.41) and high levels of particles from asphalt/bitumen (HR 1.71, CI 1.06-2.76) as well as welding fumes (HR 1.57, CI 1.12-2.21) had an increased smoking-adjusted risk for developing COPD. An increased risk was also observed among women highly exposed to various organic particles from soil, leather, plastic, soot, animal, textile, flour (HR 1.53, CI 1.15-2.04). Furthermore, a significant positive exposure-response trend was found among men exposed to RCS, iron dust, gypsum and insulation material, and diesel exhaust. A tendency towards an exposure-response relationship was also seen among both men and women exposed to welding fumes and various organic particles, and among men exposed to particles from asphalt/bitumen. The population attributable fraction for COPD from occupational exposure to particles was 10.6% among men and 6.1% among women. CONCLUSIONS: This study indicates an increased smoking-adjusted risk of developing of COPD due to occupational exposure to particles. A positive exposure-response relationship was found for RCS, gypsum and insulation, diesel exhaust, and welding fumes. Also, exposure to high levels of asphalt/bitumen and various organic particles was associated with a higher risk for COPD. Reduction of these exposures in the work environment are important to prevent future cases of COPD. More studies are needed to investigate exposure-response relationships further, but this study indicates that the European occupational exposure limit (OEL) for RCS needs to be re-evaluated.

Investigating the risk of breast cancer among women exposed to chemicals: a nested case-control study using improved exposure estimates.

PURPOSE: The aim of this study was to examine if exposures to chemicals at the workplace were associated with an increased risk of postmenopausal breast cancer, using improved exposure estimates. METHODS: The design is a case-control study, nested within a cohort of women from the Malmö Diet and Cancer Study. The study comprised 2400 women, 731 cases and 1669 matched controls, born 1923-1950 and living in Malmö, Sweden between 1991 and 1996. An occupational hygienist reclassified the probability for exposure given by a job-exposure matrix, using individual data on work tasks. First-time diagnoses of invasive breast cancer were identified through the Swedish Cancer Registry. RESULTS: Women exposed to chemicals in their occupational environment had a statistically significantly increased risk (OR 1.59, 95% CI 1.11-2.29) of breast cancer, and the risk correlated positively with duration of exposure but not with exposure intensity. Women exposed to chlorinated hydrocarbon solvents for more than 10 years had a significant higher risk of breast cancer (OR 3.06, 95% CI 1.18-7.96) as well as women exposed to oil mist for more than 10 years (OR 3.08, 95% CI 1.12-8.49). CONCLUSIONS: This study gives some support to the hypothesis that exposure to organic solvents as well as oil mist is associated with increased risk of breast cancer.

Occupational exposure to organic particles and combustion products during pregnancy and birth outcome in a nationwide cohort study in Sweden.

OBJECTIVE: To study if children of women exposed to organic particles and combustion products at work during pregnancy, have an increased risk of low birth weight, preterm birth or small for gestational age. METHODS: A nationwide cohort of all occupationally active mothers and their children from single births during 1994 to the end of 2012 (1 182 138 observations) was formed. Information on birth outcome was obtained from the medical birth register. Information on absence from work, education, occupation, age, nationality and smoking habits was obtained from national registers. A job exposure matrix (FINJEM) was used to assess the exposure. RESULTS: Pregnant women with low absence from work and high (>50th percentile) exposure to organic particles had an increased risk of giving birth to children with low birth weight (OR=1.19; 95% CI: 1.07 to 1.32), small for gestational age (OR=1.22; 95% CI: 1.07 to 1.38) or preterm birth (OR=1.17; 95% CI: 1.08 to 1.27). Subgroup analyses showed an increased risk of small for gestational age in association with exposure to oil mist. Exposure to oil mist and cooking fumes was associated with low birth weight. Paper and other organic dust was associated with preterm birth. Exposure to combustion products showed an increased risk of small for gestational age (OR=1.40; 95% CI: 1.15 to 1.71). CONCLUSIONS: The results indicate that occupational exposure to organic particles or combustion products during pregnancy is associated with restriction of fetal growth and preterm birth. More studies are needed to confirm a casual association.

Occupational exposures and the risk of amyotrophic lateral sclerosis.

OBJECTIVES: To examine the associations of specific occupations and occupational exposures with the risk of amyotrophic lateral sclerosis (ALS) in the Swedish population. METHODS: A nested case-control study was conducted in Sweden. Patients with ALS diagnosed during 1991-2010 (n=5020) were identified from the National Patient Register and 5 controls per case (n=25 100) were randomly selected from the general Swedish population, individually matched to cases by birth year and sex. Occupational history was obtained from the Swedish censuses in 1970, 1980 and 1990. The Nordic Occupational Cancer Study Job Exposure Matrix was used to identify exposures related to individual occupations. Conditional logistic regression was used to estimate ORs and their 95% CIs. RESULTS: Higher risk of ALS was associated with precision-tool manufacturing (OR 1.68, 95% CI 1.11 to 2.52) and glass, pottery and tile work (OR 1.76, 95% CI 1.03 to 3.00), whereas lower risk was associated with textile work (OR 0.44, 95% CI 0.21 to 0.91). None of the examined occupational exposures were associated with ALS risk overall. However, among individuals younger than 65 years of age, an association with a higher risk of ALS was found for formaldehyde (OR 1.29, 95% CI 1.00 to 1.65), and an association with a lower risk of ALS was found for methylene chloride (OR 0.49, 95% CI 0.26 to 0.93). CONCLUSIONS: We identified several occupations and occupational exposures that may be associated with the risk of ALS in Sweden. Occupational history obtained from censuses every 10 years remains a limitation of the study.

Occupational Exposure to Electric Shocks and Magnetic Fields and Amyotrophic Lateral Sclerosis in Sweden.

BACKGROUND: Amyotrophic lateral sclerosis (ALS) has been consistently related to "electric occupations," but associations with magnetic field levels were generally weaker than those with electrical occupations. Exposure to electric shock has been suggested as a possible explanation. Furthermore, studies were generally based on mortality or prevalence of ALS, and studies often had limited statistical power. METHODS: Using two electric shock and three magnetic field job-exposure matrices, we evaluated the relationship of occupational magnetic fields, electric shocks, electric occupations, and incident ALS in a large population-based nested case-control study in Sweden. Subanalyses, specified a priori, were performed for subjects by gender and by age (less than and more than 65 years). RESULTS: Overall, we did not observe any associations between occupational magnetic field or electric shock exposure and ALS. For individuals less than 65 years old, high electric shock exposure was associated with an odds ratio (OR) of 1.22 (95% confidence interval [CI] = 1.03, 1.43). The corresponding result for the age group 65 years or older was OR = 0.92 (95% CI = 0.81, 1.05). Results were similar regardless which job exposure matrices, exposure definitions, or cutpoints were used. For electric occupations, ORs were close to unity, regardless of age. For welders, no association was observed overall, although for welders <65 years the OR was 1.52 (95% CI = 1.05, 2.21). CONCLUSIONS: In this very large population-based study based on incident ALS case subjects, we did not confirm previous observations of higher risk of ALS in electrical occupations, and provided only weak support for associations between electric shocks and ALS.

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.

The risk for ophthalmological conditions in ulcerative colitis: A population-based case-control study. Is silica dust-exposure associated with inflammatory eye disease?

PURPOSE: To study the risk for eye diseases in individuals with Ulcerative Colitis (UC), and to assess whether silica dust-exposure could contribute to the development of inflammatory eye diseases. METHODS: A case-control study was conducted using a patient register processed by the National Board of Health and Welfare (NBHW) and Statistics Sweden. Cases were diagnosed with UC between 2007 and 2016. Matching was done with two random controls having the same age, sex and county of residence, without a systemic inflammatory disease. Using a job-exposure matrix, cases and controls were assessed for work-related silica dust exposure. The risk for eye disease was estimated by Cox regression analysis with calculation of Hazard Ratio (HR). RESULTS: A total of 58 989 individuals were included, comprising 19 663 cases and 39 326 controls. The sex distribution was similar. Overall, individuals with UC had an increased risk for eye disease, specified in ICD 10 chapter VII (H00-H59) with HR 1.25 (CI 1.20-1.32). The highest HR on block-level for cases was 1.52 (CI 1.36-1.70), (H15-H22), which includes episcleritis, keratitis and anterior uveitis. The risk for ocular disease was higher in silica dust-exposed than non-exposed with a HR of 1.44 (CI 1.16-1.78) and 1.25 (CI 1.19-1.31), respectively. Among cases, the risk for iridocyclitis (H20) was further elevated by silica dust exposure, with HR of 3.84 (CI 1.64-8.97) in exposed compared to 1.94 (1.57-2.41) in non-exposed. CONCLUSION: UC is associated with an increased risk for eye diseases, including inflammatory conditions. Our findings highlight that silica dust-exposure may be of importance in the pathogenesis of uveitis.

Hexavalent chromium still a concern in Sweden - Evidence from a cross-sectional study within the SafeChrom project.

OBJECTIVES: Hexavalent chromium (Cr(VI)) is classified as a human carcinogen. Occupational Cr(VI) exposure can occur during different work processes, but the current exposure to Cr(VI) at Swedish workplaces is unknown. METHODS: This cross-sectional study (SafeChrom) recruited non-smoking men and women from 14 companies with potential Cr(VI) exposure (n = 113) and controls from 6 companies without Cr(VI) exposure (n = 72). Inhalable Cr(VI) was measured by personal air sampling (outside of respiratory protection) in exposed workers. Total Cr was measured in urine (pre- and post-shift, density-adjusted) and red blood cells (RBC) (reflecting Cr(VI)) in exposed workers and controls. The Bayesian tool Expostats was used to assess risk and evaluate occupational exposure limit (OEL) compliance. RESULTS: The exposed workers performed processing of metal products, steel production, welding, plating, and various chemical processes. The geometric mean concentration of inhalable Cr(VI) in exposed workers was 0.15 µg/m3 (95% confidence interval: 0.11-0.21). Eight of the 113 exposed workers (7%) exceeded the Swedish OEL of 5 µg/m3, and the Bayesian analysis estimated the share of OEL exceedances up to 19.6% for stainless steel welders. Median post-shift urinary (0.60 µg/L, 5th-95th percentile 0.10-3.20) and RBC concentrations (0.73 µg/L, 0.51-2.33) of Cr were significantly higher in the exposed group compared with the controls (urinary 0.10 µg/L, 0.06-0.56 and RBC 0.53 µg/L, 0.42-0.72). Inhalable Cr(VI) correlated with urinary Cr (rS = 0.64) and RBC-Cr (rS = 0.53). Workers within steel production showed the highest concentrations of inhalable, urinary and RBC Cr. Workers with inferred non-acceptable local exhaustion ventilation showed significantly higher inhalable Cr(VI), urinary and RBC Cr concentrations compared with those with inferred acceptable ventilation. Furthermore, workers with inferred correct use of respiratory protection were exposed to significantly higher concentrations of Cr(VI) in air and had higher levels of Cr in urine and RBC than those assessed with incorrect or no use. Based on the Swedish job-exposure-matrix, approximately 17 900 workers were estimated to be occupationally exposed to Cr(VI) today. CONCLUSIONS: Our study demonstrates that some workers in Sweden are exposed to high levels of the non-threshold carcinogen Cr(VI). Employers and workers seem aware of Cr(VI) exposure, but more efficient exposure control strategies are required. National strategies aligned with the European strategies are needed in order to eliminate this cause of occupational cancer.

Narrative review of occupational exposures and noncommunicable diseases.

OBJECTIVE: Within the scope of the Exposome Project for Health and Occupational Research on applying the exposome concept to working life health, we aimed to provide a broad overview of the status of knowledge on occupational exposures and associated health effects across multiple noncommunicable diseases (NCDs) to help inform research priorities. METHODS: We conducted a narrative review of occupational risk factors that can be considered to have "consistent evidence for an association," or where there is "limited/inadequate evidence for an association" for 6 NCD groups: nonmalignant respiratory diseases; neurodegenerative diseases; cardiovascular/metabolic diseases; mental disorders; musculoskeletal diseases; and cancer. The assessment was done in expert sessions, primarily based on systematic reviews, supplemented with narrative reviews, reports, and original studies. Subsequently, knowledge gaps were identified, e.g. based on missing information on exposure-response relationships, gender differences, critical time-windows, interactions, and inadequate study quality. RESULTS: We identified over 200 occupational exposures with consistent or limited/inadequate evidence for associations with one or more of 60+ NCDs. Various exposures were identified as possible risk factors for multiple outcomes. Examples are diesel engine exhaust and cadmium, with consistent evidence for lung cancer, but limited/inadequate evidence for other cancer sites, respiratory, neurodegenerative, and cardiovascular diseases. Other examples are physically heavy work, shift work, and decision latitude/job control. For associations with limited/inadequate evidence, new studies are needed to confirm the association. For risk factors with consistent evidence, improvements in study design, exposure assessment, and case definition could lead to a better understanding of the association and help inform health-based threshold levels. CONCLUSIONS: By providing an overview of knowledge gaps in the associations between occupational exposures and their health effects, our narrative review will help setting priorities in occupational health research. Future epidemiological studies should prioritize to include large sample sizes, assess exposures prior to disease onset, and quantify exposures. Potential sources of biases and confounding need to be identified and accounted for in both original studies and systematic reviews.

Parental occupational exposure to metals and risk of cancer in the offspring: A register-based case-control study from Sweden.

BACKGROUND: Cancer risks in the offspring of mothers and fathers exposed to metals are unknown. We estimated the relative risks of childhood cancer, overall and by type, associated with parental occupational exposure to arsenic, cadmium, chromium, nickel, and lead. METHODS: We conducted a nested case-control study (1960-2015) of children born in Sweden aged 0-19 years diagnosed with cancer (National Cancer Register) matched 25:1 to controls on birth year and sex. We obtained parental occupational data around their birth from censuses and a nationwide register and identified exposure to each metal (yes/no, or higher/lower/no exposure) using the Swedish job-exposure matrix (SWEJEM). Adjusted odds ratios (OR) and 95% confidence intervals (CIs) were estimated separately for maternal and paternal exposures using conditional logistic regression. RESULTS: We compared 9653 cases to 1,72,194 controls in maternal and 12,521 cases to 2,74,434 controls in paternal analyses, respectively. We found a 38% increased risk of cancer associated with maternal occupational exposure to arsenic (OR 1.38 [95% CI 1.06, 1.82]), likely driven by higher risks for lymphoma (OR 1.52 [0.73, 3.15]), central nervous system (CNS) (OR 1.49 [0.88, 2.54]) and other solid malignancies (OR 1.74 [1.14, 2.65]). There were also indications of higher risks of lymphoma in children of mothers exposed to nickel and iron, and of CNS tumours due to chromium exposure. No associations were observed from paternal occupational exposure to any of the metals. CONCLUSIONS: We found evidence of increased risks of cancer in children of mothers but not fathers occupationally exposed to arsenic and potentially other metals.

Occupational exposure to particles and incidence of acute myocardial infarction and other ischaemic heart disease.

BACKGROUND: Ambient particulate air pollution has been linked to cardiovascular disease. Occupational particle exposure levels may be several times higher than ambient levels but has been less studied. OBJECTIVES: The authors investigated the association between occupational exposure to particles and the incidence of ischaemic heart disease (IHD). METHODS: The cohort included all manual workers in the Swedish national census of 1980 with information on demographic data and occupation. Information on hospital admissions for acute myocardial infarction or other IHDs and cause of death were obtained from nation-wide registers. A job-exposure matrix for exposure to small (<1 µm) and large (>1 µm) particles was developed. HRs were calculated with Cox regression with adjustment for sex, age, socioeconomic group and urban/rural residential area. RESULTS: Exposure to small particles was associated with an increased HR for acute myocardial infarction of 1.12 (95% CI 1.09 to 1.15), and HR for exposure to large particles was 1.14 (95% CI 1.10 to 1.18). The association was somewhat stronger for workers exposed to small particles for more than 5 years, 1.21 (95% CI 1.11 to 1.31), but no trend with exposure intensity was found. The risk associated with exposure to small particles was higher among women than among men, 1.30 (95% CI 1.12 to 1.51) and 1.10 (95% CI 1.07 to 1.14), respectively. Findings were essentially similar for other IHDs. CONCLUSIONS: This explorative study gives some support to the hypothesis that occupational exposure to particles increases the risk of acute myocardial infarction and other IHD. The findings must be interpreted cautiously due to lack of smoking data.

Risk of Cancer in Children of Parents Occupationally Exposed to Hydrocarbon Solvents and Engine Exhaust Fumes: A Register-Based Nested Case-Control Study from Sweden (1960-2015).

BACKGROUND: It remains unclear whether parental occupational exposure to hydrocarbon solvents (HCS) or engine exhaust fumes (EEF) is associated with higher risks of cancer in the offspring. OBJECTIVES: Our aim was to estimate relative risks of childhood cancers associated with maternal or paternal exposure to aliphatic/alicyclic, aromatic, or chlorinated HCS or gasoline/diesel EEF. METHODS: We conducted a case-control study in which individuals <20y old, born 1960-2014, were identified from the Swedish National Cancer Register (1960-2015) at first cancer diagnosis and matched to population controls (1 case:25 controls) on birth year and sex. Maternal and paternal occupation around the child's birth was retrieved for 9,653 cases and 172,194 controls and 12,521 cases and 274,434 controls, respectively, using information from six censuses and a nationwide register. Using the Swedish job-exposure matrix (SWEJEM), we assessed exposure to HCS and EEF (any or higher/lower). Odds ratios (ORs) and 95% confidence intervals (CIs) of 15 childhood cancer subtypes were estimated using conditional logistic regression models adjusted for several confounders. RESULTS: Maternal exposure to aromatic HCS was associated with non-Hodgkin lymphoma (OR=1.64; 95% CI: 1.05, 2.58), aliphatic/alicyclic HCS with germ cell tumors (OR=1.52; 95% CI: 0.89, 2.59), and gasoline/diesel EEF with astrocytoma (OR=1.40; 95% CI: 1.04, 1.88), myeloid leukemia (OR=1.53; 95% CI: 0.84, 2.81), lymphomas (OR=1.60; 95% CI: 0.85, 3.02 for Hodgkin; OR=1.44; 95% CI: 0.71, 2.91 for non-Hodgkin), and epithelial tumors (OR=1.51; 95% CI: 0.93, 2.44). Paternal exposure to gasoline EEF was associated with Hodgkin lymphoma (OR=1.21; 95% CI: 1.01, 1.44) and soft tissue sarcomas (OR=1.22; 95% CI: 1.00, 1.48). No notable difference was observed between higher and lower exposure. DISCUSSION: Our findings suggest that occupational exposure to HCS or EEF, especially in the mother, may increase the risk of some childhood cancers. They add to the growing literature on adverse effects from HCS and EEF in the child, but replication of these associations in other populations is warranted. https://doi.org/10.1289/EHP11035.

Time trends in occupational exposure to chemicals in Sweden: proportion exposed, distribution across demographic and labor market strata, and exposure levels.

OBJECTIVE: This study investigated time trends in occupational exposure to various chemicals in Sweden and the distribution across demographic and labor market sectors. METHODS: Exposure to six chemicals was investigated from 1980 to 2013 by application of a job exposure matrix to national population registers. Respirable crystalline silica (RCS), diesel engine exhaust, welding fumes, wood dust, chlorinated hydrocarbon solvents, and lead were selected to represent different groups of chemicals. Trends in exposure prevalence were investigated by linear regression and compared to the occupationally active population. Confidence intervals for the rate of change over time were obtained by bootstrapping. RESULTS: The proportion of workers born outside the Nordic countries increased over time in those exposed to RCS, diesel exhaust and wood dust. There was a shift of exposed jobs to small companies (<50 employees), especially for RCS, welding fumes, wood dust, and chlorinated hydrocarbon solvents. For RCS and welding fumes, there was a marked drop in exposure levels from 1980 to 1990 but small changes thereafter. Exposure to lead diminished, both in terms of prevalence and intensity. CONCLUSIONS: Over time, several exposures tended to shift to small companies, the construction sector, and migrant workers, all factors being indicative of less well-controlled working conditions. Occupational exposure to chlorinated organic solvents and lead diminished, while exposure levels to RCS and welding fumes have changed little since 1990. In view of the serious and well-established negative health effects, increased efforts to reduce exposure to RCS and welding fumes are needed.

Silica Dust Exposure Increases Risk for Rheumatoid Arthritis: A Swedish National Registry Case-Control Study.

OBJECTIVE: Rheumatoid arthritis (RA) is an inflammatory disease with unknown etiology. This study examines if silica dust exposure increases the risk for seropositive and seronegative RA. METHODS: A nationwide registry case-control study was conducted that included all cases of RA in Sweden between 2005 and 2016. In total, 31,139 cases with two matched controls were included. A JEM was used to estimate exposure. RESULTS: Silica dust exposure was associated with a statistically significant increase in odds ratio (OR) for seropositive (OR 1.22, 95% CI 1.05 to 1.40) and seronegative (OR 1.23, 95% CI 1.04 to 1.46) RA among men. CONCLUSION: This study found an increased OR for RA in silica-exposed men. The OR was equal for seropositive and seronegative RA. These findings further support the hypothesis that silica dust may be a trigger for RA.