Lung cancer mortality in stainless steel and mild steel welders: A nested case-referent study

The association between welding and lung cancer has been studied in a nested case-referent study within a cohort of 8,372 metal workers. Lifetime exposure data on welding and other occupational exposures, as well as alcohol and smoking habits, were obtained by interviews of spouses and colleagues. Analysis was based on 439 deceased referents and 94 deceased cases. There was 70% excess of lung cancer associated with “welding exposure ever” (OR ± 95% C.I.: 1.68, 1.02–2.78). Overall OR “mild steel (MS) welding ever” was 1.64, 0.99-2.72. The risk estimates for welding exposures showed an increasing tendency up to 15 years of exposure. The pattern of stainless steel (SS) welding resembles that of mild steel with an estimated OR of 1.65, 0.88–3.0. The general conclusion is that MS welding as well as SS welding seems to be associated with an increased risk of lung cancer. Further followup of the cohort will enhance precision of the estimates. © 1996 Wiley-Liss, Inc.     

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.     

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.     

Chromium in biological samples from low-level exposed stainless steel and mild steel welders

Occupational exposure to hexavalent chromium is of concern because of the carcinogenic action of this metal. The purpose of this study was to evaluate internal exposure to chromium in welders who were exposed to low levels of chromium. Chromium in urine, blood, and seminal fluid was determined among 60 welders and 45 referents. The concentration of chromium in urine and blood did not change across a workshift or across a 3-wk break in exposure. However, stainless-steel and mild-steel welders who were exposed to low levels of chromium and steel welders who were mildly exposed had significantly increased levels of chromium in post-shift urine (mean 2.1 nmol/mmol creatinine [standard deviation (SD) = 1.0] and 1.3 nmol/mmol creatinine [SD = 0.5], respectively) compared with referents (mean 0.7 nmol/mmol creatinine [SD = 0.3]). Pre-shift blood chromium concentrations showed a similar variation between exposed workers and referents. Subgroups of stainless-steel welders had very high levels of chromium in seminal fluid. This finding may, however, be explained by nonoccupational factors and, therefore, warrants further study. Attention should focus on the potential risk of delayed health effects among stainless-steel and mild-steel welders who heretofore were not thought to be at risk from chromium exposure.     

Lung function of welders of zinc-coated mild steel: cross-sectional analysis and changes over five consecutive work shifts

Spirometric lung-function measurements were conducted 5 days before and after the work shift of 11 welders of zinc-coated steel, ten nonwelders who were indirectly exposed to welding fumes, and 17 controls. The exposure to dust and zinc of all participants was monitored personally using PAS-6 samplers. Geometric mean concentrations for welders were 0.91 mg/m3 (dust) and 34.0 micrograms/m3 (zinc). Cross-sectional analysis of Monday morning values showed no differences in lung-function parameters between groups. However, the number of years the participants were engaged in welding was of borderline statistical significance and correlated negatively with values of FEV1 and FEV1/FVC. Changes in lung function over a work shift or a working week were not related to the exposure level.     

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.     

Assessment of biological chromium among stainless steel and mild steel welders in relation to welding processes

Air and biological monitoring were used for assessing external and internal chromium exposure among 116 stainless steel welders (SS welders) using manual metal arc (MMA), metal inert gas (MIG) and tungsten inert gas (TIG) welding processes (MMA: n = 57; MIG: n = 37; TIG: n = 22) and 30 mild steel welders (MS welders) using MMA and MIG welding processes (MMA: n = 14; MIG: n = 16). The levels of atmospheric total chromium were evaluated after personal air monitoring. The mean values for the different groups of SS welders were 201 μg/m³ (MMA) and 185 μg/m³ (MIG), 52 μg/m³ (TIG) and for MS welders 8.1 μg/m³ (MMA) and 7.3 μg/m³ (MIG). The curve of cumulative frequency distribution from biological monitoring among SS welders showed chromium geometric mean concentrations in whole blood of 3.6 μg/l (95th percentile = 19.9), in plasma of 3.3 μg/l (95th percentile = 21.0) and in urine samples of 6.2 μg/l (95th percentile = 58.0). Among MS welders, mean values in whole blood and plasma were rather more scattered (1.8 μg/l, 95th percentile = 9.3 and 1.3 μg/l, 95th percentile = 8.4, respectively) and in urine the value was 2.4 μg/l (95th percentile = 13.3). The analysis of variance of chromium concentrations in plasma previously showed a metal effect (F = 29.7, P < 0.001), a process effect (F = 22.2, P < 0.0001) but no metal–process interaction (F = 1.3, P = 0.25). Concerning urinary chromium concentration, the analysis of variance also showed a metal effect (F = 30, P < 0.0001), a process effect (F = 72, P < 0.0001) as well as a metal–process interaction (F = 13.2, P = 0.0004). Throughout the study we noted any significant differences between smokers and non-smokers among welders. Taking in account the relationships between chromium concentrations in whole, plasma or urine and the different welding processes, MMA-SS is definitely different from other processes because the biological values are clearly higher. These higher levels are due to the very significant concentrations of total soluble chromium, mainly hexa- valent chromium, in welding fumes. Received: 9 May 1996 / Accepted: 14 March 1997     

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.     

Respiratory symptoms and pulmonary function in welders of mild steel: A cross-sectional study

Pulmonary function measurements, respiratory symptoms, smoking history, and occupational history were obtained from 91 male welders of mild steel, with mean welding exposure of 108 months, and 80 male factory controls. Nonsmoking welders compared to nonsmoking controls reported higher frequencies of respiratory symptoms and the differences were statistically significant for two symptoms: phlegm, and episodes of cough and phlegm. In comparisons of smoking welders and smoking controls, no significant differences were found in the prevalence of respiratory symptoms. Nonsmoking welders and smoking welders, compared to respective controls, did not have significantly decreased mean values of forced vital capacity or forced expired volume in 1 sec. Mean mid-expiratory flow rates and forced expiratory flow rates at 75% of forced vital capacity were lower, but not significantly different, for welders, compared to controls. These decrements in peripheral flow rates could be trivial or they could represent the initial stages of chronic obstructive pulmonary disease. Long-term follow-up, provided by a large prospective study, is needed to make this distinction.     

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.     

Semen quality and sex hormones among mild steel and stainless steel welders: a cross sectional study

Welding may be detrimental to the male reproductive system. To test this hypothesis, semen quality was examined in 35 stainless steel welders, 46 mild steel welders, and 54 non-welding metal workers and electricians. These figures represent a participation rate of 37.1% in welders and 36.7% in non-welding subjects. The mean exposure to welding fume particulates was 1.3 mg/m3 (SD 0.8) in stainless steel welders using tungsten inert gas, 3.2 mg/m3 (SD 1.0) in low exposed mild steel welders using manual metal arc or metal active gas (n = 31), and 4.7 mg/m3 (SD 2.1) in high exposed mild steel welders (n = 15). The semen quality of each participant was defined in terms of the mean values of the particular semen parameters in three semen samples delivered at monthly intervals in a period with occupational exposure in a steady state. The sperm concentration was not reduced in either mild steel or stainless steel welders. The sperm count per ejaculate, the proportion of normal sperm forms, the degree of sperm motility, and the linear penetration rate of the sperm were significantly decreased and the sperm concentration of follicle stimulating hormone (FSH) was non-significantly increased in mild steel welders. A dose response relation between exposure to welding fumes and these semen parameters (sperm count excepted) was found. Semen quality decreased and FSH concentrations increased with increasing exposure. Significant deteriorations in some semen parameters were also observed in stainless steel welders. An analysis of information from questionnaires obtained from the whole population including subjects who declined to participate indicated an underestimation of effects due to selection bias. Potential confounding was treated by restriction and statistical analysis. The results support the hypothesis that mild steel welding and to a lesser extent stainless steel welding with tungsten inert gas is associated with reduced semen quality at exposure in the range of the Danish process specific threshold limit values of welding.     

Semen quality and sex hormones among mild steel and stainless steel welders: a cross sectional study.

Welding may be detrimental to the male reproductive system. To test this hypothesis, semen quality was examined in 35 stainless steel welders, 46 mild steel welders, and 54 non-welding metal workers and electricians. These figures represent a participation rate of 37.1% in welders and 36.7% in non-welding subjects. The mean exposure to welding fume particulates was 1.3 mg/m3 (SD 0.8) in stainless steel welders using tungsten inert gas, 3.2 mg/m3 (SD 1.0) in low exposed mild steel welders using manual metal arc or metal active gas (n = 31), and 4.7 mg/m3 (SD 2.1) in high exposed mild steel welders (n = 15). The semen quality of each participant was defined in terms of the mean values of the particular semen parameters in three semen samples delivered at monthly intervals in a period with occupational exposure in a steady state. The sperm concentration was not reduced in either mild steel or stainless steel welders. The sperm count per ejaculate, the proportion of normal sperm forms, the degree of sperm motility, and the linear penetration rate of the sperm were significantly decreased and the sperm concentration of follicle stimulating hormone (FSH) was non-significantly increased in mild steel welders. A dose response relation between exposure to welding fumes and these semen parameters (sperm count excepted) was found. Semen quality decreased and FSH concentrations increased with increasing exposure. Significant deteriorations in some semen parameters were also observed in stainless steel welders. An analysis of information from questionnaires obtained from the whole population including subjects who declined to participate indicated an underestimation of effects due to selection bias. Potential confounding was treated by restriction and statistical analysis. The results support the hypothesis that mild steel welding and to a lesser extent stainless steel welding with tungsten inert gas is associated with reduced semen quality at exposure in the range of the Danish process specific threshold limit values of welding.     

Kidney function in stainless steel welders

Summary Seventeen male manual metal-arc stainless steel welders (mean exposure time 20 years) had far higher levels of chromium in urine than individually matched controls (medians 23 vs 1.5 mol/mol creatinine;10.5 vs 0.7 g/g creatinine). However, there were no signs of kidney damage in tests of function of tubuli (-hexosaminidase, lysozyme, and ₂-microglobuline) or glomeruli (albumine clearance).     

Urinary and blood manganese in occupationally nonexposed populations and in manual metal are welders of mild steel

Summary To obtain reference values for blood and serum manganese levels, blood specimens were collected from 29 men and 36 women. Mn in blood showed a normal distribution; its upper 97.5% limit in blood was 0.38 mol/l. Mn in serum showed a skewed distribution, which did not differ from the normal one after logarithmic transformation. The respective reference limit was 19 nmol/l. In both specimens, the levels of Mn were significantly lower in men than in women. To obtain reference values for Mn in urine, midday urine specimens were collected from 58 men and 96 women. Mn in urine also showed a skewed distribution, and the upper 97.5% limit was 38 nmol/l. The levels of Mn in blood and urine were statistically significantly higher in manual metal arc (MMA) welders of mild steel (MS) than in the reference populations. Five MMA/MS welders were subjected to a further study in which the ambient intramask Mn levels and urinary Mn excretion were monitored throughout a full working week. For two welders the correlation of Mn in urine specimens voided in the afternoon was good with the before noon Mn concentrations in the hygienic measurements; for the rest the correlation was minimal. Mn in diurnal urine specimens collected in six portions showed fluctuation if specific gravity or creatinine in urine was used to standardize for the urinary flow, but it was less evident for urinary Mn excretion rate. Our results seem to indicate that the measurement of Mn in urine or blood may be used for monitoring Mn exposure in MMA/MS welders only at the group level.These results were presented in part at the 2nd COMTOX meeting, held in Montreal in 1983     

Lung cancer among long-term steel workers

A case-control study in an industrialized area of eastern Pennsylvania involving interviews with the next of kin of 335 men who died of lung cancer and of 332 controls who died of other causes revealed a significantly increased risk associated with employment in the steel industry, the area's major employer. The excess was primarily among long-term employees, particularly those who began work before 1935. Adjusted for cigarette smoking, the odds ratio associated with career employment was 1.8 (p = 0.01, 95% confidence interval, 1.2, 2.8). The increase was higher among steel workers who worked in foundry operations, but was seen for broad categories of jobs within the industry. No significant associations were found for other industries, although a 60% increase (p = 0.27, 95% confidence interval, 0.7, 3.7) was noted for zinc smelter workers employed at least 15 years. The findings help clarify the role of occupation as a risk factor for lung cancer in the area, and suggest that exposures in the steel industry contribute to an extent greater than previously recognized.     

Small airways function in aluminium and stainless steel welders

Summary The effect of welding fumes on small airways was studied in 25 male subjects who welded in aluminium (Al) and to some extent also in stainless steel (SS). Despite a low exposure to welding fumes as compared to the permissible exposure limits, excretion of Al in urine was found to be increased in all subjects (median value: 0.29 mmol/mol creatinine on Friday afternoon, as compared to an upper reference level of 0.10 mmol/mol creatinine). In addition, the welders displayed increased prevalences of work-related eye and airways (pharyngitis and non-specific bronchial hyper-reactivity) symptoms, as compared to 25 matched controls. Short-term welders ( 2.5 years) had more symptoms related to the upper airways than did long-term welders, which may indicate a selection. Spirometry, closing volume and volume of trapped gas (VTG) did not deviate. However, after methacholine inhalation, the long-term welders had a significantly steeper slope of the alveolar plateau on the single-breath nitrogen wash-out test, and a slight increase in VTG, as compared to the short-term welders and the controls. These findings may indicate a welding fume-induced increase in the reactivity of the small airways. Because Al welding was far more frequent than SS welding, an association with the former seems likely.     

Lung retention and clearance of shipyard arc welders

Summary The amount of welding fume lung contaminants was measured in 42 shipyard arc welders. The subjects were divided into four groups according to the exposure time which varied from 1 to 40 years. A new measuring method, based on magnetic properties of fume iron retained in the lungs, was used to evaluate the amount of lung contaminants. The average alveolar deposition rate seemed to be from 20 to 40 mg per year, typical alveolar retention after 5 years of continuous exposure was 200 mg and the clearance rate ranged from 10 to 20 % per year.The interindividual variation in the amount of lung dust was high, the geometric standard deviation varying between 2 and 3. The results were compared with post mortem studies of coal miners. Retention rate of welding fumes seemed to be lower than that of coal mine dust but the clearance rate was about the same.