Risk of cancer for arc welders in the Federal Republic of Germany: results of a second follow up (1983-8)

An extended follow up of 1221 chromium and nickel exposed welders in the Federal Republic of Germany confirmed an increased relative risk of 1.6 for all cancers compared with an internal reference group of 1694 turners. In an external comparison an excess of deaths from malignant tumours compared with that expected from the national mortality rates was found (standardised mortality ratio (SMR) = 109), which was clearly related to both time since first exposure and duration of exposure. Mortality from lung cancer was increased among welders (SMR = 113) but also among turners (SMR = 108). The difference remained when the subgroups were compared according to smoking information. A large excess of mesothelioma as a cause of death could be attributed to exposure to asbestos. The significantly increased SMR seen for urogenital tumours and "other or unspecified tumours" showed, however, an inverse relation with time since first exposure. This and other inconsistencies in the analysis by type of welding do not permit conclusive statements. Thus a further extension of follow up seems warranted.     

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.     

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.     

Cancer mortality among arc welders exposed to fumes containing chromium and nickel. Results of a third follow-up: 1989-1995

For the historical follow-up study among arc welders exposed to chromium and nickel, which was started in 1980 in Germany, a third follow-up extending the observation period to the years 1989 through 1995 has been carried out. By 1995, of the 1213 welders and 1688 turners (control group) who were originally included in the study, 274 welders and 448 turners had died. Death certificates could be obtained for approximately 96% of the deceased. Results of the evaluation presented in this article showed that cancer mortality remains significantly increased, compared with the general population and the control group, by approximately 35%. There was an elevation of approximately 50% or 60% in mortality from cancers of the respiratory tract, which is also statistically significant. However, this increase is predominantly due to a large excess in mortality from mesothelioma, which is known to be caused chiefly by asbestos exposure. Lung cancer mortality is nonsignificantly increased by approximately 20% to 30%. An indirect assessment of asbestos-related lung cancers and total cancer indicates that the observed increase of mortality might be mainly due to asbestos exposure. Beyond that, no indication of an elevated cancer risk specifically associated with the exposure to welding fumes containing chromium and nickel could be determined.     

Occupational exposure to ionising radiation and mortality among workers of the former Spanish Nuclear Energy Board.

OBJECTIVES: Firstly, to ascertain whether mortality among workers of the former Spanish Nuclear Energy Board (Junta de Energía Nuclear-JEN) was higher than that for the Spanish population overall; and secondly, if this were so, to ascertain whether this difference was associated with exposure to ionising radiation. METHODS: A retrospective follow up of a cohort of 5657 workers was carried out for the period 1954-92. Cohort mortality was compared with that for the Spanish population overall, with standardised mortality ratios (SMRs) adjusted for sex, age, and calendar period. Also, Poisson models were used to analyse mortality from lung cancer in the cohort by level of exposure to ionising radiation. RESULTS: Workers' median and mean cumulative exposures were 4.04 and 11.42 mSv, respectively. Mean annual exposure was 1.33 mSv. Excess mortality due to bone tumours was found for the cohort as a whole (six deaths observed; SMR 2.95; 95% confidence interval (95% CI) 1.08 to 6.43). Among miners, excess mortality was found for non-malignant respiratory diseases (SMR 2.94; 95% CI 2.27 to 3.75), and for lung cancer bordering on statistical significance (SMR 1.50; 95% CI 0.96 to 2.23; P = 0.055). Relative risks of dying of lung cancer from ionising radiation in the dose quartiles 2, 3, and 4 versus the lowest dose quartile, were 1.00, 1.64, and 0.94, respectively. CONCLUSIONS: Excess mortality from lung cancer was found among JEN miners. Nevertheless, no clear relation was found between mortality from lung cancer and level of exposure to ionising radiation in the JEN cohort. Continued follow up of the cohort is required to confirm excess mortality from bone tumours.     

Cancer mortality in an Italian rubber factory.

The purpose of the study was to describe the mortality experience of an Italian cohort of rubber workers and an attempt was made to identify any occupational cancer hazards that might currently be affecting men employed in this type of work. A total of 4917 male workers who first started working in a large rubber factory between 1962 and 1972 have been followed up until 31 January 1983. The number of deaths from all causes and from malignant neoplasms was determined and compared with the expected number of deaths calculated from mortality rates for the province in which the population of the plant lived. Mortality from all causes was 85% of that expected. A slight overall excess of deaths from cancer (SMR = 119) was found; this was entirely due to the excess mortality in the 35-44 age group. In order further to evaluate the possible existence of a cancer risk SMRs were analysed by duration of exposure, time since first exposure, and for specific sites of cancer. A trend in SMR with duration of exposure was found for employees with 10 years of follow up or more. A high risk for some tumour sites emerged.     

Cancer mortality in an Italian rubber factory

The purpose of the study was to describe the mortality experience of an Italian cohort of rubber workers and an attempt was made to identify any occupational cancer hazards that might currently be affecting men employed in this type of work. A total of 4917 male workers who first started working in a large rubber factory between 1962 and 1972 have been followed up until 31 January 1983. The number of deaths from all causes and from malignant neoplasms was determined and compared with the expected number of deaths calculated from mortality rates for the province in which the population of the plant lived. Mortality from all causes was 85% of that expected. A slight overall excess of deaths from cancer (SMR = 119) was found; this was entirely due to the excess mortality in the 35-44 age group. In order further to evaluate the possible existence of a cancer risk SMRs were analysed by duration of exposure, time since first exposure, and for specific sites of cancer. A trend in SMR with duration of exposure was found for employees with 10 years of follow up or more. A high risk for some tumour sites emerged.     

A mortality cohort study in a north Italian aircraft factory.

Mortality in a cohort of 8626 workers employed between 1954 and 1981 in an aircraft manufacturing factory in northern Italy was studied. Total follow up was 132,042 person-years, with 76% accumulated in the age range 15 to 54. Median duration of follow up from the date of first employment was 16 years. Vital status was ascertained for 98.5% of the cohort. Standardised mortality ratios were calculated based on Italian national mortality rates. Altogether 685 deaths occurred (SMR = 85). There was a significant excess of mortality for melanoma (6 cases, SMR = 561). Six deaths certified as due to pleural tumours occurred. No significant excess of mortality was found in specific jobs or work areas.     

A mortality cohort study in a north Italian aircraft factory

Mortality in a cohort of 8626 workers employed between 1954 and 1981 in an aircraft manufacturing factory in northern Italy was studied. Total follow up was 132,042 person-years, with 76% accumulated in the age range 15 to 54. Median duration of follow up from the date of first employment was 16 years. Vital status was ascertained for 98.5% of the cohort. Standardised mortality ratios were calculated based on Italian national mortality rates. Altogether 685 deaths occurred (SMR = 85). There was a significant excess of mortality for melanoma (6 cases, SMR = 561). Six deaths certified as due to pleural tumours occurred. No significant excess of mortality was found in specific jobs or work areas.     

Mortality study in an Italian oil refinery: Extension of the follow‐up

This article present the results of the extension of the follow‐up of a cohort of workers employed in an Italian oil refinery. 1,583 workers employed in 1949–1982 in a northern Italy oil refinery plant were followed‐up for mortality as of May 31, 1991. Environmental measurements documented potential exposure to benzene. Standardized mortality ratios (SMR) and their 95% confidence intervals (95% CI) were calculated using as references national (1949–1968) and regional mortality rates (1969–1991). Elevated mortality from lymphoma (seven deaths, SMR 190, 95% CI 76–391) and leukemia (eight deaths, SMR 225, 95% CI 97–443) was observed. No consistent trends by length of employment or time since first exposure were apparent. Nonetheless, the excess risk was particularly and significantly increased among workers with 15 or more years of employment, and 30 or more years since first employment. The findings of elevated mortality from leukemia and lymphoma are in agreement with those of other oil refinery studies. Chance, confounding, or other biases might have played a marginal, if any, role in determining the results. Exposure to benzene is a biologically plausible explanation. Am. J. Ind. Med. 35:287–294, 1999. © 1999 Wiley‐Liss, Inc.     

Cancer and other mortality patterns among United States furniture workers

Cause specific mortality was investigated among 36,622 members of a national furniture workers' union who were first employed in unionised shops between 1946 and 1962. Overall mortality for each race and sex group was less than expected when compared with United States death rates (white men SMR = 0.8, black men SMR = 0.7, white women SMR = 0.8, black women SMR = 0.5); however, raised risks were observed among white men employed in specific types of furniture industries and followed up for 20 or more years after first employment. Lymphatic and haematopoietic cancers were significantly raised (SMR = 1.8) among wood furniture workers followed up for at least 20 years due to excess deaths from leukaemia (SMR = 2.0) and non-Hodgkin's lymphoma (SMR = 2.0). Mortality from acute myeloid leukaemia was particularly high in this group (SMR = 4.7) based on six observed cases. Metal furniture workers followed up for at least 20 years experienced a significant excess of all cancers combined (SMR = 1.6), with non-significant increases in cancers of the lung, stomach, and colorectum. This group also had non-significant excesses of liver cirrhosis, arteriosclerotic heart disease, and cerebrovascular disease. Nasal cancer was not found to be significantly raised in this cohort, though the average follow up period may not have been sufficient to detect an excess risk for this uncommon tumour.     

Cancer and other mortality patterns among United States furniture workers.

Cause specific mortality was investigated among 36,622 members of a national furniture workers' union who were first employed in unionised shops between 1946 and 1962. Overall mortality for each race and sex group was less than expected when compared with United States death rates (white men SMR = 0.8, black men SMR = 0.7, white women SMR = 0.8, black women SMR = 0.5); however, raised risks were observed among white men employed in specific types of furniture industries and followed up for 20 or more years after first employment. Lymphatic and haematopoietic cancers were significantly raised (SMR = 1.8) among wood furniture workers followed up for at least 20 years due to excess deaths from leukaemia (SMR = 2.0) and non-Hodgkin's lymphoma (SMR = 2.0). Mortality from acute myeloid leukaemia was particularly high in this group (SMR = 4.7) based on six observed cases. Metal furniture workers followed up for at least 20 years experienced a significant excess of all cancers combined (SMR = 1.6), with non-significant increases in cancers of the lung, stomach, and colorectum. This group also had non-significant excesses of liver cirrhosis, arteriosclerotic heart disease, and cerebrovascular disease. Nasal cancer was not found to be significantly raised in this cohort, though the average follow up period may not have been sufficient to detect an excess risk for this uncommon tumour.     

Lung cancer risk among refractory brick workers exposed to crystalline silica: a retrospective cohort study.

We conducted a retrospective cohort study among 1,022 refractory brick workers exposed to crystalline silica. Mortality from lung cancer (SMR = 1.77) and respiratory diseases (SMR = 3.15) was elevated in workers first employed less than or equal to 1957 who are likely to have shared the highest exposure to crystalline silica. Workers with at least 19 years of cumulative employment in the plant experienced particularly increased risks for lung cancer (SMR = 2.01) and respiratory diseases (SMR = 3.89). Relative mortality from these specific causes increased with years since first employment (that is, first exposure) and decreased with age at first employment. Indirect adjustment for smoking habits and the lack of excess mortality from cardiovascular diseases and emphysema indicated little effect of smoking on the increased risks for lung cancer and respiratory diseases.     

Update of the Texaco mortality study 1947-93: Part II. Analyses of specific causes of death for white men employed in refining, research, and petrochemicals

OBJECTIVE: To examine patterns of mortality for specific causes of death with increases in the Texaco mortality study to determine if the patterns are related to employment in the petroleum industry. METHODS: Mortality patterns by duration of employment in various job groups were examined for mesothelioma, non-Hodgkin's lymphoma, multiple myeloma, cell type specific leukaemia, and brain tumours. RESULTS: Mortality from mesothelioma was examined for the total cohort and for two maintenance groups with the greatest potential for exposure to asbestos. The insulator group had a standardised mortality ratio (SMR) of 3029, and a larger group consisting of insulators, carpenters, labourers, electricians, pipefitters, boiler-makers, and welders had an SMR of 411. The mortalities from mesothelioma increased with increasing duration of employment. Mortality was lower for those first employed after 1950. An analysis of all brain tumours for the total cohort and some job and unit subgroups resulted in an SMR of 178 for those employed on the units related to motor oil and 166 for those employed as laboratory workers. Mortality from brain tumours in both of these job groups was higher for those employed > or = 5 years in the group. An analysis of non-Hodgkin's lymphoma showed no consistent patterns among the various employment groups. Mortality from multiple myeloma was non-significantly increased among people employed on the crude (SMR = 155) and fluid catalytic cracking units (SMR = 198). Leukaemia mortality was not increased for the total cohort, and a cell type analysis of leukaemia mortality for the total cohort showed no significant increases for the major cell types. However, there were significant increases for acute unspecified leukaemia (SMR = 276) and leukaemia of unknown cell type (SMR = 231). CONCLUSIONS: Analyses of specific causes of death by duration of employment in various job and process units did not show any patterns which suggest that, other than for mesothelioma, any of these increases in mortalities were likely to have resulted from workplace exposures or from employment at one of the places included in the Texaco mortality study.

 

     

Mortality from bladder cancer in dyestuff workers exposed to aromatic amines: A 73-year follow-up

Objective:To update the analysis of mortality of a cohort of dyestuff workers, in northern Italy, heavily exposed to carcinogenic aromatic amines.Methods:We updated to 2018 overall and cause-specific mortality in a cohort of 590 male workers heavily exposed to carcinogenic aromatic amines in a dyestuff factory from 1922 to 1972. Workers were censored at age 85. Expected cases for the period 1946-2018 were computed using Piedmont mortality rates and standardized mortality ratios (SMR) were computed.Results:Between 1946 and 2018, 470 deaths were reported. The overall SMR from all causes was 1.59 (95% confidence interval [CI] 1.45-1.74) and the SMR from all cancers was 2.05 (95% CI = 1.77-2.37); compared to a previous report, there were 4 additional deaths from bladder cancer, for a total of 60 deaths compared with 4.0 expected (SMR 14.86, 95% CI 11.34-19.12). The SMR for bladder cancer increased with younger age at first exposure and longer duration of exposure, while it decreased with time since last exposure, albeit it was still 3.5, 30, or more years since last exposure. An increased risk was observed among workers exposed to fuchsine or ortho-toluidine (SMR=16.3; 95% CI = 6.0-35.5).Conclusions:This 73-year follow-up confirms the results from previous analyses, with increased overall mortality, and increased mortality from all cancers and especially for bladder cancer. The excess risk of bladder cancer persisted several decades after stopping exposure.     

Mortality among workers in the diatomaceous earth industry.

A cohort mortality study was conducted among workers from two plants in the diatomaceous earth mining and processing industry in California. Diatomaceous earth consists of the skeletal remains of diatoms. Exposure to amorphous (non-crystalline) and crystalline silica in the form of quartz results from open pit mining and exposure to crystalline silica (principally cristobalite) occurs in the processing of the material. Lung cancer and non-malignant respiratory diseases have been the health outcomes of greatest concern. The main study cohort included 2570 white men (533 Hispanic and 2017 non-Hispanic workers) who were employed for at least 12 months cumulative service in the industry and who had worked for at least one day during the follow up period, 1942-87. Vital status was ascertained for 91% of the cohort and death certificate information was retrieved for 591 of 628 (94%) identified deaths. The all causes combined standardised mortality ratio (SMR) was slightly increased (SMR = 1.12; 628 observed) compared with rates among US white males. The principal contributors to this excess were increased risks from lung cancer (SMR = 1.43; 59 observed) and non-malignant respiratory disease (NMRD) excluding infectious diseases and pneumonia (SMR = 2.59; 56 observed). The excess of lung cancer persisted when local county rates were used for comparison (SMR = 1.59). Internal rate comparisons by Poisson regression analysis were conducted to assess potential dose-response relations for lung cancer and NMRDs. Mortality trends were examined in relation to duration of employment in dust exposed jobs and with respect to an index of cumulative exposure to crystalline silica. The crystalline silica index was a semiquantitative measure that combined information on duration of exposure, differences in exposure intensity between jobs and calendar periods, the crystalline content of the various product mixes, and the use of respiratory protection devices. Increasing gradients of risk were detected for lung cancer and NMRD with both exposure indices. The relative risk trends for lung cancer and NMRD with crystalline silica exposure lagged 15 years were respectively: 1.00, 1.19, 1.37, and 2.74, and 1.00, 1.13, 1.58, and 2.71. Based on a review of available but limited data on cigarette smoking in the cohort and from application of indirect methods for assessing confounding variables, it seems unlikely that smoking habits could account for all of the association between exposure to dust and lung cancer. The intense and poorly controlled dust exposures encountered before the 1950s were probably the most aetiologically significant contributors to risks from lung cancer and NMRDs. The absence of an excess of lung cancer among workers hired since 1960, and the finding of no deaths attributed to pneumoconiosis as an underlying cause of death among workers hired since 1950 indicate that exposure reductions in the industry during the past 40 years have been successful in reducing excess risks to workers. Further mortality follow up of the cohort and the analysis of radiographic data will be needed to determine conclusively the long term patterns of disease risks in this industry.     

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.     

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.