Incidence of cancer among welders, platers, machinists, and pipe fitters in shipyards and machine shops.

The incidence of cancer in 12,693 shipyard and machine shop male workers (1689 welders, 4308 platers, 6003 machinists, 693 pipe fitters) employed for at least one year between 1945 and 1960 was investigated in a retrospective cohort study. The welders had welded only mild steel and had not been exposed to hexavalent chromium containing fume. The follow up was 99.7% complete and the total number of person-years was 304,682. The incidence of cancer in 1953-81 was ascertained through the Finnish Cancer Registry. The observed numbers of cases of cancer were compared with the expected numbers based on regional urban rates. The smoking habits of the cohort were surveyed with a postal questionnaire sent to a sample of 961 workers. The smoking habits of the cohorts were similar and smoking was not more common than among the general population. The total number of cases of cancer was 611 (exp 629) among the shipyard workers and 376 (exp 388) among the machine shop workers. The incidence of lung cancer was increased among the shipyard workers (obs 227, exp 192). This excess was observed in all the worker groups and was most evident for the pipe fitters and platers. Among the machine shop workers, the incidence of lung cancer was lower than expected with the exception of the welders who had a slightly raised risk of lung cancer (obs 14, exp 10). The incidence of laryngeal cancer was slightly raised among the shipyard workers (obs 24, exp 20) but not in the machine shop workers. No excess risk was observed among the welders. The incidence of cancer of the prostate was increased among the machine shop workers (obs 39, exp 31) but not in the shipyard workers. The excess was statistically significant for the welders. No pronounced excess could be found for other types of cancer. Analysis by the duration or exposure showed that the excess of lung cancer in the shipyard workers was most evident during the last period of observation (1972-81). No other trends were obvious and the slight excess of lung cancer observed among the welders did not increase with increasing follow up time. No excess risk for mesothelioma was found. The small excess of lung cancer in welders could be due to chance. The fact that only a small and statistically insignificant excess of lung cancer could be found among this group of heavily exposed welders suggest that if the risk of lung cancer was associated with welding this risk must nowadays be low and probably too low to be unequivocally detected in most epidemiological studies.     

Incidence of cancer among welders and other shipyard workers with information on previous work history

The incidence of cancer among 4480 shipyard workers, including 861 welders, was investigated for a potential relationship between exposure to welding fumes and lung cancer. A subcohort of 3150 workers with information on previous work history was studied separately. This investigation is a historical prospective cohort study. Environmental air samples were collected in 1973, 1977, and 1989. Information on smoking habits was surveyed in 1976 and 1984. The employment work histories were collected from the personnel register. There were 411 observed cancers of all sites versus 387.5 expected, and 45 cases of lung cancer versus 51.3 expected. Nine cases of lung cancer were found among the welders versus 7.1 expected. Among 310 former seamen with welding experience, there was 1 case of lung cancer versus 2.1 expected. These shipyard workers showed no excess risk of lung cancer. Tobacco smoking and asbestos exposure are potential confounders in the study. There was no clear relationship between exposure to welding fumes and lung cancer, but welders with the longest experience had a relative risk of 1.9 for lung cancer. The differences in lung cancer incidence among the different shipyard workers could not be attributed to differences in recruitment patterns or previous work history.     

Medical wastage in shipyard welders: a forty-year historical cohort study

Summary A 40-year historical cohort study of medical wastage among about 550 shipyard welders and 1100 controls (shipwrights and engine fitters), all employed at the same shipyard, was carried out. The welders left their job 20% more often than the controls; the excess considerably increased with duration of employment. Wastage was particularly due to respiratory, cardiovascular, locomotor and mental disorders. Both welders and controls contributed considerably (about 20%) to permanent work disability. Medical wastage among welders because of respiratory diseases was more than four times higher than among controls, which could not be explained by differential smoking habits alone. The study raises concern about locomotor health hazards for shipyard workers. Moreover, it underscores the need to reduce the large excess risk of respiratory diseases among shipyard welders. The same may be true for welders in other large metal construction plants, e.g. in boiler production.     

Incidence of cancer among welders of mild steel and other shipyard workers.

The incidence of cancer among 4571 shipyard workers with first employment between 1940 and 1979, including 623 welders of mild steel, was investigated in a historical cohort study. The loss to follow up was 1.1%. The total number of deaths was 1078 (974.5 expected) and there were 408 cases of cancer v 361.3 expected. Sixty five cases of lung cancer were found v 46.3 expected based on the national rates for males. Four pleural mesotheliomas had occurred (1.2 expected), none among the welders. An excess of lung cancers was found among the welders (nine cases v 3.6 expected). There were six cases of lung cancer v 1.6 expected in a high exposure group of 255 welders. A survey of the smoking habits as of 1984 indicated 10%-20% more daily smokers among the shipyard production workers than among Norwegian males. Exposure to smoking and asbestos were confounding variables in this study.     

Mortality of welders and other craftsmen at a shipyard in NE England

Personnel records of over 1000 welders and electricians but only 235 caulkers and 557 platers employed at a shipyard in NE England between 1940 and 1968 were obtained and the mortality followed up to December 1982. The observed number of deaths (13 from mesothelial tumours, nine among the electricians) were compared with the number to be expected in the Newcastle connurbation. Welders and caulkers were most exposed to welding fumes, electricians to asbestos. The study was limited by the lack of accurate job exposure details, and there was no record of smoking habits, but welders and caulkers showed a higher standardised mortality ratio for all causes, lung cancer, ischaemic heart disease, pneumonia, and accidents than platers and electricians.     

Mortality of welders and other craftsmen at a shipyard in NE England.

Personnel records of over 1000 welders and electricians but only 235 caulkers and 557 platers employed at a shipyard in NE England between 1940 and 1968 were obtained and the mortality followed up to December 1982. The observed number of deaths (13 from mesothelial tumours, nine among the electricians) were compared with the number to be expected in the Newcastle connurbation. Welders and caulkers were most exposed to welding fumes, electricians to asbestos. The study was limited by the lack of accurate job exposure details, and there was no record of smoking habits, but welders and caulkers showed a higher standardised mortality ratio for all causes, lung cancer, ischaemic heart disease, pneumonia, and accidents than platers and electricians.     

Lung cancer in Yorkshire chrome platers, 1972-97

OBJECTIVES—To investigate mortality from lung cancer in chrome platers, a group exposed to chromic acid.
METHODS—The mortality of a cohort of 1087 chrome platers (920 men, 167 women) from 54 plants situated in the West Riding of Yorkshire, United Kingdom, was investigated for the period 1972-97. All subjects were employed as chrome platers for 3 months and all were alive on 31 May 1972. Mortality data were also available for a cohort of 1163 comparison workers with no known occupational exposure to chrome compounds (989 men, 174 women). Information on duration of chrome work and smoking habits collected for a cross sectional survey carried out in 1969-72 were available for 916 (84.3%) of the chrome platers; smoking habits were available for 1004 (86.3%) comparison workers. Two analytical approaches were used, indirect standardisation and Poisson regression.
RESULTS—Based on serial mortality rates for the general population of England and Wales, significantly increased mortality from lung cancer was observed (obs) in male chrome platers (obs 60, expected (exp) 32.5, standardised mortality ratio (SMR) 185, p<0.001) but not in male comparison workers (obs 47, exp 36.9, SMR 127). Positive trends were not shown for duration of employment exposed to chrome, although data on working after 1972 were not available.
CONCLUSIONS—Confident interpretation is not possible but occupational exposures to hexavalent chromium may well have been involved in the increased mortality from lung cancer found in this cohort of chrome platers.


Keywords: chromium plating; lung cancer     

Incidence of lung cancer among shipyard welders investigated for siderosis

The incidence of lung cancer among 428 shipyard welders exposed for more than ten years to welding fumes was investigated. The welders were examined for siderosis by the Directorate of Labor Inspection in 1975. The present study was a follow-up based on historical information from the Norwegian registry of dust-exposed workers. Twenty-three welders with siderosis, and 156 welders working at the same shipyards as the siderosis cases were studied as sub-cohorts. There was no loss on follow-up. The observation period was 1976 through 1992. There were 32 cases of cancer from all causes vs 41.3 expected. A nonsignificant excess of lung cancer was observed; 10 cases vs 6.5 expected. The incidence of lung cancer was highest for the welders with more than 30 years since first exposure (7 cases vs 4.1 expected). The sub-cohort of welders with siderosis had no case of lung cancer vs 0.5 expected. These welders were assumed to have experienced high exposure levels for welding fumes. The morbidity of cancer from all causes was low for this small group of blue-collar workers, but the incidence of lung cancer was slightly increased. The increase was not attributable to welders with siderosis. Smoking and asbestos exposure are potential confounders.     

Ten-year update on mortality among mild-steel welders

OBJECTIVES: This study is an update on the lung cancer risk of mild-steel welders with no asbestos exposure using a cohort of nonwelders for comparison. METHODS: The subjects came from three United States (US) plants that manufactured heavy equipment. The follow-up was extended from 1988 to 1998. The welders were not exposed to asbestos (typical of shipyard welders) or to chromium or nickel (present in stainless steel). RESULTS: There were 108 lung cancer deaths among the welders and 128 such deaths among the nonwelders (double the previous number of lung cancer deaths). The standardized mortality ratio (SMR) for lung cancer was 1.46 [95% confidence interval (95% CI 1.20-1.76] for the welders and 1.18 (95% CI 0.98-1.40) for the nonwelders, both in comparison with the US general population. Direct comparison between the welders and nonwelders yielded a rate ratio of 1.22 (95% CI 0.93-1.59). Analyses using a 15-year lag time did not differ greatly from those of an unlagged analysis. There were no marked trends for lung cancer risk by duration of exposure or latency. Evidence from cross-sectional data from a sample of the cohort indicated that the welders smoked somewhat more than the US population and more than the nonwelders. An approximate adjustment of the rate ratios for possible confounding by smoking suggested that smoking may have accounted for about half of the excess lung cancer observed among the welders versus that of either reference population. CONCLUSIONS These data provide suggestive but not conclusive evidence of a modest lung cancer risk from mild-steel welding.     

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.     

Incidence of cancer among welders and other workers in a Norwegian shipyard

The incidence of cancer among 4778 male shipyard workers, including 783 mild steel welders, was investigated in a historical cohort study. The workers had been employed for at least three months between 1 January 1946 and 31 March 1977. The incidence of cancer was observed from 1 January 1953 through 1986. The loss during follow-up was only 0.9%. There were 53 observed cases of lung cancer in the whole cohort versus 31.3 expected on the basis of the national rates for men. There was an increased incidence of lung cancer among the welders, with seven observed cases versus 3.2 expected. Twenty-two cases of bladder cancer were observed versus 15.2 expected. Two malignant mesotheliomas had occurred (0.7 expected). Smoking was likely to be a confounder in the present study. Due to concomitant exposure to asbestos, the results are inconclusive concerning the possible relationship between exposure to welding fumes and lung cancer.     

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.     

Mortality study of cancer risk among oil refinery workers

The mortality experience of 1595 male workers employed in one of the largest Italian refineries in the period from 1949-1982 was examined. From the comparison with national and local death rates, increases in mortality owing to lung and kidney cancers, brain tumors, and leukemias emerged. No definite trends according to duration of exposure and years since first exposure were apparent. The increases regarding cancer of the lung, kidney and brain appeared to be associated with the early period of operations. Analysis by exposure category suggested an association of the increased mortality from leukemias with working in production (observed = 2; expected = 0.61). Kidney cancer mortality was elevated among maintenance workers (obs. = 2; exp. = 0.18). Small numbers prevented firmer conclusions. Workers in the moving department had a significantly increased mortality from all cancers (obs. = 22; exp. = 11.7), and lung cancer (obs. = 11; exp. = 3.6). Confounding by smoking could be excluded as sufficient explanation of the three-fold increase in lung cancer deaths. It was in moving that highest airborne levels of polynuclear aromatic hydrocarbons had been discovered in an independent environmental investigation.     

Pleural plaques and exposure to asbestos: a mathematical model.

The objective of this study was to find a model to describe the relationship between the occurrence of pleural plaques and exposure to asbestos. A simple model based on the cumulative exposure was postulated and empirically tested on shipyard workers occupationally exposed to asbestos. Exposure time was used to approximate the cumulative dose. It was found that the incidence of pleural plaques could be described as K(t-w)a where 't' is time since onset of exposure; 'K' is a constant that would depend on the level of asbestos exposure; 'w' is a latency period and was around 13 years; 'a' is a constant that was 0.4. In subgroups of the workers, i.e. plumbers, fitters and platers, 'a' was 0.4, 0.6 and 0.2 respectively.     

Lung cancer mortality in a french cohort of hard-metal workers

A cohort mortality study was carried out among workers of a plant producing hard metals using cobalt as a binder. This study was aimed at assessing possible lung cancer risks in relation with cobalt exposure. Seven hundred nine male workers with at least 1 year of employment were included in the cohort and followed for mortality from 1956 to 1989. Job histories were provided by the administration of the plant, whereas smoking habits were collected from medical records and by interview. The causes of deaths were ascertained from hospital and general practitioner records. The observed numbers of deaths (obs) were compared with the expected based on national rates with adjustment for age, sex, and calendar time (standardized mortality ratio; SMR). The overall mortality did not differ from that expected (obs = 75, SMR = 1.05), whereas mortality due to lung cancer was in significant excess (obs = 10, SMR = 2.13). This excess was higher among workers employed in the areas with the highest exposure (obs = 6, SMR = 5.03). No trend was observed, however, with duration of employment or time since first employment. Smoking data were available for 81% of the workers and 69% of the deceased and showed that smoking alone does not account for these lung cancer excesses, yet, because of the small numbers involved, no firm conclusion should be drawn from this study.     

Assessment of risk of lung cancer for welders

Certain welding fumes contain significant amounts of chromium, manganese, and nickel, and trace amounts of arsenic and lead. These metals exhibit mutagenicity in one or more in vitro bioassays, and several are strongly suspected human carcinogens, albeit in unknown forms. It might, therefore, be expected that welders experience an excess risk of respiratory tract cancer because of their occupation. A survey of the world literature has disclosed 22 epidemiological studies of cancer incidence among welders, 16 of which yield a total of 586 cases of lung cancer observed, based on approximately 600,000 man-years at risk; a risk ratio of less than unity was excluded within 95% confidence limits for 5 of these studies. A risk ratio of 1.3 was not excluded in any study. Although there may be many possible origins to the excess risk, if welders of stainless steels suffer an "equivalent lung cancer risk" to that of chromate workers because of their equivalent chromium (VI) exposure, then a resulting three-fold risk ratio for 10% of all welders engaged in stainless steel welding would account for the total over-incidence experienced by the entire occupational group.     

Mortality from respiratory cancer and other causes in United Kingdom chromate production workers

This report updates a 1981 study of mortality at three United Kingdom chromate producing factories, and pays special attention to workers engaged after major plant and process changes were completed during 1958-60. The study covers 2298 payroll workers in post on 1 January 1950 or entering employment up to 30 June 1976 and remaining at least one year, with mortality observed up to 31 December 1988. Expected numbers of deaths were calculated from national death rates adjusted for social class and area differences. At the two largest factories 1422 men starting work before the process changes showed a highly significant excess of deaths from lung cancer (observed deaths/adjusted expected deaths (obs/expA) 175/88.97, adjusted standardised mortality ratio (SMRA) 197). They also had a significant excess of deaths from nasal cancer (obs/expA 4/0.26, SMRA 1538); the four affected men all had over 20 years of employment. Six hundred and seventy seven men starting work after the completion of process changes showed no excess of lung cancer deaths (obs/expA 14/13.7, SMRA 102, 95% confidence interval (95% CI) 56-171), but the possibility of the risk persisting at a reduced level cannot be excluded. The risk among earlier entrants affected men with two or more years of employment and was highest among those working for 10 years or longer (SMRA 225). The relative risk was already raised 5-14 years after first employment; it was highest in the 25-40 year period, but was still raised 50 years after first exposure. The risk showed most clearly at young ages, with a SMRA of 355 for ages under 50 (obs/expA 21/5.91). The excess was greater among men in jobs with high exposure to chromates (obs/expA 151/61.73, SMRA 245) than among men in less exposed jobs (obs/expA 21/19.57, SMRA 107). Less evidence of a lung cancer excess was found among 199 men employed at a third small factory (obs/expA 12/9.91, SMRA 121). No risk was apparent in further groups of 214 salaried works staff (obs/expA 1/2.53), or 95 workers at an adjacent fertiliser plant (obs/expA 3/3.95). No significant excesses of deaths from cancers of other sites were found.     

Mortality from respiratory cancer and other causes in United Kingdom chromate production workers.

This report updates a 1981 study of mortality at three United Kingdom chromate producing factories, and pays special attention to workers engaged after major plant and process changes were completed during 1958-60. The study covers 2298 payroll workers in post on 1 January 1950 or entering employment up to 30 June 1976 and remaining at least one year, with mortality observed up to 31 December 1988. Expected numbers of deaths were calculated from national death rates adjusted for social class and area differences. At the two largest factories 1422 men starting work before the process changes showed a highly significant excess of deaths from lung cancer (observed deaths/adjusted expected deaths (obs/expA) 175/88.97, adjusted standardised mortality ratio (SMRA) 197). They also had a significant excess of deaths from nasal cancer (obs/expA 4/0.26, SMRA 1538); the four affected men all had over 20 years of employment. Six hundred and seventy seven men starting work after the completion of process changes showed no excess of lung cancer deaths (obs/expA 14/13.7, SMRA 102, 95% confidence interval (95% CI) 56-171), but the possibility of the risk persisting at a reduced level cannot be excluded. The risk among earlier entrants affected men with two or more years of employment and was highest among those working for 10 years or longer (SMRA 225). The relative risk was already raised 5-14 years after first employment; it was highest in the 25-40 year period, but was still raised 50 years after first exposure. The risk showed most clearly at young ages, with a SMRA of 355 for ages under 50 (obs/expA 21/5.91). The excess was greater among men in jobs with high exposure to chromates (obs/expA 151/61.73, SMRA 245) than among men in less exposed jobs (obs/expA 21/19.57, SMRA 107). Less evidence of a lung cancer excess was found among 199 men employed at a third small factory (obs/expA 12/9.91, SMRA 121). No risk was apparent in further groups of 214 salaried works staff (obs/expA 1/2.53), or 95 workers at an adjacent fertiliser plant (obs/expA 3/3.95). No significant excesses of deaths from cancers of other sites were found.     

Incidence of cancer among Norwegian boiler welders.

OBJECTIVES: The cancer incidence among 2957 boiler welders was investigated. The subjects were registered electrical welders from 1942 to 1981. A subcohort of 606 stainless steel welders was studied separately. METHODS: The investigation was a historical prospective cohort study based on a national registry. The loss of follow up was 4.9%. RESULTS: There were 625 deaths (659 expected). There were 269 cancer cases (264 expected). An excess of lung cancer was found; 50 cases v 37.5 expected. There were three cases of pleural mesotheliomas v 1.1 expected. The subcohort of stainless steel welders had six cases of lung cancer v 5.8 expected, and one case of pleural mesothelioma v 0.2 expected. CONCLUSIONS: The welders in the study were assumed to represent a qualified work force. These welders had a small excess risk of lung cancer. The excess risk did not seem to be associated with stainless steel welding. Smoking and asbestos exposure were potential confounders.     

A proportionate mortality study of granite cutters

Several recent studies (animal and human) have suggested an association between lung cancer and silica exposure. To test the hypothesis, we have studied death benefit records of 1,905 members of the Granite Cutters Union. A proportionate mortality analysis (PMR) was conducted, using U.S. deaths as a comparison population. Statistically (PMR) was conducted, using U.S. deaths as a comparison population. Statistically significant excesses were observed for death from nonmalignant respiratory significant excesses were observed for death from nonmalignant respiratory disease (largely silicosis) (183 obs, 43.7 exp) and for tuberculosis (largely silicotuberculosis) (262 obs, 19.3 exp). Other significant excesses were observed for bone cancer (6 obs, 1.9 exp) and arthritis (5 obs, 1.5 exp). A significant decrease was observed for leukemia (5 obs, 13.0 exp). For lung cancer a slight but nonsignificant excess was observed (97 obs, 81.1 exp, PMR = 1.19, 95% CI 0.97-1.46). A proportionate cancer mortality analysis (PCMR) showed similar results for lung cancer (PCMR = 1.09, 95% CI 0.89-1.33). Lung cancer mortality also failed to show any trend with either calendar time or duration of exposure. Although no significant excess of lung cancer was observed for the entire silica-exposed cohort, there was an indication that those who were silicotic had an excess risk of lung cancer, based on a review of contributing causes on the death certificate.