Diagnosing metal fume fever--an integrated approach.

BACKGROUND: Exposure to high concentrations of zinc oxide fume can cause metal fume fever (MFF). Two cases occurring following the oxy-acetylene cutting of galvanized steel frames are reported. AIMS: To show that integrated working is valuable as secondary health care staff may not be familiar with MFF. METHODS: Site visits by Her Majesty's Medical, Health and Safety (H&S) and Specialist Occupational Hygiene Inspectors to gather information and cooperation with occupational health, primary and secondary health care staff to diagnose MFF. RESULTS: Poor exposure control caused metal fume inhalation in these cases. Multidisciplinary working established diagnosis, causation and compliance with H&S legislation. CONCLUSIONS: Risk assessments are required to identify health risks and to determine required exposure control measures. Failure to do this resulted in an unusual case of MFF leading to hospital admission. Diagnosis can be delayed if a full occupational history is not taken. Successful investigation of such cases benefits from collaborative working.

A survey of occupational exposure to 4,4'-methylene-bis (2-chloroaniline) (MbOCA) in the UK.

OBJECTIVES: The main objective of the study was to gather information about the current controls and levels of exposure to 4,4'-methylene-bis (2-chloroaniline) (MbOCA) in a representative cross section of workplaces that use it to manufacture polyurethane elastomers. The study also aimed to investigate whether controls and guidance could be improved and to investigate exposure to isocyanates in these workplaces using biological monitoring. METHODS: An occupational hygienist and a field scientist visited the two UK suppliers and 20 out of the 25 workplaces known to be using MbOCA in the UK during 2005 and 2006. They collected air samples, surface wipes, gloves, and urine samples and made observations to assess exposure and the adequacy of controls. All samples were analysed for MbOCA and urine samples were additionally analysed for isocyanate metabolites. A statistical analysis was made of the results. RESULTS: Only 2.5% of the 80 personal inhalation exposures to MbOCA exceeded the workplace exposure limit of 5 microg m(-3) 8-h time-weighted average and 84% were below the limit of detection (LOD). Surface samples (n = 334) were collected from MbOCA users and suppliers and 60% had detectable levels of MbOCA ranging from 0.019 to 400 microg cm(-2). The highest levels were around a hopper, ovens, and the weighing and pouring areas. MbOCA was also detected in 8 of the 75 samples collected from areas not likely to be in contact with MbOCA. At the two suppliers, samples (n = 28) were collected from the outside surfaces of recently imported kegs, pallets, and the floor around kegs. Six samples had detectable levels and four of these (0.2, 0.8, 1, and 6 microg cm(-2)) were from the floor and pallets in both suppliers. The other two positive results were found on the outside rim (18 microg cm(-2)) and side (23 microg cm(-2)) of a keg at one supplier indicating contamination by the manufacturer. Urine samples (n = 79) were collected and 49% were below the LOD for MbOCA and only three samples had levels of MbOCA that exceeded the biological monitoring guidance value (BMGV) of 15 micromol mol(-1) creatinine. The highest urinary MbOCA concentrations were in samples from workers casting and moulding. The 90th percentile of the urine MbOCA results was 8.6 micromol MbOCA per mol creatinine. Urine samples were also analysed for the diamine metabolites of toluene diisocyanate and hexamethylene diisocyanate and 33% had detectable levels with 22 and 13% of results, respectively, above the BMGV for isocyanates (1 micromol isocyanate-derived diamine per mol creatinine). The maximum urinary concentration of toluene diamine and hexane diamine were 15.6 and 10.1 micromol mol(-1) creatinine, respectively. CONCLUSIONS: The survey found that the measures used to control exposure to MbOCA could be improved. Although air levels of MbOCA were generally low, there was evidence of spread of surface contamination and poor maintenance of controls such as local exhaust ventilation. A BMGV based on the 90th percentile of data from workplaces with good control would be less than the 90% value of 8.6 micromol mol(-1) creatinine found in this study and suggests that the current BMGV of 15 micromol mol(-1) creatinine is no longer acting as a stimulus to reduce exposure. The metabolites of isocyanates found in urine samples in this study could arise from inhalation exposure to isocyanates or from dermal exposure to either isocyanates or their diamine breakdown product and need further investigation.

Development of a push-pull ventilation system to control solder fume.

Hand soldering using rosin core solder wire is common in the electronics industry and several studies have implicated the aerosol produced when rosin flux is heated in causing respiratory sensitisation. Control of solder fume is generally achieved using local exhaust hoods, simple blowers with a filter or low-volume high-velocity (LVHV) ventilation systems. None of these provide an ideal control system and so a push-pull ventilation design was developed as an alternative. Laboratory tests of the system's capture efficiency were carried out using nitrous oxide tracer gas. Capture efficiency was generally greater than 90% with the push airflow operating. However, without the push airflow, capture efficiency decreased sharply with increasing distance from the exhaust hood (between 38 and 58% at 420 mm from the front of the exhaust hood with the same exhaust airflow used by the push-pull system). The push-pull system was found to be relatively insensitive to obstructions placed in the path of the air flow or the influence of cross draughts. The system was tested in five electronics factories and the effectiveness was compared to their existing ventilation systems. Where only a small amount of soldering was carried out both the in-house and push-pull systems seemed to provide adequate control of inhalation exposure to rosin-based solder flux fume measured as total resin acids. However, the push-pull system provided more consistent control than the existing ventilation systems when larger quantities of solder were used. In these situations the mean personal exposure level was reduced to below the UK Maximum Exposure Limit (MEL) of 0.05 mg/m(3) 8-h time weighted average in most instances. The corresponding mean personal exposure level with the in-house systems in operation was about three to four times the long-term MEL. Interpretation of these data is complicated because of high background contribution to exposure from poorly controlled soldering operations elsewhere in the factories. However, this study suggests that the in-house systems were relatively inefficient.

A custom impression tray made with the aid of an existing prosthesis: a clinical technique.

Prostheses for patients with intraoral defects usually have complex contours. The replacement of a successful prosthesis is more readily accomplished with the aid of a custom impression tray that reproduces the contours of the existing prosthesis. In the technique presented, an irreversible hydrocolloid impression is made of the intaglio surface of the prosthesis to be replaced. Autopolymerizing acrylic resin tray material is poured into the impression, creating a custom impression tray. This procedure can simplify the impression process and reduce the need for multistep impression techniques.

Sterilization of reusable implant components: a pilot study.

STATEMENT OF PROBLEM: The placement and restoration of dental implants require the use of numerous reusable instruments and components. The adequate sterilization of reusable instruments and components is essential to prevent cross contamination between patients. Sterilization usually is accomplished with single-use sterilization envelopes. A reusable sterilization vehicle would reduce costs as well as the waste generated in patient care. PURPOSE: This study was designed to determine the efficacy of a 10-cc Pyrex test tube as a sterilization vehicle for reusable dental implant instruments and components. MATERIAL AND METHODS: In this study, a reusable dental implant component was placed in a Pyrex test tube, along with a biologic test strip. A control biologic test strip was kept for each test tube. The test tube was closed with a cotton roll folded in half and placed in the opening. Twenty test tubes were prepared. five sets of 4 test tubes were placed in an autoclave in different locations with varying orientations. The autoclave completed a standard sterilization cycle. RESULTS: The biological monitoring service indicated that the biologic test strips in 100% of the test tubes were sterile, whereas the control strips were 100% nonsterile. CONCLUSION: A Pyrex test tube sealed with a cotton roll can serve as a sterilization vehicle for reusable dental implant instruments and components.

A survey of exposure to diesel engine exhaust emissions in the workplace.

Forty sites were visited during a survey of exposures to diesel engine exhaust emissions. Personal and background exposure to gaseous components, respirable dust, elemental carbon, organic carbon and total carbon were measured and details of control systems were recorded. The results show a wide spread in exposure patterns reflecting the different work practices, job categories of employees and the control methods used. However, sites where fork-lift trucks were in use consistently produced the highest exposures. The survey results suggest that the measurement of elemental carbon could be used as an indicator of exposure to diesel engine exhaust emissions.

Air movement visualization in the workplace: current methods and new approaches.

Airflow visualization in the workplace to assess containment, ventilation, or general air movements is often carried out using smoke tracers. The most prevalent method uses a disposable smoke tube that generates a plume of concentrated sulfuric acid fume. However, use of the smoke tube exposes occupational hygienists to the risk of sulfuric acid exposure through inhalation or dermal contact, as well as injury from sharps. Following concern over the potential health hazard associated with smoke tube usage, alternative flow visualization methods and technologies have been reviewed. Methods of generating smoke or bubbles other than using smoke tubes suitable for visualizing air movements include heated element smoke generators, combustion generators, generation of metallic chlorides and ammonium chloride, generation of neutral density bubbles, and water fog generation. Some of these methods are applicable in specific workplace situations. However, there is no commercially available smoke or bubble generator currently available that matches the smoke tube for cost effectiveness, ease of use, and wide applicability, while also reducing the potential health risks associated with smoke tube usage. Despite this, certain technologies, in particular water/glycerol smoke generation using heated element generators, have the potential to be developed into viable alternatives to the smoke tube. Thus, with further development, an air movement visualization method that poses a significantly lower health hazard than the smoke tube is feasible.

Soft liner-retained, implant-supported overdenture: a technical note.

This paper describes the design and fabrication of a soft liner-retained, implant-supported overdenture used in 10 patients over a period of 1 to 6 years. A final complete denture impression is made of the dental arch, including implant abutments extending 5 mm above the gingival tissue. The master cast is fabricated with actual abutments placed in the impression. After the final wax try-in, the denture is flasked in the usual manner with the metal abutments in place. Before packing with acrylic resin, plastic tubing 1 to 2 mm thick is placed around each abutment. The denture is trial packed and allowed to bench cure over night. The plastic tubing is then removed and a soft denture lining material is placed in these areas only. The flask is closed and cured according to the manufacturer's recommendation. The denture is delivered as a conventional overdenture.

Prosthodontic restoration with dental implants and an intraoral cranial bone onlay graft: a case report.

In 1988, a 54-year-old edentulous patient received a cranial bone onlay graft with the immediate placement of five dental implants. Treatment procedures and early results of restoration are described.

Production, physiological, and behavioral responses of laying hens in different management environments.

Responses of commercial laying hens to 16 management systems were examined for 10 laying periods of 28 days each. Twelve cage treatments consisted of housing three, four, or five hens in deep and shallow cages of different dimensions which provided .035 and .046 m2/hen. Four floor treatments housed 35 hens or 32 hens and three roosters at densities of .094 or .373 m2/bird, in two replicated pens each. Quantitative data were collected simultaneously for 23 production, physiological, and behavioral characteristics throughout the study. When comparing all caged with floor pen hens, caged hens had better (P less than .05) egg production rates (76.3 vs. 73.9%), gained more weight, had better feed efficiency, and had greater egg and egg shell weights than floor hens. All floor pen hens had higher (P less than .01) viability (98.9 vs. 95.0%), higher (P less than .01) plasma corticosterone levels (595.0 vs. 445.4 pg/ml), a greater (P less than .01) response to adrenocorticotropin (ACTH) challenges, and lower (P less than .01) antibody titers to Salmonella pullorum challenges than all caged hens. Caged hens preened, stood, crouched, and feather pecked more than floor hens, while floor hens drank and moved about more than caged hens. This study attempted to quantify production, physiological, and behavioral traits, all on the same flock of hens, in order to separate stressful from nonstressful management environments. Integration of all measurements indicates that properly managed caged hens were subjected to significantly fewer stressors than laying hens housed in floor pens, although the hens' well-being in the two environments could not be quantitatively compared.

Effects of dietary and parenteral estrogens on bobwhite reproduction.

Bobwhites were fed one of several doses (.01 to 1,000 micrograms/day) of estriol (E3), beta-estradiol-3-benzoate (E2B), diethylstilbestrol (DES), or biochanin-A (BA) during two 10-week trials. The initial 2 weeks of each trial were short day length (10L:14D) followed by 8 weeks of long day length (16L:8D). In addition, female bobwhites were given daily injections containing dosages (.01 to 10 micrograms/day) of E2B, E3, and DES while housed on the same light regimen. Reproductive performance as assessed by onset of lay, egg production, and egg fertility was depressed in a dose-dependent manner and was inhibited by dietary dosages of 1,000 micrograms/day of E3, DES, and E2B. No consistent effects on reproductive performance were observed in bobwhites fed up to 1,000 micrograms/day of the phytoestrogen BA. Injected estrogens appeared approximately 100 times more potent than dietary estrogens. It was concluded that both dietary and parenteral estrogen can inhibit reproduction, but in order for phytoestrogen (BA) in natural feedstuffs to impair reproduction in bobwhites it would have to be consumed in excess of 1 mg/day.

Corticosterone sampling of laying hens in different management systems.

Plasma corticosterone was measured as a stress indicator of laying hens in different management conditions. Laying hens housed in cages and floor pens were sampled repeatedly in the morning and the afternoon. Plasma corticosterone concentrations of afternoon samples of hens from floor treatments were significantly higher than those from cage treatments, but morning values were not different. These results suggest that management systems, producing subtle adverse conditions for laying hens, are associated with elevated baseline corticosterone levels during the nadir of the diurnal response, whereas peak values may not be affected.

Prosthetic treatment for chemical burns of the oral cavity.

Chemical burns of the mouth, pharynx, and digestive passages have been reviewed in regard to the nature of the injury and wound description. Fabrication of custom mouth protectors to minimize oral scar contracture and its sequelae has been described. Mouth protectors provide flexible but active resistance to the forces of scar contracture and avoid a constant unyielding force that could cause pressure necrosis. Protectors are easy to fabricate and adjust, and permit movement and function of the injured area.

The influence of exogenous estradiol on bobwhite quail (Colinus virginianus) reproductive systems.

Mean plasma 17-beta-estradiol (E2) concentrations of nonphotostimulated adult bobwhite quail were less than 31.2 and 119.9 pg/ml for males and females, respectively. Dietary beta-estradiol-3-benzoate (E2 beta) dosages of 10, 100 or 500 micrograms/bird/day caused mean plasma E2 concentrations of females to increase by 1.2, 2.0 or 5.6 times. Oviduct weights were significantly increased in females fed E2 beta dosages of greater than 100 micrograms/bird/day for five days. Gonad weights were not significantly effected in either sex. Ten- to fifty-fold greater doses of dietary E2 beta were required to induce oviduct growth responses equivalent to those produced by injected E2 beta.

Performance, behavior, plasma corticosterone, and economic returns of laying hens in several management alternatives.

Production, physiological, and behavioral data were collected simultaneously on commercial hens housed for 10 months of lay in housing alternatives of cages, deep litter floor pens, and outside range pens. Treatments consisted of housing 1, 2, or 3 hens in small cages 3, 4, 5, or 6 hens in large cages, floor pens housing 51 hens each at three densities, and range pens with 50 hens at .74 m2 (8 ft2) per hen. Egg production rates were greater for all caged hen treatments than for any floor or range groups. Egg numbers favored 2 hens per cage, but economic benefits favored 5 hens per cage. Viability was highest for 1 hen per cage and range pen groups. Feed efficiency was poorer in floor and range groups; however, body weight was generally greater for caged hens. Plasma corticosterone levels did not differ among any cage or range groups, but floor pen hens had significantly elevated levels. Behavioral data for walking and object pecking showed clear differences between cage and floor management alternatives. Preening, standing, and drinking activities were different between some treatments but not clearly different between management alternatives. Feeding activity did not differ among any groups. Although correlations between stress and well-being have not been well elucidated, the sum of the stressors of cage confinement appeared to be less than those from floor pens. Therefore, it was concluded that the well-being of hens in cages was equal to or better than that for free ranging hens or those in floor pens.