Cancer incidence among mild steel and stainless steel welders and other metal workers

The cancer incidence in a historical cohort of 10,059 metal workers employed during the period 1964–1984 was investigated. Standardized incidence ratios (SIR) were calculated based on registry extracts from the Danish Cancer registry. Lifetime exposure data (occupational and other) were obtained by a postal questionnaire in living cohort members and interviews by proxy for deceased and emigrated subjects. The incidence of lung cancer was increased among workers ever “employed as welders” (SIR = 1.38, 95% C.I. 1.03–1.81). There was a significant excess risk of lung cancer among “mild steel (MS) only welders” (SIR = 1.61, 95% C.I. 1.07–2.33) and “nonwelders” (SIR = 1.69, 95% C.I. 1.23–2.26) (indicating carcinogenic exposures other than welding), a borderline significant lung cancer excess among “MS ever welders” (SIR = 1.32, 95% C.I. 0.97–1.76), and a nonsignificant excess risk of lung cancer among “stainless steel (SS) only welders” (SIR = 2.38, 95% C.I. 0.77–5.55). In spite of signs of inconsistency in the risk estimation by duration and latency, we find the results support the conclusions of other studies: employment as a welder is associated with an increased lung cancer risk. © 1996 Wiley-Liss, Inc.     

Risk of lung cancer according to mild steel and stainless steel welding

OBJECTIVES: Whether the elevated risk of lung cancer observed among welders is caused by welding emissions or by confounding from smoking or asbestos exposure is still not resolved. This question was addressed in a cohort with a long follow-up and quantified estimates of individual exposure to welding fume particulates. METHODS: Male metal workers employed at least 1 year at one or more Danish stainless or mild steel industrial companies from 1964 through 1984 were enrolled in a cohort. Data on occupational and smoking history were obtained by questionnaire in 1986. Welders in the cohort who started welding in 1960 or later (N=4539) were followed from April 1968 until December 2003, when information on cancer diagnosis was obtained from the Danish Cancer Registry. During the follow-up, 75 cases of primary lung cancer were identified. Lifetime accumulated exposure to welding fume particulates was estimated by combining questionnaire information and more than 1000 welding-process-specific measurements of fume particulates in the Danish welding industry. RESULTS: The standardized incidence ratio (SIR) for lung cancer was increased among the welders [SIR 1.35, 95% confidence interval (95% CI) 1.06-1.70)]. Among the stainless steel welders, the risk increased significantly with increasing accumulative welding particulate exposure, while no exposure-response relation was found for mild steel welders, even after adjustment for tobacco smoking and asbestos exposure. CONCLUSIONS: The study corroborates earlier findings that welders have an increased risk of lung cancer. While exposure-response relations indicate carcinogenic effects related to stainless steel welding, it is still unresolved whether the mild steel welding process carries a carcinogenic risk.     

A historical prospective study of European stainless steel, mild steel, and shipyard welders

A multicentre cohort of 11,092 male welders from 135 companies located in nine European countries has been assembled with the aim of investigating the relation of potential cancer risk, lung cancer in particular, with occupational exposure. The observation period and the criteria for inclusion of welders varied from country to country. Follow up was successful for 96.9% of the cohort and observed numbers of deaths (and for some countries incident cancer cases) were compared with expected numbers calculated from national reference rates. Mortality and cancer incidence ratios were analysed by cause category, time since first exposure, duration of employment, and estimated cumulative dose to total fumes, chromium (Cr), Cr VI, and nickel (Ni). Overall a statistically significant excess was reported for mortality from lung cancer (116 observed v 86.81 expected deaths, SMR = 134). When analysed by type of welding an increasing pattern with time since first exposure was present for both mild steel and stainless steel welders, which was more noticeable for the subcohort of predominantly stainless steel welders. No clear relation was apparent between mortality from lung cancer and duration of exposure to or estimated cumulative dose of Ni or Cr. Whereas the patterns of lung cancer mortality in these results suggest that the risk of lung cancer is higher for stainless steel than mild steel welders the different level of risk for these two categories of welding exposure cannot be quantified with precision. The report of five deaths from pleural mesothelioma unrelated to the type of welding draws attention to the risk of exposure to asbestos in welding activities.     

A historical prospective study of European stainless steel, mild steel, and shipyard welders.

A multicentre cohort of 11,092 male welders from 135 companies located in nine European countries has been assembled with the aim of investigating the relation of potential cancer risk, lung cancer in particular, with occupational exposure. The observation period and the criteria for inclusion of welders varied from country to country. Follow up was successful for 96.9% of the cohort and observed numbers of deaths (and for some countries incident cancer cases) were compared with expected numbers calculated from national reference rates. Mortality and cancer incidence ratios were analysed by cause category, time since first exposure, duration of employment, and estimated cumulative dose to total fumes, chromium (Cr), Cr VI, and nickel (Ni). Overall a statistically significant excess was reported for mortality from lung cancer (116 observed v 86.81 expected deaths, SMR = 134). When analysed by type of welding an increasing pattern with time since first exposure was present for both mild steel and stainless steel welders, which was more noticeable for the subcohort of predominantly stainless steel welders. No clear relation was apparent between mortality from lung cancer and duration of exposure to or estimated cumulative dose of Ni or Cr. Whereas the patterns of lung cancer mortality in these results suggest that the risk of lung cancer is higher for stainless steel than mild steel welders the different level of risk for these two categories of welding exposure cannot be quantified with precision. The report of five deaths from pleural mesothelioma unrelated to the type of welding draws attention to the risk of exposure to asbestos in welding activities.     

Welding and lung cancer in Central and Eastern Europe and the United Kingdom

Occupation as a welder has been associated with a 25%-40% increase in lung cancer risk. This study aims to elucidate to what extent confounding by smoking and asbestos drives this association and to evaluate the role of welding-related exposures such as chromium. The study included 2,197 male incident lung cancer cases and 2,295 controls from Romania, Hungary, Poland, Russia, Slovakia, the Czech Republic, and the United Kingdom from 1998 to 2001. Information on risk factors was collected through face-to-face interviews. Experts assessed exposure to 70 agents, and risk estimates were adjusted for smoking and occupational exposures. Occupation as a welder/flame cutter (prevalence controls: 3.7%) was associated with an odds ratio of 1.36 (95% confidence interval (CI): 1.00, 1.86) after adjustment for smoking and occupational exposures including asbestos. An odds ratio of 1.18 (95% CI: 1.01, 1.38) was found for welding fumes (prevalence controls: 22.8%), increasing to 1.38 for more than 25 exposure years (95% CI: 1.09, 1.75). A duration-response association was also observed for mild steel welding without chromium exposure. In this population, occupational exposure to welding fumes accounted for approximately 4% of lung cancer cases, to which both stainless and mild steel welding contributed equally. Given that welding remains a common task for many workers, exposure to welding fumes represents an important risk factor for lung cancer.     

Acute respiratory effects of exposure to stainless steel and mild steel welding fumes

Over the past few years, many studies, including one on our previous work, have examined the chronic effects of fumes from stainless steel (SS) welding on the health of welders. These chronic effects have been related to concentrations of chromium and nickel in SS welding fumes. The present study examined the acute respiratory effects of welding fumes in the workplace by measuring the across-shift changes in a population of 144 SS and mild steel (MS) welders and 223 controls. Manual Metal Arc, Metal Inert Gas, and Tungsten Inert Gas welding processes were studied. Pulmonary function tests were performed at the start (ante, or A) and at the end (post, or P) of the work shift. The study of sensitization to harmful respiratory effects of welding was based on the study of the (P-A)/A ratio (%) of the spirometric variations during the shift. The means of these ratios in the control subjects were used to account for the circadian effect. In SS welders we observed a significant decrease in forced vital capacity (FVC) during the shift. Significant across-shift decrements in forced expiratory volume in 1 second (FEV1) and FVC were related to the SS welding exposure compared with MS welding. Moreover, the across-shift decreases in FEV1, FVC, and peak expiratory flow (PEF) were significantly related to the Manual Metal Arc welding process, compared with Metal Inert Gas techniques (respectively, PEF = -2.7% of baseline values [SD, 11.9] vs 2.0% of baseline values [SD, 7.7] P = 0.04; FVC = -1.5% of baseline values [SD, 4.8] vs 0.2% of baseline values [SD, 4.5] P = 0.05). We also demonstrated the influence of duration of SS welding exposure on the course of lung function during the work shift. After 20 years of SS welding activity, SS welders had more significant across-shift decreases than MS welders with a similar MS exposure duration (respectively, FEV1 = -2.7% of baseline values [SD, 5.9] vs 0.7% of baseline values [SD, 4.2] P = 0.008; PEF = -3.8% of baseline values [SD, 9.6] vs 2.3% of baseline values [SD, 6.5] P = 0.04). We concluded that welding-related lung function responses are seen in SS compared with MS welders and in those with a longer lifetime welding history.     

Lung cancer in mild steel welders

To investigate lung cancer risk, the authors conducted a historical cohort mortality study of 4,459 mild steel welders who had been employed at three midwestern plants which manufactured heavy equipment. Follow-up began in the mid-1950s and extended through 1988. All welders had at least 2 years welding experience (average duration, 8.5 years). This cohort had no occupational exposure to asbestos or stainless steel fumes (containing nickel and chromium), two potential confounders in previous welders studies. A comparison population of 4,286 nonwelders, all with at least 2 years employment at the same plants, was also studied. Nonwelders had never been welders and were allowed to have no more than 90 days employment as a painter, foundryman, or machinist. Sampling data collected from 1974-1987 indicated that welders were exposed to 6-7 mg/m3 of total particulate and 3-4 mg/m3 of iron oxide, while nonwelders had negligible exposures to welding fumes. When compared with the United States population, both welders and nonwelders had elevated rates for lung cancer (standardized mortality ratios (SMRs): welders, SMR = 1.07; nonwelders, SMR = 1.17), but neither SMR was significantly elevated. Limited smoking data based on a 1985 survey indicated that both welders and nonwelders smoked more than the United States population, possibly accounting for part of their elevated lung cancer rates. There was no trend of increased risk for welders with increased duration of exposure. The only other cause of death significantly elevated was emphysema among welders. Nonmalignant respiratory disease was not elevated for welders (SMR = 0.96). When welders were compared with nonwelders directly for lung cancer, the rate ratio was 0.90.     

Case-control study of exposure to carbon black in the occupational setting and risk of lung cancer

Although it has been hypothesized that carbon black exposure may carry an excess risk of lung cancer, evidence to date is insufficient to assess the hypothesis properly. The relationship between workplace exposure to carbon black and lung cancer risk was examined in a population-based case-control study carried out in Montreal, Canada. Detailed job histories were elicited from 857 incident cases with histologically confirmed lung cancer as well as from 1,360 cancer controls and 533 population controls. Job histories were evaluated by a team of hygienists and chemists for evidence of exposure to a host of occupational substances, including carbon black. Logistic regression analyses adjusting for smoking and other nonoccupational and occupational potential confounders suggested no significant increase in risk with relatively low exposure to carbon black. Some increase in risk for all lung cancers was apparent with relatively high exposure using cancer controls (OR = 2.17; 95% CI = 0.95–4.91) and population controls (OR = 1.52; 95% CI = 0.58–3.97). Individuals with relatively high exposure had a significantly greater risk of oat-cell carcinoma using either control series (OR = 5.05; 95% CI = 1.72–14.87 using cancer controls and OR = 4.82; 95% CI = 1.36–17.02 using population controls). These results provide some evidence for an association between exposure to carbon black and lung cancer. © 1996 Wiley-Liss, Inc.     

Increased risk of lung cancer in the melting department of a second Ontario steel manufacturer

A study of lung cancer among workers at an electric arc steel making operation was performed to follow up on the observation of a lung cancer cluster in the melt shop of another plant. The study group comprised 335 deceased men identified from plant records. Eight of thirty men who had ever worked in the pouring pit area died of lung cancer (PMR 276; p less than 0.01), but increased risk was not found elsewhere in the melting department. There was a significant trend in lung cancer risk with the length of employment in the pit area during a time window 18-30 years before death. Smoking data suggested that smoking alone could not account for the increased risk. An industrial hygiene assessment found present exposures to carcinogenic metals and silica to be within current guidelines. No polycyclic aromatic hydrocarbons were detected. This is the second steel plant for which we have found increased lung cancer risk in the pouring areas. The causative factors have not yet been identified.     

Lung cancer risk and welding: Results from a case-control study in Germany

In a case-control study, 839 male hospital-based cases of primary lung cancer and the same number of population-based controls—matched by sex, age, and region of residence—were personally interviewed for their job and smoking histories. The study allows to quantify occupational asbestos exposure that was thought to be a welding-associated risk: 6% of cases and 2% of controls were classified into the occupational category “welders or burners” (odds ratio [OR] = 2.65). This OR was reduced to 1.93 (95% confidence limit [CL]: 1.03–3.61) after adjustment for smoking and asbestos. In contrast, a history of welding in general for at least a half-year is 28% among cases and 23% among controls, yielding an OR of 1.25 (95% CL: 0.94–1.65) after adjustment for both confounders. The OR of welding for more than 6,000 hr is 1.45 (95% CL = 1.04–2.02), reduced to 1.10 after adjustment for smoking and asbestos. Oxyacetylene welding for more than 6,000 hr lifelong is associated with an OR of 1.86 (95% CL = 1.01–3.43) reduced to 1.46 (n.s.) after adjustment for smoking and asbestos. The risk of oxyacetylene welding seems to be highest for oat cell carcinoma with an adjusted OR for ever-exposure of 1.46 (95% CL = 0.69–3.10). Therefore, the present study supports the hypothesis that some, but not all, of the excess risk of welders observed in the literature may be due to a history of cigarette smoking and occupanional asbestos exposure. The elevated risk for the subgroup of employees in the aircraft industry reported for the midterm evaluation of the study still prevails, though no longer statistically significant. However, employees in this industry who ever welded show an OR of 2.29 (95% CL = 1.19–4.42) after adjustment for smoking and asbestos. Am. J. Ind. Med. 33:313–320, 1998. © 1998 Wiley-Liss, Inc.     

Mortality study among workers producing ferroalloys and stainless steel in France.

A mortality study was carried out among the workers of a plant that had produced ferrochromium and stainless steel, and was still producing stainless steel, in order to determine whether exposure to chromium compounds, to nickel compounds, and to polycyclic aromatic hydrocarbons (PAH) could result in a risk of lung cancer for the exposed workers. The cohort comprised 2269 men whose vital status were recorded between 1 January 1952 and 31 December 1982. The smoking habits of 67% of the cohort members were known from medical records. The observed numbers of deaths were compared with the expected ones based on national rates with adjustment for age, sex, and calendar time. A low mortality, achieving statistical significance, was found from all causes (observed = 137, standardised mortality ratio (SMR) = 0.82) and from benign respiratory diseases (observed = one, SMR = 0.15). With regard to mortality from lung cancer, a non-significant excess appeared in the whole cohort (observed = 12, SMR = 1.40). Among the exposed workers, however, a significant lung cancer excess was found (observed = 11, SMR = 2.04) that contrasted with a low SMR (0.32) in the non-exposed group. This excess is unlikely to be explained by smoking, as the tobacco consumption of these two groups was similar. No trend was observed for mortality from lung cancer either according to time since first exposure, or according to duration of exposure. A nested case-control study clearly suggested that this excess of deaths from lung cancer was attributable to former PAH exposures in the ferrochromium production workshops rather than to exposures in the stainless steel manufacturing areas.     

Mortality study among workers producing ferroalloys and stainless steel in France

A mortality study was carried out among the workers of a plant that had produced ferrochromium and stainless steel, and was still producing stainless steel, in order to determine whether exposure to chromium compounds, to nickel compounds, and to polycyclic aromatic hydrocarbons (PAH) could result in a risk of lung cancer for the exposed workers. The cohort comprised 2269 men whose vital status were recorded between 1 January 1952 and 31 December 1982. The smoking habits of 67% of the cohort members were known from medical records. The observed numbers of deaths were compared with the expected ones based on national rates with adjustment for age, sex, and calendar time. A low mortality, achieving statistical significance, was found from all causes (observed = 137, standardised mortality ratio (SMR) = 0.82) and from benign respiratory diseases (observed = one, SMR = 0.15). With regard to mortality from lung cancer, a non-significant excess appeared in the whole cohort (observed = 12, SMR = 1.40). Among the exposed workers, however, a significant lung cancer excess was found (observed = 11, SMR = 2.04) that contrasted with a low SMR (0.32) in the non-exposed group. This excess is unlikely to be explained by smoking, as the tobacco consumption of these two groups was similar. No trend was observed for mortality from lung cancer either according to time since first exposure, or according to duration of exposure. A nested case-control study clearly suggested that this excess of deaths from lung cancer was attributable to former PAH exposures in the ferrochromium production workshops rather than to exposures in the stainless steel manufacturing areas.     

A mortality study among mild steel and stainless steel welders.

A mortality study was carried out in conjunction with the European mortality study among welders coordinated by the International Agency for Research on Cancer (IARC). The study was aimed at assessing risks for lung cancer in relation to exposure to asbestos, welding fumes containing chromium and nickel, and tobacco smoke. The study included a cohort of 2721 welders and an internal comparison group of 6683 manual workers employed in 13 factories in France. The mortality of the two cohorts was studied from 1975 to 1988 by the historical prospective method. Job histories of welders were traced including welding processes used, metals welded, and proportion of worktime spent in welding. Data on smoking habits were collected from medical records. The observed number of deaths were compared with those expected (standardised mortality ratio (SMR)) based on national rates with adjustments for age, sex, and calendar time. The smoking habits of 87% of the whole study population were known. The distribution of welders and controls according to smoking was not statistically different. The overall mortality was slightly higher for welders (SMR = 1.02, 95% confidence interval (95% CI) 0.89-1.18) than for controls (SMR = 0.91, 95% CI 0.84-0.99). For lung cancer, the SMR was 1.24 (95% CI 0.75-1.94) for welders, whereas the corresponding value was lower for controls (SMR = 0.94, 95% CI 0.68-1.26). The SMR for lung cancer was 1.59 among non-shipyard mild steel welders (95% CI 0.73-3.02). This contrasted with the results for all stainless steel welders (SMR = 0.92, 95% CI 0.19-2.69), and for stainless steel welders predominantly exposed to chromium VI (SMR = 1.03, 95% CI 0.12-3.71). Moreover, SMRs for lung cancer for mild steel welders tended to increase with duration of exposure and time since first exposure, leading to significant excesses for duration > or = 20 years and latency > or = 20 years. Such a pattern was not found for stainless steel welders.     

Occupational exposure to carcinogens and risk of lung cancer: results from The Netherlands cohort study.

OBJECTIVES: To investigate risk of lung cancers associated with common established carcinogenic occupational exposures (asbestos, paint dust, polycyclic aromatic hydrocarbons, and welding fumes) in a prospective cohort study among the general population, and to estimate the proportion of lung cancer cases attributable to these occupational exposures. METHODS: A prospective cohort study on diet, other lifestyle factors, job history, and cancer risk that started in 1986 in The Netherlands on 58,279 men, aged 55-69 years. Based on information about job history obtained from a self-administered questionnaire, case by case expert assessment was carried out to assign to each study subject a cumulative probability of occupational exposure for each carcinogenic exposure. For analysis, a case-cohort approach was used, in which the person-years at risk were estimated from a randomly selected subcohort (n = 1688). After 4.3 years of follow up, 524 lung cancer cases with complete job history were available. RESULTS: After adjustment for age, each of the other occupational exposures, and for smoking habits and intake of vitamin C, beta-carotene, and retinol, significant associations were found between risk of lung cancer and cumulative probability of occupational exposure to asbestos (relative risk (RR) highest/no exposure = 3.49, 95% confidence interval (95% CI) 1.69 to 7.18, trend P < 0.01 or paint dust (RR highest/no exposure = 2.48, 95% CI 0.88 to 6.97, trend P < 0.01). The population attributable risks (PARs) for the four exposures based on the multivariately adjusted RRs for ever exposed versus never exposed workers were calculated. The PAR of lifetime occupational exposure to asbestos was calculated to be 11.6%. CONCLUSIONS: This prospective cohort study among the general population showed that occupational exposure to asbestos or paint dust is associated with higher RRs for lung cancer. This study shows that after adjustment for smoking and diet about 11.6% of the cases of lung cancer in men is attributable to lifetime occupational exposure to asbestos.     

Study of occupational risk factors for pregnancy-induced hypertension among active duty enlisted navy personnel

The relationship between occupational exposures and the risk of pregnancy-induced hypertension (PIH) was investigated in a cohort of 5,605 enlisted active duty military women who gave birth during a 2-year period of time. A panel of experts, unaware of disease status, classified the women's job titles as “high,” “medium,” or “low” for a variety of occupational exposures. PIH was identified through hospital discharge ICD-9 diagnosis codes. Nulliparas were found to have a significantly increased risk ratio (RR) for PIH (RR = 2.3) compared with parous women. Nulliparas employed in jobs involving high levels of physical activity were at significantly decreased risk of PIH compared to nulliparas working at low levels of physical activity (construction craftsmen, RR = 0.37; unskilled laborers RR = 0.71). Occupational exposure to hazardous chemicals was not related to risk of PIH. Although the study results are limited by aggregate exposure classification, they suggest no adverse influence of occupational exertion and a possible beneficial role among nulliparas. © 1994 Wiley-Liss, Inc.     

Inter-rater agreement for a retrospective exposure assessment of asbestos, chromium, nickel and welding fumes in a study of lung cancer and ionizing radiation

A retrospective exposure assessment of asbestos, welding fumes, chromium and nickel (in welding fumes) was conducted at the Portsmouth Naval Shipyard for a nested case-control study of lung cancer risk from external ionizing radiation. These four contaminants were included because of their potential to confound or modify the effect of a lung cancer-radiation relationship. The exposure assessment included three experienced industrial hygienists from the shipyard who independently assessed exposures for 3519 shop/job/time period combinations. A consensus process was used to resolve estimates with large differences. Final exposure estimates were linked to employment histories of the 4388 study subjects to calculate their cumulative exposures. Inter-rater agreement analyses were performed on the original estimates to better understand the estimation process. Although concordance was good to excellent (78-99%) for intensity estimates and excellent (96-99%) for frequency estimates, overall simple kappa statistics indicated only slight agreement beyond chance (kappa < 0.2). Unbalanced distributions of exposure estimates partly contributed to the weak observed overall inter-rater agreement. Pairwise weighted kappa statistics revealed better agreement between two of the three panelists (kappa = 0.19-0.65). The final consensus estimates were similar to the estimates made by these same two panelists. Overall welding fume exposures were fairly stable across time at the shipyard while asbestos exposures were higher in the early years and fell in the mid-1970s. Mean cumulative exposure for all study subjects was 520 fiber-days cc(-1) for asbestos and 1000 mg-days m(-3) for welding fumes. Mean exposure was much lower for nickel (140 microg-days m(-3)) and chromium (45 microg-days m(-3)). Asbestos and welding fume exposure estimates were positively associated with lung cancer in the nested case-control study. The radiation-lung cancer relationship was attenuated by the inclusion of these two confounders. This exposure assessment provided exposure estimates that aided in understanding of the lung cancer-radiation relationship at the shipyard.     

Exposure to stainless steel welding fumes and lung cancer: a meta-analysis.

Stainless steel welding is associated with exposure to metals including hexavalent chromium and nickel. This study is a meta-analysis of five studies of stainless steel welders and the occurrence of lung cancer. Asbestos exposure and smoking habits have been taken into account. The calculated pooled relative risk estimate was 1.94 with a 95% confidence interval of 1.28-2.93. This result suggests a causal relation between exposure to stainless steel welding and lung cancer.     

Paternal occupational exposure around conception and spina bifida in offspring

A multi-center case-referent study was conducted on the relation between paternal occupational exposure and spina bifida in offspring. Cases were born between 1980 and 1992 in The Netherlands. Referents were recruited from hospitals and from the general population. Postal questionnaires were used to gather information on occupation and potential confounders. Through job-specific telephone interviews with 122 case fathers and 411 referent fathers, detailed exposure information was collected on specific tasks, the use of chemical or physical agents, frequency of exposure, and use of protective equipment. The study yielded statistically significant associations between spina bifida and low exposure to welding fumes (OR = 1.6, 95% CI: 1.0–2.6) and low exposure to UV radiation during welding (OR = 2.6, 95% CI: 1.2–5.6), and suggestive findings of an association between spina bifida and moderate or high exposure to cleaning agents, moderate or high pesticide exposure (OR = 1.7, 95% CI: 0.7–4.0), and stainless steel dust (OR = 2.0, 95% CI: 0.8–5.2). No associations were identified for other paternal occupational exposures, such as organic solvents. Am. J. Ind. Med. 32:283-291, 1997. © 1997 Wiley-Liss, Inc.     

Lung cancer risk in iron and steel foundry workers: a nested case control study in Asturias, Spain

BACKGROUND: Workers of iron and steel foundries have a high lung cancer risk but the findings on specific processes associated with this risk are inconsistent. We examined the risk of lung cancer among workers in the main industrial processes of a large iron and steel foundry in Asturias, Spain. METHODS: We conducted a nested case-control study comprised of 144 male lung cancer cases and 558 controls, selected from a study base of about 24,400 workers employed in the industry between 1952 and 1995. Cases were identified through linkage of industry records with those of two cancer registries. Controls were selected through industry records using incidence density sampling, were matched to cases by age and date of birth and had to be alive and without lung cancer at the time of selection. Smoking history was obtained through company medical records. Unconditional logistic regression was applied and all ORs were adjusted for age and tobacco consumption. RESULTS: Workers were, on an average, heavy smokers and a very strong relation was observed for smoking (OR for "ever smoker" = 32.4). Workers having ever been employed in the blast furnace had an excess lung cancer risk (OR = 2.55, 95% CI 1.25-5.21) compared to a reference group of workers not employed in metal producing departments. A similar excess was observed for workers having as their longest held job employment in the blast furnace. A two-fold risk was also observed for workers in the main foundry. For subgroups of workers, tobacco smoking appeared to be an important positive or negative confounder. CONCLUSIONS: In this large Spanish foundry, a high risk was observed for workers employed in departments with high exposure to crystalline silica, PAHs, and various other carcinogenic chemicals. Although comparisons were made between workers of the same industry, smoking habits differed and adjustment by smoking modified considerably the risk estimates.     

Case-control study of lung cancer in civilian employees at the Portsmouth Naval Shipyard, Kittery, Maine

Case-control analysis of deaths due to lung cancer (International Classification of Diseases, Eighth Revision, code 162) among persons who worked at the Portsmouth Naval Shipyard, Kittery, Maine, between 1952 and 1977 found elevated odds ratios for exposures to ionizing radiation, asbestos, and welding byproducts. The radiation-related excess was statistically significant in persons with cumulative lifetime exposures of 1.0-4.999 rem. When asbestos and welding histories were combined into a single risk factor, odds ratios for the combined exposure were significantly elevated for two of three duration-of-exposure categories examined. Further analysis of data on radiation exposure, controlling for exposures to asbestos and welding, found reductions in initial estimates of radiation risk at all levels of radiation exposure. This reduction suggests that radiation workers were more heavily exposed to asbestos and/or welding fumes than were other workers and that those exposures confounded the observed association between radiation and lung cancer. Analysis of mortality by time since first exposure to radiation revealed no pattern of progressive increase as latency increased. By contrast, odds ratios for asbestos/welding increased with latency. Data on cigarette smoking and socioeconomic status were not available. The results of this study do not preclude a possible association between radiation exposure at the Portsmouth Naval Shipyard and excess mortality from lung cancer. However, they provide no evidence in support of such a relation.