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PubMed1995

Maintenance of stellite and tungsten carbide saw tips: respiratory health and exposure-response evaluations.

OBJECTIVE: To study exposure to cobalt and chromium in saw maintenance rooms and test respiratory health among saw filers at lumber mills. Hard-metal lung disease is associated with cobalt in the manufacture of tungsten carbide tools; recently it has also been reported among tool maintenance workers. Lumber mills often use saws tipped with tungsten carbide or with a newer alloy, stellite (containing more cobalt, as well as chromium). METHODS: A cross sectional study of 118 saw filers at eight lumber mills was carried out that included a standardised questionnaire, spirometry, personal air sampling, and examination of tasks every 10 minutes (by observation). Comparison data were from a study of bus mechanics tested with similar methods. RESULTS AND CONCLUSION: Cobalt exposure was associated with tungsten carbide grinding but not with stellite grinding. Chromium exposure was associated mainly with stellite welding. Saw filers had a twofold increase in phlegm and wheeze (P < 0.01) and a threefold increase in cough, phlegm, and wheeze related to work (P < 0.001), but no increase in breathlessness. Stellite welding was associated with a significant increase in nasal symptoms and cough related to work and a small decrease in airflow (forced expiratory volume in one second/forced vital capacity (FEV1/FVC%), P < 0.05). Saw filers wet grinding with tungsten carbide had significant reductions in forced expiratory lung volumes (FEV1 and FVC, P < 0.05) and were significantly more likely to have FEV1 and FVC values in the abnormal range. Cobalt exposure (in wet grinding) and duration of work that involved tungsten carbide grinding were both associated with significant reductions in FEV1 and FVC. Average cobalt exposures in this study were about 5 micrograms/m3, well below the currently accepted permissible concentration, which suggests that the current workplace limit for cobalt may be too high.

Adult↗
PubMed2002

Systemic sclerosis and occupational risk factors: a case-control study.

AIMS: A case-control study was carried out between 1998 and 2000 to investigate the relation between systemic sclerosis and occupational exposure. METHODS: Eighty cases of systemic sclerosis admitted consecutively to the Department of Internal Medicine at the University Hospital of Tours from 1998 to 2000 were included. For each case, two age, gender, and smoking habits matched controls hospitalised during the same period in the same department were selected. A committee of experts was set up retrospectively to assess occupational exposure. Exposure to silica dust and organic solvents (such as trichlorethylene and other chlorinated solvents, and benzene and other aromatic solvents) was investigated using semiquantitative estimates of exposure. An exposure score was calculated for each subject based on probability, intensity, daily frequency, and duration of exposure for each period of employment. The final cumulative exposure score was obtained, taking into account all periods of employment. RESULTS: Significant associations with SS were observed for crystalline silica, trichlorethylene, chlorinated solvents, toluene, aromatic solvents, ketones, white spirit, epoxy resins, and welding fumes. Risk of SS was significantly associated with a high final cumulative exposure score of occupational exposure to crystalline silica, trichlorethylene, chlorinated solvents, welding fumes, and any types of solvents. CONCLUSION: Results confirm the influence of occupational risk factors in the occurrence of SS in both men and women. The link is not only with silica but also with other compounds such as solvents.

Case-Control Studies↗
PubMed1995

Effect of dietary sodium on airways responsiveness and its importance in the epidemiology of asthma: an evaluation in three areas of northern England.

BACKGROUND: Although several investigations have shown a relationship between asthma (or its surrogate, airways responsiveness) and dietary or urinary sodium, others have not, and the matter remains controversial. This "salt effect" has been investigated during two recent epidemiological surveys of men in northern England. The first assessed the possible effect on airways responsiveness of occupational exposure to welding fumes, and the second characterised airways responsiveness in two geographically distinct residential areas. Thus, three separate study areas/populations were involved. METHODS: Investigation 1 involved 1059 shipyard workers aged 16-27 years who were exposed variously to welding fumes, and Investigation 2 involved 587 men aged 20-44 years who lived in rural West Cumbria or in urban Newcastle upon Tyne. In Investigation 1, a 24 hour urine specimen was requested from each subject with quantifiable airways responsiveness (PD20 < or = 6400 micrograms methacholine) and from an equal number of subjects without measurable airways responsiveness from the same occupational subgroup. In Investigation 2, every subject was asked to provide a 24 hour urine specimen. RESULTS: Of the men undergoing methacholine tests, satisfactory 24 hour urine specimens were obtained from 234 (22.1%) in Investigation 1 and 232 (39.5%) in Investigation 2. Analysis using multiple linear regression, multiple linear logistic regression, and multiple regression for censored data produced consistent results within each study population but conflicting results between them, such that there was no hint of a relationship between airways responsiveness and 24 hour urinary sodium excretion in the shipyard workers of Investigation 1 nor in the rural West Cumbrian population of Investigation 2, but an association was found in the urban Newcastle population of Investigation 2. All study populations were sufficiently large to demonstrate anticipated relationships between airways responsiveness and atopy, baseline FEV1, and (Newcastle only) age. CONCLUSIONS: If airways responsiveness is related to dietary sodium the relationship is not likely to be strong.

Adolescent↗
PubMed1998

Effectiveness of eye drops protective against ultraviolet radiation.

BACKGROUND: To test the effectiveness of commercially available ultraviolet (UV)-protective eye drops (8-hydroxy-1-methylchinolinium methylsulphate) which are recommended for protection against both solar and artificial UV radiation. METHODS: The spectral transmission in the wavelength range from 250 to 500 nm was investigated in 1-nm steps using a high-resolution double monochromator with holographic gratings of 2,400 lines/mm and a 1,000-watt halogen lamp as light source. The transmission spectrum was measured for different values of the layer thickness. RESULTS: The transmission of a liquid layer of about 10 microns, which corresponds to the thickness of the human tear film, shows a cut-off at 290 nm with a transmission of about 25-50% at shorter wavelengths. For wavelengths longer than 290 nm the transmission is higher than 90%. The threshold time ratio for keratitis formation with and without eye drops is above 0.93 considering solar radiation on the earth's surface and above 0.65 considering radiation from arc-welding, respectively. DISCUSSION: The transmission spectrum of the eye drops under realistic conditions does not show a protective effect against solar UV radiation. However, there exists reduction of UVC radiation in the spectral range typical of artificial UV sources such as arc-welding. We cannot recommend the application of these eye drops as an UV-protective aid against eye damage by solar UV radiation.

Eye↗
PubMed2002

Evaluation of blue-light hazards from various light sources.

Visible light of short wavelength (blue light) may cause a photochemical injury to the retina, called photoretinitis or blue-light hazard. In this study, various light sources were evaluated for blue-light hazard. These sources include the sun, the arc associated with arc welding and plasma cutting, molten steel, iron and glass, the interior of furnaces, the arc or envelope of discharge lamps, the filament or envelope of incandescent lamps, the envelope of fluorescent lamps and light-emitting diodes. The spectral radiance of each light source was measured, and blue-light effective radiance and the corresponding permissible exposure time per day were calculated in accordance with the ACGIH (American Conference of Governmental Industrial Hygienists) standard. The sun, arc welding, plasma cutting and the arc of discharge lamps were found to have extremely high effective radiances with corresponding permissible exposure times of only 0.6-40 s, suggesting that viewing these light sources is very hazardous to the retina. Other light sources were found to have low effective radiances under the study conditions and would pose no hazard, at least for short exposure times.

Dose-Response Relationship, Radiation↗
PubMedDate not supplied

Fluphenazine and its toxic maculopathy.

Ten years ago a 45-year-old female presented with bilateral maculopathy with visual acuity of 6/18 on the right and 6/24 on the left. She had been on fluphenazine for the past 10 years for schizophrenia. Investigation including fluorescein angiogram, colour vision assessment and electrophysiological testing confirmed the nature of the retinal damages. Her maculopathy deteriorated further despite discontinuation of the medication. A previous publication has reported maculopathy with fluphenazine in association with the welding arc injury, but that particular patient had not been exposed to welding flash or other extreme photochemical sources. We believe this is the first reported incidence that fluphenazine has directly caused a maculopathy secondary to its accumulation at the retinal pigment epithelium and its toxic effect.

Antipsychotic Agents↗
PubMed1985

Comparative study of microepineurial anastomoses with the use of CO2 laser and suture techniques in rat sciatic nerves: Part 1. Surgical technique, nerve action potentials, and morphological studies.

The possibility of utilizing the CO2 laser for neural anastomoses was investigated in a rat sciatic nerve model. One nerve in each animal was acutely divided and anastomosed using 10-0 nylon epineurial sutures, while the opposite side was joined by "welding" the opposed nerve ends together with CO2 laser pulses. The surgical incisions were reexplored 60 days postoperatively, action potentials were recorded across the anastomoses, and the nerves were removed for light and electron microscopy. The operative patency rate in the suture group was 100%, compared to 87% in the laser group. Among those animals with bilaterally intact nerves, action potentials could be recorded across the anastomotic site in 78% of the sutured preparations and in 85% of nerves spot-welded with the CO2 laser. Morphological studies showed a greater degree of scar tissue formation and constriction in the anastomotic zone of the nerves joined by sutures than was present in laser-treated animals. We believe these preliminary observations suggest that the CO2 laser may have a role to play in peripheral nerve surgery. Further study of this technique is warranted.

Action Potentials↗
PubMed1983

Detection by replica plating of false revertant colonies induced in the Salmonella-mammalian microsome assay by hexavalent chromium.

The replica plating method as developed by Lederberg has been used to differentiate between "true" and "false" histidine-requiring revertant bacterial colonies which develop on minimal agar plates in the Ames test. Strains of S. typhimurium LT2, TA 100, when exposed to either sodium dichromate or the fumes from the welding of stainless steel, develop colonies whose apparent numbers are directly in proportion to the Cr(VI) content per plate in both cases, over a wide dose range. Replica impressions of the resulting colonies were transferred to Vogel Bonner minimal agar plates and incubated for 48 hr at 37 degrees C. It was then observed that considerable numbers of "false" revertant colonies were obtained at those Cr(VI) doses which resulted in a pronounced toxic effect, albeit with an acceptable level of the bacterial background lawn. No morphological distinction between "true" and "false" revertant colonies could be made. Although it would appear that at low doses (i.e., low toxicity) the true mutagenicity of stainless steel welding fumes can be completely accounted for by the presence of Cr(VI), the dose range over which the mutagenicity assay is reliable cannot be estimated from examination of the background lawn or from an estimate of the degree of survival of the treated cultures. Thus there is raised a serious question concerning the reliability of quantitative data published in bacterial mutagenicity testing where replica testing of the histidine requirement of the resulting "revertant" colonies is not routinely made. It is suggested that the replica technique can easily be developed as a simple and useful tool for the control of histidine requirement and ampicillin resistance in routine mutagenicity testing.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed2003

Compact effector optics for processing in limited physical access situations.

A major advantage of fiber-optic beam delivery in laser materials processing is the ability to guide the laser power to the location where it is needed, leaving the laser itself remote and protected from the process. This is of special importance if the processing is to be performed in a hazardous environment. Particular problems are faced by the nuclear industry where weld repair and surface treatment work are required inside radioactive installations. By use of fiber beam delivery, only part of the delivery system and effector optics become contaminated, but the expensive laser system does not. However, in many cases the region where repair is required is not only radioactive but has only limited physical access, e.g., inside tubes or into corners, which prevents use of standard effector optics. We present a new design to deal with such constraints of a 2-mm outer diameter employing a hollow waveguide and gas shielding. This design is optically characterized and its performance assessed in welding and surface treatment applications. The potential of this compact effector optics in limited physical access situations is clearly demonstrated.

Journal Article↗
PubMed2006

On-line surveillance of a dynamic process by a moving system based on pulsed digital holographic interferometry.

A method based on pulsed digital holographic interferometry for the measurement of dynamic deformations of a surface by using a moving system is presented. The measuring system may move with a speed of several meters per minute and can measure deformation of the surface with an accuracy of better than 50 nm. The deformation is obtained by comparison of the wavefronts recorded at different times with different laser pulses produced by a Nd:YAG laser. The effect due to the movement of the measuring system is compensated for by digital processing of the different holograms. The system is well suited for on-line surveillance of a dynamic process such as laser welding and friction stir welding. Experimental results are presented, and the advantages of the method are discussed.

Journal Article↗
PubMedDate not supplied

Occupational exposure to ultraviolet radiation: a health risk assessment.

This review applies health risk assessment methodology to the subject of occupational exposure to ultraviolet radiation (UVR). Ultraviolet radiation is produced by many sources, and for most people the sun is their main source of exposure. In the occupational environment, there are also many artificial sources, of which welding arcs are the predominant and most intense. Adverse health effects include photokeratitis, erythema, pterygium, some types of cataract, non-melanocytic skin cancer, and malignant melanoma. Outdoor workers and workers who are exposed to certain artificial sources (particularly welding arcs), frequently are exposed to UVR levels that are above the current exposure limits. Such workers may also be at an additional risk of developing nonmelanocytic skin cancer along with other chronic conditions, including malignant melanoma. A range of control measures is available but nevertheless, many workers (particularly those exposed to solar UVR) do not make full use of these measures. Therefore, the implementation of health education campaigns and other initiatives that encourage use are needed. Overall, although exposure to UVR presents a substantial risk for certain occupations, the current exposure standards and currently available control measures (if used) are considered to provide adequate protection for most workers.

Eye↗
PubMed2002

Immediate loading implants: a clinical report of 1301 implants.

The purpose of this study is to suggest 4 immediate load of implants techniques that are alternative and/or complementary to the traditional submersion technique. These techniques meet the criteria for implant immobilization during the entire period of osteointegration, and are based on the principles of splinting and load sharing. One hundred fifty-three maxillary and 309 mandibular arches were treated with 1301 implants. Only implants that satisfied the primary retention were immediately loaded with a provisional crown with wings (94), provisional plastic prosthesis (478), provisional plastic prosthesis with metal frame (293), and intraoral welding (436). Facies morphology, type of occlusion, size and function of the tongue, bone density, number, and length of implants appeared to have an influence on the results. Success rates achieved over 21 years are 99.3% with the intraoral welding machine, 98.3% with the provisional plastic prosthesis with metal frame, 97.9% with metal wings, and 88.02% with provisional plastic prosthesis. This last percentage is reflective of the years 1974 to 1984 when only blade-forms and root-forms with unscrewable abutments were available and a provisional plastic prosthesis was the only immobilization technique known. Guidelines are proposed for a treatment plan indicating when and why immediate loading implants can be suggested.

Adolescent↗
PubMed1996

A tapered titanium femoral stem inserted without cement in a total hip arthroplasty. Radiographic evaluation and stability.

The results of 416 total hip arthroplasties performed in 372 patients with insertion of a Mallory-Head titanium femoral component without cement were reviewed retrospectively, to determine the stability and the radiographic parameters of stability for this type of stem. The average duration of clinical and radiographic follow-up was 3.7 years (range, 2.0 to 6.5 years). No revisions were performed to treat instability of the stem, pain, or osteolysis by the time of the latest follow-up examination. Although the clinical results were excellent, the radiographic signs of fixation that have been well described for chromium-cobalt stems were frequently absent. So-called endosteal spot welds, commonly seen in association with long, extensively coated stems, were seen infrequently. Resorptive bone-remodeling rarely extended beyond zones 1 and 7 of Gruen et al. Both endosteal and periosteal distal cortical hypertrophy was common, but the cause was unknown. Osteolysis of the distal aspect of the femur, shedding of the porous coating, and breakage of the stem were not seen. Forty-four stems (11 per cent) had initial subsidence; however, it nearly always stabilized within six months postoperatively and did not affect the eventual stability at the time of the short-term follow-up. The short-term clinical outcome confirmed the stability of these stems that had been determined from the radiographic findings and the lack of revisions. At the latest follow-up examination, 323 (87 per cent) of the patients (362 [87 per cent] of the hips) had no or slight pain in the lower limb over-all and only twenty-two (6 per cent) of the patients (twenty-seven [6 per cent] of the hips) had pain in the thigh. This tapered titanium femoral component appears to provide excellent short-term stability, without resorptive bone-remodeling, osteolysis, or a high prevalence of pain in the thigh. Radiographic evaluation of stability of this stem is clearly different from that of chromium-cobalt stems-particularly extensively coated anatomic medullary locking stems-in that so-called spot welds and severe resorptive bone changes were uncommon and distal cortical hypertrophy was common.

Adolescent↗
PubMed2002

Successful experiences with a handy equipment to measure dust concentrations in various workplaces.

Performance of a direct-reading handy equipment for dust counting in workroom air, PDR (MIE, USA), was field-tested in comparison with the results of low-volume air sampling-gravimetry. Application in 64 workplaces of various type dust work with dust concentrations of up to 1.6 mg/m3 showed that the agreement was generally good with a correlation coefficient (r) >0.64. The calculated regression line had a slope close to one, and the intercept on the axis was next to nil, suggesting that the measurement with PDR is essentially the same with that by low-volume air sampling. Further analysis by types of dust work disclosed that the correlation was best when examined in 12 foundries with r as large as 0.95. In contrast, r was small (0.52) in 11 welding workplaces, possibly due to smaller particle size of dust generated during welding.

Air Pollutants, Occupational↗
PubMed1990

Association between exposure to asbestos and pleural effusion. Results from a questionnaire study of 31,000 persons.

All visitors to a general health survey in 1979, 17,140 men and 14,371 women, completed a questionnaire on smoking habits, exposure to asbestos, silica and welding fumes, and diseases such as pleural effusion, pneumonia, cough, asthma and diabetes. Seven per cent of the men reported exposure to asbestos, 10% to welding fumes, and 6% to silica. Among those who reported work related dust exposure there was a higher proportion of smokers, and smokers exposed to dust smoked more tobacco per day than non exposed smokers. In the group of men 30-59 years of age, who did not indicate exposure to occupational pollutants 2.7% reported previous pleural effusions. However, among asbestos exposed men of the same ages, the prevalence was more than doubled (5.7%, p less than 0.01). This finding was highly significant in a logistic regression model where age and smoking habits were included. The data indicate that 10% or more of diagnosed cases of pleurisy could be associated with previous asbestos exposure.

Adult↗
PubMed1985

Metallurgic and design development in response to mechanical dysfunction of Björk-Shiley heart valves.

In 16 years' experience with the Björk-Shiley tilting disc valve, the failures encountered have been disc-related. A. Obstruction of the disc movement in the aortic area has been due to faulty implantation technique, i.e. a suture cut too long and caught between the disc and the valve ring. Immediate reexploration, with cutting of the suture, has restored function. Disc obstruction in the mitral area has also been attributable to technique--leaving chordae tendineae too long. The author utilizes the universal sewing ring, which prevents the suture from encroaching on the disc. B. Disc escape by strut dislocation or strut fracture is a risk which can be reduced by care during valve implantation, always using only the valve holder to orient the valve. Forceful use of forceps, or use of the disc itself as a handle, may produce a crack in the weld which can propagate a strut fracture in the course of a year. When a patient's condition suddenly deteriorates, with dyspnea and tachycardia, immediate referral to the heart surgeon can be life-saving. Stethoscopy and chest X-ray suffice to reveal disc location and/or outflow strut fracture. Other investigations waste crucial time, as only reoperation with ex-change of the valve can save the patient. To strengthen the valve and avoid a weld, a mono-outflow strut has now been used for three years at the Karolinska Hospital, with no mechanical dysfunction and with excellent hemodynamic results.

Equipment Design↗
PubMed1993

Tissue repair using lasers: a review.

Numerous attempts have been made to use heating of tissue to effect an anastomotic union of severed tissue edges. Improvements in electrocautery and lasers have made experimental tissue anastomosis feasible; but clinical application of tissue welding has involved only limited clinical trials. Using heat to anastomose tissue is fraught with complications. The factors that lead to successful tissue welding and the technique's limitations are reviewed.

Anastomosis, Surgical↗
PubMed1993

Effects of the current used on determining a critical temperature by electrical resistivity measurements in dental alloys.

The electrical resistivity measurement to determine a critical temperature (Tc) in a stoichiometric CuAu alloy is discussed on the dependence of the current used. The temperature was measured on two ways: With the thermocouple connected to the specimen by spot-welding, and with them separated. In the latter case, the greater the current, the lower the apparent Tc because of the generation of Joule heat. To obtain a more precise Tc, the current should be as small as possible or the thermocouple should be located as close as possible to the specimen. It is highly desirable for the thermocouple and the specimen to be welded together, if the effects of some contamination can be ignored in measuring system.

Copper↗