Occupational exposures and cancer: a review of agents and relative risk estimates

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.

Triple Primary Cancers: An Analysis of Genetic and Environmental Factors

The occurrence of multiple primary cancers (MPC) is thought to reflect increased cancer susceptibility in patients due to a combination of genetic and environmental factors. Here we conducted a retrospective review of 2,894 consecutive patients evaluated at a single institution and identified 31 (1.14%) individuals with a history of three or more primary cancers, then analyzed the genetic and environmental influences associated with their propensity for developing malignancies. We found that 35.5% of patients had a hereditary cancer syndrome (HCS), with high penetrance HCS in 72.7% of cases, suggesting that monogenic causes underly a significant proportion of triple primary cancer risk. Analysis of cancer frequencies found that the diagnosis of breast cancer was associated with a significantly lower likelihood of HCS, while the diagnosis of colorectal, prostate, and pancreas cancer was associated with a significantly higher likelihood of HCS. Comparison of HCS-positive and HCS-negative patients revealed similar demographic characteristics, mean age at first diagnosis, and family history of cancer. Moreover, no significant differences in lifestyle behaviors, occupational exposures, chronic health conditions, or treatment with chemotherapy and radiation were observed between HCS-positive and -negative groups, though outliers in tobacco smoking, as well as systemic treatment after both first and second primary cancers were observed. These findings indicate a robust contribution of HCS to cancer susceptibility among patients with triple primary cancers while environmental influences were less evident. This emphasizes the need for larger MPC cohorts incorporating additional genetic and environmental factors to more comprehensively characterize drivers of cancer risk.

PREVENTION RELEVANCE

In patients with three or more primary cancers, genetic predisposition explained a significant proportion of cases; however, treatment history, lifestyle habits, and other exposures appeared to play a less significant role. This highlights the value of early genetic screening and the need to develop more sensitive markers of cancer susceptibility. See related Spotlight, p. 193.

Cancer mortality and premature deaths among hairdressers in Brazil

Hairdresser is an occupation classified by the International Agency for Research on Cancer as probably carcinogenic (Group 2A) for lung and bladder cancer, but evidence is accumulating on its association with other cancer types. To our knowledge, this is the first study aimed to compare the cancer mortality and premature mortality between hairdressers and other workers in Brazil.

METHODS

In this exploratory study, information on deaths by selected cancers that occurred in Brazil, from 1996 to 2020, among workers aged 20-70y, with identified occupation was gathered from the Brazilian Mortality Information System. Sociodemographic characteristics, sex-specific mortality ratio, and Years of Potential Life Lost (YPLL) were compared between hairdressers, service workers, and general workers. We used logistic regression models to estimate crude (ORC) and adjusted (ORADJ) odds ratios. Models were adjusted by age, educational level, and ethnicity. We also used Poisson regression models to compare the YPLL rates across the occupational groups.

RESULTS

From 1996 to 2020, 23 557 deaths occurred among hairdressers, 576 428 among service workers, and 13 332 996 among general workers in Brazil. Higher mortality ORs and YPLL were observed for several types of cancer among hairdressers, compared to service and general workers, especially for women. Hairdressers' mortality was significantly higher among whites, women, younger workers, and those who completed high school. Female hairdressers had significantly higher odds of dying from cancer of the digestive, respiratory, reproductive, urinary, and hematological systems, both in crude and adjusted models. For male hairdressers, higher odds were found only for urinary tract and bladder cancer, while other significant associations indicated lower mortality than the comparison groups. YPLL analyses revealed significant premature deaths among Brazilian hairdressers. In women, this was more evident among those who died of neoplasms of salivary glands, bones and articular cartilages, and acute lymphoid leukemia; in men, tongue, pharynx, and thyroid.

CONCLUSIONS

Our results suggest that Brazilian female hairdressers are more likely to die from several cancers, with potential consequences on premature deaths. Causal associations to occupational risks, such as exposure to chemicals, should be investigated by observational epidemiologic studies. Meanwhile, it is important to promote public policies, regulations, and Occupational Safety and Health (OSH) strategies to protect hairdressers' health, mitigate occupational risks, and ensure safe workplaces.

Lifetime exposure to unemployment and prior working conditions are associated with retiree's health: A retrospective study in a large population-based French cohort

It is unclear whether unemployment exposure, as well as working conditions, can have sustained effects on the health of retirees who are no longer exposed. The aim of the present study is to investigate this issue in 29,281 French retirees from the CONSTANCES cohort in whom the prevalence of suboptimal self-rated health, disability for routine tasks, cardiovascular diseases and cancers is assessed according to lifetime exposure to unemployment and prior working conditions. The analyses are performed retrospectively using multivariable logistic regression models with adjustment for potential confounders such as sex, birth year, parental histories of cardiovascular disease and cancer, social position, retirement age and duration. High lifetime exposure to unemployment is associated with an increased prevalence of suboptimal self-rated health (adjusted odds ratio (95% CI), 1.39 (1.23-1.57)), disability for routine tasks (1.41 (1.26-1.57)) and several cardiovascular diseases including stroke (1.66 (1.19-2.31)), myocardial infarction (1.65 (1.18-2.31)) and peripheral arterial disease (2.38 (1.46-3.90)). Bad prior working conditions are associated with an increased prevalence of disability for routine tasks (1.17 (1.04-1.33)) and cancers (1.27 (1.04-1.54)), notably prostate cancer (1.60 (1.01-2.64)). These findings suggest that unemployment and working conditions have long-term health effects that may cumulate over lifetime, emphasizing that risk evaluation and preventive strategies in retirees, as in workers, should take into account the life-course of individuals in addition to traditional risk factors.

Effect of environmental exposures on cancer risk: Emerging role of non-coding RNA shuttled by extracellular vesicles

Environmental and lifestyle exposures have a huge impact on cancer risk; nevertheless, the biological mechanisms underlying this association remain poorly understood. Extracellular vesicles (EVs) are membrane-enclosed particles actively released by all living cells, which play a key role in intercellular communication. EVs transport a variegate cargo of biomolecules, including non-coding RNA (ncRNA), which are well-known regulators of gene expression. Once delivered to recipient cells, EV-borne ncRNAs modulate a plethora of cancer-related biological processes, including cell proliferation, differentiation, and motility. In addition, the ncRNA content of EVs can be altered in response to outer stimuli. Such changes can occur either as an active attempt to adapt to the changing environment or as an uncontrolled consequence of cell homeostasis loss. In either case, such environmentally-driven alterations in EV ncRNA might affect the complex crosstalk between malignant cells and the tumor microenvironment, thus modulating the risk of cancer initiation and progression. In this review, we summarize the current knowledge about EV ncRNAs at the interface between environmental and lifestyle determinants and cancer. In particular, we focus on the effect of smoking, air and water pollution, diet, exercise, and electromagnetic radiation. In addition, we have conducted a bioinformatic analysis to investigate the biological functions of the genes targeted by environmentally-regulated EV microRNAs. Overall, we draw a comprehensive picture of the role of EV ncRNA at the interface between external factors and cancer, which could be of great interest to the development of novel strategies for cancer prevention, diagnosis, and therapy.

High Dietary Phosphorus Is Associated with Increased Breast Cancer Risk in a U.S. Cohort of Middle-Aged Women

Research has shown that high amounts of dietary phosphorus that are twice the amount of the U.S. dietary reference intake of 700 mg for adults are associated with all-cause mortality, phosphate toxicity, and tumorigenesis. The present nested case-control study measured the relative risk of self-reported breast cancer associated with dietary phosphate intake over 10 annual visits in a cohort of middle-aged U.S. women from the Study of Women's Health Across the Nation. Analyzing data from food frequency questionnaires, the highest level of daily dietary phosphorus intake, >1800 mg of phosphorus, was approximately equivalent to the dietary phosphorus levels in menus promoted by the United States Department of Agriculture. After adjusting for participants' energy intake, this level of dietary phosphorus was associated with a 2.3-fold increased risk of breast cancer incidence compared to the reference dietary phosphorus level of 800 to 1000 mg, which is based on recommendations from the U.S. National Kidney Foundation, (RR: 2.30, 95% CI: 0.94-5.61, p = 0.07). Despite the lack of statistical significance, likely due to the small sample size of the cohort, the present nested case-control study's clinically significant effect size, dose-response, temporality, specificity, biological plausibility, consistency, coherence, and analogy with other research findings meet the criteria for inferred causality in observational studies, warranting further investigations. Furthermore, these findings suggest that a low-phosphate diet should be tested on patients with breast cancer.

Distinct cardiovascular and cancer burdens associated with social position, work environment and unemployment: a cross-sectional and retrospective study in a large population-based French cohort

OBJECTIVES

Distinguish the respective effects of social position, work environment and unemployment on cardiovascular and cancer risks.

DESIGN

A cross-sectional and retrospective observational study.

SETTING

A population-based French cohort (CONSTANCES).

PARTICIPANTS

130 197 adults enrolled between 2012 and 2021 without missing values.

PRIMARY OUTCOME MEASURES

The associations of social position, work environment and unemployment exposure with the prevalence of cardiovascular events and cancers simultaneously tested using logistic regression models adjusting for common risk factors.

RESULTS

While social position, work environment and unemployment exposure are strongly inter-related with each other, they are not linked to the same cardiovascular and cancer outcomes. Low social position and long unemployment duration are significantly associated with an increased prevalence of angina pectoris, myocardial infarction and peripheral arterial disease (OR=1.22 to 1.90, p<0.04 to p<0.0001) but not of stroke. In contrast, a bad work environment is associated with an increased prevalence of stroke (OR=1.29, p<0.01) but not of angina pectoris, myocardial infarction and peripheral arterial disease. Low social position is associated with an increased prevalence of cervical and lung cancers (OR=1.73 and 1.95, p<0.002 and p<0.03) and a decreased prevalence of skin cancer (OR=0.70, p<0.0001) while a bad work environment is associated with an increased prevalence of breast, skin, prostate and colon cancers (OR=1.31 to 2.91, p<0.0002 to p<0.0001). Unemployment exposure is not associated with the prevalence of any type of cancers.

CONCLUSIONS

Social position, work environment and unemployment are associated with distinct cardiovascular and cancerous diseases that could add up during lifetime, they should therefore be considered all together in any preventive strategy.

How Does Environmental and Occupational Exposure Contribute to Carcinogenesis in Genitourinary and Lung Cancers?

Environmental and occupational exposures have been associated with an increased risk of different types of cancers, although the exact mechanisms of higher carcinogenesis risk are not always well understood. Lung cancer is the leading cause of global cancer mortality, and, also, genitourinary neoplasms are among the main causes of cancer-related deaths in Western countries. The purpose of this review is to describe the main environmental and occupational factors that increase the risk of developing lung and genitourinary cancers and to investigate carcinogenesis mechanisms that link these agents to cancer onset. Further objectives are to identify methods for the prevention or the early detection of carcinogenic agents and, therefore, to reduce the risk of developing these cancers or to detect them at earlier stages.

A Multicenter Study to Assess a Systematic Screening of Occupational Exposures in Lung Cancer Patients

Occupational lung cancer cases remain largely under-reported and under-compensated worldwide. In order to improve the detection and compensation of work-related lung cancers, we implemented a systematic screening of occupational exposures, combining a validated self-administered questionnaire to assess occupational exposures and a specialized occupational cancer consultation. After a pilot study, the present prospective, open-label, scale-up study aimed to assess this systematic screening of occupational exposures in lung cancer patients in five sites in France by associating university hospitals with cancer centers. Patients with lung cancer were sent a self-administered questionnaire to collect their job history and potential exposure to lung carcinogens. The questionnaire was assessed by a physician to determine if a specialized occupational cancer consultation was required. During the consultation, a physician assessed if the lung cancer was occupation-related and, if it was, delivered a medical certificate to claim for compensation. Patients were offered help from a social worker for the administrative procedure. Over 15 months, 1251 patients received the questionnaire and 462 returned it (37%). Among them, 176 patients (38.1%) were convened to the occupational cancer consultation and 150 patients attended the consultation. An exposure to occupational lung carcinogen was identified in 133 patients and a claim for compensation was judged possible for 90 patients. A medical certificate was delivered to 88 patients and 38 patients received compensation. Our national study demonstrated that a systematic screening of occupational exposures is feasible and will bring a significant contribution to improve the detection of occupational exposures in lung cancer patients.

Occupational asbestos exposure and survival among lung cancer patients

OBJECTIVE

This study investigated the association between occupational asbestos exposure (OAE) and survival in patients with histologically confirmed lung cancer (LC).

METHODS

This monocentric study was conducted in the Comprehensive Cancer Centre Léon Bérard, Lyon, France. A systematic screening has been in place since 2014 for occupational exposure to carcinogens using a self-assessment questionnaire sent to all patients newly diagnosed with histologically confirmed LC identified through the multidisciplinary LC board from 2014 to 2019. When the physician suspected a work-related exposure from the questionnaire including job history, an occupational cancer consultation was carried out to detail carcinogen exposures and assess if the LC was work-related. Demographics, clinical characteristics and survival data were extracted from medical records. The association between asbestos exposure and overall survival (hazard ratio and 95% confidence intervals) was estimated by Cox proportional hazards regression.

RESULTS

Overall, 702 patients were eligible to the present study, including 180 patients with OAE. In the crude analysis, LCs assessed as moderately or highly attributable to OAE were associated with decreased overall survival (HR = 1.32, 95 %CI 1.04-1.67) compared to LC without OAE or with a low degree of imputability to OAE (median follow-up 28.8 months). After adjustment for confounding (age at diagnosis, smoking status, stage, brain metastasis at diagnosis, and histology), the association of OAE with overall survival was no longer statistically significant (HR = 1.21, 95 %CI 0.94-1.56).

CONCLUSION

Overall survival in occupationally asbestos exposed LC patients may be decreased in comparison with non-exposed LC patients, warranting further investigations in larger studies.

Effect of Low-Thermal Treatment on the Particle Size Distribution in Wood Dust after Milling

The thermal treatment of wood can improve the appearance of the wood product's surface, its dimensional stability, and resistance to fungal attacks. However, the heat treatment changes the technological properties of wood, making it a new engineering material. This work investigates the effect of the low-thermal treatment of birch wood (Betula pendula Roth.), European beech wood (Fagus sylvatica L.), and alder wood (Alnus glutinosa L.) on the fine dust particles creation during woodworking. The samples of thermally treated wood with temperatures commonly used for the change of wood colour (105, 125, and 135 °C) were compared with reference samples made of natural wood. All 12 variants of the tested woods were milled using the 5-axis CNC machining center (20 mm diamond cutter, rotational speed 18,000 rev·min^-1, the depth of cut 3 mm, feed rates of 2, 4 and 6 m∙min^-1). A sieving analysis method allowed measuring the dust particle size distributions in all dust samples. The experiment's result analysis points out that wood type, thermal treatment, and feed rate meaningfully affect the size distribution of dust particles. Compared to birch wood and beech wood, the milling of alder wood samples created a much higher content of the finest dust particles, with particle sizes smaller than 0.032 mm. Increased temperatures in thermal treatment increase the share of fine dust particles with sizes smaller than 0.125 mm, compared to wood in its natural state. Milling with a lower feed rate (2 m·min^-1) creates finer dust than processing with higher feed rates (4 and 6 m·min^-1). Generally, the milling of alder in a natural or thermally treated state is a source of fine dust particles, particularly at low feed speed-rate milling, compared to birch and beech wood. In general, these results indicate that the low temperature thermal treatment parameters attribute new technological properties to all thermally modified types of wood tested.

Estimated number of cancers attributable to occupational exposures in France in 2017: an update using a new method for improved estimates

BACKGROUND

Over the last 50 years, occupational exposure to carcinogenic agents has been widely regulated in France.

OBJECTIVE

Report population-attributable fraction (PAF) and number of attributable cancer cases linked to occupational exposure in France based on an updated method to estimate lifetime occupational exposure prevalence.

METHODS

Population-level prevalence of lifetime exposure to ten carcinogenic agents (asbestos, benzene, chromium VI, diesel engine exhaust, formaldehyde, nickel compounds, polycyclic aromatic hydrocarbons, silica dust, trichloroethylene, wood dust) and two occupational circumstances (painters and rubber industry workers) were estimated using the French Census linked with MATGÉNÉ job-exposure matrices and French occupational surveys. PAF and number of attributable cancer cases were calculated using the estimated prevalence, relative risks from systematic review and national estimates of cancer incidence in 2017.

RESULTS

The lifetime occupational exposure prevalences were much higher in men than in women ranging from 0.2% (workers in the rubber industry) to 10.2% in men (silica), and from 0.10% (benzene, PAH and workers in the rubber industry) to 5.7% in women (formaldehyde). In total, 4,818 cancer cases (men: 4,223; women: 595) were attributable to the ten studied carcinogens and two occupational circumstances, representing 5.2% of cases among the studied cancer sites (M: 7.0%; W: 1.9%). In both sexes, mesothelioma (M: 689 cases; W: 160) and lung cancer (M: 3,032; W: 308) were the largest cancer sites impacted by the studied occupational agents and circumstances.

SIGNIFICANCE

A moderate proportion of the cancer cases in France is linked to carcinogens in occupational settings. Our method provides more precise estimates of attributable cancer taking into account evolution of exposure to occupational agents by sex, age and time. This methodology can be easily replicated using cross-sectional occupational data to aid priority making and implementation of prevention strategies in the workplace.

Lung cancer risk in relation to jobs held in a nationwide case-control study in Iran

BACKGROUND

Globally, lung cancer is the most frequent occupational cancer, but the risk associated with the occupations or occupational environment in Iran is not clear. We aimed to assess occupations with the risk of lung cancer.

METHODS

We used the IROPICAN nationwide case-control study data including 658 incident lung cancer cases and 3477 controls. We assessed the risk of lung cancer in relation to ever working in major groups of International Standard Classification of Occupations, high-risk occupations for lung cancer and duration of employment and lung cancer subtype among construction workers and farmers while controlling for cigarette smoking and opium consumption. We used unconditional regression logistic models to estimate ORs for the association between increased lung cancer risk and occupations.

RESULTS

We observed elevated ORs for lung cancer in male construction workers (OR=1.4; 95% CI: 1.0 to 1.8), petroleum industry workers (OR=3.2; 95% CI: 1.1 to 9.8), female farmers (OR=2.6; 95% CI: 1.3 to 5.3) and female bakers (OR=5.5; 95% CI: 1.0 to 29.8). A positive trend by the duration of employment was observed for male construction workers (p< 0.001). Increased risk of squamous cell carcinoma was observed in male construction workers (OR=1.9; 95% CI: 1.2 to 3.0) and female farmers (OR=4.3; 95% CI: 1.1 to 17.2), who also experienced an increased risk of adenocarcinoma (OR=3.8; 95% CI: 1.4 to 9.9).

DISCUSSION

Although we observed associations between some occupations and lung cancer consistent with the literature, further studies with larger samples focusing on exposures are needed to better understand the occupational lung cancer burden in Iran.

Occupational disease predictors in the nickel pyrometallurgical production: a prospective cohort observation

Background

Pyrometallurgical nickel production exposes workers to a wide range of occupational risk factors, including nickel aerosol, occupational noise and heat, but occupational (compensation) claims do not get enough attention in the literature. We, therefore, aimed to identify and analyze new occupational disease predictors in order to tailor prevention measures in the nickel pyrometallurgical production workers.

Methods

In a prospective observational study, a cohort of workers grouped in 16 occupations (N = 1424, 88% males, median age 39 (interquartile range (IQR) 31–47 years)), was fixed in 2007 at a large nickel production plant in the Russian High North. We then followed the cohort until 2021 and analyzed the association of selected predictors, including exposure to nickel and occupational group, with the risk of an occupational (compensation) claim in a Cox regression analysis.

Results

With 18,843 person-years of observation, occupational disease claims were confirmed in 129 workers (9% of the initial cohort, N = 108 men (84%)). Top three diagnoses were chronic bronchitis (3.81 cases/1000 workers/year), sensorineural deafness (2.36 cases/1000 workers /year) and musculoskeletal disorders (1.90 cases/1000 workers/year). Smoking was significantly associated with each diagnosis (adjusted hazard ratio (HR) ranged from 2.56 (95% confidence interval (CI) 1.17–5.57) for bronchitis to 6.69 (95% CI 1.46–30.64) for chronic obstructive pulmonary disease (COPD)). High nickel exposure was associated with occupational bronchitis and occupational asthma, whereas associations of occupational groups were also identified for COPD, asthma and musculoskeletal disorders.

Conclusion

Smoking, high exposure to nickel and specific exposure in the occupational groups increase the risk of occupational disease claims and should be prioritized directions for targeted intervention.

Work-Related Factors and Lung Cancer Survival: A Population-Based Study in Switzerland (1990-2014)

While previous Swiss studies have demonstrated differences in lung cancer mortality between occupational groups, no estimates are available on the association of occupation-related factors with lung cancer survival. This study aimed at determining whether occupation or work-related factors after diagnosis affect lung cancer survival. We used cancer registry records to identify lung cancer patients diagnosed between 1990 and 2014 in western Switzerland (n = 5773) matched with the Swiss National Cohort. The effect of occupation, the skill level required for the occupation, and the socio-professional category on 5-year lung cancer survival was assessed using non-parametric and parametric methods, controlling for histological type and tumour stage. We found that the net survival varied across skill levels and that the lowest skill level was associated with worse survival in both men and women. In the parametric models with minimal adjustment, we identified several occupational groups at higher risk of mortality compared to the reference category, particularly among men. After adjustment for histological type of lung cancer and tumour stage at diagnosis, most hazard ratios remained higher than 1, though non-statistically significant. Compared to top managers and self-employed workers, workers in paid employment without specific information on occupation were identified as the most at-risk socio-professional category in nearly all models. As this study was conducted using a relatively small sample and limited set of covariates, further studies are required, taking into account smoking habits and administrated cancer treatments. Information on return to work and working conditions before and after lung cancer diagnosis will also be highly valuable for analysing their effect on net lung cancer survival in large nationwide or international studies. Such studies are essential for informing health and social protection systems, which should guarantee appropriate work conditions for cancer survivors, beneficial for their quality of life and survival.

Estimate of Occupational Exposure to Carcinogens among Migrant Workers in the United Arab Emirates: A Cross-Sectional Study

Occupational illnesses, such as cancer, cause more deaths each year than occupational accidents. Occupational carcinogens include physical, chemical, biological and organizational hazards. In the United Arab Emirates (UAE), migrant workers account for 80% of labor. Being sometimes employed as unskilled workers and more willing to work in demanding jobs, their vulnerability and exposure may be increased. This study aimed to estimate the prevalence of occupational exposure to workplace carcinogens among migrant workers in the UAE. A sample of employees working in construction, cleaning, dry cleaning, mechanic workshops and hair salons were recruited and interviewed. Using OccIDEAS (an online assessment tool), participants were asked questions about their demographics, work history and regular tasks. Exposure to various carcinogens was estimated using the in-built algorithms of OccIDEAS. A sample of 1778 workers was included. The sample consisted of workers from Bangladesh (19.2%), India (31%), Nepal (4.7%), Pakistan (29.9%) and the Philippines (4.8%), with the rest from other nationalities. Overall, the prevalence of probable exposure was considerable, with the highest among drivers (96%) and the lowest among laundry workers (52%). Moderate to high exposure was found to 20 different carcinogens. Self-rated health among those who were exposed to carcinogens was significantly lower than among those not exposed (AOR = 0.783, 95% CI [0.638-0.961]). Exposure to several different carcinogens is relatively common in the UAE among migrant workers. Further strengthening policies and the implementation of tailored interventions are needed to prevent exposure to occupational carcinogens and, consequently, to combat occupational cancer in the UAE.

Contribution of causal factors to disease burden: how to interpret attributable fractions

What proportion of the risk in a given population is attributable to a risk factor? The population attributable fraction (PAF) answers this question. "Attributable to" is understood as "due to", which makes PAFs closely related to the concept of potential impact or potential benefits of reducing the exposure. The PAF is a tool at the border between science and decision making. PAFs are estimated based on strong assumptions and the calculations are data intensive, making them vulnerable to gaps in knowledge and data. Current misconceptions include summing up PAFs to 100% or subtracting a PAF for a factor from 100% to deduce what proportion is left to be explained or prevented by other factors. This error is related to unrecognised multicausality or shared causal responsibility in disease aetiology. Attributable cases only capture cases in excess and should be regarded as a lower bound for aetiological cases, which cannot be estimated based on epidemiological data alone (exposure-induced cases). The population level might not be relevant to discuss prevention priorities based on PAFs, for instance when exposures concentrate in a subgroup of the population, as for occupational lung carcinogens and other workplace hazards. Alternative approaches have been proposed based on absolute rather than relative metrics, such as estimating potential gains in life expectancy that can be expected from a specific policy (prevention) or years of life lost due to a specific exposure that already happened (compensation).

The shared genetic architecture between epidemiological and behavioral traits with lung cancer

The complex polygenic nature of lung cancer is not fully characterized. Our study seeks to identify novel phenotypes associated with lung cancer using cross-trait linkage disequilibrium score regression (LDSR). We measured pairwise genetic correlation (rg) and SNP heritability (h2) between 347 traits and lung cancer risk using genome-wide association study summary statistics from the UKBB and OncoArray consortium. Further, we conducted analysis after removing genomic regions previously associated with smoking behaviors to mitigate potential confounding effects. We found significant negative genetic correlations between lung cancer risk and dietary behaviors, fitness metrics, educational attainment, and other psychosocial traits. Alcohol taken with meals (rg = - 0.41, h2 = 0.10, p = 1.33 × 10-16), increased fluid intelligence scores (rg = - 0.25, h2 = 0.22, p = 4.54 × 10-8), and the age at which full time education was completed (rg = - 0.45, h2 = 0.11, p = 1.24 × 10-20) demonstrated negative genetic correlation with lung cancer susceptibility. The body mass index was positively correlated with lung cancer risk (rg = 0.20, h2 = 0.25, p = 2.61 × 10-9). This analysis reveals shared genetic architecture between several traits and lung cancer predisposition. Future work should test for causal relationships and investigate common underlying genetic mechanisms across these genetically correlated traits.

Occupational exposure and risk of colon cancer: a nationwide registry study with emphasis on occupational exposure to zoonotic gastrointestinal pathogens

OBJECTIVES

While colon cancer (CC) risk is associated with several lifestyle-related factors, including physical inactivity, smoking and diet, the contribution of occupation to CC morbidity remains largely unclear. Growing evidence indicates that gastrointestinal infections like salmonellosis could contribute to CC development. We performed a nationwide registry study to assess potential associations between occupation (history) and CC, including also those occupations with known increased exposure to gastrointestinal pathogens like Salmonella. METHODS: Person-level occupational data for all residents in The Netherlands were linked to CC diagnosis data. Differences in the incidence of (overall, proximal and distal) CC among occupational sectors and risk groups were tested for significance by calculating standardised incidence ratios (SIRs) with 95% CIs using the general population as reference group. Effects of gender, age, exposure duration and latency were also assessed.

RESULTS

Significant differences in CC incidence were observed only for a few occupational sectors, including the manufacturing of rubber and plastics, machinery and leather, the printing sector and the information service sector (SIRs 1.06-1.88). No elevated risk of CC was observed among people with increased salmonellosis risk through occupational exposure to live animals, manure or among those working in the sale of animal-derived food products (SIRs 0.93-0.95, 0.81-0.95 and 0.93-1.09 for overall, proximal and distal CC, respectively).

CONCLUSIONS

The results of this study suggest that occupation in itself provides a relatively small contribution to CC incidence. This is consistent with previous studies where a similar degree of variation in risk estimates was observed. The lack of an association with the high-risk occupations for salmonellosis might be due to higher levels of physical activity, a known protective factor for CC and other diseases, of people working in the agricultural sector, which might outweigh the potential Salmonella-associated risk of CC.

An innovative method to estimate lifetime prevalence of carcinogenic occupational circumstances: the example of painters and workers of the rubber manufacturing industry in France

BACKGROUND

Existing methods to estimate lifetime exposure to occupational carcinogenic agents could be improved.

OBJECTIVE

We propose a new method to estimate the lifetime prevalence of exposure to occupational carcinogens using the example of painters and workers of the rubber industry in France.

METHODS

From census, we calculated the proportion of painters and rubber industry workers using predefined occupational codes related to each occupation by sex and 10-year age group in 1982, 1990, 1999, 2007, and 2013. Using a beta-regression model, we obtained the yearly prevalence of exposure by 10-year age group over the period 1967-2007. We estimated the age- and sex-specific lifetime prevalence of exposure of the population in 2017 over 1967-2007, summing up the estimated prevalence of exposure for years 1967, 1977, 1987, 1997, and 2007 combined with a sex- and age-specific turnover factor. Corresponding population-attributable fractions were estimated for lung and bladder cancers in 2017.

RESULTS

In 2017, we estimated that 5.6 and 0.2% of men in France had ever worked as a painter or in the rubber industry, respectively, during their working time. The lifetime prevalence of ever having worked as a painter or in the rubber industry was much lower in women: 1.8% and 0.1%, respectively. We estimated that 950 lung cancer and 40 bladder cancer cases were attributable to these occupations in 2017.

SIGNIFICANCE

Based on accurate data and taking into account evolution of specific jobs over time, the proposed method provides good estimates of lifetime prevalence of exposure to occupational carcinogens. It could be applied in any other country with similar data.

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

OBJECTIVE

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

METHODS

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

RESULTS

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

CONCLUSIONS

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

Occupational exposure to carcinogens in Brazil: An approach

This study aims to estimate the prevalence of the primary occupational exposures, considered risk factors for Cancer in Brazil. We elaborated two exposure scenarios considering the agents' classification and the intensity of exposure, stratified by Brazilian regions and sex. Two pairs of specialists performed the classification of economic activities and occupations due to exposure. There was an excellent overall agreement (94%) and acceptable overall reliability (kappa 0.92, 95% CI 0.89-0.95). There is a notable difference (595%) in occupational exposure between the north (with a higher concentration of rural areas and extractivism) and southeast (with a higher level of industrial activities). There is a difference in prevalence from 833% for solvents to 1170% for inorganic dust between the two scenarios. There is a heterogeneity of exposures according to location, sex, circumstance, and sensitiveness of classification.

Occupational cancer burden: the contribution of exposure to process-generated substances at the workplace

Respirable crystalline silica in mineral dust, wood dust, diesel engine exhaust emissions and welding fumes are among the most common process-generated substances to which millions of workers are exposed daily. The composition of process-generated substances can vary substantially, depending on the parameters of the underlying processes; for example, the composition and intensity of diesel motor emissions differs among the various generations of diesel engines and working environments (e.g. surface or underground mining). We illustrate how common these occupational exposures are and discuss challenges in estimating their global prevalence and their contribution to the burden of occupational cancer. Estimates of the number and proportion of workers exposed in most countries and on a global scale are generally scarce. A remarkable exception is based on the proactive bottom-up estimates generated within the European Network for Silica. Actions to reduce exposures and research to fill gaps in knowledge adapted to local settings are warranted to mitigate the occupational cancer burden, especially in under-researched settings including low- and middle-income countries.

Education, income and risk of cancer: results from a Norwegian registry-based study

INTRODUCTION

Several studies have shown an association between socioeconomic status and incidence of cancer. In this study, we have examined the association between socioeconomic factors, using income and education as proxies, and cancer incidence in Norway, a country known to be egalitarian, with universal access to health care and scoring high on the human development index.

METHODS

We linked individual data for the total Norwegian population with information on all cancer patients registered in the Cancer Registry of Norway (CRN) with any cancer diagnosed between 2012 and 2016. Data on education, and individual income, were provided from Statistics Norway. We used Poisson regression to obtain incidence rate ratios (IRR) across education and income levels for 23 cancer sites.

RESULTS

A total of 9 cancers among men and 13 cancers among women were observed to have significantly higher incidence rates in cases with the lowest level of education. Melanoma for both sexes, testis and prostate cancer in men, and breast cancer in women were found to have a higher incidence rate among those with the highest level of education. The largest differences in IRR were found for lung cancer, where men and women with college or university education as their highest completed education had a two- to threefold decreased risk, compared to those with primary school (IRR men; 0.40 [0.37-0.43], women 0.34 [0.31-0.37]). The results for income mirrored the results for education among men, while for women we did not observe many differences in cancer risk across income groups.

CONCLUSION

Our findings were consistent with findings from other studies showing that the incidence rate of cancer differs across levels of socioeconomic status. We may need behavioral change campaigns focused on lifestyle changes that lower the risk of cancer and target perhaps to those with lower socioeconomic status.

[Primary lung cancer and occupational exposure in a North African population]

Les cancers broncho-pulmonaires (CBP) sont parmi les cancers les plus fréquents, de pronostic redoutable, l´origine professionnelle est fréquente, mais souvent sous-estimés. L'objectif était d´évaluer la proportion des Cancers Broncho-pulmonaires (CBP) présumés d´origine professionnelle et de rechercher la relation entre la nature de l´exposition et le type histologique du CBP. Cette étude épidémiologique rétrospective, a été réalisée au service de pneumologie de l´Etablissement Public Hospitalier (EPH) de Rouïba. Entre janvier 2014 et juin 2019, nous avons colligé 357 cas atteints de CBP avec preuve histologique. Le recueil des histoires médicales et professionnelles fut effectué. Les matrices emploi-exposition ont été utilisées pour le repérage des différentes expositions professionnelles. La population d´étude comprenait 357 patients dont la moyenne d´âge était de 63,9±11,1 ans et un sex-ratio de 7,4 hommes pour une femme. Il y avait 76,5% des sujets qui fumaient ou avaient fumé en moyenne 42 P/A. Le type histologique était dans 88,8% un carcinome bronchique non à petite cellule. L'ensemble des professions étudiées seraient responsables de 50,7% des cancers bronchiques primitifs, dont 26,5% pour les professions de chauffeurs poids lourds et conducteurs d´engins. L´imputabilité des cancers broncho-pulmonaires (CBP) à l´origine professionnelle est loin d´être négligeable mais souvent méconnue; du fait du caractère multifactoriel et du temps de latence entre l´exposition et l´apparition de la maladie, avec un impact sur le type histologique du cancer broncho-pulmonaire.

Cancer cases and deaths attributable to lifestyle risk factors in Chile

Background

To identify modifiable risk factors that contribute to cancer holds important public health relevance for setting up prevention strategies. Therefore, the aim of this study was to estimate the proportion of cancer cases and deaths attributable to alcohol consumption, high body mass index (BMI), low fruits and vegetables consumption, lack of physical activity, tobacco smoking, and passive smoking in Chile in 2018.

Methods

We retrieved data from a national representative survey to describe the distribution of six lifestyle risk factors. Relative risks of each risk factor-cancer pair were obtained from published meta-analysis and pooled cohort studies. Cancer cases and deaths were obtained from the GLOBOCAN 2018.

Results

Nearly 30% of all cancer cases (15,097 out of 50,320 cases) and 36% of all cancer deaths (10,155 out of 28,010 deaths) in Chile in 2018 were attributable to lifestyle risk factors. Smoking and high BMI accounted for most of the cancer cases (9232 and 4394, respectively) and deaths (6868 and 2572). The cancer burden of other lifestyle risk factors varied by sex. In men, the proportion of all cancer cases attributed to alcohol were 3.7% compare to 2.0% for women. Cancers cases and deaths of the larynx, lung, oral/cavity, esophagus and bladder could be at least halved if lifestyle risk factors were eliminated.

Conclusion

Smoking and high BMI were the leading causes of preventable cancer cases and deaths within the six lifestyles factors considered. Cancer prevention strategies should consider evidence-based interventions and public policies to encourage the adoption of a healthier lifestyle.

Contemporary Age-adjusted Incidence and Mortality Rates of Renal Cell Carcinoma: Analysis According to Gender, Race, Stage, Grade, and Histology

BACKGROUND

Recent data showed that North America has the highest incidence of renal cell carcinoma (RCC) worldwide.

OBJECTIVE

To assess contemporary gender-, race-, and stage-specific incidence; survival rates; and trends of RCC patients in the USA.

DESIGN, SETTING, AND PARTICIPANTS

Within the Surveillance, Epidemiology, and End Results database (2001-2016), all patients aged ≥18 yr with histologically confirmed renal parenchymal tumors were included.

OUTCOME MEASUREMENTS AND STATISTICAL ANALYSIS

Age-adjusted incidence rates and 5-yr cancer-specific survival (CSS) rates were estimated. Temporal trends were calculated through Joinpoint regression analyses to describe the average annual percent change (AAPC).

RESULTS AND LIMITATIONS

The age-adjusted incidence rate of RCC was 11.3/100 000 person years (AAPC+2.0%, p<0.001). Five-year CSS rates increased from 78.4% to 84.5% (AAPC +0.8%, p<0.001). Male incidence was double that of females (15.5 and 7.7, respectively). CSS marginally favored females (84.5% vs 82.0%), but improved equally in both genders (both AAPC +0.8%). The highest incidence (14.1/100 000 person years, AAPC +2.8%) and lowest survival (80.1%) were recorded in non-Hispanic American Indian/Alaska Native populations. T1aN0M0 had the highest incidence rates (4.6/100 000 person years), the highest increase over time (AAPC +3.6%), and the highest CSS (97.6%) of all stages. Limitations include retrospective nature and lack of information on risk factors.

CONCLUSIONS

The incidence of RCC increased significantly from 2001 to 2016, and 5-yr CSS after RCC improved. This was mainly due to T1aN0M0 tumors that showed the highest increase in the incidence and highest CSS. Unfavorable outcomes in specific ethnic groups warrant further research.

PATIENT SUMMARY

We examined contemporary incidence and cancer-specific survival rates of kidney cancer. Males had double the incidence rates of females, but lower survival. Natives showed the highest incidence rates and the lowest survival rates. Small renal masses showed the highest incidence and survival rates.

[Cancers and environmental exposures: Between uncertainties and certainties]

While improvements in the environment and living conditions have contributed to a significant increase in human longevity for over a century, the role of environmental factors in the occurrence of cancer has become a public health concern. It is recognized that a number of environmental factors such as environmental quality (air, water, soil), or environmental changes contribute to the occurrence of certain cancers. Despite this awareness, their potential impacts on health raise many scientific questions. The development of new methodological tools for the characterization of exposure, the study of the association between environmental agents and cancer through an exposure-cancer approach and the health impacts associated, have led to changes in scientific paradigms including the concept of exposome. This concept, at the heart of health and environmental issues, takes into account the determinants of health related to the quality of populations' living environments and provides assistance in public policy decision-making. Ultimately, the aim is to develop measures likely to reduce exposure and prevent health risks and damage to the most vulnerable populations, both in their physical environment and in their living environment, including the economic and social determinants.

Case-control study of paternal occupational exposures and childhood lymphoma in Great Britain, 1962-2010

BACKGROUND

This nationwide study investigates associations between paternal occupational exposure and childhood lymphoma.

METHODS

The UK National Registry of Childhood Tumours provided cases of childhood lymphoma born and diagnosed in Great Britain 1962-2010. Control births, unaffected by childhood cancer, were matched on sex, birth period and birth registration sub-district. Fathers' occupations were assigned to one or more of 33 exposure groups and also coded for occupational social class.

RESULTS

We analysed 5033 childhood lymphoma cases and 4990 controls. Total lymphoma and the subgroups Hodgkin, Burkitt and non-Hodgkin lymphoma were considered separately. No one exposure was significantly associated with increased risk within all subgroups and for total lymphoma. However, exposure to "ceramics and glass" was significantly associated with increased risk of total lymphoma, Hodgkin and non-Hodgkin lymphoma. Paternal lead exposure was associated with Burkitt lymphoma and exposure to metal fumes was associated with Hodgkin lymphoma.

CONCLUSIONS

This study provides no support for previous suggestions of an association between childhood lymphoma and paternal occupational exposure to pesticides, solvents/hydrocarbons or infections potentially transmitted by father's social contacts. An association with exposure to "ceramics and glass" was noted for the two major lymphoma subtypes together comprising 80% of total lymphoma.

Occupational Lung Disease

Occupational exposures are a major cause of lung disease and disability worldwide. This article reviews the broad range of types of occupational lung diseases, including airways disease, pneumoconioses, and cancer. Common causes of occupational lung disease are reviewed with specific examples and clinical features. Emphasis on the importance of a detailed history to make an accurate diagnosis of an occupational lung disease is discussed.

Cancers in France in 2015 attributable to occupational exposures

BACKGROUND

Recent and comprehensive estimates for the number of new cancer cases in France attributable to occupational exposures are lacking.

OBJECTIVES

To estimate the number of new cancer cases attributable to occupational exposures, using a newly developed methodology and the most recent data, for a comprehensive set of occupational carcinogens in France in 2015.

METHODS

Surveys among employees, the national labor force data, a cohort of agricultural workers, national monitoring of workers exposed to ionizing radiation and job-exposure matrix in France were used. The number and proportion of new cancer cases attributable to established occupational carcinogens (Group 1) was estimated using estimation of lifetime exposure and risk estimates from cohort studies. Cancer data were obtained from the French Cancer Registries Network.

RESULTS

In France in 2015, an estimated 7905 new cancer cases, 7336 among men and 569 among women, were attributable to occupational exposures, representing 2.3% of all new cancer cases (3.9% and 0.4% among men and women respectively). Among men and women, lung cancer was impacted the most, followed by mesothelioma and bladder cancer in men, and by mesothelioma and ovary in women. These cancers contributed to 89% of the total cancers attributable to occupational carcinogens in men, and to 80% in women. The main contributing occupational agent was asbestos among men (45%) and women (60%).

CONCLUSIONS

Currently, occupational exposures contribute to a substantial burden of cancer in France. Enhanced monitoring and implementation of protective labor policies could potentially prevent a large proportion of these cancers.

Cancers related to lifestyle and environmental factors in France in 2015

BACKGROUND

Cancer is a major cause of premature illness and death in France. To quantify how cancer prevention could reduce the burden, we present estimates of the contribution of lifestyle and environmental risk factors to cancer incidence in France in 2015, comparing these with other high-income countries.

METHOD

Prevalences of, and relative risks for tobacco smoking, alcohol consumption, inadequate diet, overweight and obesity, physical inactivity, exogenous hormones, suboptimal breastfeeding, infectious agents, ionising radiation, air pollution, ultraviolet exposure, occupational exposures, arsenic in drinking water and indoor benzene were obtained to estimate the population attributable fraction (PAF) and the number of attributable cancers by the cancer site and sex.

RESULTS

In 2015, 41% (or 142,000 of 346,000) of all new cancers diagnosed in France could be attributed to the aforementioned risk factors. The numbers and PAF were slightly higher in men than in women (84,000 versus 58,000 cases and 44% versus 37%, respectively). Smoking (PAF: 20%), alcohol consumption (PAF: 8%), dietary factors (PAF: 5%) and excess weight (PAF: 5%) were the most important factors. Infections and occupational exposures each contributed to an additional 4% of the cancer cases in 2015.

CONCLUSION

Today, two-fifths of cancers in France are attributable to preventable risk factors. The variations in the key amenable factors responsible in France relative to other economically similar countries highlight the need for tailored approaches to cancer education and prevention. Reducing smoking and alcohol consumption and the adoption of healthier diet and body weight remain important targets to reduce the increasing number of new cancer patients in France in the decades to follow.