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PubMed2002

Control of exposure to hexavalent chromium and ozone in gas metal arc welding of stainless steels by use of a secondary shield gas.

Previous work has demonstrated that the shield gas composition in gas metal arc welding can have a considerable effect on hexavalent chromium [Cr(VI)] concentration in the fume and on ozone concentrations near the arc. Normally a single shield gas is used. This paper describes a double shroud torch that allows used of concentric shield gases of different compositions. A solid stainless steel wire was used for welding. The double shroud torch used secondary shield gases containing small amounts of the reducing agents NO and C2H4. The Cr(VI) concentration in the fume and ozone concentration at a fixed point relative to the arc were measured and compared with results when using a single shield gas. Use of the reducing agents in secondary shielding using the double shroud torch was found to offer advantages for ozone concentration reduction compared with use in a conventional torch, but this was not found to be an advantage for reducing Cr(VI) concentrations.

Chromium↗
PubMed1995

Soft tissue injury in resistance welding.

Electrical resistance welding is commonly used in industries where light sheet metal is bonded. The process uses a combination of heat and pressure to form the weld, which frequently results in the production of high-velocity metal-fragment projectiles. The process is described and case studies are presented to illustrate the nature of the injuries which occasionally result from these missiles. The difficulties in preventing these injuries and potential approaches for doing so are discussed.

Accident Prevention↗
PubMed1985

The management of risk: application to the welding industry.

The management of health risk in the welding industry is considered based on a discussion of the major sources of harm to welders arising from their employment (e.g., accidents and inhalation of fumes and gases). It is shown that present methods neither enable the assessment of the societal and human costs involved, nor permit the specific association of delayed health effects to occupational fume exposures. Reported accidents usually occur early in the working experience and contribute to a large number of working days lost, while fume exposures may contribute to a reduction in life quality which is poorly defined. It is concluded that risk management can only be attempted after much more information is made available concerning the origin, nature, and duration of health effects, especially as related to individual welding technologies and applications.

Accidents, Occupational↗
PubMed1999

Clinical experiences of implant-supported prostheses with laser-welded titanium frameworks in the partially edentulous jaw: a 5-year follow-up study.

BACKGROUND: Titanium frameworks have been used in the endentulous implant patient for the last 10 years. However, knowledge of titanium frameworks for the partially dentate patient is limited. PURPOSE: To report the 5-year clinical performance of implant-supported prostheses with laser-welded titanium frameworks in the partially edentulous jaw. MATERIALS AND METHODS: A consecutive group of 383 partially edentulous patients were, on a routine basis, provided with fixed partial prostheses supported by Brånemark implants in the mandible or maxilla. Besides conventional frameworks in cast gold alloy, 58 patients were provided with titanium frameworks with three different veneering techniques, and clinical and radiographic 5-year data were collected for this group. RESULTS: The overall cumulative survival rate was 95.6% for titanium-framework prostheses and 93.6% for implants. Average bone loss during the follow-up period was 0.4 mm. The most common complications were minor veneering fractures. Loose and fractured implant screw components were fewer than 2%. An observation was that patients on medications for cardiovascular problems may lose more implants than others (p < .05). CONCLUSIONS: The clinical performance of prostheses with implant-supported laser-welded titanium frameworks was similar to that reported for conventional cast frames in partially edentulous jaws. Low-fusing porcelain veneers also showed clinical performance comparable to that reported for conventional porcelain-fused-to-metal techniques.

Adult↗
PubMed1978

The resistance welded stainless steel interface.

The results obtained using single impulse and multiple impulse welds for joining orthodontic band and wire material showed that the single impulse produced an autogenous nugget of fused parent material and several nuggets were formed with the multiple impulse weld. Excessive current was deleterious.

Dental Soldering↗
PubMed1984

Urinary fluoride concentration as an estimator of welding fume exposure from basic electrodes.

Urinary fluoride concentrations have been measured in electric arc welders using basic electrodes. The fluoride concentration and the total welding fume concentration in air showed a linear relation with postshift urinary fluoride concentration. The measured concentrations were below internationally recommended postshift urinary fluoride concentrations believed to cause fluorosis. Biological monitoring by postshift urinary fluoride measurements is evaluated for the prediction of total welding fume exposure, when a specific basic electrode was used, by means of confidence limits and tests of validity.

Adult↗
PubMed1994

Exposure to stainless steel welding fumes and lung cancer: a meta-analysis.

Stainless steel welding is associated with exposure to metals including hexavalent chromium and nickel. This study is a meta-analysis of five studies of stainless steel welders and the occurrence of lung cancer. Asbestos exposure and smoking habits have been taken into account. The calculated pooled relative risk estimate was 1.94 with a 95% confidence interval of 1.28-2.93. This result suggests a causal relation between exposure to stainless steel welding and lung cancer.

Causality↗
PubMed1995

Occupational asthma due to gas metal arc welding on mild steel.

Occupational asthma has been documented in electric arc welders exposed to manual metal arc welding on stainless steel. A subject is described who developed late and dual asthmatic reactions after occupational-type challenge exposure to gas metal arc welding on uncoated mild steel.

Adult↗
PubMed1987

Cancer incidence among welders: possible effects of exposure to extremely low frequency electromagnetic radiation (ELF) and to welding fumes.

Epidemiological studies of cancer incidence among welders disclose a pooled total of 146 cases of leukemia observed versus 159.46 expected, a risk ratio of 0.92, and 40 cases of acute leukemia observed versus 43.39 expected, a risk ratio of 0.92. For respiratory tract cancer, the pooled total is 1789 cases observed versus 1290.7 expected, a risk ratio of 1.39. Most electric welders are exposed to extremely low frequency electromagnetic radiation (ELF) (magnetic flux densities of up to 100,000 microT), a suspected leukemogen, and to concentrated metallic aerosols (up to 200 mg/m3), which can contain the putative respiratory tract carcinogens Cr(VI) and Ni. The two exposures are usually coincident, since welding with an electric current produces welding fumes. The observation of an excess risk for respiratory tract cancer strongly suggests significant exposure both to fumes and to ELF. The absence of increased risk for all leukemia or for acute leukemia among ELF-exposed welders does not support the hypothesis that the observed excess risk for leukemia or acute leukemia among workers in the electrical trades is due to their ELF exposure, which on the average is lower than that of welders.

Air Pollutants, Occupational↗
PubMed2004

Respiratory effects from work-related exposure to welding fumes in Hamadan, Iran.

The authors studied respiratory symptoms and lung function among welders at welding workshops, and among nonwelders, in Hamadan, Iran. They used a questionnaire to record demographic data, smoking habits, and respiratory symptoms. The authors measured pulmonary functions with subjects standing upright. They collected metal fume samples from the respiratory zone of workers and analyzed the samples by atomic absorption spectroscopy. The concentrations of iron and manganese were higher than threshold limit values. The prevalence of asthma and clinical symptoms was higher in welders than nonwelders. Also, bronchitis was more common among welders (17.45%) than among nonwelders (2.56%). The average respiratory function values of welders were lower than those of nonwelders, with a significant difference between the means (p < 0.001 for all terms). The results of this study also strongly suggest a synergistic relationship between the effects of smoking and welding exposure.

Adult↗
PubMed1991

Fever and respiratory symptoms after welding on painted steel.

Electric-arc welding generates particles and gases that can induce chronic bronchitis and airway obstruction. In this case report two welders are described who had fever, spirometric deterioration, and bronchial hyperreactivity after welding steel painted with chloro-containing polymer lacquer. Pyrolysis of this paint releases many different compounds, for example, hydrogen chloride and complex chlorinated compounds.

Air Pollutants, Occupational↗
PubMed1985

Exposure and urinary excretion of aluminum during welding.

The exposure and urinary excretion of aluminum was studied among three previously unexposed volunteers and six welders exposed to welding fumes containing aluminum. The aluminum concentrations in air and urine were determined. The urinary aluminum concentrations rose rapidly in volunteers exposed only for 1 d and returned to the preexposure levels with an estimated half-time of about 8 h. The welders were monitored for one workweek. During the subsequent weekend a decrease in the urinary concentrations occurred in the three welders exposed for two years or less, but such a decrease was not observed among welders exposed for more than 15 years. The urinary concentrations of aluminum were dependent partly on the level of current exposure and partly on the duration of exposure. The data suggest that welders exposed to welding fumes containing aluminum may retain some of the inhaled metal fume for extended periods of time.

Adult↗
PubMed1979

A simple analytical technique for the determination of hexavalent chromium in welding fumes and other complex matrices.

A systematic study of analytical methods for the determination of hexavalent chromium showed that currently existing techniques are unsatisfactory when used with welding fumes, the s-diphenylcarbazide method proposed by the U.S. National Institute for Occupational Safety and Health permitting less than 1% recovery of hexavalent chromium from synthetic welding fumes of known composition. A new (carbonate leaching) technique is proposed which permits better than 80% recovery of both soluble and insoluble chromium (VI). This technique is then used as part of a general method for the determination of total chemical composition as distributed among sample fractions of different solubility. The method is specifically designed for use in the analysis of small samples and is especially suitable for the routine evaluation of health risks as found in the work environment.

Air Pollutants↗
PubMed1975

Effects of a welding helmet and dust respirators on respiration at rest and during exercise.

The influence of welders' protective devices on respiration at rest and during exercise was studied under laboratory conditions. During exercise the devices caused increased ventilation and increased arterial carbon dioxide tension. In the case of the welding helmet the increase was probably a consequence of increased dead space. It is concluded that the physiological affects on respiration are of minor importance in themselves, but they should be taken into account when the degree of exposure to welding fumes is evaluated.

Adult↗
PubMed1995

Male-mediated risk of spontaneous abortion with reference to stainless steel welding.

OBJECTIVES: It was hypothesized that the welding of stainless steel involves a risk of male-mediated developmental toxicity because of exposure to mutagenic substances, including hexavalent chromium. The purpose of the present study was to corroborate or refute earlier findings that spouses of stainless steel welders have an increased risk of spontaneous abortion. METHODS: The occurrence of spontaneous abortion among 2520 pregnancies of spouses of 1715 married metal workers from 1977 through 1987 was examined. Occupational histories were collected with a postal questionnaire in a previous study. Information on children born live, spontaneous abortion, and induced abortion was obtained from national medical registers. RESULTS: The proportion of spontaneous abortions was not increased for pregnancies at risk from stainless steel welding when compared with pregnancies not at risk (odds ratio 0.78, 95% confidence interval 0.55-1.1). The risk estimate was robust to adjustment for potential confounding effects of maternal age and parity and male smoking and alcohol consumption. CONCLUSIONS: This study does not corroborate earlier findings that spouses of stainless steel welders have increased risk of spontaneous abortion. A reanalysis indicated that earlier findings were probably biased because the job exposure of male metal workers is apparently modified by the outcome of their partners' first pregnancy.

Abortion, Spontaneous↗
PubMed2000

[Stress-corrosion test of TIG welded CP-Ti].

In this study TIG (Tungsten Inert Gas) welded CP-Ti were subjected to stress-corrosion test under 261 MPa in artificial saliva of 37 degrees C for 3 months. No significant difference was noted on mechanical test (P > 0.05). No color-changed and no micro-crack on the sample's surface yet. These results indicate that TIG welded CP-Ti offers excellent resistance to stress corrosion.

Biocompatible Materials↗
PubMed2001

[Hygienic regulation of welding aerosols in air of workplace and pneumoconiosis in welders (review of literature)].

The authors represent review of literature on fibrogenic effects of welding aerosols and results of own clinical and epidemiologic studies concerning pneumoconiosis course in electric welders compared to other occupational groups. In conclusion, the authors necessitate more strict control over total concentration of welding aerosol solid component (WASC) in air of workplace and determination of MAC for WASC.

Aerosols↗