Mortality from lung cancer and population risk attributable to asbestos in an asbestos cement manufacturing town in Italy

OBJECTIVE: To estimate mortality from lung cancer and the risk attributable to asbestos separately for asbestos cement workers and for the general (non-occupationally exposed) population in the town of Casale Monferrato, where the largest Italian asbestos cement factory had been in operation in 1907-86. According to cancer registry data, in the same town the incidence of malignant mesothelioma in the general population is about 10 times higher than in comparable Italian provinces. METHOD: Decedents from lung cancer in 1989-95 were nominally identified in the list of decedents kept at the Local Health Authority of Casale Monferrato. Workers in the asbestos cement factory have been identified with a search in the nominal list of workers and the same was done for the wives of asbestos cement workers. These lists have already been used in cohort studies. Sensitivity and specificity of the linkage procedure with occupational activity in asbestos cement production have been evaluated in a previous study. Population at risk was estimated on the basis of official figures and on the results of the cohort study of asbestos cement workers. RESULTS: 227 deaths from lung cancer were included (184 men and 43 women). Among the asbestos cement workers mortalities were 234.0 x 100,000 person-years among men and 35.5 among women. Corresponding figures in the general (non- occupationally exposed) population in Casale Monferrato were 80.6 and 18.7. The rates in the general population were not higher than in the rest of the region. Attributable risk (AR) among the asbestos cement workers (and wives) is 67.5% (95% confidence interval (95% CI) 56.8 to 78.2) for men and 51.3% (95% CI 14.9 to 87.8) among women. Population AR to occupational or paraoccupational exposure in the asbestos cement production is 18.3% (95% CI 11.1 to 25.6) among men and 10.1% (95% CI 0 to 24.6) among women. CONCLUSION: This work did not show an increase in mortality from lung cancer for the population not exposed occupationally, but a large excess was found among men and women occupationally exposed in asbestos cement production. The total burden of lung cancer due to occupational exposure to asbestos may be underestimated, as only occupational exposure in asbestos cement production was taken into consideration. Nevertheless even a single factory can be responsible for a considerable proportion of deaths from lung cancer in a population.

 

     

Risk of mesothelioma from exposure to crocidolite asbestos: a 1995 update of a South African mortality study

OBJECTIVE—To find the risk of developing mesothelioma in a cohort born in 1916-36 in Prieska, Northern Cape Province, South Africa.
METHODS—A birth cohort mortality study was carried out in a small town in the Northern Cape Province, South Africa, with a history of crocidolite asbestos mining and milling. The cohort comprised all white births registered in the magisterial district of Prieska from 1916 to 1936, inclusive (2390). Causes of death due to mesothelioma and other cancers as recorded on medical certificates of cause of death were investigated. Person-years analysis was used to calculate mortalities due to mesothelioma, other respiratory cancers, and other non-respiratory cancers. Proportional cancer mortalities were also calculated for mesothelioma and other specific neoplasms.
RESULTS—The follow up rate for the cohort was 74.3% in 1995, and 683 traced members (38.6%) had died. Cause of death was unknown for 6.4% of deaths. There were 118 cases of cancer, 28 of them from mesothelioma, giving a cause specific mortality for mesothelioma of 277 (170-384) per 10⁶ person-years. The rates for men and women were 366 and 172 per 10⁶ person-years, respectively. The mortality for lung cancer (29 deaths) was 287 (135-436) per 10⁶ person-years, and that for other non-respiratory cancers (60 deaths) was 593 (442-745). Two cases of laryngeal and four of colon cancer were observed. All cancer mortality, mesothelioma, and lung cancer proportional cancer mortality ratios were increased.
CONCLUSION—The mortality for mesothelioma in men was twice that in women, probably because men were more likely to have had both occupational and environmental exposure to asbestos. Nevertheless, the mortality in women was still high and is probably indicative of the environmental exposure as white women were rarely employed in the asbestos industry in the Prieska area. Due to the long latency from first exposure to diagnosis of the neoplasm, the cause specific mortality in this cohort could be expected to increase rapidly over the next 10 years.


Keywords: South Africa; asbestos; environmental exposure; occupational exposure; cohort; mesothelioma; lung cancer     

Three decades of pleural cancer and mesothelioma registration in Austria where asbestos cement was invented

Recently, a new mesothelioma epidemic was predicted from observations made in Western Europe. From early observations in Austria the lower increase in cases of mesothelioma compared with neighbor countries had been related to different uses of asbestos. In order to test this hypothesis, incidence and mortality of pleural cancer [International Classification of Diseases (ICD)-8/9 163] were analyzed for three decades and supplemented by data from a cohort study in the factory that had been the largest consumer of asbestos imported to Austria and from all Austrian occupational diseases registered between 1990 and 2001. In men, mortality rates (based on 15 to 45 deaths/year) were lowest in 1980-1989, but similar in 1970-1979 and 1990-2001. No increase in younger-birth cohorts was detected. Incidence rates (based on 13 to 44 cases/year) increased (36%) non-significantly ( P=0.14). In women, a significant decrease in mortality and incidence rates ( P<0.01) was observed from 1970. Rates from work-related mesothelioma (based on only 0-7 men and 0-4 women/year) must be interpreted with caution. In the cohort of 2,816 asbestos cement workers 26 pleural mesotheliomas were registered from 1990 through mid-1999. Six of these cases (three male and three female) had not been registered as an occupational disease, but all of these cases had been encoded under ICD 163 in mortality statistics. One female cohort member registered as having asbestosis according to the death certificate had died from mesothelioma according to the statistics of occupational diseases. We conclude that no epidemic of mesothelioma due to past asbestos exposure is to be expected in Austria.     

Estimation of the past and future burden of mortality from mesothelioma in France

OBJECTIVES: Firstly to evaluate future mortality from mesothelioma in France with an age-period-cohort approach and evaluate different hypotheses on risk of mesothelioma for the most recent birth cohort. Secondly to compare the results with a British and an American study. Thirdly to study if any trends were detectable on data for women which would be consistent with the consequences of increasing environmental exposure to asbestos. METHODS: Estimates of mortality from mesothelioma among men and women in France from 1950 to 1995 were based on the analysis of the pleural cancer mortality data coded 163 in the ninth revision of the international classification of diseases (ICD-9). Correction factors were used to derive the mortality from mesothelioma from these data, based on two regional registries. The analysis of the past mortality data has been performed by an age-cohort model (with a maximum likelihood technique). Predictions of deaths from mesothelioma over the next 50 years were based on four different assumptions on the risk of death from mesothelioma in future birth cohorts. RESULTS: The predicted lifetime probability of dying from mesothelioma increases until the last birth cohort 1964-8 among men whereas it decreases strongly from the 1954-8 birth cohort among women. The projected numbers of deaths from mesothelioma in France until 2020 are similar, whichever hypothesis is considered: around 20,000 deaths from mesothelioma might occur among men and 2900 among women from 1996 to 2020. CONCLUSIONS: French data show an increasing lifetime probability of death from mesothelioma in the more recent male cohorts. Although the mortality burden can be predicted until 2020, and is intermediate between the United Kingdom and United States estimates, there is still high uncertainty on the figures after 2020. No increase is found in women, and this does not support the hypothesis that current environmental exposure to asbestos could be associated with a detectable risk of death. Specific surveillance should be set up to monitor future trends or their absence.       

Cancer mortality and incidence of mesothelioma in a cohort of wives of asbestos workers in Casale Monferrato, Italy

BACKGROUND: Family members of asbestos workers are at increased risk of malignant mesothelioma (MM). Although the hazard is established, the magnitude of the risk is uncertain, and it is unclear whether risk is also increased for other cancers. Few cohort studies have been reported. OBJECTIVE: The "Eternit" factory of Casale Monferrato (Italy), active from 1907 to 1986, was among the most important Italian plants producing asbestos-cement (AC) goods. In this article we present updated results on mortality and MM incidence in the wives of workers at the factory. METHODS: We studied a cohort of 1,780 women, each married to an AC worker during his employment at the factory but not personally occupationally exposed to asbestos. Cohort membership was defined starting from the marital status of each worker, which was ascertained in 1988 from the Registrar's Office in the town where workers lived. At the end of follow-up (April 2003), 67% of women were alive, 32.3% dead, and 0.7% lost to follow-up. Duration of exposure was computed from the husband's period of employment. Latency was the interval from first exposure to the end of follow-up. RESULTS: The standardized mortality ratio (SMR) for pleural cancer [21 observed vs. 1.2 expected; SMR = 18.00; 95% confidence interval (CI), 11.14-27.52] was significantly increased. Mortality for lung cancer was not increased (12 observed vs. 10.3 expected; SMR = 1.17; 95% CI, 0.60-2.04). Eleven incident cases of pleural MM were observed (standardized incidence ratio = 25.19; 95% CI, 12.57-45.07). CONCLUSIONS: Household exposure, as experienced by these AC workers' wives, increases risk for pleural MM but not for lung cancer.     

Prediction of mesothelioma and lung cancer in a cohort of asbestos exposed workers

BACKGROUND: Several papers have reported state-wide projections of mesothelioma deaths, but few have computed these predictions in selected exposed groups. OBJECTIVE: To predict the future deaths attributable to asbestos in a cohort of railway rolling stock workers. METHODS: The future mortality of the 1,146 living workers has been computed in term of individual probability of dying for three different risks: baseline mortality, lung cancer excess, mesothelioma mortality. Lung cancer mortality attributable to asbestos was calculated assuming the excess risk as stable or with a decrease after a period of time since first exposure. Mesothelioma mortality was based on cumulative exposure and time since first exposure, with the inclusion of a term for clearance of asbestos fibres from the lung. RESULTS: The most likely range of the number of deaths attributable to asbestos in the period 2005-2050 was 15-30 for excess of lung cancer, and 23-35 for mesothelioma. CONCLUSION: This study provides predictions of asbestos-related mortality even in a selected cohort of exposed subjects, using previous knowledge about exposure-response relationship. The inclusion of individual information in the projection model helps reduce misclassification and improves the results. The method could be extended in other selected cohorts.     

Asbestos and cancer: a cohort followed up to death

The mortality experience of 1074 white men who retired from a United States asbestos company during the period 1941-67 and who were exposed to asbestos working as production and maintenance employees for the company is reported to the end of 1980 when 88% of this cohort was known to be dead. As noted in earlier reports the mortality for respiratory and gastrointestinal cancer was raised. A more detailed examination of causes of death shows that the excess in gastrointestinal cancer was largely due to a statistically significant excess in stomach cancer. A statistically significant excess was also noted for kidney cancer, cancer of the eye, and non-malignant respiratory disease. Eight deaths from malignant mesothelioma were observed, two of which were peritoneal. Asbestos exposures for these mesothelioma cases were low relative to other members of the cohort. Continuing follow up of this cohort shows a dose response relation for respiratory cancer that has become increasingly linear. Standardised mortality ratios peaked 10 to 15 years after retirement and were relatively constant at around 250 in each five year interval starting in 1950. This excess might have been detected as early as 1960 but certainly by 1965. The mortality experience of this cohort reflects the ultimate effects of asbestos since nearly all of the cohort has now died.     

Lung cancer and mesothelioma in the pleura and peritoneum among Swedish insulation workers

OBJECTIVES: To estimate the risk of cancer and death in Swedish insulation workers some years after their exposure to asbestos had stopped. One hypothesis was that the risk of lung cancer would tend to decrease some years after the exposure had ended. METHODS: In a cohort study the cancer morbidity and cause of death was investigated in 248 insulation workers and compared with the corresponding morbidity and mortality in the general population. Due to stringent regulations, exposure to asbestos of all types had almost ended in Sweden in the mid- 1970s. Through a questionnaire, surviving insulation workers were asked about their exposure to asbestos and their smoking habits. RESULTS: Between 1970 and 1994 there were 86 deaths compared with the 46.0 expected (standardised incidence ratio (SIR) 1.9; 95% confidence interval (95% CI) 1.5 to 2.3), the increase was mainly due to an increased cancer mortality. The morbidity was increased for lung cancer (11 cases v 2.5 expected (SIR 4.4; 95% CI 2.2 to 7.9)), peritoneal mesothelioma (seven cases; no expected incidence could be calculated as the occurrence is too rare in the general population), cancer in pancreas (five cases v 0.7 expected (SIR 7.1; 95% CI 2.3 to 16.7)). No cases of pleural mesothelioma were found. The risk of lung cancer did not tend to approach that of the general population after the exposure to asbestos decreased. CONCLUSIONS: In the 1980s and the early 1990s, Swedish insulation workers still have a highly increased risk of diseases related to asbestos. The attributable risk for death and cancer was about 50%. The study also confirms the previous finding that mesothelioma in insulation workers seems to be situated in the peritoneum more often than in the pleura.     

Asbestos and cancer: a cohort followed up to death.

The mortality experience of 1074 white men who retired from a United States asbestos company during the period 1941-67 and who were exposed to asbestos working as production and maintenance employees for the company is reported to the end of 1980 when 88% of this cohort was known to be dead. As noted in earlier reports the mortality for respiratory and gastrointestinal cancer was raised. A more detailed examination of causes of death shows that the excess in gastrointestinal cancer was largely due to a statistically significant excess in stomach cancer. A statistically significant excess was also noted for kidney cancer, cancer of the eye, and non-malignant respiratory disease. Eight deaths from malignant mesothelioma were observed, two of which were peritoneal. Asbestos exposures for these mesothelioma cases were low relative to other members of the cohort. Continuing follow up of this cohort shows a dose response relation for respiratory cancer that has become increasingly linear. Standardised mortality ratios peaked 10 to 15 years after retirement and were relatively constant at around 250 in each five year interval starting in 1950. This excess might have been detected as early as 1960 but certainly by 1965. The mortality experience of this cohort reflects the ultimate effects of asbestos since nearly all of the cohort has now died.     

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.     

Mortality from all cancers of asbestos factory workers in east London 1933-80

OBJECTIVE—To give the observed and expected deaths due to cancer at all separate sites in asbestos workers in east London, and to analyse these for overall effect and exposure-response trend.
METHODS—The mortality experience of a cohort of over 5000 men and women followed up for over 30 years since first exposure to asbestos has been extracted.
RESULTS—There was a large excess of deaths due to cancer (537 observed, 222 expected). Most of these were due to cancer of the lung (232 observed, 77 expected) and pleural (52) and peritoneal (48) mesothelioma. The exposure-response trend for all these three causes was highly significant. There was also an excess of cancer of the colon (27 observed, 15 expected) which was significantly related to exposure. There were significant excesses of cancer of the ovary, of the liver, and of the oesophagus but with no consistent relation to exposure.
CONCLUSIONS—The excess risk of cancer after exposure to asbestos was mainly due to cancer of the lung and mesothelioma. An exposure related excess of cancer of the colon was also detected but the possibility that some of these deaths may have been peritoneal mesotheliomas could not be excluded. There was no consistent evidence of exposure related excesses at any other site.


Keywords: asbestos; cancer; exposure-response     

Asbestos-related lung cancer and mesothelioma in Japan

In Japan, crocidolite had been used for asbestos cement pipe and spraying, and amosite had been used for building board and spraying. These two types of asbestos had stopped to use in Japan in the late 1970s. An extreme increase in imported asbestos (all 3 commercial types) was observed between 1960 and 1974. In 1960, 77,000 tons of asbestos were imported, and reached the peak as 352,316 tons in 1974. This extreme rise of asbestos imports corresponds with the recent rapid increase in mortality of malignant pleural mesothelioma. Between 1995 and 1999, an estimated mean annual death from pleural mesothelioma was about 500. The annual number of compensated occupational respiratory cancers due to asbestos exposure has also been increasing. Up to the end of March 2000, 162 cases with malignant mesothelioma and 197 cases with lung cancer were compensated. As for lung cancer, epidemiological studies are scanty in Japan. Limited environmental data of the working places in asbestos textile factories suggests that heavy asbestos exposure in the past made deaths from respiratory diseases. Less asbestos exposure will enable exposed workers to survive enough to reach cancer age. Even now smoking rate among males in Japan are over 50%. So lung cancer deaths caused by the interaction between smoking and asbestos exposure will be continuing.     

Follow up study of workers manufacturing chrysotile asbestos cement products.

A cohort study has been carried out of 2167 subjects employed between 1941 and 1983 at an asbestos cement factory in England. The production process incorporated the use of chrysotile asbestos fibre only, except for a small amount of amosite during four months in 1976. Measured airborne fibre concentrations available since 1970 from personal samplers showed mean levels below 1 fibre/ml, although higher levels had probably occurred previously in certain areas of the factory. No excess of lung cancer was observed in the mortality follow up by comparison with either national or local death rates, and analyses of subgroups of the workforce by job, exposure level, duration of employment, duration since entry, or calendar years of employment gave no real suggestion of an asbestos related excess for this cause of death. There was one death from pleural mesothelioma and one with asbestosis mentioned as an associated cause on the death certificate, but neither is thought to be linked to asbestos exposure at this factory. Other suggested asbestos related cancers, such as laryngeal and gastrointestinal, did not show raised risks. Although the durations of exposure were short in this study, the findings are consistent with two other studies of workers exposed to low concentrations of chrysotile fibre in the manufacture of asbestos cement products which reported no excess mortality.     

Individual asbestos exposure: smoking and mortality--a cohort study in the asbestos cement industry

A historical prospective cohort study comprised all persons employed from 1950 to 1981 for at least three years in the oldest asbestos cement factory in the world. From 2816 persons eligible for the study, record based estimates and measurements of dust and fibres and histories of smoking based on interviews were used to calculate individual exposures over time. After observation of 51,218 person-years and registration of 540 deaths, underlying causes of death for this cohort were compared with those for the regional population on the basis of death certificates. Deaths from lung cancer in asbestos cement workers were higher (standard mortality ratio (SMR) 1.7), but after adjustment for age and sex specific smoking habits this was not significant (SMR 1.04). The study had a probability of greater than 92% of detecting a smoking adjusted SMR of 1.5 or more. Using the best available evidence (including necropsy records) 52 deaths were assigned to lung cancer and five to mesothelioma. Life table analyses confirmed the predominant influence of smoking on lung cancer. Mesothelioma was associated with the use of crocidolite in pipe production. From present working conditions with much lower concentrations of chrysotile and no crocidolite no more occupational cancers are expected in the asbestos cement industry.     

Individual asbestos exposure: smoking and mortality--a cohort study in the asbestos cement industry.

A historical prospective cohort study comprised all persons employed from 1950 to 1981 for at least three years in the oldest asbestos cement factory in the world. From 2816 persons eligible for the study, record based estimates and measurements of dust and fibres and histories of smoking based on interviews were used to calculate individual exposures over time. After observation of 51,218 person-years and registration of 540 deaths, underlying causes of death for this cohort were compared with those for the regional population on the basis of death certificates. Deaths from lung cancer in asbestos cement workers were higher (standard mortality ratio (SMR) 1.7), but after adjustment for age and sex specific smoking habits this was not significant (SMR 1.04). The study had a probability of greater than 92% of detecting a smoking adjusted SMR of 1.5 or more. Using the best available evidence (including necropsy records) 52 deaths were assigned to lung cancer and five to mesothelioma. Life table analyses confirmed the predominant influence of smoking on lung cancer. Mesothelioma was associated with the use of crocidolite in pipe production. From present working conditions with much lower concentrations of chrysotile and no crocidolite no more occupational cancers are expected in the asbestos cement industry.     

Follow up study of workers manufacturing chrysotile asbestos cement products

A cohort study has been carried out of 2167 subjects employed between 1941 and 1983 at an asbestos cement factory in England. The production process incorporated the use of chrysotile asbestos fibre only, except for a small amount of amosite during four months in 1976. Measured airborne fibre concentrations available since 1970 from personal samplers showed mean levels below 1 fibre/ml, although higher levels had probably occurred previously in certain areas of the factory. No excess of lung cancer was observed in the mortality follow up by comparison with either national or local death rates, and analyses of subgroups of the workforce by job, exposure level, duration of employment, duration since entry, or calendar years of employment gave no real suggestion of an asbestos related excess for this cause of death. There was one death from pleural mesothelioma and one with asbestosis mentioned as an associated cause on the death certificate, but neither is thought to be linked to asbestos exposure at this factory. Other suggested asbestos related cancers, such as laryngeal and gastrointestinal, did not show raised risks. Although the durations of exposure were short in this study, the findings are consistent with two other studies of workers exposed to low concentrations of chrysotile fibre in the manufacture of asbestos cement products which reported no excess mortality.     

Historical cohort study of US man-made vitreous fiber production workers: II. Mortality from mesothelioma

As part of our ongoing mortality surveillance program for the US man-made vitreous fiber (MMVF) industry, we examined mortality from malignant mesothelioma using data from our 1989 follow-up of 3478 rock/slag wool workers and our 1992 follow-up of 32,110 fiberglass workers. A manual search of death certificates for 1011 rock/slag wool workers and 9060 fiberglass workers revealed only 10 death certificates with any mention of the word "mesothelioma." A subsequent review of medical records and pathology specimens for 3 of the 10 workers deemed two deaths as definitely not due to mesothelioma and one as having a 50% chance of being caused by mesothelioma. Two other deaths, for which only medical records were available, were given less than a 50% chance of being due to mesothelioma. Eight of the 10 decedents had potential occupational asbestos exposure inside or outside the MMVF industry. We also estimated the mortality risk from malignant mesothelioma in the cohort using two cause-of-death categorizations that included both malignant and benign coding rubrics. Using the more comprehensive scheme, we observed overall deficits in deaths among the total cohort and fiberglass workers and an overall excess among rock/slag wool workers. The excess in respiratory system cancer is largely a reflection of elevated lung cancer risks that we attributed mainly to confounding by smoking, to exposures outside the MMVF industry to agents such as asbestos, or to one or more of the several co-exposures present in many of the study plants (including asbestos). The second scheme, which focused on pleural mesothelioma in time periods when specific malignant mesothelioma coding rubrics were available, classified only one cohort death as being caused by malignant mesothelioma, compared with 2.19 expected deaths (local county comparison). We conclude that the overall mortality risk from malignant mesothelioma does not seem to be elevated in the US MMVF cohort.     

Mortality of female gas mask assemblers.

A 30-year follow-up study of the mortality of 500 women employed in manufacturing gas masks during the second world war showed a pronounced excess of deaths from mesothelioma and lung cancer. Although these women were subject only to short periods of exposure, greater excesses were found for those exposed for between one and five years than for those exposed for under one year. Even in the latter group, however, five deaths from lung cancer and four deaths from mesothelioma were recorded compared with 1.5 deaths and 0.1 deaths expected (p approximately equal to 0.02). An excess of deaths from cancer of the ovary was also found, and this appeared to be related to exposure to asbestos.     

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.