Comparison of exposure estimates in the Finnish job-exposure matrix FINJEM with a JEM derived from expert assessments performed in Montreal

Context: Retrospective exposure assessment in population-based case-control studies poses a major challenge due to the wide range of occupations and industries involved. The FINJEM is a generic job-exposure matrix developed in Finland which represents a potentially cost effective exposure assessment tool. While FINJEM has been used in several studies outside Finland, little is known of its applicability in other countries. Methods: We compared prevalence and intensity of exposure in FINJEM with a job-exposure matrix developed from expert assessments of occupational histories obtained in a population-based case-control study in Montreal. Agreement for prevalence of exposure was measured by weighted kappa coefficients between prevalence categories. Agreement for exposure intensity was measured by Spearman correlation coefficients between cells with non-null exposure. Results: The comparison involved 27 chemicals, the time period 1945-1995, and included 4,743 jobs initially assessed by the Montreal experts. 4,293 combinations of agent, occupational title, and period were available for comparison of prevalence. Agent-specific prevalence was consistently higher in the Montreal JEM (median difference 1.7%). Agent-specific kappas between prevalence categories varied from 0.89 (welding fumes) to 0.07 (flour dust). The comparison of exposure levels involved 14 agents and 198 cells with non-null exposure in both sources. Agent-specific Spearman correlation varied from 0.89 (flour dust) to -0.35 (Benzo[a]pyrene). Conclusion: Our observations suggest that information concerning several agents (e.g. metals, welding fumes) can be successfully transported from Finland to Canada and probably other countries. However, for other agents there was considerable disagreement and hence transportability of FINJEM cannot be assumed by default.This is the author's peer-reviewed final manuscript, as accepted by the publisher. The published article is copyrighted by BMJ Publishing Group Ltd. and can be found at: http://oem.bmj.com/.Keywords: Validity and Reliability, Job-exposure matrix, Case-Control Study, Occupational exposure assessmentKeywords: Validity and Reliability, Job-exposure matrix, Case-Control Study, Occupational exposure assessmen

INTEROCC case–control study: lack of association between glioma tumors and occupational exposure to selected combustion products, dusts and other chemical agents

Background: The aim was to investigate possible associations between glioma (an aggressive type of brain cancer) and occupational exposure to selected agents: combustion products (diesel and gasoline exhaust emissions, benzo (a) pyrene), dusts (animal dust, asbestos, crystalline silica, wood dust) and some other chemical agents (formaldehyde, oil mist, sulphur dioxide). Methods: The INTEROCC study included cases diagnosed with glioma during 2000-2004 in sub-regions of seven countries. Population controls, selected from various sampling frames in different centers, were frequency or individually matched to cases by sex, age and center. Face-to-face interviews with the subject or a proxy respondent were conducted by trained interviewers. Detailed information was collected on socio-economic and lifestyle characteristics, medical history and work history. Occupational exposure to the 10 selected agents was assessed by a job exposure matrix (JEM) which provides estimates of the probability and level of exposure for different occupations. Using a 25% probability of exposure in a given occupation in the JEM as the threshold for considering a worker exposed, the lifetime prevalence of exposure varied from about 1% to about 15% for the different agents. Associations between glioma and each of the 10 agents were estimated by conditional logistic regression, and using three separate exposure indices: i) ever vs. never; ii) lifetime cumulative exposure; iii) total duration of exposure. Results: The study sample consisted of 1,800 glioma cases and 5,160 controls. Most odds ratio estimates were close to the null value. None of the ten agents displayed a significantly increased odds ratio nor any indication of dose-response relationships with cumulative exposure or with duration of exposure. Conclusion: Thus, there was no evidence that these exposures influence risk of glioma.This is the publisher’s final pdf. The published article is copyrighted by BioMed Central Ltd. and can be found at: http://www.biomedcentral.com/Keywords: Brain cancer, Case-control study, International, Job exposure matrix, Risk facto

Evaluation of exposure assessment methods in epidemiological studies: The welding example

Exposure assessment quality is a fundamental consideration in the design and evaluation of observational studies. High quality exposure assessment is particularly relevant for outcomes with long latency, such as cancer, where detailed information on past exposures are often missing and must therefore be estimated. For the IARC Monograph on welding, the exposure group provided an overview of assessment methods used in the key epidemiological studies. Strengths and weaknesses of each study were assessed, along with their potential effects on interpretation of risk estimates. For the association between lung cancer and welding fume exposure, 9 cohort and 10 case-control studies were reviewed. For ocular melanoma and ultraviolet radiation (UVR) from welding, 7 case-control studies were reviewed. Quality criteria were: full occupational histories, and standardized, blinded and quantitative exposure assessment. Additional criteria for lung cancer: specifically assessing welding fumes and using information on welding tasks. For ocular melanoma: assessing artificial and solar radiation separately, taking into account eye burns, eye protection and welding type. Exposure assessment of welding fumes by applying a 'welding-exposure matrix' (n=2) or welding-specific questionnaires (n=3) were considered highest quality, followed by case-by-case expert assessment (n=5) or general job-exposure matrices (JEMs, n=4). Job title alone was considered less informative (n=5). For exposure to UVR, JEMs were most informative (n=2), followed by self-reported eye burns and self-reported exposure from specific welding types (n=2), although caution is advised regarding recall bias. Assessing welding fume exposure or ever exposure to welding arcs as proxy for UVR was considered less informative. For both exposures, ever versus never welder, or assessments based on data collected from proxies, were considered least informative. The overall evaluation was that there is sufficient evidence in humans for the carcinogenicity of welding fumes and ultraviolet radiation from welding

KinclLaurelPublicHealthHumanSciencesComparisonExposureEstimatesAnnex1.xlsx

Context: Retrospective exposure assessment in population-based case-control studies poses a major challenge due to the wide range of occupations and industries involved. The FINJEM is a generic job-exposure matrix developed in Finland which represents a potentially cost effective exposure assessment tool. While FINJEM has been used in several studies outside Finland, little is known of its applicability in other countries. Methods: We compared prevalence and intensity of exposure in FINJEM with a job-exposure matrix developed from expert assessments of occupational histories obtained in a population-based case-control study in Montreal. Agreement for prevalence of exposure was measured by weighted kappa coefficients between prevalence categories. Agreement for exposure intensity was measured by Spearman correlation coefficients between cells with non-null exposure. Results: The comparison involved 27 chemicals, the time period 1945-1995, and included 4,743 jobs initially assessed by the Montreal experts. 4,293 combinations of agent, occupational title, and period were available for comparison of prevalence. Agent-specific prevalence was consistently higher in the Montreal JEM (median difference 1.7%). Agent-specific kappas between prevalence categories varied from 0.89 (welding fumes) to 0.07 (flour dust). The comparison of exposure levels involved 14 agents and 198 cells with non-null exposure in both sources. Agent-specific Spearman correlation varied from 0.89 (flour dust) to -0.35 (Benzo[a]pyrene). Conclusion: Our observations suggest that information concerning several agents (e.g. metals, welding fumes) can be successfully transported from Finland to Canada and probably other countries. However, for other agents there was considerable disagreement and hence transportability of FINJEM cannot be assumed by default

Assessing occupational exposure to chemicals in an international epidemiological study of brain tumours

The INTEROCC project is a multi-centre case–control study investigating the risk of developing brain cancer due to occupational chemical and electromagnetic field exposures. To estimate chemical exposures, the Finnish Job Exposure Matrix (FINJEM) was modified to improve its performance in the INTEROCC study and to address some of its limitations, resulting in the development of the INTEROCC JEM. An international team of occupational hygienists developed a crosswalk between the Finnish occupational codes used in FINJEM and the International Standard Classification of Occupations 1968 (ISCO68). For ISCO68 codes linked to multiple Finnish codes, weighted means of the exposure estimates were calculated. Similarly, multiple ISCO68 codes linked to a single Finnish code with evidence of heterogeneous exposure were refined. One of the key time periods in FINJEM (1960–1984) was split into two periods (1960–1974 and 1975–1984). Benzene exposure estimates in early periods were modified upwards. The internal consistency of hydrocarbon exposures and exposures to engine exhaust fumes was improved. Finally, exposure to polycyclic aromatic hydrocarbon and benzo(a)pyrene was modified to include the contribution from second-hand smoke. The crosswalk ensured that the FINJEM exposure estimates could be applied to the INTEROCC study subjects. The modifications generally resulted in an increased prevalence of exposure to chemical agents. This increased prevalence of exposure was not restricted to the lowest categories of cumulative exposure, but was seen across all levels for some agents. Although this work has produced a JEM with important improvements compared to FINJEM, further improvements are possible with the expansion of agents and additional external data

INTEROCC case-control study: lack of association between glioma tumors and occupational exposure to selected combustion products, dusts and other chemical agents

BACKGROUND: The aim was to investigate possible associations between glioma (an aggressive type of brain cancer) and occupational exposure to selected agents: combustion products (diesel and gasoline exhaust emissions, benzo(a)pyrene), dusts (animal dust, asbestos, crystalline silica, wood dust) and some other chemical agents (formaldehyde, oil mist, sulphur dioxide). METHODS: The INTEROCC study included cases diagnosed with glioma during 2000–2004 in sub-regions of seven countries. Population controls, selected from various sampling frames in different centers, were frequency or individually matched to cases by sex, age and center. Face-to-face interviews with the subject or a proxy respondent were conducted by trained interviewers. Detailed information was collected on socio-economic and lifestyle characteristics, medical history and work history. Occupational exposure to the 10 selected agents was assessed by a job exposure matrix (JEM) which provides estimates of the probability and level of exposure for different occupations. Using a 25% probability of exposure in a given occupation in the JEM as the threshold for considering a worker exposed, the lifetime prevalence of exposure varied from about 1% to about 15% for the different agents. Associations between glioma and each of the 10 agents were estimated by conditional logistic regression, and using three separate exposure indices: i) ever vs. never; ii) lifetime cumulative exposure; iii) total duration of exposure. RESULTS: The study sample consisted of 1,800 glioma cases and 5,160 controls. Most odds ratio estimates were close to the null value. None of the ten agents displayed a significantly increased odds ratio nor any indication of dose–response relationships with cumulative exposure or with duration of exposure. CONCLUSION: Thus, there was no evidence that these exposures influence risk of glioma