Amy L Hall

CAREX Canada: an enhanced model for assessing occupational carcinogen exposure

Objectives To estimate the numbers of workers exposed to known and suspected occupational carcinogens in Canada, building on the methods of CARcinogen EXposure (CAREX) projects in the European Union (EU). Methods CAREX Canada consists of estimates of the prevalence and level of exposure to occupational carcinogens. CAREX Canada includes occupational agents evaluated by the International Agency for Research on Cancer as known, probable or possible human carcinogens that were present and feasible to assess in Canadian workplaces. A Canadian Workplace Exposure Database was established to identify the potential for exposure in particular industries and occupations, and to create exposure level estimates among priority agents, where possible. CAREX EU data were reviewed for relevance to the Canadian context and the proportion of workers likely to be exposed by industry and occupation in Canada was assigned using expert assessment and agreement by a minimum of two occupational hygienists. These proportions were used to generate prevalence estimates by linkage with the Census of Population for 2006, and these estimates are available by industry, occupation, sex and province. Results CAREX Canada estimated the number of workers exposed to 44 known, probable and suspected carcinogens. Estimates of levels of exposure were further developed for 18 priority agents. Common exposures included night shift work (1.9 million exposed), solar ultraviolet radiation exposure (1.5 million exposed) and diesel engine exhaust (781 000 exposed). Conclusions A substantial proportion of Canadian workers are exposed to known and suspected carcinogens at work.

Exposed! Or Not? The Diminishing Record of Workplace Exposure in Canada

The Canadian Workplace Exposure Database (CWED) is the first of its kind in Canada. It was originally developed in 2008 by the Canadian Carcinogen Exposure project (CAREX Canada) to assist in estimating worker exposures to carcinogens across the country.Following the CWED’s establishment, all Canadian federal and provincial agencies responsible for administering occupational health and safety regulation were surveyed to obtain a clearer picture of the quantity and quality of regulatory exposure data available. This revealed troubling reductions in exposure measurement collection, retention, and centralization by these agencies in recent years.Such trends will limit access to workplace exposure measurements for federal and provincial regulatory agencies as well as health researchers. Workplace exposure databases are used around the world for a variety of important purposes, such as identifying hazardous workplaces and workers at risk, assessing temporal–spatial trends, setting priorities for prevention, and informing epidemiological research.Efforts are underway to preserve historical data and promote prospective collection, however future success of the CWED will require collaboration and long-term vision on the part of those responsible for collecting workplace exposure measurements in Canada.RésuméLa Base de données canadienne sur l’exposition professionnelle aux agents cancérogènes (BCEPC) est la première du genre au Canada. Créée en 2008 par le projet CAREX Canada, elle sert à estimer l’exposition des travailleurs du pays aux agents cancérogènes.Après la création de la BCEPC, nous avons sondé les organismes fédéraux et provinciaux du Canada chargés d’administrer la réglementation sur la santé et la sécurité au travail pour obtenir un portrait plus clair de la quantité et de la qualité des données réglementaires sur l’exposition disponibles. Ce sondage a révélé des réductions troublantes dans la collecte, la conservation et la centralisation des indicateurs d’exposition par ces organismes au cours des dernières années.De telles tendances limiteront l’accès des organismes de réglementation fédéraux et provinciaux et des chercheurs médicaux aux indicateurs d’exposition en milieu de travail. Les bases de données sur l’exposition en milieu de travail sont utilisées autour du monde dans divers buts importants, notamment pour identifier les lieux de travail dangereux et les travailleurs à risque, évaluer les tendances spatio-temporelles, décider des priorités en matière de prévention et éclairer la recherche épidémiologique.Des efforts sont en cours pour préserver les données historiques et promouvoir la collecte prospective, mais le succès futur de la BCEPC exigera une collaboration et une vision à long terme de la part des responsables de la collecte des indicateurs d’exposition professionnelle aux agents cancérogènes au Canada.

Organisational characteristics associated with shift work practices and potential opportunities for intervention: findings from a Canadian study

Introduction Shift work is a common working arrangement with wide-ranging implications for worker health. Organisational determinants of shift work practices are not well characterised; such information could be used to guide evidence-based research and best practices to mitigate shift works negative effects. This exploratory study aimed to describe and assess organisational-level determinants of shift work practices thought to affect health, across a range of industry sectors. Methods Data on organisational characteristics, shift work scheduling, provision of shift work education materials/training to employees and night-time lighting policies in the workplace were collected during phone interviews with organisations across the Canadian province of British Columbia. Relationships between organisational characteristics and shift work practices were assessed using multivariable logistic regression models. Results The study sample included 88 participating organisations, representing 30 700 shift workers. Long-duration shifts, provision of shift work education materials/training to employees and night-time lighting policies were reported by approximately one-third of participating organisations. Odds of long-duration shifts increased in larger workplaces and by industry. Odds of providing shift work education materials/training increased in larger workplaces, in organisations reporting concern for shift worker health and in organisations without seasonal changes in shift work. Odds of night-time lighting policies in the workplace increased in organisations reporting previous workplace accidents or incidents that occurred during non-daytime hours, site maintenance needs and client service or care needs. Conclusions This study points to organisational determinants of shift work practices that could be useful for targeting research and workplace interventions. Results should be interpreted as preliminary in an emerging body of literature on shift work and health.

Occupational Exposures to Antineoplastic Drugs and Ionizing Radiation in Canadian Veterinary Settings: Findings From a National Surveillance Project

ObjectivesAlthough veterinary workers may encounter various occupational health hazards, a national characterization of exposures is lacking in Canada. This study used secondary data sources to identify veterinary exposure prevalence for ionizing radiation and antineoplastic agents, as part of a national surveillance project.MethodsFor ionizing radiation, data from the Radiation Protection Bureau of Health Canada were used to identify veterinarians and veterinary technicians monitored in 2006. This was combined with Census statistics to estimate a prevalence range and dose levels. For antineoplastic agents, exposure prevalence was estimated using statistics on employment by practice type and antineoplastic agent usage rates, obtained from veterinary licensing bodies and peer-reviewed literature.ResultsIn 2006, 7,013 (37% of all) Canadian veterinary workers were monitored for ionizing radiation exposure. An estimated 3.3% to 8.2% of all veterinarians and 2.4% to 7.2% of veterinary technicians were exposed to an annual ionizing radiation dose above 0.1 mSv, representing a total of between 536 and 1,450 workers. All monitored doses were below regulatory limits. For antineoplastic agents, exposure was predicted in up to 5,300 (23%) of all veterinary workers, with an estimated prevalence range of 22% to 24% of veterinarians and 20% to 21% of veterinary technicians.ConclusionThis is the first national-level assessment of exposure to ionizing radiation and antineoplastic agents in Canadian veterinary settings. These hazards may pose considerable health risks. Exposures appeared to be low, however our estimates should be validated with comprehensive exposure monitoring and examination of determinants across practice areas, occupations, and tasks.RésuméObjectifsBien que les agents vétérinaires puissent être exposés à divers dangers pour la santé au travail, il manque au Canada une caractérisation nationale de ce type d’exposition. Dans le cadre d’un projet de surveillance national, nous avons utilisé des sources de données secondaires pour cerner la prévalence des expositions aux rayonnements ionisants et aux antinéoplasiques en milieu vétérinaire.MéthodePour les rayonnements ionisants, les données du Bureau de la radioprotection de Santé Canada ont servi à identifier les vétérinaires et les techniciens vétérinaires surveillés en 2006. Nous avons combiné ces données aux chiffres du Recensement pour estimer un intervalle de prévalence et des niveaux de dose. Pour les antinéoplasiques, la prévalence de l’exposition a été estimée à l’aide des statistiques sur l’emploi par type de pratique et des taux d’utilisation des antinéoplasiques, lesquels ont été obtenus dans les revues évaluées par les pairs et auprès des organismes de réglementation de la profession vétérinaire.RésultatsEn 2006, 7 013 (37%) des agents vétérinaires canadiens ont été surveillés pour leur exposition aux rayonnements ionisants. On estime qu’entre 3,3% et 8,2% des médecins vétérinaires et entre 2,4% et 7,2% des techniciens vétérinaires ont été exposés à une dose annuelle de rayonnements ionisants supérieure à 0,1 mSv, soit entre 536 et 1 450 personnes en tout. Toutes les doses surveillées étaient en deçà des limites réglementaires. Pour les antinéoplasiques, une exposition était prévisible chez jusqu’à 5 300 agents vétérinaires (soit 23%), avec un intervalle de prévalence estimatif de 22% à 24% des médecins vétérinaires et de 20% à 21% des techniciens vétérinaires.ConclusionIl s’agit de la première évaluation nationale de l’exposition aux rayonnements ionisants et aux antinéoplasiques en milieu vétérinaire au Canada. Ces dangers peuvent poser des risques considérables pour la santé. Les niveaux d’exposition semblent être faibles, mais nos estimations devraient être validées par une surveillance complète de l’exposition et par un examen des déterminants selon la sphère de pratique, la profession et la tâche.

579 Work schedule and prospective antidepressant prescriptions in the swedish workforce: a 2-year study using national drug registry data

Introduction Mood disorders affect millions of individuals worldwide and contribute to substantial morbidity and disability. A better understanding of modifiable work-related risk factors for depression could inform and advance prevention efforts in this area. This study used a large Swedish longitudinal occupational survey to prospectively examine the effect of self-reported work schedule on registry-based antidepressant prescriptions over a two-year period. Methods The analytic sample (n=8643) was obtained from the Swedish Longitudinal Occupational Survey of Health. Sex-stratified and unstratified analyses were conducted using logistic regression. For exposure, 8 categories were used to describe work schedule in 2008: ‘regular days’ (3 categories: night work history=none,≤3 years, or 4+years) ‘night work (regular, rostered, or rotating)’, ‘regular shift work (no nights)’, ‘rostered work (no nights)’, ‘flexible/non-regulated hours’, and ‘other’. For the outcome, all prescriptions coded N06A according to the Anatomical Therapeutic Chemical System were obtained from the Swedish National Prescribed Drug Register and dichotomized into ‘any’ or ‘no’ prescriptions between 2008 and 2010. Estimates were adjusted for potential sociodemographic, health, and work confounders, and for prior depressive symptoms. Results In unadjusted analyses, an increased odds ratio for depression was observed for ‘Other’ work hours in unstratified (OR=1.75, 95% CI: 1.21 to 2.51) and female (OR=1.62, 95% CI: 1.05 to 2.51) models; in adjusted models effects persisted but confidence intervals widened to non-significance at the p=0.05 level. In models adjusted for previous depressive symptoms, females in ‘flexible/non-regulated’ schedules showed an increased odds ratio for depression (OR=2.01, 95% CI: 1.08 to 3.76), while a decreased odds ratio was observed for the unstratified model ‘regular shift work (no nights)’ category (OR=0.61; 95% CI: 0.38 to 0.97). Discussion This study’s findings support prospective relationships between work schedule and antidepressant prescriptions in the Swedish workforce. Future research should continue to assess sex-stratified relationships, using detailed shift work exposure categories and objective registry data where possible.

Examining Exposure Assessment in Shift Work Research: A Study on Depression Among Nurses

Introduction Coarse exposure assessment and assignment is a common issue facing epidemiological studies of shift work. Such measures ignore a number of exposure characteristics that may impact on health, increasing the likelihood of biased effect estimates and masked exposure-response relationships. To demonstrate the impacts of exposure assessment precision in shift work research, this study investigated relationships between work schedule and depression in a large survey of Canadian nurses. Methods The Canadian 2005 National Survey of the Work and Health of Nurses provided the analytic sample (n = 11450). Relationships between work schedule and depression were assessed using logistic regression models with high, moderate, and low-precision exposure groupings. The high-precision grouping described shift timing and rotation frequency, the moderate-precision grouping described shift timing, and the low-precision grouping described the presence/absence of shift work. Final model estimates were adjusted for the potential confounding effects of demographic and work variables, and bootstrap weights were used to generate sampling variances that accounted for the survey sample design. Results The high-precision exposure grouping model showed the strongest relationships between work schedule and depression, with increased odds ratios [ORs] for rapidly rotating (OR = 1.51, 95% confidence interval [CI] = 0.91-2.51) and undefined rotating (OR = 1.67, 95% CI = 0.92-3.02) shift workers, and a decreased OR for depression in slow rotating (OR = 0.79, 95% CI = 0.57-1.08) shift workers. For the low- and moderate-precision exposure grouping models, weak relationships were observed for all work schedule categories (OR range 0.95 to 0.99). Conclusions Findings from this study support the need to consider and collect the data required for precise and conceptually driven exposure assessment and assignment in future studies of shift work and health. Further research into the effects of shift rotation frequency on depression is also recommended.

Priority Setting for Occupational Cancer Prevention

Background Selecting priority occupational carcinogens is important for cancer prevention efforts; however, standardized selection methods are not available. The objective of this paper was to describe the methods used by CAREX Canada in 2015 to establish priorities for preventing occupational cancer, with a focus on exposure estimation and descriptive profiles. Methods Four criteria were used in an expert assessment process to guide carcinogen prioritization: (1) the likelihood of presence and/or use in Canadian workplaces; (2) toxicity of the substance (strength of evidence for carcinogenicity and other health effects); (3) feasibility of producing a carcinogen profile and/or an occupational estimate; and (4) special interest from the public/scientific community. Carcinogens were ranked as high, medium or low priority based on specific conditions regarding these criteria, and stakeholder input was incorporated. Priorities were set separately for the creation of new carcinogen profiles and for new occupational exposure estimates. Results Overall, 246 agents were reviewed for inclusion in the occupational priorities list. For carcinogen profile generation, 103 were prioritized (11 high, 33 medium, and 59 low priority), and 36 carcinogens were deemed priorities for occupational exposure estimation (13 high, 17 medium, and 6 low priority). Conclusion Prioritizing and ranking occupational carcinogens is required for a variety of purposes, including research, resource allocation at different jurisdictional levels, calculations of occupational cancer burden, and planning of CAREX-type projects in different countries. This paper outlines how this process was achieved in Canada; this may provide a model for other countries and jurisdictions as a part of occupational cancer prevention efforts.

0283 Examining exposure assessment in shift work research: a study on depression among nurses

Objectives Exposure misclassification is a common challenge in shift-work epidemiology. This study used a large national survey of Canadian nurses to examine shift-work’s effects on depression; multiple exposure definitions with varying levels of specificity were applied to illustrate the impacts of exposure assessment. Methods The analytic sample (n=11,450) was obtained from the 2005 National Survey of the Work and Health of Nurses. Logistic regression was used to assess relationships between shift-work and depression for high, moderate, and low specificity definitions of shift-work exposure. The low and moderate specificity definitions described shift timing (day/shift and day/evening/night/rotating, respectively); the high specificity definition described both shift timing (day/evening/night/rotating) and frequency of rotation (slow/medium/rapid/undefined). All model estimates were bootstrapped and adjusted for the potential confounding effects of sociodemographic, health, and work variables. Results The high specificity shift-work definition model showed the strongest relationships, with increased odds of depression in the rapid rotating shift group (OR=1.51, 95% CI=0.91–2.51) and in the undefined rotating group (OR=1.67, CI=0.92–3.02), relative to the regular day group. Odds of depression were decreased in the slow rotating group (OR=0.79, 95% CI=0.57–1.08). For the low and moderate specificity exposure definition models, weak relationships were observed for all shift categories (OR range 0.95 to 0.99). Conclusions This study’s findings support associations between shift-work and depression, and the need for specific and hypothesis-driven exposure assessment in future studies to correctly identify exposure-response relationships and to appropriately target health interventions.

S10-2 Carex canada: innovations and applications

Ten years ago the CAREX Canada project was initiated with the objective of identifying how many Canadians are exposed to workplace and environmental carcinogens as well as how and where they are exposed. While the occupational component of the project was largely based on the European CAREX project, CAREX Canada sought to incorporate a number of innovations based on the Finnish job exposure matrix (FinJEM), other CAREX projects such as Costa Rica’s, and large exposure database projects that were being initiated at the time. CAREX Canada sought to enhance the original CAREX model in two major ways. First, prevalence of exposure was assessed based on both industry (328 categories) and occupation (520 categories), using much finer groups than previous projects. This allowed for both better assessment of exposure and a finer level of reporting for targeting prevention efforts. Second, where possible, levels of exposure were estimated as three categories of low, medium, and high using cut-points based on occupational exposure limits. To facilitate this classification, the Canadian Workplace Exposure Database was created, using several hundred thousand measurements acquired from regulatory agencies. For example, we estimated that 380,000 workers are exposed to crystalline silica, 14% high (>0.025 mg/m3), 39% moderate (0.0125–0.025 mg/m3), and 47% low. These enhancements have made CAREX Canada a much more effective tool for use in both prevention and, through creation of job exposure matrixes, epidemiologic applications. The greater granularity of the prevalence estimates and the availability of measured exposure levels for many common carcinogens have facilitated the use of this data for cancer surveillance and burden of cancer projects. Level of exposure estimation has been particularly useful, but has been limited to what can be called the “data-rich” exposures. This project has also provided a systematic means of identifying where significant data gaps exist.

O06-6 Quantifying shiftworkers’ exposure to light-at-night in healthcare and emergency service settings

Background Shiftworkers’ increased risk of adverse health outcomes has been linked to their exposure to light-at-night (LAN). However, few data characterising light exposures in nighttime working environments have been reported. The purpose of this study was to measure and compare shiftworkers’ exposures to LAN in the province of British Columbia, Canada. Methods Between October 2015 and March 2016, over 150 personal full-shift data were collected from more than 100 shiftworkers in emergency health services (paramedics, dispatchers) and healthcare (nurses, support aides, security, pharmacy, laboratory staff). Participants wore a small continuous monitoring device to measure LAN exposure once per minute. Preliminary analyses during the 23:00–05:00 period were conducted to characterise exposure levels with potential impacts on melatonin secretion and alertness. Results Personal light exposure levels ranged from <5 lux (minimum) to >650 lux (maximum). Cumulative time ≥1 hour above 30 lux (minimum level influencing melatonin secretion) occurred in over 60% of samples, and in over 40% of samples using a 100 lux cut point (midpoint of light’s maximum alerting effect). Significant exposure differences were seen across occupations and workplaces. Nurses, aides, and laboratory workers had the longest cumulative time exceeding 100 lux; dispatchers had the longest cumulative time below 30 lux. By workplace, laboratory, intensive care, and labour and delivery workers had the longest cumulative time exceeding 100 lux; call centre workers had the longest cumulative time below 30 lux. Within-worker variation across shifts was most pronounced among laboratory assistants and least pronounced among dispatch officers. Conclusions This study constitutes an initial step in documenting and comparing levels of LAN exposure across shiftwork occupations, workplaces, and time. Results will be useful for planning future LAN sampling strategies, assigning exposure estimates in epidemiological analyses, and identifying groups of shiftworkers at greatest risk of circadian disruption and/or fatigue at work.