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 in welders before and after three weeks of non-exposure.

In a cross sectional field study concerning the male reproductive system in metalworkers, the major findings were a moderate deterioration of semen quality in mild steel welders and less reliable changes in semen quality in low exposed stainless steel welders. In the present study, a longitudinal design was adopted to deal with methodological drawbacks inherent in the cross sectional approach. The study relies on the assumption that the effect of welding is causal and reversible. The semen quality of 19 mild steel welders, 18 stainless steel welders and 16 non-welding metal-workers, was examined before and three, five, and eight weeks after a three week break in exposure (summer vacation). No consistent improvement in any semen parameter in the follow up period relative to the prevacation period was found in either mild steel or stainless steel welders. The results indicate either a non-causal nature of reported associations between welding exposure and poor semen quality, or that the effect of welding is non-reversible within the rather short non-exposure period.     

Semen quality in welders before and after three weeks of non-exposure

In a cross sectional field study concerning the male reproductive system in metalworkers, the major findings were a moderate deterioration of semen quality in mild steel welders and less reliable changes in semen quality in low exposed stainless steel welders. In the present study, a longitudinal design was adopted to deal with methodological drawbacks inherent in the cross sectional approach. The study relies on the assumption that the effect of welding is causal and reversible. The semen quality of 19 mild steel welders, 18 stainless steel welders and 16 non-welding metal-workers, was examined before and three, five, and eight weeks after a three week break in exposure (summer vacation). No consistent improvement in any semen parameter in the follow up period relative to the prevacation period was found in either mild steel or stainless steel welders. The results indicate either a non-causal nature of reported associations between welding exposure and poor semen quality, or that the effect of welding is non-reversible within the rather short non-exposure period.     

Respiratory impairment and metal exposure in a group of 68 industrial welders

A group of 68 currently employed welders were examined who were exposed to welding fumes either for the whole or for at least half the working day and who used at least two welding processes, which were mainly manual metal arc welding and metal active gas welding, but also metal and tungsten inert gas welding, or oxyacetylene welding. The welders were classified into 3 groups according to the class of materials used, i.e.: 1) only mild and stainless steel; 2) mild and stainless steel and other metals; 3) only other metals. Chronic bronchitis symptoms were observed in 22% of the subjects; signs of suspected radiological fibrosis were present in 18%, initial signs of radiological fibrosis in 4%. Small airway disease was prevalent in the smokers (28 smokers versus 2 nonsmokers); one worker had an obstructive syndrome and another a restrictive syndrome (both were smokers). There was a good correlation between years of exposure and: 1) MEF25 in non-smokers; 2) urinary cobalt in the whole group. There was also a correlation between smoking and FEV1, MEF50, MEF25, PaO2 and urinary cadmium. Serum copper was higher in workers exposed full time than in those exposed part time. Urinary chromium and cobalt and serum copper were high in steel welders, lower in welders using steel and other metals and low in welders using other metals. Urinary chromium was similar in smokers and non-smokers. Serum zinc was found to be of little use for biological monitoring of welders. Urinary chromium was studied for one week in 10 full-time exposed steel welders. The difference between the chromium values at the end of the workshift and those at the beginning was small (low current exposure); the chromium values at the end of the workshift were not uniform in the whole group (different past exposure levels).     

Erythrocyte antioxidant system and serum ceruloplasmin levels in welders

Summary The erythrocyte antioxidant system (superoxide dismutase, catalase, glutathione peroxidase, reduced glutathione) and serum ceruloplasmin were studied in workers chronically exposed to welding fumes and gases, which are thought to be oxidant pollutants. Fifty-four healthy men using two electric arc welding processes (manual metal arc on stainless steel and mild steel, and metal inert gas on mild steel) were studied. The possible effects of cigarette smoking were also considered. The erythrocyte antioxidant system was in the normal range for all welders. Serum ceruloplasmin was significantly enhanced only in smoking welders and higher in manual metal arc than in metal inert gas welders, suggesting that the increase is related to the severity of the oxidant threat, which is more stressful for the workers using the manual metal arc technique because of the presence of stainless steel particles in the fumes. Although cigarette smoking alone did not increase serum ceruloplasmin levels, it affected the response to oxidant stress in welders.     

Risk of lung cancer according to mild steel and stainless steel welding

OBJECTIVES: Whether the elevated risk of lung cancer observed among welders is caused by welding emissions or by confounding from smoking or asbestos exposure is still not resolved. This question was addressed in a cohort with a long follow-up and quantified estimates of individual exposure to welding fume particulates. METHODS: Male metal workers employed at least 1 year at one or more Danish stainless or mild steel industrial companies from 1964 through 1984 were enrolled in a cohort. Data on occupational and smoking history were obtained by questionnaire in 1986. Welders in the cohort who started welding in 1960 or later (N=4539) were followed from April 1968 until December 2003, when information on cancer diagnosis was obtained from the Danish Cancer Registry. During the follow-up, 75 cases of primary lung cancer were identified. Lifetime accumulated exposure to welding fume particulates was estimated by combining questionnaire information and more than 1000 welding-process-specific measurements of fume particulates in the Danish welding industry. RESULTS: The standardized incidence ratio (SIR) for lung cancer was increased among the welders [SIR 1.35, 95% confidence interval (95% CI) 1.06-1.70)]. Among the stainless steel welders, the risk increased significantly with increasing accumulative welding particulate exposure, while no exposure-response relation was found for mild steel welders, even after adjustment for tobacco smoking and asbestos exposure. CONCLUSIONS: The study corroborates earlier findings that welders have an increased risk of lung cancer. While exposure-response relations indicate carcinogenic effects related to stainless steel welding, it is still unresolved whether the mild steel welding process carries a carcinogenic risk.     

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.     

Semen quality and reproductive hormones among welders —A preliminary study

Objectives Welders are exposed to intense heat, toxic metals and their oxides and toxic gases during welding, and some of these substances reported to have adverse effects on reproductive organs. Thus, the present study was planned to investigate the sperm quality as well as reproductive hormones among welders exposed to a complex mixture of pollutants. Methods Seventeen welders aged 43.8±12.0 (mean±SD) years with welding exposure of 1 to 10 years or more participated in this study. They were performing are and gas welding in a workshop. Blood (5–6 ml) and semen samples by masturbation were collected from them. Serum was separated and analyzed for reproductive hormones by RIA techniques. Semen was processed for microscopic examination. Results The results of this study indicated that sperm concentration was in the normal range (≥20 million/ml) in all seventeen welders, however, motility, morphology as well as Hypo Osmotic Swelling test (HOS) demonstrated impairment in few welders, indicating deterioration in sperm quality compared to the reported normal reference value. Compared with the normal value of hormones provided in diagnostic kits brochure, follicle stimulating hormone (FSH), leutinizing hormone (LH) and testosterone levels were in the normal range, except in two subjects who showed higher FSH and LH levels and one who showed a lower value of testosterone. Conclusions This study suggests that welding might have had some adverse effects on sperm motility, morphology and physiologic function even though sperm concentration was in the normal range. Hormonal changes did not show any definite pattern, indicating a need for further study.     

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.     

Thorium-232 exposure during tungsten inert gas arc welding and electrode sharpening

To assess the exposure of welders to thorium-232 (232Th) during tungsten inert gas arc (TIG) welding, airborne concentrations of 232Th in the breathing zone of the welder and background levels were measured. The radioactive concentrations were 1.11 x 10(-2) Bq/m3 during TIG welding of aluminum (TIG/Al), 1.78 x 10(-4) Bq/m3 during TIG welding of stainless steel (TIG/SS), and 1.93 x 10(-1) Bq/m3 during electrode sharpening, with 5.82 x 10(-5) Bq/m3 background concentration. Although the annual intake of 232Th estimated using these values did not exceed the annual limit intake (ALI, 1.6 x 10(2) Bq), we recommend reducing 232Th exposure by substituting thoriated electrodes with a thorium-free electrodes, setting up local ventilation systems, and by using respiratory protective equipment. It is also necessary to inform workers that thoriated tungsten electrodes contain radioactive material.     

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.     

Semen quality in welders exposed to radiant heat.

Several studies suggest that welding is detrimental to the male reproductive system. Welding fume and radiant heat are of interest as possible causal factors. This study investigates semen quality and sex hormone concentrations among 17 manual metal arc alloyed steel welders with a moderate exposure to radiant heat (globe temperature ranging from 31.1 degrees to 44.8 degrees C), but without substantial exposure to welding fume toxicants. During exposure to heat the skin temperature in the groin increased on average by 1.4 degrees C (SE +/- 0.72 degrees C). Sperm count and motile sperm count were non-significantly reduced among welders in comparison with two different reference groups. Within the group of welders the proportion of sperm with normal shape declined significantly after six weeks of exposure to heat and increased after a break in exposure. Sperm count and sperm concentration had the same pattern of intraindividual change in relation to exposure to radiant heat, but the changes were not statistically significant. No consistent changes in concentrations of sex hormones were found. The welders investigated were more exposed to radiant heat than welders in general. The results suggest that the study group of welders experienced a reversible decrease in semen quality, most likely caused by a moderate exposure to radiant heat (about five hours a day through several weeks). It remains to be established if even lower levels of exposure to radiant heat in the general population of welders has any impact on semen quality and fertility.     

Acute respiratory effects of exposure to stainless steel and mild steel welding fumes

Over the past few years, many studies, including one on our previous work, have examined the chronic effects of fumes from stainless steel (SS) welding on the health of welders. These chronic effects have been related to concentrations of chromium and nickel in SS welding fumes. The present study examined the acute respiratory effects of welding fumes in the workplace by measuring the across-shift changes in a population of 144 SS and mild steel (MS) welders and 223 controls. Manual Metal Arc, Metal Inert Gas, and Tungsten Inert Gas welding processes were studied. Pulmonary function tests were performed at the start (ante, or A) and at the end (post, or P) of the work shift. The study of sensitization to harmful respiratory effects of welding was based on the study of the (P-A)/A ratio (%) of the spirometric variations during the shift. The means of these ratios in the control subjects were used to account for the circadian effect. In SS welders we observed a significant decrease in forced vital capacity (FVC) during the shift. Significant across-shift decrements in forced expiratory volume in 1 second (FEV1) and FVC were related to the SS welding exposure compared with MS welding. Moreover, the across-shift decreases in FEV1, FVC, and peak expiratory flow (PEF) were significantly related to the Manual Metal Arc welding process, compared with Metal Inert Gas techniques (respectively, PEF = -2.7% of baseline values [SD, 11.9] vs 2.0% of baseline values [SD, 7.7] P = 0.04; FVC = -1.5% of baseline values [SD, 4.8] vs 0.2% of baseline values [SD, 4.5] P = 0.05). We also demonstrated the influence of duration of SS welding exposure on the course of lung function during the work shift. After 20 years of SS welding activity, SS welders had more significant across-shift decreases than MS welders with a similar MS exposure duration (respectively, FEV1 = -2.7% of baseline values [SD, 5.9] vs 0.7% of baseline values [SD, 4.2] P = 0.008; PEF = -3.8% of baseline values [SD, 9.6] vs 2.3% of baseline values [SD, 6.5] P = 0.04). We concluded that welding-related lung function responses are seen in SS compared with MS welders and in those with a longer lifetime welding history.     

Semen quality in welders exposed to radiant heat.

Several studies suggest that welding is detrimental to the male reproductive system. Welding fume and radiant heat are of interest as possible causal factors. This study investigates semen quality and sex hormone concentrations among 17 manual metal arc alloyed steel welders with a moderate exposure to radiant heat (globe temperature ranging from 31.1 degrees to 44.8 degrees C), but without substantial exposure to welding fume toxicants. During exposure to heat the skin temperature in the groin increased on average by 1.4 degrees C (SE +/- 0.72 degrees C). Sperm count and motile sperm count were non-significantly reduced among welders in comparison with two different reference groups. Within the group of welders the proportion of sperm with normal shape declined significantly after six weeks of exposure to heat and increased after a break in exposure. Sperm count and sperm concentration had the same pattern of intraindividual change in relation to exposure to radiant heat, but the changes were not statistically significant. No consistent changes in concentrations of sex hormones were found. The welders investigated were more exposed to radiant heat than welders in general. The results suggest that the study group of welders experienced a reversible decrease in semen quality, most likely caused by a moderate exposure to radiant heat (about five hours a day through several weeks). It remains to be established if even lower levels of exposure to radiant heat in the general population of welders has any impact on semen quality and fertility.     

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.     

Risk for reduced sperm quality among metal workers, with special reference to welders

The purpose of this study was to investigate whether men employed in the metal industry have sperm of poorer quality than men in other types of work. A postal questionnaire was sent to men employed in the metal industry, certain other types of nonmetal industries, and other types of employment in which the factors suspected to influence sperm quality were not present. By means of this questionnaire survey, it was hoped to define the possible influences of the work environment on sperm quality. Out of the total of 3,119 men included in the investigation, 2,517 (81%) filled out the questionnaire satisfactorily. Semen analysis was performed for all 3,119 men. There was a greater risk for poor sperm quality among welders than among men not employed in welding. The risk for poor sperm quality was increased for those welders who worked with stainless steel. Welding in general, and specifically with stainless steel, is connected with a risk of reduced sperm quality.     

Fertility among Danish male welders

Welding may be detrimental to the male reproductive system. Fertility was examined in a Danish cohort of 3702 male metalworkers over a follow-up of 47 674 person-years. Occupational histories were gathered by postal questionnaires. Information on births was obtained by record linkage to the Danish Central Population Register. Among persons who had ever worked as welders, the probability of having a child was slightly reduced the year after a year of welding exposure, even after control for differences in age, birth cohort, paternal parity, birth of a child in the preceding five years, smoking, and consumption of alcoholic beverages (odds ratio 0.89, 95% confidence interval 0.83-0.97). The reduction in fertility was associated with the welding of mild steel, but not with the welding of stainless steel. These findings are consistent with results of previous studies of time to conception and semen quality in welders.     

Modelling of exposure to respirable and inhalable welding fumes at German workplaces

Abstract

The International Agency for Research on Cancer classified welding fumes as carcinogenic to humans, and occupational exposure limits should be established to protect welders. The aim of this study is to estimate exposure levels to inhalable and respirable welding fumes by welding process to use them for exposure assessment in epidemiological studies and to derive occupational exposure limits. In total, 15,473 mass concentrations of inhalable and 9,161 concentrations of respirable welding fumes could be analyzed along with welding-related and sampling information, which were compiled in the German database MEGA between 1983 and 2016. In both particle-size fractions, model-based geometric means of the concentrations were estimated by welding process and material for frequently used welding processes adjusted for sampling time and median-centered for calendar years. The inhalable concentrations were approximately twice the respirable concentrations, with medians of 3?mg/m³ (inter-quartile range: 1.2–7.0?mg/m³) and 1.5?mg/m³ (inter-quartile range: < limit of detection ?3.8?mg/m³), respectively. The adjusted geometric means of flux-cored arc welding, metal inert and active gas welding, shielded metal arc welding and torch cutting ranged from 0.9 to 2.2?mg/m³ for respirable welding fumes and from 2.3 to 4.7?mg/m³ for inhalable fumes. In both particle-size fractions, geometric means were between 0.1 and 0.9?mg/m³ when performing tungsten inert gas, autogeneous, resistance, laser, and plasma welding or spraying. Results derived from this large dataset are useful for a quantitative exposure assessment to estimate health risks of welders.     

Relation between various chromium compounds and some other elements in fumes from manual metal arc stainless steel welding.

For the years 1987-1990 160 individual samples of manual metal arc stainless steel (MMA/SS) welding fumes from the breathing zone of welders in four industrial plants were collected. Concentrations of soluble and insoluble chromium (Cr) III and Cr VI compounds as well as of some other welding fume elements (Fe, Mn, Ni, F) were determined. Concentration of welding fumes in the breathing zone ranged from 0.2 to 23.4 mg/m3. Total Cr amounted to 0.005-0.991 mg/m3 (including 0.005-0.842 mg/m3 Cr VI). Total Cr content of fumes varied from 0.1 to 7.4%. The distribution of particular Cr compounds was: 52.6% soluble Cr (including 50.7% Cr VI), 65.5% total Cr VI, and 11.4% insoluble Cr VI. The results obtained indicate that MMA/SS welding is a process that could be highly hazardous to human health. Evaluation of occupational exposure has shown that MMA/SS welders may exceed the admissible concentrations of soluble and insoluble Cr VI forms as well as of Mn and Ni. In the plants investigated the sum of the ratios of concentrations of particular welding fumes in the breathing zone of welders exceeded corresponding maximum allowable concentration values by 24 times (including 17 times for total Cr VI). Due to the variety and changeability of particular parameters occurring in the working environment, the composition of MMA/SS welding fumes (in the welder's breathing zone) is so variable that it is not possible to assess the exposure by means of one universal exposure indicator (maximum additive hygienic limit value). The evaluation should be based on the results of measurements of concentrations of particular elements in welding fumes.