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.     

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.     

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.     

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.     

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.     

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     

Evaluation of biological monitoring among stainless steel welders

Summary Ten manual metal arc (MMA) high alloy stainless steel (SS) welders were studied during one week and the concentrations of chromium (Cr) and nickel (Ni) were determined in their urine and blood. Stationary and personal air samples were collected from the immediate work environment; they covered the entire work period. Spot urine samples were collected during the follow-up period. Whole blood and plasma samples were taken from the workers before and after one shift, and the retention rate of magnetic dust in the lungs was estimated with magnetopneumography. On the basis of the results, indices of short-term exposure to Cr and Ni were evaluated. Urinary Cr and Ni concentrations (corrected to creatinine) reflect both the body burden caused by long-term and short-term exposure to easily soluble fractions of these metals. The results indicated that the use of Cr and Ni urinary analyses as indices of short-term exposure is not as dependable as previously assumed. The Cr and Ni concentrations in whole blood and plasma did not correlate with the measured exposure, but the daily mean increase in the Cr concentration reflected exposure to total Cr and Cr (VI) very well. The large variation in the Cr concentration of the morning urine (0.01–2.7 mol/l) and blood (0.05–1.43 mol/l) indicated large personal variations of body burden among the exposed welders. The retention rate of magnetic dust in the lungs correlated well (P<0.01) with the daily mean increase of Cr in blood. Very good correlations (P<0.001) were found between the retention rate of magnetic dust and the personal air samples of Cr and Cr (VI).     

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.     

Male-mediated spontaneous abortion among spouses of stainless steel welders

OBJECTIVES: Male-mediated spontaneous abortion has never been documented for humans. The welding of stainless steel is associated with the pulmonary absorption of hexavalent chromium, which has genotoxic effects on germ cells in rodents. Clinical and early subclinical spontaneous abortions were examined among spouses of stainless-steel welders. METHODS: A cohort of first-pregnancy planners was recruited from members of the union of metal workers and 3 other trade unions. The cohort was followed for 6 menstrual cycles from the cessation of contraceptive use. Altogether, 280 pregnancies were conceived, of which 35 were detected by human chorionic gonadotrophic hormone analysis and did not survive to a clinically recognized pregnancy. Information on exposure was collected prospectively in relation to the outcome and was available for all cycles resulting in a pregnancy. Information on pregnancy outcome was collected for all 245 clinically recognized pregnancies. RESULTS: Increased risk of spontaneous abortion was found for pregnancies with exposure to paternal stainless-steel welding (adjusted relative risk 3.5, 95% confidence interval 1.3-9.1). The results were consistent in analyses of both biochemically and clinically recognized abortions. There was no increased risk for spontaneous abortion in pregnancies with paternal exposure to the welding of metals other than stainless steel. CONCLUSIONS: Male welding of stainless steel was associated with an increased risk of spontaneous abortion in spouses. A mutagenic effect of hexavalent chromium has been found previously in both somatic and germ cells, and the findings could be due to mutations in the male genome.     

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.     

Lung-retained contaminants,urinary chromium and nickel among stainless steel welders

Summary The magnetic method of measuring the amount of lung retained contaminants as well as urinary chromium and nickel determinations have been performed among 83 stainless steel (SS) welders who have used matural metal arc (MMA) and tungsten inert gas (TIG) welding techniques. The welders were divided into four groups according to the time percentage used for MMA welding. Only exposure to MMA/SS welding fumes resulted in clearly elevated chromium concentrations in the urine, the correlation coefficient between the values of urinary chromium and MMA/SS percentage being very significant (P < 0.001). Among the smokers the urinary chromium values were increased (P < 0.05) perhaps owing to contaminated cigarettes. In many workplaces the urinary chromium values of several welders exceeded the value of 30 g/l which is the recommended reference value in Finland. Owing to the solubility properties of nickel compounds in SS welding fumes urinary nickel concentrations were only slightly elevated among MMA/SS welders, and therefore, the urinary nickel determinations do not reflect the level of exposure to nickel compounds. The measured average remanent magnetic field of the chest area correlated well (P < 0.01) with the use of the MMA technique. A very significant correlation (P < 0.001) existed between the average remanent magnetic fields of the chest and the urinary chromium values of MMA/SS welders.     

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).     

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.     

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.     

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.     

Respiratory symptoms and pulmonary function among welders working with aluminum, stainless steel and railroad tracks

Sixty-four aluminum welders, 46 stainless steel welders, and 149 railroad track welders were investigated regarding respiratory symptoms and pulmonary function (forced vital capacity and forced expiratory volume in 1 s). Referents consisted of nonwelding industrial workers and railroad workers. All groups of welders showed a higher frequency of chronic bronchitis symptoms than their respective referents. Respiratory symptoms were related to ozone concentrations in welders working with aluminum. In stainless steel and railroad track welders respiratory symptoms were related to chromium exposure rather than to total particle exposure. The pulmonary function was not affected in any of the welding groups studied.     

No cytogenetic effects in lymphocytes of stainless steel welders

In 24 manual metal arc stainless steel welders (means: exposure time 19 years, 100 electrodes/d, air chromium level 81 micrograms/m3, urinary chromium 47 mumol/mol creatinine) and 24 matched referents, lymphocytes in peripheral blood were analyzed for cytogenetic effects. No statistically significant differences were observed as to frequency of cells with breaks and fragments (1.5% for the welders, 1.9% for the referents); gaps and isogaps (1.8 vs 2.0%); interchanges, dicentrics, rings and markers (0.8 vs 0.5%); total number of cells with structural aberrations (4.1 vs 4.4%); hyperdiploidy (0.3 vs 0.2%); or total number of cells with aberrations (4.4 vs 4.6%). Neither were there any differences in the frequencies of micronuclei (7.8 vs 7.9 per mille) or sister chromatid exchanges (11 vs 12 per cell) in lymphocytes of peripheral blood.