Search PubMed⌕ Search

SEARCH · Search PubMed

Results for “WELDING”

Search indexed PubMed citations on genomics, clinical trials, systematic reviews and public health. Explore titles, authors and supplied subject terms, then open the PubMed record.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 1,603 records · Page 89Linked to original sources
PubMed1999

Prevalence of elevated blood leads and exposure to lead in construction trades in Iowa and Illinois.

BACKGROUND: Despite lowering of the permissible exposure level for lead in construction from 200 to 50 microg/m3 in 1993, excessive lead exposure continues to be a problem. Relatively little data are available from the Midwestern U.S. on the environmental lead concentrations generated during various construction activities and the potential for worker exposure. This study characterized the prevalence of blood lead concentrations in high-risk construction trades in Iowa/Illinois, and identified risk factors for occupational exposure to lead in these construction workers. METHODS: A sample of 459 workers was selected from the total population of all union members from trade groups of painters, plumbers/pipefitters, ironworkers, laborers, and electricians. Participants completed an interviewer-administered questionnaire obtaining information on demographics, symptoms, occupational history, work practices, personal protective equipment, and training. Venous blood samples were collected from each participant and analyzed for blood lead (using atomic absorption spectroscopy) and free erythrocyte protoporphyrin levels. RESULTS: Blood lead levels (BLLs) of construction workers ranged from 0.1 to 50 microg/dL. Geometric mean blood lead concentrations by trade group were: laborers (7.6 microg/dL, n = 80); painters (5.9 microg/dL, n = 83); ironworkers (5.2 microg/dL, n = 87); plumbers (4.4 microg/dL, n = 82); electricians (2.4 microg/dL, n = 91). Blood lead levels for painters and laborers were significantly higher than other trade groups, and levels for electricians were significantly lower (p < 0. 01). Participants reported working primarily on commercial and industrial projects including new construction, renovation, and demolition. There were significant differences between the types of projects performed by different trade groups with laborers performing more highway/bridge renovation (p < 0.01), and plumbers reporting more residential remodeling (p = 0.05), repair of water lines containing lead (p = 0.04), or work on lead joints (p < 0.01). In addition to trade, elevated blood lead levels were associated with the type of construction project (especially bridge renovation and residential remodeling) and activities that include welding, cutting, rivet busting. The age of the home in which the worker lived, and hobbies such as casting/smelting lead for bullets or sinkers, were also important risk factors. Compliance with OSHA's Construction Lead Standard, and implementation of good occupational health and safety practices in general, was poor. CONCLUSIONS: Blood lead levels of 459 construction workers differed by the type of trade, type of project and specific job activity owing to differences in the inherent exposure potential of each task. Although the numbers of workers performing lead abatement projects were small, the trend for lower BLL in this group provides evidence that training, implementation of engineering controls, and proper use of personal protective equipment such as respirators is effective in controlling lead poisoning.

Adult↗
PubMed1997

Coronary AVE micro stents: serial quantitative angiography and histology in a canine model.

The AVE Micro Stent (AVE Inc., Santa Rosa, CA) is composed of helically welded 3 mm long, zigzag crowns with stent lengths from 6 to 39 mm and diameters from 2.5 to 4.5 mm. Quantitative coronary angiography and histologic analyses of acute and chronic implantation were obtained in 52 stented coronary segments of 18 dogs. Three hearts with 8 stented coronary segments were harvested after 24 hr, 3 hearts with 9 stented segments were harvested after 2 weeks, 6 hearts with 15 stented segments were harvested at 8 weeks, and 6 hearts with 20 stented segments were harvested at 24 weeks post-deployment. There were no procedural complications, deaths, or acute vessel closures. The average lumen diameter of the stented segment was largest at 2 weeks (3.3 +/- 0.3 mm). The smallest average diameters were observed at 8 weeks after the stent deployment (2.7 +/- 0.4, P < 0.05) with an increase again at 24 weeks (2.9 +/- 0.6). The pre-explant percent of stenosis was <30% in all animals. Histologically, a peak of inflammation was visible at 2 weeks; however, the extent of luminal narrowing reached its peak at 8 weeks and the lumen dimension increased somewhat at 24 weeks. The degree of intimal thickening remained relatively constant throughout the different time points (<200 microm). Overall, these data suggest that constrictive remodeling within the stented segment occurs at 8 weeks in this animal model. The later increase of the stented segment dimensions as well as higher net gain at 24 weeks compared to 8 weeks after deployment suggests that this constriction is a transitory phenomenon.

Angioplasty, Balloon, Coronary↗
PubMed1999

Corrosion testing of stents: a novel fixture to hold entire device in deployed form and finish.

Stainless steel and nickel-titanium alloy stents for cardiac, biliary, and prostatic clinical applications may be susceptible to loss of mechanical integrity/failure due to their small size and unique geometry. Because their corrosion behavior is a critical aspect of their biocompatibility, it is necessary to test such devices for corrosion behavior using a final deployed form and finish condition. Welding wire leads or holding with metallic clips can result in surface variability or damage to the stents. A novel fixture to hold stents for corrosion testing was designed and evaluated in this study. This fixture design minimally influenced the properties of stents, and also facilitated easy removal post-testing for other types of characterization.

Alloys↗
PubMedDate not supplied

Closed hollow-fiber bioreactor: a new approach to retroviral vector production.

BACKGROUND: The ability to obtain high-titer and large quantities of retroviral vector production in a 'closed' system would have profound implications in clinical and experimental gene therapy. METHODS: We studied the cell growth and vector production of three retroviral packaging cell lines in a variety of conditions using hollow-fiber bioreactors designed as an 'artificial capillary system' (ACS) and enhanced with the application of a hermetically sealing device for sterile welding of connecting plastic tubings. Vector titer, fetal bovine serum (FBS) concentration, volume and the duration of productivity were assessed to optimize vector production. RESULTS: In this pilot study, we observed that retroviral vector production (frozen-and-thawed) from cultures containing as low as 2.5% FBS yielded titers up to 2.2 x 10(7) cfu/ml, 14.4-fold higher than titers obtained from control dish cultures. Up to 3 liters of vector supernatant were generated during a 2-month large-scale production run. There was a potential to double this volume of higher-titer supernatant by increasing the frequency of harvest. It seemed that a lower metabolic rate (i.e. lactate production) in the packaging cell culture was associated with higher vector producing ability. CONCLUSIONS: These data demonstrated the feasibility of producing retroviral vector with enhanced titers and clinically useful quantities in a 'closed' ACS. Thus a new approach for large-scale retroviral vector production is developed.

Animals↗
PubMed1989

A case-control study of risk factors for hepatoblastoma. A report from the Childrens Cancer Study Group.

Parents of 75 children with hepatoblastoma, registered with the Childrens Cancer Study Group, and 75 age-matched controls, who had been identified through random digit dialing were interviewed. No evidence was found to support the primary study hypotheses relating to hepatitis infection, maternal estrogen exposure, alcohol consumption, smoking, or potential sources of nitrosamines. Case mothers were more likely to report occupational exposure to metals (odds ratio [OR] = 8.0, P = 0.01), petroleum products (OR = 3.7, P = 0.03), and paints or pigments (OR = 3.7, P = 0.05). Metal exposures were commonly to welding or soldering fumes, and most occurred daily, before and during the index pregnancy. Petroleum product exposures were predominantly to lubricating oils or protective greases. The only significant paternal exposure was to metals (OR = 3.0, P = 0.01) and the risk with exposure to petroleum products was marginally significant (OR = 1.9, P = 0.06). These findings provide further evidence that occupational exposures may increase the risk of cancer in offspring.

Adult↗
PubMed2001

A historical cohort mortality study among shipyard workers in Genoa, Italy.

BACKGROUND: A historical cohort mortality study was conducted among 3984 shipyard workers assigned to ship repair, refitting, and construction in the harbor of Genoa, Italy, between 1960 and 1981. These workers were exposed to asbestos fibers, welding fumes and gases, silica dust, polycyclic aromatic hydrocarbons, and solvents. METHODS: Workers were classified in 20 different job-titles depending upon the type of activity. Standardized mortality ratios (SMRs) were computed using male residents of the Province of Genoa as the referent population. RESULTS AND CONCLUSIONS: For the whole cohort significantly increased SMRs were detected for all causes, all cancers, liver, larynx, lung, pleural and bladder cancers, respiratory tract diseases, and cirrhosis of the liver. The analysis by job-title showed increased SMRs not only for pleural cancer, but also for lung, laryngeal cancers and respiratory tract diseases in occupations entailing heavy asbestos exposure. Bladder and liver cancers and liver cirrhosis mortality also appeared to be related to occupational exposure.

Adult↗
PubMed2005

Urinary metal and polycyclic aromatic hydrocarbon biomarkers in boilermakers exposed to metal fume and residual oil fly ash.

BACKGROUND: Boilermakers are occupationally exposed to known carcinogens. METHODS: The association of urinary 1-hydroxy-pyrene (1-OHP), a biomarker of polycyclic aromatic hydrocarbon (PAH) exposure, with biomarkers of metal exposure (vanadium, chromium, manganese, nickel, copper, and lead) in boilermakers exposed to metal fume from welding and dust particulates from residual oil fly ash (ROFA) was examined. A repeated measures cohort study was conducted during the overhaul of an oil-fired boiler. Twice-daily urine samples were obtained for 5 days and analyzed for cotinine, 1-OHP, and metals. Generalized estimating equations (GEE) were used to model the multivariate relationship of 1-OHP to the explanatory variables. RESULTS: Metal and 1-OHP levels were determined for 165 urine samples from 20 boilermakers and these levels increased during the workweek. However, the 1-OHP level was not significantly associated with any individual metal level at any time point. CONCLUSION: This suggests that boilermakers were occupationally exposed to PAH and metals, but 1-OHP as a PAH biomarker was unable to serve as a surrogate marker of metal exposure for the metals measured in this study.

Adolescent↗
PubMed2006

Immunotoxic effects of chemicals: A matrix for occupational and environmental epidemiological studies.

BACKGROUND: Many biological and chemical agents have the capacity to alter the way the immune system functions in human and animals. This study evaluates the immunotoxicity of 20 substances used widely in work environments. METHODS: A systematic literature search on the immunotoxicity of 20 chemicals was performed. The first step was to review literature on immunotoxicity testing and testing schemes adopted for establishing immunotoxicity in humans. The second step consisted of providing a documentation on immunotoxicity of substances that are widely used in work environment, by building tables for each chemical of interest (benzene, trichloroethylene, PAHs, crystalline silica, diesel exhausts, welding fumes, asbestos, styrene, formaldehyde, toluene, vinyl chloride monomer, tetrachloroethylene, chlorophenols, 1,3-butadiene, mineral oils, P-dichlorobenzene, dichloromethane, xylene, 1,1,1-trichloroethane, ethylene oxide). The third step was the classification of substances; an index (strong, intermediate, weak, nil) was assigned on the basis of the evidence of toxicity and type of immunotoxic effects (immunosuppression, autoimmunity, hypersensitivity) on the basis of the immune responses. Finally substances were assigned a score of immunotoxic power. RESULTS: Tables have been produced that include information for the 20 substances of interest, based on 227 animal studies and 94 human studies. Each substance was assigned an index of immunotoxic evidence, a score of immunotoxic power and type of immunotoxic effect. CONCLUSIONS: This matrix can represent a tool to identify chemicals with similar properties concerning the toxicity for the immune system, and to interpret epidemiological studies on immune-related diseases.

Animals↗
PubMed1983

Cadmium induced metal fume fever: results of inhalation challenge.

Inhalation challenges were performed on a patient who had developed symptoms of metal fume fever, after six years of welding. Vital signs, white blood cell count and differential, nasal smears, chest X-ray, and pulmonary function tests were monitored during each inhalation challenge. There was no significant reaction to methylcholine, or to fumes of zinc, copper, and mild steel. Significant restrictive ventilatory impairment, leucocytosis, fever, and symptoms of metal fume fever were noticed after exposure to fumes of silver solder containing twenty four percent cadmium.

Adult↗
PubMed1985

Safety and health in boatbuilding and repair.

Boatbuilding is a complex, chemically intensive industry which employs approximately 43,000 workers in the United States, 77% of them in shops with fewer than 20 workers. Boatbuilders and repairers are at high risk of occupational injury from falls, lacerations, low back trauma, repetitive motion, noise, burns, fires, and explosions. Also they are at risk of acute and chronic illness, including dermatitis, toxic hepatitis, peripheral neuropathy, and chronic encephalopathy as a result of their occupational exposures to such materials as styrene, resins, solvents, paints, welding fumes, and coating systems. Boatbuilders also are exposed to toxic woods and to lead. Hazard recognition is the first step toward reduction of injury and disease in boat building. Control of recognized hazards is achieved through engineering controls, ventilation in particular, and through medical surveillance. Strong programs for injury prevention and for health and safety education will produce significant health and economic benefit in the boatbuilding industry.

Accidents, Occupational↗
PubMed1987

Proportionate mortality ratio analysis of automobile mechanics and gasoline service station workers in New Hampshire.

A proportionate mortality ratio (PMR) analysis of all deaths recorded from 1975 to 1985 among New Hampshire white male residents (age 20 years or older) was performed using death certificate information. Among automobile mechanics, the analysis revealed increases in mortality from leukemia (PMR = 178, N = 6); cancers of the oral cavity (PMR = 163, N = 4), lung (PMR = 112, N = 36), bladder (PMR = 169, N = 5), rectum (PMR = 182, N = 4), and lymphatic tissues (PMR = 200, N = 6); and cirrhosis of the liver (PMR = 140, N = 13) and suicide (PMR = 177, N = 22; p less than 0.05). Workers in the gasoline service station industry experienced a leukemia mortality excess (PMR = 328, N = 3; p less than 0.05) as well as increases in deaths from suicide (PMR = 162, N = 4), emphysema (PMR = 245, N = 4), and mental and psychoneurotic conditions (PMR = 394, N = 3). These workers are potentially exposed to a variety of substances including gasoline vapor, benzene, solvents, lubricating oils and greases, and asbestos (from brake and clutch repair) as well as welding fumes and car and truck exhaust. Despite limitations regarding the small number of deaths and methodologic constraints, the results of this analysis suggest that one or more of the exposures experienced by these workers poses a significant carcinogenic risk. More definitive epidemiologic studies are required to determine if the leukemia excess is associated with exposure to benzene, gasoline, or other workplace substances.

Adult↗
PubMed1988

Mortality among California highway workers.

Standardized proportional mortality ratios (PMR) were computed for a population of highway workers. Hazards of highway maintenance work include exposure to solvents, herbicides, asphalt and welding fumes, diesel and auto exhaust, asbestos, abrasive dusts, hazardous material spills, and moving motor vehicles. Underlying cause of death was obtained for 1,570 workers who separated from the California Department of Transportation between 1970 and 1983, and who died in California between 1970 and 1983 (inclusive). Among 1,260 white males, the major findings were statistically significant excesses of cancers of digestive organs (PMR = 128), skin (PMR = 218), lymphopoietic cancer (PMR = 157), benign neoplasms (PMR = 343), motor vehicle accidents (PMR = 141), and suicide (PMR = 154). Black males (N = 66) experienced nonsignificant excesses of cancer of the digestive organs (PMR = 191) and arteriosclerotic heart disease (PMR = 143). Among 168 white females, deaths from lung cancer (PMR = 189) and suicide (PMR = 215) were elevated. White male retirees, a subgroup with 5 or more years of service, experienced excess mortality due to cancers of the colon (PMR = 245), skin (PMR = 738), brain (PMR = 556), and lymphosarcomas and reticulosarcomas (PMR = 514). Deaths from external causes (PMR = 135) and cirrhosis of the liver (PMR = 229) were elevated among white males with a last job in landscape maintenance. White males whose last job was highway maintenance experienced a deficit in mortality from circulatory diseases (PMR = 83) and excess mortality from emphysema (PMR = 250) and motor vehicle accidents (PMR = 196). Further epidemiologic and industrial hygiene studies are needed to confirm the apparent excess mortality and to quantify occupational and nonoccupational exposures. However, reduction of recognized hazards among highway maintenance workers is a prudent precautionary measure.

Accidents, Occupational↗
PubMed1990

Respiratory morbidity of pattern and model makers exposed to wood, plastic, and metal products.

Pattern and model makers are skilled tradespersons who may be exposed to hardwoods, softwoods, phenol-formaldehyde resin-impregnated woods, epoxy and polyester/styrene resin systems, and welding and metal-casting fumes. The relationship of respiratory symptoms (wheezing, chronic bronchitis, dyspnea) and pulmonary function (FVC% predicted, FEV1% predicted, FEV1/FVC% predicted) with interview-derived cumulative exposure estimates to specific workplace agents and to all work with wood, plastic, or metal products was investigated in 751 pattern and model makers in southeast Michigan. In stratified analyses and age- and smoking-adjusted linear and logistic regression models, measures of cumulative wood exposures were associated with decrements in pulmonary function and dyspnea, but not with other symptoms. In similar analyses, measures of cumulative plastic exposures were associated with wheezing, chronic bronchitis, and dyspnea, but not with decrements in pulmonary function. Prior studies of exposure levels among pattern and model makers and of respiratory health effects of specific agents among other occupational groups support the plausibility of wood-related effects more strongly than that of plastic-related effects.

Adult↗
PubMed1991

Alcohol, smoking, and occupational factors in cancer of the larynx: a case-control study.

A hospital-based case-control study of laryngeal cancer was conducted in Bremen in 1986 and 1987 with 100 prevalent male laryngeal cancer patients and 100 male hospital controls with diseases not considered to be related to smoking, alcohol, or occupational exposures, who were frequency matched by age. The odds ratio for heavy smoking (more than 30 pack-years) reached a value of 3.5 (95% confidence limits (CL) 1.1, 7.9). Ex-smokers showed a significant decrease in risk; this reached the level of those who had never smoked about 15 years after smoking cessation. For daily consumers of alcohol an odds ratio of 3.2 (95% CL 1.4, 7.5) was observed. Among the 17 occupations in which at least ten subjects had worked, excess risks were observed for stock keeping and transportation workers, and for leather and textile workers. The odds ratio was significantly increased for the latter (p less than 0.05). Among all those persons ever employed in a priori defined-risk occupations, an odds ratio of 2.74 (95% CL 1.23, 6.06) was observed. Considering responses to an exposure check-list, no increased risks could be shown for exposure to asbestos, coal tar, or welding fumes. On the other hand, excess risks were observed for exposures to diesel oil, gasoline, and mineral oil, controlling for smoking and alcohol. The findings in occupational and exposure subgroups were based on small numbers of cases and controls and, consequently, were subject to large sampling errors. Many of the results are consistent, however, with occupational risk factors reported from other studies.

Adult↗
PubMed1992

Revised estimate of the prevalence of multiple sclerosis in the United States.

Using three adjustments, we have revised a 1976 prevalence count for multiple sclerosis in the United States. The adjustments were made to data from a US national survey; they used 1990 population projections from the US Bureau of the Census, and results of investigations conducted in Weld and Larimer Countries, Colorado, and Olmsted County, Minnesota. It is estimated that approximately 250,000 to 350,000 persons in the United States in 1990 had physician-diagnosed multiple sclerosis.

Age Factors↗
PubMed1983

Current concepts in soft connective tissue wound healing.

The strength and integrity of intact soft connective tissues are related to the forces which exist between collagen fibrils and these in turn appear to depend on collagen fibril size, density and architecture en masse. The genetic type of collagen, enzymic modifications to the collagen monomer and the proteoglycan environment all affect fibril size. Current evidence suggests that the restoration of tissue continuity and the early redevelopment of tissue strength following wounding are initially achieved by the formation of a myofibroblast-reticulin network which eventually disappears as the healing wound ages. The extent of this network defines the area in which repair tissue will be laid down and the network is equipped with the sensory apparatus to monitor the physical and chemical environment where healing is taking place and thus to direct the various facets of connective tissue synthesis outlined above. The maturation of the scar connective tissue matrix and the development of attachment between new and original connective tissues are simultaneous, related but independent processes. It takes some time before the weld is achieved by the same forces that hold connective tissue fibres together in intact tissues and the myofibroblast-reticulin network is replaced.

Animals↗
PubMed1991

Successful mitral valvuloplasty using the Inoue balloon in a patient with mitral stenosis associated with subvalvular fibrosis and reduced left ventricular inflow cavity: a case report.

Percutaneous transvenous mitral valvuloplasty (PTMV) was performed with two cylindric pigtail balloon catheters in a 52-year-old woman with symptomatic mitral stenosis. The subvalvular apparatus was fibrous with welded chordae and the subvalvular left ventricular space was markedly reduced. As a result of this distorted anatomy, during the inflations, the two balloons constantly slipped back into the left atrium before full inflation was obtained. After the procedure, the mitral valve area (MVA), as estimated by echo-doppler (ED), increased from 1.00 to 1.34 cm2. After 2 months of mild clinical improvement, the patient again became symptomatic and ED examination showed a MVA of 1.25 cm2. A second PTMV was performed with an Inoue balloon, the entire procedure taking less than 1 hour. A stable position of the Inoue balloon and complete dilatation were achieved. ED examination showed a mitral valve area of 2.30 cm2. There was no mitral regurgitation nor atrial septal defect. After 3 months, she has only N.Y.H.A. class I symptoms and MVA, as estimated by ED, was 2.40 cm2.

Catheterization↗
PubMed2006

Covalent connection of individualized, neutral, dendronized polymers on a solid substrate using a scanning force microscope.

The synthesis of a neutral, high-molar-mass, acrylamide-based, third-generation dendronized polymer (denpol) with a defined number of azide groups at its periphery is reported. An attach-to route is used in which a first-generation denpol is reacted with second-generation (G2) dendrons. The degree of structure perfection of the resulting denpol is quantified as 99.8 %. This value was obtained after the introduction of a fluorescence label at the sites that remained unaffected by the dendronization. The high coverage was independently confirmed for the dendronization of another first-generation polymer and a closely related G2 dendron. The third-generation denpol resulting from the first dendronization experiment was spin-coated as a sub-monolayer onto highly oriented graphite precoated with an ultrathin layer of C12H25NH2, which was introduced to provide a well-defined substrate for denpol adsorption and manipulation. Scanning force microscopy revealed single denpols, which could be moved across the surface and "welded" by covalent cross-linking induced by photochemical decomposition of the azides into highly reactive nitrenes. The successful formation of covalent bonds between two denpols was confirmed by mechanically challenging the link with the scanning force microscope (SFM) tip. This is the second reported case of a move-connect-prove sequence using polymers and the SFM, which for the first time employs noncharged denpols, thus widening the applicability of this method significantly.

Journal Article↗