Nils Plato

Occupational exposure to carcinogens in the European Union

OBJECTIVES To construct a computer assisted information system for the estimation of the numbers of workers exposed to established and suspected human carcinogens in the member states of the European Union (EU). METHODS A database called CAREX (carcinogen exposure) was designed to provide selected exposure data and documented estimates of the number of workers exposed to carcinogens by country, carcinogen, and industry. CAREX includes data on agents evaluated by the International Agency for Research on Cancer (IARC) (all agents in groups 1 and 2A as of February 1995, and selected agents in group 2B) and on ionising radiation, displayed across the 55 industrial classes. The 1990–3 occupational exposure was estimated in two phases. Firstly, estimates were generated by the CAREX system on the basis of national labour force data and exposure prevalence estimates from two reference countries (Finland and the United States) which had the most comprehensive data available on exposures to these agents. For selected countries, these estimates were then refined by national experts in view of the perceived exposure patterns in their own countries compared with those of the reference countries. RESULTS About 32 million workers (23% of those employed) in the EU were exposed to agents covered by CAREX. At least 22 million workers were exposed to IARC group 1 carcinogens. The exposed workers had altogether 42 million exposures (1.3 mean exposures for each exposed worker). The most common exposures were solar radiation (9.1 million workers exposed at least 75% of working time), environmental tobacco smoke (7.5 million workers exposed at least 75% of working time), crystalline silica (3.2 million exposed), diesel exhaust (3.0 million), radon (2.7 million), and wood dust (2.6 million). CONCLUSION These preliminary estimates indicate that in the early 1990s, a substantial proportion of workers in the EU were exposed to carcinogens.

Myocardial infarction among professional drivers.

Background. Professional drivers are at an increased risk of myocardial infarction but the underlying causes for this increased risk are uncertain. Methods. We identified all first events of myocardial infarction among men age 45–70 years in Stockholm County for 1992 and 1993. We selected controls randomly from the population. Response rates of 72% and 71% resulted in 1067 cases and 1482 controls, respectively. We obtained exposure information from questionnaires. We calculated odds ratios (ORs), with and without adjustment for socioeconomic status, tobacco smoking, alcohol drinking, physical inactivity at leisure time, overweight status, diabetes and hypertension. Results. The crude OR among bus drivers was 2.14 (95% confidence interval = 1.34–3.41), among taxi drivers 1.88 (1.19–2.98) and among truck drivers 1.66 (1.22–2.26). Adjustment for potential confounders gave lower ORs: 1.49 (0.90–2.45), 1.34 (0.82–2.19) and 1.10 (0.79–1.53), respectively. Additional adjustment for job strain lowered the ORs only slightly. An exposure-response pattern (by duration of work) was found for bus and taxi drivers. Conclusions. The high risk among bus and taxi drivers was partly explained by unfavorable life-style factors and social factors. The work environment may contribute to their increased risk. Among truck drivers, individual risk factors seemed to explain most of the elevated risk.

Exposure to Diesel Motor Exhaust and Lung Cancer Risk in a Pooled Analysis from Case-Control Studies in Europe and Canada

RATIONALE Diesel motor exhaust is classified by the International Agency for Research on Cancer as probably carcinogenic to humans. The epidemiologic evidence is evaluated as limited because most studies lack adequate control for potential confounders and only a few studies have reported on exposure-response relationships. OBJECTIVES Investigate lung cancer risk associated with occupational exposure to diesel motor exhaust, while controlling for potential confounders. METHODS The SYNERGY project pooled information on lifetime work histories and tobacco smoking from 13,304 cases and 16,282 controls from 11 case-control studies conducted in Europe and Canada. A general population job exposure matrix based on ISCO-68 occupational codes, assigning no, low, or high exposure to diesel motor exhaust, was applied to determine level of exposure. MEASUREMENTS AND MAIN RESULTS Odds ratios of lung cancer and 95% confidence intervals were estimated by unconditional logistic regression, adjusted for age, sex, study, ever-employment in an occupation with established lung cancer risk, cigarette pack-years, and time-since-quitting smoking. Cumulative diesel exposure was associated with an increased lung cancer risk highest quartile versus unexposed (odds ratio 1.31; 95% confidence interval, 1.19-1.43), and a significant exposure-response relationship (P value < 0.01). Corresponding effect estimates were similar in workers never employed in occupations with established lung cancer risk, and in women and never-smokers, although not statistically significant. CONCLUSIONS Our results show a consistent association between occupational exposure to diesel motor exhaust and increased risk of lung cancer. This association is unlikely explained by bias or confounding, which we addressed by adjusted models and subgroup analyses.

Cancer mortality among man-made vitreous fiber production workers.

We have updated the follow‐up of cancer mortality for a cohort study of man‐made vitreous fiber production workers from Denmark, Finland, Norway, Sweden, United Kingdom, Germany, and Italy, from 1982 to 1990. In the mortality analysis, 22,002 production workers contributed 489,551 person‐years, during which there were 4,521 deaths. Workers with less than 1 year of employment had an increased mortality [standardized mortality ratio (SMR) = 1.45; 95% confidence interval (CI) = 1.37–1.53]. Workers with 1 year or more of employment, contributing 65% of person‐years, had an SMR of 1.05 (95% CI = 1.02–1.09). The SMR for lung cancer was 1.34 (95% CI = 1.08–1.63, 97 deaths) among rock/slag wool workers and 1.27 (95% CI = 1.07–1.50, 140 deaths) among glass wool workers. In the latter group, no increase was present when local mortality rates were used. Among rock/slag wool workers, the risk of lung cancer increased with time‐since‐first‐employment and duration of employment. The trend in lung cancer mortality according to technologic phase at first employment was less marked than in the previous follow‐up. We obtained similar results from a Poisson regression analysis limited to rock/slag wool workers. Five deaths from pleural mesothelioma were reported, which may not represent an excess. There was no apparent excess for other categories of neoplasm. Tobacco smoking and other factors linked to social class, as well as exposures in other industries, appear unlikely to explain the whole increase in lung cancer mortality among rock/slag wool workers. Limited data on other agents do not indicate an important role of asbestos, slag, or bitumen. These results are not sufficient to conclude that the increased lung cancer risk is the result of exposure to rock/slag wool; however, insofar as respirable fibers were an important component of the ambient pollution of the working environment, they may have contributed to the increased risk.

Construction of job-exposure matrices for the Nordic Occupational Cancer Study (NOCCA)

Introduction. The Nordic Occupational Cancer study (NOCCA) is a cohort study based on employed populations in one or more censuses in Denmark, Finland, Iceland, Norway and Sweden. The large size of the cohort allows us to study rare cancers and to identify even small risks by occupation and by specific occupational exposures. This paper describes principles and experiences of the construction of job-exposure matrices (JEMs), an instrument to transform the history of occupational titles into quantitative estimates of exposure to potential carcinogenic substances. Material and methods. For each Nordic country, a national JEM was constructed by a team of experts on the basis of the Finnish matrix (FINJEM) that has been used in similar national studies since the mid-1990s. Results. The structure of the Nordic JEMs is three-dimensional (over 300 occupations, over 20 agents, 4 periods covering 1945–1994). Exposure is characterised by estimates of the prevalence and level of exposure. Important differences between the Nordic countries were observed for several exposures. Discussion. The selection of priority agent-occupation combinations and the adoption of general principles in the beginning of the work were necessary because of the high number of estimates to be evaluated (over 50 000/country). The selective modification of an existing JEM for use in other countries was a feasible, albeit challenging task, because exposure data and information about the use of chemicals in the past was scanty. As compared to the use of FINJEM for all Nordic countries, the modification process will probably increase the validity of dose-response and risk estimates of occupational cancer which is to be expected soon as the main outcome of the NOCCA project.

Occupational exposures and risk of esophageal and gastric cardia cancers among male Swedish construction workers.

Objective: The rising incidence and the strong male predominance among patients with esophageal and gastric cardia adenocarcinoma remain unexplained. We hypothesized that occupational airborne exposures in a traditional male dominated industry might contribute to these observations.Methods: A prospective, large cohort study of Swedish construction workers was linked to the Swedish population-based registers of Cancer, Causes of Death and Total Population. 260,052 men were followed from 1971 through 2000. Industrial hygienists assessed specific exposures for 200 job titles, and occupational airborne exposures were analyzed separately and combined. Incidence rate ratios (IRR), with 95% confidence intervals (CI), were estimated in multivariable Cox regression models adjusted for attained age, calendar period, smoking status and body mass.Results: We found positive associations between high exposure to asbestos (IRR 4.5 [95% CI 1.4–14.3]) and cement dust (IRR 3.8 [95% CI 1.5–9.6]) and risk of esophageal adenocarcinoma. Associations were seen between high exposure to asphalt fumes (IRR 2.3 [95% CI 1.0–5.3]) and wood dust (IRR 4.8 [95% CI 1.2–19.4]) and risk of cardia adenocarcinoma. No consistent associations regarding esophageal squamous-cell carcinoma were found.Conclusions: Exposure to asbestos and cement dust may be risk factors for esophageal adenocarcinoma, and exposure to asphalt fumes and wood dust may increase the risk of cardia adenocarcinoma. However, these associations cannot explain the major sex differences or the increasing incidence trends of these tumors.

A population-based case-referent study of myocardial infarction and occupational exposure to motor exhaust, other combustion products, organic solvents, lead, and dynamite

This case-referent study investigated the risk of myocardial infarction from occupational exposure to motor exhaust, other combustion products, organic solvents, lead, and dynamite. We identified first-time, nonfatal myocardial infarctions among men and women 45–70 years of age in Stockholm County from 1992 through 1994. We selected referent subjects from the population to match the demographic characteristics of the cases. A lifetime history of occupations was obtained by questionnaire. The response rate was 81% for the cases and 74% for the referents, with 1,335 cases and 1,658 referents included in the study. An occupational hygienist assessed occupational exposures, coding the intensity and probability of exposure for each subject. We adjusted relative risk estimates for tobacco smoking, alcohol drinking, hypertension, diabetes mellitus, overweight, and physical inactivity at leisure time. The relative risk of myocardial infarction was 2.11 (95% confidence interval = 1.23–3.60) among those who were highly exposed and 1.42 (95% confidence interval = 1.05–1.92) among those who were intermediately exposed to combustion products from organic material. We observed an exposure-response pattern, in terms of both maximum exposure intensity and cumulative dose. Exposure to dynamite and organic solvents was possibly associated with an increased risk. The other exposures were not consistently associated with myocardial infarction.

Exposures in the Painting Trades and Paint Manufacturing Industry and Risk of Cancer Among Men and Women in Sweden

Using data from the 1960 and 1970 Swedish censuses and the Swedish Cancer Register for 1971 to 1989, this study investigated variations in cancer risk by gender associated with employment in painting trades and paint manufacturing. Among men, standardized incidence ratios were significantly increased for lung cancer among painters and lacquerers; bladder cancer among artists; and pancreas cancer, lung cancer, and nonlymphocytic leukemia among paint and varnish plant workers. Risks for women were elevated for cancers of the esophagus, larynx, and oral cavity among lacquerers and for oral cancer among glazers. These findings are consistent with the report of the International Agency for Research on Cancer that classified painting as an occupationally related cause of cancer and provide further evidence that the risk of certain cancers is increased by exposures in the paint manufacturing process.

Development of an Exposure Measurement Database on Five Lung Carcinogens (ExpoSYN) for Quantitative Retrospective Occupational Exposure Assessment

BACKGROUND SYNERGY is a large pooled analysis of case-control studies on the joint effects of occupational carcinogens and smoking in the development of lung cancer. A quantitative job-exposure matrix (JEM) will be developed to assign exposures to five major lung carcinogens [asbestos, chromium, nickel, polycyclic aromatic hydrocarbons (PAH), and respirable crystalline silica (RCS)]. We assembled an exposure database, called ExpoSYN, to enable such a quantitative exposure assessment. METHODS Existing exposure databases were identified and European and Canadian research institutes were approached to identify pertinent exposure measurement data. Results of individual air measurements were entered anonymized according to a standardized protocol. RESULTS The ExpoSYN database currently includes 356 551 measurements from 19 countries. In total, 140 666 personal and 215 885 stationary data points were available. Measurements were distributed over the five agents as follows: RCS (42%), asbestos (20%), chromium (16%), nickel (15%), and PAH (7%). The measurement data cover the time period from 1951 to present. However, only a small portion of measurements (1.4%) were performed prior to 1975. The major contributing countries for personal measurements were Germany (32%), UK (22%), France (14%), and Norway and Canada (both 11%). CONCLUSIONS ExpoSYN is a unique occupational exposure database with measurements from 18 European countries and Canada covering a time period of >50 years. This database will be used to develop a country-, job-, and time period-specific quantitative JEM. This JEM will enable data-driven quantitative exposure assessment in a multinational pooled analysis of community-based lung cancer case-control studies.

Occupational exposure to organic dust increases lung cancer risk in the general population

Background Organic dust is a complex mixture of particulate matter from microbial, plant or animal origin. Occupations with exposure to animal products have been associated with an increased lung cancer risk, while exposure to microbial components (eg, endotoxin) has been associated with a decreased risk. To date there has not been a comprehensive evaluation of the possible association between occupational organic dust exposure (and its specific constituents) and lung cancer risk in the general population. Methods The SYNERGY project has pooled information on lifetime working and smoking from 13 300 lung cancer cases and 16 273 controls from 11 case–control studies conducted in Europe and Canada. A newly developed general population job-exposure matrix (assigning no, low or high exposure to organic dust, endotoxin, and contact with animals or fresh animal products) was applied to determine level of exposure. ORs for lung cancer were estimated by logistic regression, adjusted for age, sex, study, cigarette pack-years, time since quitting smoking, and ever employment in occupations with established lung cancer risk. Results Occupational organic dust exposure was associated with increased lung cancer risk. The second to the fourth quartile of cumulative exposure showed significant risk estimates ranging from 1.12 to 1.24 in a dose-dependent manner (p<0.001). This association remained in the highest quartile after restricting analyses to subjects without chronic obstructive pulmonary disease or asthma. No association was observed between lung cancer and exposure to endotoxin or contact with animals or animal products. Conclusion Occupational exposure to organic dust was associated with increased lung cancer risk in this large pooled case–control study.