Occupational exposure and laryngeal and hypopharyngeal cancer risk in central and eastern Europe

A multicenter case-control study was conducted during 1999-2002 in four European countries (Poland, Romania, Russia, and Slovakia) to evaluate the role of occupational exposures in risk of laryngeal/hypopharyngeal cancer. Male cancer cases (34 hypopharyngeal, 316 laryngeal) with full data on occupational history and nonoccupational factors were compared with 728 hospital controls for occupational exposure to 73 suspected carcinogens. Occupational history was evaluated by industrial hygienists blinded to case/control status. Elevated risks for ever exposure to coal dust were found for both hypopharyngeal (odds ratio (OR) = 4.19, 95% confidence interval (CI): 1.18, 14.89) and laryngeal (OR = 1.81, 95% CI: 0.94, 3.47) cancer, with clear dose-response patterns. Inclusion of a 20-year lag in the analysis strengthened these associations. Hypopharyngeal cancer risk was also significantly associated with exposure to mild steel dust (OR = 3.04, 95% CI: 1.39, 6.64) and iron compounds and fumes (OR = 2.74, 95% CI: 1.29, 5.84), without clear dose-response relations. Laryngeal cancer was significantly associated with exposure to hard-alloys dust (OR = 2.23, 95% CI: 1.08, 4.57) and chlorinated solvents (OR = 2.18, 95% CI: 1.03, 4.61), without dose-response relations. A possible link between high formaldehyde exposure and laryngeal cancer was suggested. No association was found for exposure to asbestos or inorganic acid mists. These data indicate that occupational exposure to coal dust may play a role in laryngeal and hypopharyngeal cancer. Other possible relations need further evaluation.     

Lung cancer and exposure to man-made vitreous fibers: results from a pooled case-control study in Germany

BACKGROUND: To investigate the association between lung cancer and occupational exposure to man-made vitreous fibers (MMVF), a pooled analysis of two case-control studies was conducted in the years 1988-1994. METHODS: The case series consisted of 3498 males who were histologically or cytologically verified primary lung cancer cases. 3541 male population controls were drawn at random from the general population and matched to cases by sex, age, and place of residence. To examine the relationship between MMVF and lung cancer we asked all study subjects who worked for at least 6 months as construction and installation workers whether they ever installed or removed insulations and what kind of insulation material they used. RESULTS: Some 304 (8.7%) cases and 170 (4.8%) controls reported to have insulated with glass wool or mineral wool mats. Coded as ever/never exposed, the odds ratio was 1.48 (95% CI: 1.17-1.88), adjusted for smoking and asbestos. To be sure to exclude any confounding effect of asbestos, we tried to identify those cases and controls who insulated with glass wool or mineral wool mats only and never reported any asbestos exposure. For this group we calculated an odds ratio of 1.56 (95% CI: 0.92-2.65), after adjustment for smoking. An elevated risk was also estimated on the basis of an expert rating which was done for a subgroup of cases and controls. Ever exposure to MMVF (but not to asbestos) in this subgroup yielded an odds ratio of 1.30 (95% CI: 0.82-2.07). CONCLUSIONS: Our study provides some indication for an excess risk of man-made vitreous fibers. This result also persists after adjustment for smoking and asbestos.     

Association between asbestos exposure,cigarette smoking,myeloperoxidase (MPO) genotypes,and lung cancer risk

BACKGROUND: As observed in tobacco-associated carcinogenesis, genetic factors such as the polymorphic metabolic/oxidative enzyme myeloperoxidase (MPO) could modulate individual susceptibility to asbestos-associated carcinogenesis. METHODS: RFLP-PCR analysis identified the MPO genotypes in 375 Caucasian lung cancer cases and 378 matched controls. An epidemiological interview elicited detailed information regarding smoking history and occupational history and exposures. RESULTS: Asbestos exposure was associated with a significantly elevated risk estimate (OR = 1.45; 95% CI 1.04-2.02). On stratified analysis, we found the MPO genotypes modified the effect of asbestos exposure on lung cancer risk. Specifically, G/G carriers who were exposed to asbestos had an odds ratio (OR) of 1.72 (95% CI; 1.09-2.66), while A-allele carriers (G/A + A/A) exposed to asbestos exhibited a reduced OR of 0.89 (95% CI; 0.56-1.44). The OR was further reduced to 0.73 (0.49-1.06) for A-allele carriers not exposed to asbestos. A similar trend was observed for the joint effects between the MPO genotypes and pack-years smoking. Next, all three risk factors (MPO genotypes, asbestos exposure, and smoking) were analyzed simultaneously for joint effects. Heavy smokers with the G/G genotype and a history of asbestos exposure demonstrated a statistically significant elevated risk estimate (OR = 2.19; 95% CI 1.16-4.11), while the A-allele carriers with the same exposure profile were at a lower risk for lung cancer (OR = 1.18; 95% CI 0.58-2.38). The A-allele genotypes demonstrated similar protective effects for the other three exposure profiles. CONCLUSIONS: For a similar level of exposure to established carcinogens, individuals with the MPO A-allele genotypes appear to have a reduced risk of lung cancer.     

Occupational dust exposure and the risk of laryngeal cancer in Turkey

OBJECTIVES: A hospital-based case-referent study was conducted to identify occupational risk factors for laryngeal cancer. In a previous report an association was found between laryngeal cancer and occupations with potential dust exposure; a job-exposure matrix was developed to aid further evaluation of laryngeal cancer risks from five occupational dust exposures. METHODS: Among 7631 cancer cases from the Okmeydani Hospital, Istanbul, between 1979 and 1984, 958 larynx cancer cases were identified among men. After exclusions, 940 laryngeal cancer cases and 1519 referents were available. A standardized questionnaire was used to obtain basic information on the patients. Seven-digit standard occupational and industrial codes were created to classify the job and industrial titles. A job-exposure matrix was developed for occupational dusts, including silica, asbestos, wood, cotton, and grain, and age-, smoking-, and alcohol-adjusted odds ratios (OR) and 95% confidence intervals (95% CI) were calculated to evaluate risks of laryngeal cancer. RESULTS: An excess of laryngeal cancer occurred for workers potentially exposed to silica and cotton dust, particularly for supraglottic cancer (OR 1.8, 95% CI 1.3-2.3, for silica and OR 1.6, 95% CI 1.1-2.5, for cotton dust), and there was a significant dose-response relationship with silica exposure. No relationship was found between laryngeal cancer and asbestos, grain, or wood dust exposures. CONCLUSION: Laryngeal cancer, especially supraglottic tumors, is associated with silica and cotton dust exposures in Turkey.     

Environmental exposure to tremolite and respiratory cancer in New Caledonia: a case-control study

A case-control study on respiratory cancers was conducted in New Caledonia (South Pacific), where a high incidence of malignant pleural mesothelioma had been observed. The disease pattern suggested an environmental exposure to asbestos. The first results showed that, in some areas, tremolite asbestos derived from local outcroppings was used as whitewash (locally named "p?"). All cases diagnosed between 1993 and 1995 (including 15 pleural mesotheliomas, 228 lung cancers, and 23 laryngeal cancers) and 305 controls were included in the study. Detailed information on past or present use of the whitewash, residential history, smoking, diet, and occupation was collected. The risk of mesothelioma was strongly associated with the use of the whitewash (odds ratio (OR) = 40.9; 95% confidence interval (CI): 5.15, 325). All Melanesian cases had been exposed. Among Melanesian women, exposure to the whitewash was associated with an increased risk of lung cancer (OR = 4.89; 95% CI: 1.13, 21.2), and smokers exposed to po had an approximately ninefold risk (OR = 9.26; 95% CI: 1.72, 49.7) compared with women who never smoked and had never used the whitewash. In contrast, no association was noted between exposure to p? and lung cancer risk among Melanesian men, probably because of lower exposure levels. Among non-Melanesians, the numbers of exposed subjects were too small to assess the effect of exposure to po. There was no indication of elevated risks for the other cancer sites.     

Laryngeal and hypopharyngeal cancer and occupation: results of a case control-study.

OBJECTIONS: To ascertain whether certain occupations are associated with laryngeal or hypopharyngeal cancer. METHODS: A hospital based case-control study was carried out in 15 hospitals in France. It included 528 male cases diagnosed between January 1989 and April 1991, and 305 male controls with various other types of cancer. Interviews were carried out to obtain lifetime job histories and information on potential confounders. Logistic regression was used to compute the odds ratios (OR) for each of about 80 occupations and industries. RESULTS: There was an excess risk of laryngeal and hypopharyngeal cancer among service workers (OR 2.2, 95% confidence interval (95% CI) 1.3 to 3.9), agricultural and animal husbandry workers (OR 1.6, 95% CI 0.9 to 2.8), miners and quarrymen (OR 2.0, 95% CI 0.9 to 4.3), plumbers and pipe fitters (OR 2.6, 95% CI 0.8 to 8.1), glass formers and potters (OR 4.3, 95% CI 1.0 to 18) transport equipment operators (OR 1.5, 95% CI 1.0 to 2.5), and unskilled workers (OR 1.7, 95% CI 1.0 to 2.9). Analysis by industrial branch showed an excess risk for coal mining (OR 2.1, 95% CI 1.1 to 4.1), manufacture of metal products (OR 1.9, 95% CI 1.0 to 3.3), and administration and sanitary services (OR 1.7, 95% CI 1.1 to 2.5). CONCLUSION: These results suggest that occupational exposure might have a role in generating laryngeal and hypopharyngeal cancer, and indicate the need for further evaluation of these findings, an for the identification of the carcinogens which might account for the excess risks found for certain occupations.     

Occupational risk factors for renal cell carcinoma: agent-specific results from a case-control study in Germany. MURC Study Group. Multicenter urothelial and renal cancer study

BACKGROUND: This case-control study was conducted to estimate the renal cell cancer (RCC) risk for exposure to occupation-related agents, besides other suspected risk factors. METHODS: In a population-based multicentre study, 935 incident RCC cases and 4298 controls matched for region, sex, and age were interviewed between 1991 and 1995 for their occupational history and lifestyle habits. Agent-specific exposure was expert-rated with two job-exposure matrices and a job task-exposure matrix. Conditional logistic regression was used to calculate smoking adjusted odds ratios (OR). RESULTS: Very long exposures in the chemical, rubber, and printing industries were associated with risk for RCC. Males considered as 'substantially exposed to organic solvents' showed a significant excess risk (OR = 1.6, 95% CI : 1.1-2.3). In females substantial exposure to solvents was also a significant risk factor (OR = 2.1, 95% CI : 1.0-4.4). Excess risks were shown for high exposure to cadmium (OR = 1.4, 95% CI : 1.1-1.8, in men, OR = 2.5, 95% CI : 1.2-5.3 in women), for substantial exposure to lead (OR = 1.5, 95% CI : 1.0-2.3, in men, OR = 2.6, 95% CI : 1.2-5.5, in women) and to solder fumes (OR = 1.5, 95% CI : 1.0-2.4, in men). In females, an excess risk for the task 'soldering, welding, milling' was found (OR = 3.0, 95% CI : 1.1-7.8). Exposure to paints, mineral oils, cutting fluids, benzene, polycyclic aromatic hydrocarbons, and asbestos showed an association with RCC development. CONCLUSIONS: Our results indicate that substantial exposure to metals and solvents may be nephrocarcinogenic. There is evidence for a gender-specific susceptibility of the kidneys.     

A case-control study of occupational risk factors for laryngeal cancer.

To determine whether specific jobs and occupational exposures are associated with laryngeal cancer lifetime occupational histories from a population-based case-control study in western Washington were examined. The study included 235 cases diagnosed between September 1983 and February 1987, and 547 controls identified by random digit dialing. After controlling for alcohol use, cigarette smoking, age and education, significantly increased risks were found for painters in construction (odds ratio (OR)) = 2.8, (95% confidence interval (95% CI) 1.1-6.9), supervisors and miscellaneous mechanics (OR = 2.3, 95% CI 1.1-4.8), construction workers (OR = 3.4, 95% CI 1.4-8.1), metalworking and plastic working machine operators (OR = 2.6, 95% CI 1.3-4.9) and handlers, and equipment cleaners and labourers (OR = 1.5, 95% CI 1.0-2.2). Allowing for a 10 year induction and latent period did not have a consistent effect on the associations. Potential exposures to asbestos, chromium, nickel, formaldehyde, diesel fumes, and cutting oils were assessed by using a job exposure matrix developed for this study. Three measures of exposure were examined--namely, peak, duration, and an intensity weighted exposure score. No significantly raised risks were seen, although increased risk was suggested among those exposed long term to formaldehyde in jobs with the highest exposures.     

A case-control study of occupational risk factors for laryngeal cancer.

To determine whether specific jobs and occupational exposures are associated with laryngeal cancer lifetime occupational histories from a population-based case-control study in western Washington were examined. The study included 235 cases diagnosed between September 1983 and February 1987, and 547 controls identified by random digit dialing. After controlling for alcohol use, cigarette smoking, age and education, significantly increased risks were found for painters in construction (odds ratio (OR)) = 2.8, (95% confidence interval (95% CI) 1.1-6.9), supervisors and miscellaneous mechanics (OR = 2.3, 95% CI 1.1-4.8), construction workers (OR = 3.4, 95% CI 1.4-8.1), metalworking and plastic working machine operators (OR = 2.6, 95% CI 1.3-4.9) and handlers, and equipment cleaners and labourers (OR = 1.5, 95% CI 1.0-2.2). Allowing for a 10 year induction and latent period did not have a consistent effect on the associations. Potential exposures to asbestos, chromium, nickel, formaldehyde, diesel fumes, and cutting oils were assessed by using a job exposure matrix developed for this study. Three measures of exposure were examined--namely, peak, duration, and an intensity weighted exposure score. No significantly raised risks were seen, although increased risk was suggested among those exposed long term to formaldehyde in jobs with the highest exposures.     

Asbestos and colon cancer: lack of association in a large case-control study.

Previous studies linking exposure to asbestos with human colon cancer have used mortality rather than incidence as their endpoint and have neither assessed nor controlled for confounding by diet, genetic factors, or other risk factors for colon cancer. A case-control study of 746 histologically confirmed cases of colon cancer and 746 matched neighborhood controls was conducted in Los Angeles County, California. In univariate analyses of the 419 male pairs, a weak association was found between asbestos exposure and colon cancer (odds ratio (OR) = 1.16, 95% confidence interval (CI) 0.80-1.69). When confounding by family history of large bowel cancer, diet, body weight, and physical activity was controlled, there was no association between colon cancer and exposure to asbestos among males (OR = 0.99, 95% CI 0.66-1.50). When asbestos exposure was restricted to occurrences preceding diagnosis by more than 15 years, there was no clear association between such exposure and colon cancer, either before (OR = 1.14, 95% CI 0.76-1.70) or after confounding was controlled (OR = 0.93, 95% CI 0.60-1.44). Further analyses by frequency and duration of exposure failed to show any association between asbestos and risk of colon cancer, but did show a consistent pattern of confounding by nonoccupational factors that, when controlled, invariably produced a weak protective effect of asbestos exposure. Among the 327 female pairs, only 6 cases and 11 controls reported asbestos exposure (OR = 0.55, 95% CI 0.20-1.48), and there was no evidence of risk increasing as the frequency or duration of exposure increased. This study suggests not only that occupational exposure to asbestos is not a risk factor for colon cancer in the general population of Los Angeles, but also that observed associations between asbestos and colon cancer should not be interpreted as causal unless confounding by nonoccupational factors has been evaluated and controlled.     

Occupational exposures and head and neck cancers among Swedish construction workers

OBJECTIVES: Occupational exposures in the construction industry may increase the risk of head and neck cancers, although the epidemiologic evidence is limited by problems of low study power and inadequate adjustment for tobacco use. In an attempt to address this issue, the relationship between selected occupational exposures and head and neck cancer risk was investigated using data from a large cohort of Swedish construction workers. METHODS: Altogether 510 squamous cell carcinomas of the head and neck (171 in the oral cavity, 112 in the pharynx, 227 in the larynx) were identified during 1971-2001 among 307 799 male workers in the Swedish construction industry. Exposure to diesel exhaust, asbestos, organic solvents, metal dust, asphalt, wood dust, stone dust, mineral wool, and cement dust was assessed using a semi-quantitative job-exposure matrix. Rate ratios (RR) and 95% confidence intervals (95% CI) were calculated for head and neck cancers in relation to occupational exposure, using Poisson regression with adjustment for age and smoking status. RESULTS: Asbestos exposure was related to an increased laryngeal cancer incidence (RR 1.9, 95% CI 1.2-3.1). Excesses of pharyngeal cancer were observed among workers exposed to cement dust (RR 1.9, 95% CI 1.2-3.1). No occupational exposures were associated with oral cavity cancer. These findings did not materially change upon additional adjustment for cigarette pack-years. CONCLUSIONS: These findings offer further evidence that asbestos increases the risk of laryngeal cancer. The observation of a positive association between cement dust exposure and pharyngeal cancer warrants further investigation.     

Occupational risks for laryngeal cancer: a case-control study

The most solidly established risk factors for laryngeal cancer are tobacco and alcohol. As for occupational factors, the only established carcinogen is exposure to strong inorganic acid mists. However, asbestos, pesticides, paints, gasoline, diesel engine emissions, dusts, and other factors have been reported in the literature as occupational agents that increase the risk of laryngeal cancer. A hospital-based case-control study was conducted to investigate occupational risk factors for laryngeal cancer. Detailed data on smoking, alcohol consumption, and occupational history were collected for 122 laryngeal cancers and 187 controls matched by frequency (according to sex and age). Laryngeal cancer was associated with exposure to respirable free crystalline silica (OR = 1.83; 95%CI: 1.00-3.36), soot (from coal, coke, fuel oil, or wood) (odds ratio - OR = 1.78; 95% confidence interval - 95%CI: 1.03-3.03), fumes (OR = 2.55; 95%CI: 1.14-5.67), and live animals (OR = 1.80; 95%CI: 1.02-3.19).     

Occupational lung cancer risk for men in Germany: results from a pooled case-control study

Occupational exposures such as crystalline silica, diesel engine exhaust, polycyclic aromatic hydrocarbons, and man-made mineral fibers are strongly suspected to increase lung cancer risk. Two case-control studies in Germany conducted between 1988 and 1996 were pooled for a joint analysis. A total of 3,498 male cases and 3,541 male population controls, frequency matched for age and region, were included in the study. The lifelong history of all jobs and industries was coded and occupational exposures were evaluated by expert rating. Odds ratios, crude and adjusted for smoking and asbestos exposure, were calculated by conditional logistic regression. Job-related evaluation showed a statistically significant increased odds ratio adjusted for smoking among farmers; forestry workers, fishermen, and livestock workers; miners and quarrymen; chemical processors; cabinet makers and related wood workers; metal producers and processors; bricklayers and carpenters; road construction workers, pipelayers and well diggers; plasterers, insulators, and upholsterers; painters and lacquerers; stationary engine and heavy equipment operators; transport workers and freight handlers; and service workers. With regard to specific occupational exposures, elevated odds ratios (OR) (95% confidence intervals (CI)) for lung cancer risk adjusted for smoking and asbestos exposure were observed for man-made mineral fibers (OR = 1.48, 95% CI 1.17, 1.88); crystalline silica (OR = 1.41, 95% CI 1.22, 1.62); diesel engine exhaust (OR = 1.43, 95% CI 1.23, 1.67); and polycyclic aromatic hydrocarbons (OR = 1.53, 95% CI 1.14, 2.04). The risk of asbestos exposure, adjusted for smoking was also increased (OR = 1.41, 95% CI 1.24, 1.60).     

Respiratory cancer and exposure to man-made vitreous fibers: a systematic review

BACKGROUND: Man-made vitreous fibers (MMVF's) have some structural features similar to those found in asbestos. This has lead to concern that exposure to MMVF's could increase the risk of respiratory cancer. METHODS: Bibliographic resources were used to identify 10 case-control and 10 cohort studies, which analyzed the relationship between exposure to MMVF's and cancer of the respiratory system. Standardized mortality ratio's (SMR's) were extracted from the cohort studies for a meta-analysis. RESULTS: A significant increase in SMR was observed for workers exposed to rock and glass wool, but not in workers exposed to glass filament. Meta-analysis of SMR's after stratification by fiber type resulted in aggregate estimates of risk of 1.23 (95% CI = 1.10-1.38), 1.08 (95% CI = 0.93-1.26), and 1.32 (95% CI = 1.15-1.52) for exposure to glass wool, glass filament, and rock wool, respectively. Some or all of the increased mortality could be attributed to tobacco use. CONCLUSIONS: The results highlight the difficulty of assessing small increases in risk of respiratory cancer potentially caused by occupational exposure in populations with high prevalence of tobacco use.     

Exposure to asbestos and lung and pleural cancer mortality among pulp and paper industry workers

We studied the mortality from lung and pleural cancers in a cohort of 62,937 male workers employed for at least 1 year in the pulp and paper industry in 13 countries during 1945 to 1996. Mill departments were classified according to probability and level of exposure to asbestos on the basis of available dust measurements and mill-specific information on exposure circumstances. Thirty-six percent of workers were classified as ever exposed to asbestos. Standardized mortality ratios of lung cancer were 0.99 (95% confidence interval [CI], 0.90 to 1.08) among unexposed and 1.00 (95% CI, 0.90 to 1.11) among ever exposed workers. The number of pleural cancer deaths among unexposed workers was 10; that among exposed workers was 14, most of which occurred among maintenance workers. In internal analyses, a trend in mortality from either neoplasm was suggested for estimated cumulative exposure to asbestos, weighted for the individual probability of exposure within the department and for duration of exposure (relative risk for lung cancer for 0.78+ f/cc-years, as compared with < or = 0.01 f/cc-years: 1.44; 95% CI, 0.85 to 2.45; corresponding relative risk for pleural cancer: 2.43; 95% CI, 0.43 to 13.63). Despite a possible nondifferential misclassification of exposure and outcome, this study suggests that the carcinogenic effect of asbestos can be detected among workers employed in industries such as the pulp and paper industry, in which it is not considered to be a major hazard.     

Laryngeal and hypopharyngeal cancers and occupational exposure to formaldehyde and various dusts: a case-control study in France

OBJECTIVES—A case-control study was conducted in France to assess possible associations between occupational exposures and squamous cell carcinomas of the larynx and hypopharynx.
METHODS—The study was restricted to men, and included 201 hypopharyngeal cancers, 296 laryngeal cancers, and 296 controls (patients with other tumour sites). Detailed information on smoking, alcohol consumption, and lifetime occupational history was collected. Occupational exposure to seven substances (formaldehyde, leather dust, wood dust, flour dust, coal dust, silica dust, and textile dust) was assessed with a job exposure matrix. Exposure variables used in the analysis were probability, duration, and cumulative level of exposure. Odds ratios (ORs) with their 95% confidence intervals (95% CIs) were estimated by unconditional logistic regression, and were adjusted for major confounding factors (age, smoking, alcohol, and when relevant other occupational exposures).
RESULTS—Hypopharyngeal cancer was found to be associated with exposure to coal dust (OR 2.31, 95% CI 1.21 to 4.40), with a significant rise in risk with probability (p<0.005 for trend) and level (p<0.007 for trend) of exposure. Exposure to coal dust was also associated with an increased risk of laryngeal cancer (OR 1.67, 95% CI 0.92 to 3.02), but no dose-response pattern was found. A significant relation, limited to hypopharyngeal cancer, was found with the probability of exposure to formaldehyde (p<0.005 for trend), with a fourfold risk for the highest category (OR 3.78 , 95% CI 1.50 to 9.49). When subjects exposed to formaldehyde with a low probability were excluded, the risk also increased with duration (p<0.04) and cumulative level of exposure (p<0.14). No significant association was found for any other substance.
CONCLUSION—These results indicate that exposure to formaldehyde and coal dust may increase the risk of hypopharyngeal cancer.


Keywords: laryngeal cancer; hypopharyngeal cancer; occupational exposure; job exposure matrix; formaldehyde; coal dust     

A case-control study of malignant and non-malignant respiratory disease among employees of a fiberglass manufacturing facility. II. Exposure assessment.

A case-control study of malignant and non-malignant respiratory disease among employees of the Owens-Corning Fiberglas Corporation's Newark, Ohio plant was undertaken. The aim was to determine the extent to which exposures to substances in the Newark plant environment, to non-workplace factors, or to a combination may play a part in the risk of mortality from respiratory disease among workers in this plant. A historical environmental reconstruction of the plant was undertaken to characterise the exposure profile for workers in this plant from its beginnings in 1934 to the end of 1987. The exposure profile provided estimates of cumulative exposure to respirable fibres, fine fibres, asbestos, talc, formaldehyde, silica, and asphalt fumes. Employment histories from Owens-Corning Fiberglas provided information on employment characteristics (duration of employment, year of hire, age at first hire) and an interview survey obtained information on demographic characteristics (birthdate, race, education, marital state, parent's ethnic background, and place of birth), lifetime residence, occupational and smoking histories, hobbies, and personal and family medical history. Matched, unadjusted odds ratios (ORs) were used to assess the association between lung cancer or non-malignant respiratory disease and the cumulative exposure history, demographic characteristics, and employment variables. Only the smoking variables and employment characteristics (year of hire and age at first hire) were statistically significant for lung cancer. For non-malignant respiratory disease, only the smoking variables were statistically significant in the univariate analysis. Of the variables entered into a conditional logistic regression model for lung cancer, only smoking (smoked for six months or more v never smoked: OR = 26.17, 95% confidence interval (95% CI) 3.316-206.5) and age at first hire (35 and over v less than 35: OR = 0.244, 95% CI 0.083-0.717) were statistically significant. There were, however, increased ORs for year of employment (first hired before 1945 v first hire after 1945: OR = 1.944, 95% CI 0.850-4.445), talc (cumulative exposure >1000 fibres/ml days v never exposed: OR = 1.355, 95% CI 0.407-5.515), and asphalt fumes (cumulative exposure >0.01 mg/m(3) days v never exposed: OR 1.131, 95% CI 0.468-2.730). For non-malignant respiratory disease, only the smoking variable was significant in the conditional logistic regression analysis (OR = 2.637, 95% CI 1.146-6.069). There were raised ORs for the higher cumulative exposure categories for respirable fibres, asbestos, silica, and asphalt fumes. For both silica and asphalt fumes, ORs were more than double the reference groups for all exposure categories. A limited number of subjects were exposed to fine fibres. The scarcity of cases and controls limits the extent to which analyses for fine fibre may be carried out. Within those limitations, among those who had worked with fine fibre, the unadjusted, unmatched OR for lung cancer was (1.0 (95% CI 0.229-4.373) and for non-malignant respiratory disease, the OR was 1.5 (95% CI 0.336-6.702). The unadjusted OR for lung cancer for exposure to fine fibre was consistent with that for all respirable fibre and does not suggest an association. For non-malignant respiratory disease, the unadjusted OR for fine fibre was opposite in direction from that for all respirable fibres. Within the limitations of the available data on fibre, there is o suggestion that exposure to fine fibre has resulted in an increase in risk of lung cancer. The increased OR for non-malignant respiratory disease is inconclusive. The results of this population, in this place and time, neither respirable fibres nor any of the substances investigated as part of the plant environment are statistically significant factors for lung cancer risk although there are increased ORs for exposure to talc and asphalt fumes. Smoking is the most important factors in risk for lung cancer in this population. The situation is less clear for non-malignant respiratory disease. Unlike lung cancer, non-malignant respiratory represents a constellation of outcomes and not a single well defined end point. Although smoking was the only statistically significant factor for non-malignant respiratory disease in this analysis, the ORs for respirable fibres, asbestos, silica, and asphalt fumes were greater than unity for the highest exposure categories. Although the raised ORs for these substances may represent the results of a random process, they may be suggestive of an increased risk and require further investigation.     

Lung fibre burden in lung cancer cases employed in the rock and slag wool industry

OBJECTIVES: To evaluate the relationship between estimated exposure to man-made vitreous fibres (MMVF) and to asbestos fibres and their concentration in the lung tissue of lung cancer cases amongst MMVF production workers. METHODS: Retrospective retrieval of available lung tissue specimens was conducted following a case-control study that assessed estimated occupational exposures of MMVF workers. Fibre recovery and analysis by transmission electron microscopy (TEM) were conducted to determine fibre type, fibre dimension and numbers per gram of dry lung tissue. For cases with detailed exposure data, geometric mean (GM) concentrations were compared across the exposure categories, and regression models were used to investigate the relationship between the lung fibres and the variables of estimated exposure, with and without additional variables that may affect fibre retention. RESULTS: A total of 24 samples from 17 cases of lung cancer were available for analysis: MMVF were detected in all cases. Asbestos fibres were detected in 16. No difference or trend in GM MMVF concentration was observed across the estimated exposure categories. Odds ratio (OR) for MMVF g(-1) dry lung was 0.5 (95% confidence interval: 0.1-2.4) for the second, and 3.5 (0.6-18.9) for the third quartile of index of average exposure to MMVF in industry, compared with the first (lowest exposed) quartile (no cases in the highest quartile). CONCLUSIONS: No observable relationship existed between estimated exposure and directly-measured lung fibres among this sample of cases. Retrospective specimen collection, intra-individual variability in fibre concentration, effect of unknown factors on fibre retention and small sample size militated against this study providing evidence for or against a relationship between estimated exposure and lung fibre concentrations.     

Insulation,asbestos, smoking habits,and lung cancer cell types

The association between occupational exposure to asbestos and histological type of lung cancer was analyzed in a multicenter hospital-based case-control study (2,871 male cases and 5,240 male controls) conducted from 1981-1991. Twenty-two percent of cases and 18% of controls were employed in asbestos-related occupations for at least 1 year. Most of these asbestos jobs were in the construction field. The odds ratio (OR) among current smokers was 1.0 [95% confidence intervals (CI) 0.9 to 1.3]; for ex-smokers, the OR was 1.4 (95% CI 1.1 to 1.6). In contrast, 10% of cases and 5% of controls self-reported that they were chronically exposed to asbestos for at least 1 year. Self-reported asbestos exposure was significantly related to all lung cancer cell types among smokers and ex-smokers, although a trend in the ORs with duration of self-reported exposure was not found for current smokers. Among 48 cases and 52 controls reporting distinct exposure to building insulation, the OR was 2.2 (95% CI 1.2 to 4.3) for current smokers, and 1.8 (95% CI 0.9 to 3.6) for ex-smokers, compared to subjects who were not exposed to building insulation and asbestos. A nonsignificant association with self-reported exposure to asbestos was observed for a small number of never smokers (eight of 83 nonsmoking cases, OR = 2.0, 95% CI 0.9 to 4.6). When examining these results and their causal implications, possible misclassification and reporting biases need to be considered.     

Work activities and the risk of multiple myeloma. A case-control study

The incidence of multiple myeloma is increasing in western countries, and several environmental and occupational risk factors have been suggested to explain this trend. A case-control study was conducted in order to investigate the relationship between occupation, exposure to chemicals, and risk of multiple myeloma. A total of 170 cases of multiple myeloma, 98 males and 72 females, aged 43-84 (mean age = 67 D.S. = 10), and 170 matched hospital controls (mean age = 68 D.S. = 9) were identified for the years 1970-1988. All subjects were interviewed about socioeconomic status, current or previous occupation, and if they had ever been exposed to one or more of a list of toxic substances. Exposure were grouped in 21 risk categories. Poor socioeconomic status was associated with a significant risk for multiple myeloma (OR = 2.8; 95% Confidence Interval: 1.61-3.05), as well as agricultural work (OR = 2.71; 95% CI: 1.87-4.42), and work in industry (OR = 3.20; 95% CI: 2.00-5.75). Regarding toxic substance exposure, a significant association was found for asbestos (OR = 4.00; 95% CI: 2.02-8.05), mineral oils (OR = 3.00; 95% CI: 1.98-5.08), pesticides (OR = 2.83; 95% CI: 1.87-4.78), and radiation (OR = 9.00; 95% CI: 0.81-21.73). No significant association was demonstrated for alcohol intake and tobacco smoking. High odds ratios were also found for fertilizers, paints, cosmetics and/or hairdressing products, and dust. These findings agree with previously reported studies, suggesting a relationship between some occupational exposures and the risk of multiple myeloma. The data, however, require clarification in prospective, larger, population-based studies.