France Labrèche

Objective: To systematically review the evidence on the association between occupational exposure to pesticides and the risk of amyotrophic lateral sclerosis (ALS). Methods: A systematic search, conducted in eight bibliographic databases for publications between 1990 and 2025, identified observational studies estimating the risk of ALS after occupational pesticide exposure. Study quality was assessed using the WHO Risk of Bias (RoB) assessment instrument for systematic reviews, with the ROBINS-E (RoB in non-randomised studies of exposure) tool domains of bias. Pooled risk estimates were produced using random-effects models with restricted maximum likelihood, heterogeneity was assessed with I² statistics, and meta-regressions and publication bias explored with funnel plots and Egger’s test. Results: Eight case-control studies (1734 cases) were retained for meta-analysis from 767 initially screened articles. ‘Ever’ occupational exposure to pesticides was associated with an increased risk of ALS (n=6 studies, pooled OR (pOR)=1.6; 95% CI 1.1, 2.2; I²=57%), for combined sexes. The risk for exposure to herbicides was slightly greater (pOR=1.7, I ² =0.0%) than for exposure to insecticides or fungicides (pORs=1.6, I ² =0.0%). Based on three studies, ever exposure to high levels of pesticides was associated with a higher risk (pOR=2.7; 95% CI=1.4, 5.0) than exposure to low levels (pOR=1.9; 95% CI=1.0, 3.7). Self-reported exposure assessment methods and older publication dates (<2015) were statistically significant predictors of the effect size. Conclusion: Despite the small number of studies and some heterogeneity, our results add to the evidence suggesting that occupational exposure to pesticides may increase the risk of ALS.

We aimed to identify circumstances associated with feelings of pride in healthcare workers (HCWs) during the COVID-19 pandemic. A prospective cohort of Canadian HCWs reported pride-reinforcing events in April 2020 (Phase 1). In spring/summer 2022 (Phase 4), they completed a self-reported retrospective comparison rating of whether they ‘now feel more [professional] pride than before the pandemic’. Among 4964 HCWs, 4360 (88%) described pride-reinforcing events in Phase 1; 3926 (79%) rated feeling more professional pride than before the pandemic in Phase 4. Teamwork (34%) and public appreciation (13%) were most cited in Phase 1. At Phase 4, male and older HCWs and community-based staff reported feeling more pride. Working as a physician, in hospital, with COVID-19 patients, and early anxiety/depression were associated with lower pride. Higher ratings were associated with greater organizational support. Many HCWs reported feeling more professional pride than before the pandemic. External support may help mitigate negative feelings.

The dental workforce comprises a variety of professions, most of which are predominantly occupied by women. Dental workers can be exposed to numerous toxic chemicals such as mercury, methacrylate polymers, and silica. This scoping review aims to synthesize the scientific literature on quantified chemical exposures and to identify research gaps in occupational chemical hazards faced by dental professionals. This review followed the Joanna Briggs Institute approach and PRISMA-ScR guidelines, using three concepts to search PubMed, Embase, and Web of Science: workers, dental care, and chemicals. Studies from high-income countries, published in French or English between 2000 and 2024 and reporting direct quantitative exposure data, were included. A descriptive analysis presents exposures measured in urine, blood, and air samples for the most assessed chemicals. Thirty articles were included in the review, with two-thirds focused on exposures of dentists and none of denturists. Exposure assessments most often focused on mercury (n = 17 studies), followed by nitrous oxide (n = 6), methacrylate compounds (n = 4), and silica (n = 3). Most studies showed exposure levels below occupational exposure standards; however, certain aerosol-releasing tasks could exceed recommended occupational exposure limits of 0.025 mg/m³ for mercury and silica. Dental students in a simulation laboratory were exposed to a 4-hr mercury vapor level up to 3 mg/m³, and dentists' exposure in clinics reached 0.45 mg/m³. Silica concentrations were below occupational exposure limits in dental clinics but reached twice the standard in a dental laboratory during prosthodontics polishing activities. The review emphasizes the need for comprehensive exposure assessments among dental workers and highlights the lack of focus on denturists, dental technicians, and dental assistants. To adequately assess the overlooked risks posed by multi-exposures to chemicals among dental workers, future studies need to analyze and report on exposures and risks stratified by occupation, task, and sex.

Objective: This study aimed to estimate the associations between occupational exposure to textile fibers/dusts and incidence of postmenopausal invasive breast cancer. Methods: A population-based case-control study conducted in Montreal (2008–2011) identified hospital cases (N = 695) and population controls (N = 608) from the electoral list. Occupational hygienists examined participants' occupations and tasks, and attributed exposures to several textile fibers. For all tumors and according to biomolecular subtypes, odds ratios (ORs) and 95% confidence intervals (95% CIs) were estimated using logistic regression models with different exposure indices, adjusting for potential confounders. Results: Ever exposure to cotton dust was associated with an increased risk (OR, 1.42; 95% CI, 0.95–2.16) as was ever exposure to treated textile fibers before age 36 years and/or before first full-term pregnancy (OR, 1.39; 95% CI, 0.97–2.01). Conclusions: These suggestive associations and the rapid evolution of textile fibers treatment warrant additional scrutiny, especially among younger women.

Background: Many studies have documented exposure to psychosocial factors in healthcare workers (HCWs) during the coronavirus disease 2019 (COVID-19) pandemic. Few have done it prospectively with open-ended questions. Aims: To describe the evolution of stress factors reported by HCWs during the pandemic. Methods: A prospective cohort of 4964 HCWs (physicians, nurses, healthcare aides and personal support workers), from four Canadian provinces, received four online questionnaires between the spring 2020 and 2022. Responses to an open-ended question on stressful events were coded into 25 stressors. Multilevel logistic regressions assessed trends in stressors, and the effect of gender, occupation and age. Results: In 2020, 91% of participants reported at least one stressor compared to 51% in spring 2022. Overall, eight stressors were reported 1000 times or more among 16 786 questionnaires. Five stressors decreased over time: fear of COVID-19, problems with personal protective equipment, changing guidelines, management of difficult cases and changes to work routine. Conversely, an increasing trend was noted for volume of work, and poor behaviour from the public or colleagues. Difficulties managing patients’ deaths remained steady. Changes in stressors over time were similar by gender, professional role and age group, although the reporting of some stressors varied within subgroups. Conclusions: Reporting of most stressors decreased over the pandemic, except for stressors arising from the changing demands on staff and patients as the pandemic progressed. Such changes in workplace psychosocial factors need to be addressed by prevention programmes to ensure an appropriate support response to the needs of HCWs.

Objective: We aimed to estimate prevalence of post-COVID conditions (PCCs) among healthcare workers (HCWs) and to identify predisposing factors. Methods: A cohort of Canadian HCWs completed four questionnaires during the pandemic. At the final questionnaire, HCWs reported conditions attributed to earlier COVID-19. The proportion developing a PCC was estimated. Risk factors were evaluated by logistic regression. Results: Among 4964 HCWs, 995 had one positive COVID test >90 days before completing the final questionnaire. A total of 266 (27%) developed a PCC. Factors predisposing HCWs to a PCC included depression and increased alcohol consumption reported preinfection, chronic ill-health prepandemic, and a perception that the infection was work-related. PCCs were less likely following vaccination. Most HCWs (98%) returned to work within 30 days, with 8% reporting severe PCC (n = 80). Conclusions: Predisposing factors reflected poor health preinfection. Most conditions were mild.

Objective: The aim of the study was to identify determinants of mental health in healthcare workers (HCW) during the COVID-19 pandemic. Methods: A cohort of Canadian HCW completed four questionnaires giving details of work with patients, ratings of workplace supports, a mental health questionnaire, and substance use. Principal components were extracted from 23 rating scales. Risk factors were examined by Poisson regression. Results: A total of 4854 (97.8%) of 4964 participants completed ratings and mental health questionnaires. Healthcare workers working with patients with COVID-19 had high anxiety and depression scores. One of three extracted components, ‘poor support,’ was related to work with infected patients and to anxiety, depression, and substance use. Availability of online support was associated with feelings of better support and less mental ill-health. Conclusions: Work with infected patients and perceived poor workplace support were related to anxiety and depression during the pandemic.

We investigated the availability and use of workplace mental health (MH) supports during the COVID-19 pandemic in a Canadian cohort of healthcare workers (HCW) and measured anxiety and depression by the Hospital Anxiety and Depression Scale (HADS) completed at four contacts 2020-2022. Reports were available for 4400 HCW working with patients. Half the HCWs had a clinically significant HADS score at one or more contacts Access to MH supports increased during the pandemic, with 94% reporting access to some workplace support by 2022: 47% had made use of at least one support. 25% of those with high HADS scores used no support. Older women and men with depressive conditions were less likely to report use. Reported use of an Employee Assistance Program was associated with a reduction in HADS scores in the following months.

Il est reconnu que les femmes et les hommes ont des profils professionnels différents qui peuvent donc se traduire par des risques de maladie professionnelle différents. Pourtant, la plupart de nos connaissances actuelles sur les maladies professionnelles découlent d'études menées auprès des hommes. Or, les femmes représentent actuellement 48 % de la population active au Québec. La santé des femmes dans l’environnement de travail demeure un domaine sous-étudié et nous sommes particulièrement freinés par le manque de compréhension de l'impact du genre sur l'exposition en milieu de travail. Il a été démontré que l'attribution des tâches et les conditions de travail peuvent différer même lorsque les femmes et les hommes exercent les mêmes professions. Ces différences dans l'attribution des tâches peuvent se traduire par des expositions différentes aux produits chimiques toxiques, aux contraintes ergonomiques, aux risques d'accident et aux facteurs de stress psychosociaux. Alors que les différences biologiques entre les femmes et les hommes peuvent être un facteur causal sous-jacent dans l'étiologie des maladies, la prise en compte des différences de genre dans l'évaluation de l'exposition reste un défi dans la recherche sur la santé au travail en raison du manque d'outils existants qui tiennent compte de ces différences. Dans le contexte d'expositions survenues dans le passé ou sur une longue période, l'évaluation par des experts est supérieure aux expositions autodéclarées, car les experts peuvent tenir compte de la période d'exposition, des particularités locales, des processus de fabrication ou des matériaux utilisés, ainsi que des tâches particulières accomplies par le sujet. Néanmoins, l'évaluation par des experts reste coûteuse quant à la durée de travail des ressources et, par conséquent, plusieurs chercheurs éminents ont préconisé l'utilisation de matrices emploi exposition (JEM). En particulier, les JEM construites à partir de données dérivées d'évaluations d'experts ont été proposées comme une alternative rentable à l'évaluation par des experts. Une telle matrice, connue sous le nom de Canadian Job Exposure Matrix (CANJEM), a été créée par Jérôme Lavoué et Jack Siemiatycki à partir des informations sur l'exposition obtenues dans le cadre de quatre études cas-témoins menées à Montréal entre 1979 et 2004, qui ont porté sur plus de 12 000 sujets (plus de 30 000 emplois), où la majorité des sujets de l'étude étaient des hommes. L'amélioration des estimations de CANJEM concernant les expositions chimiques et physiques des femmes sur le lieu de travail était un objectif important de ce projet. À cette fin, une évaluation des histoires professionnelles des femmes (4 362 descriptions d’emploi) ayant participé à l'étude cas-témoins sur le cancer du sein à Montréal de 2008 à 2011, dirigée par Mark S. Goldberg et France Labrèche, a été effectuée par des experts. Une équipe de chimistes et d'hygiénistes industriels qualifiés a examiné les histoires professionnelles détaillées recueillies auprès des participantes à l’étude afin de leur attribuer des codes de profession et d'industrie normalisés et d'estimer les expositions pour chaque emploi exercé. En ajoutant ces données enrichies à CANJEM, notre étude visait à déterminer si les expositions professionnelles différaient entre les femmes et les hommes occupant les mêmes emplois. Afin d'évaluer les différences possibles en matière d'exposition, des JEM spécifiques au sexe ont été développées pour comparer la fréquence des professions et la prévalence des agents entre les sexes. Ensuite, la concordance entre chaque JEM des paramètres de la probabilité, de la fréquence, de l’intensité et de l’intensité d’exposition pondérée en fréquence a été calculée. Des modèles bayésiens hiérarchiques ont ensuite été créés pour estimer les différences notables entre les JEM spécifiques aux femmes et aux hommes en fonction de la probabilité d'exposition à un agent donné. Enfin, à partir de l'information enrichie contenue dans CANJEM, nous avons obtenu des estimations de la prévalence de l'exposition à 258 agents en milieu de travail chez les femmes de Montréal. En comparant les JEM spécifiques au sexe, la fréquence des professions diffère entre les sexes, que l'on examine toutes les professions de chaque JEM séparées ou les professions communes aux deux JEM. En outre, la prévalence des agents différait d'une JEM à l'autre, avec peu de chevauchements entre les agents les plus prévalents. Les professions communes aux femmes et aux hommes présentaient une concordance modérée quant à la probabilité, à la fréquence, à l'intensité et à l'intensité pondérée en fonction de la fréquence de l'exposition aux agents CANJEM. Les professions principalement occupées par des femmes étaient fréquemment exposées aux solvants organiques, aux agents de nettoyage et aux aldéhydes aliphatiques, alors que les professions principalement occupées par des hommes étaient fréquemment exposées aux hydrocarbures aromatiques polycycliques (HAP,...