VOC sources and exposures in nail salons: a pilot study in Michigan, USA.

PURPOSE: Exposures of nail salon technicians have received attention due to the potentially toxic materials used in nail products, which include volatile organic compounds (VOCs) such as formaldehyde and methyl methacrylate (MMA). This study characterized area and personal concentrations and other indoor air parameters in 17 nail salons in fall and winter seasons in three areas of Michigan. METHODS: VOC samples were analyzed using thermal desorption, gas chromatography and mass spectroscopy, and the VOC composition of 35 nail products (e.g., polish, top coat, base coat) was measured using headspace sampling. Ventilation rates were derived using CO2 concentrations, occupancy and building information, and VOC sources were apportioned by a novel application of chemical mass balance models. RESULTS: We detected ethyl acetate, propyl acetate, butyl acetate, MMA, n-heptane and toluene in most salons, and benzene, D-limonene, formaldehyde, and ethyl methacrylate in some salons. While MMA was not measured in the consumer and professional products, and the use of pure MMA in salons has been not been permitted since the 1970s, MMA was found in air at concentrations from 100 to 36,000 µg/m3 in 15 of 17 salons; thus its use appears to be commonplace in the industry. Personal measurements, representing exposures to workers and clients, were about twice those of the area measurements for many VOCs. CONCLUSION: This study identifies the products responsible for emissions, shows the widespread presence of MMA, and documents low ventilation rates in some salons. It also demonstrates that "informal" short-term sampling approaches can evaluate chemical exposures in nail salons, providing measurements that can be used to protect a potentially susceptible and vulnerable population. Additional controls, including restrictions on the VOC compositions and improved ventilation, can reduce exposures to salon workers and clients.

Determination of monomer conversion in methacrylate-based polymer monoliths fixed in a capillary column by pyrolysis-gas chromatography.

Monomer conversion and the resultant copolymer composition of polymer monolith columns are important factors for controlling column characteristics. We propose a new method to determine monomer conversion to a polymer monolith fixed in a capillary column using pyrolysis-gas chromatography. Small pieces of a poly(butyl methacrylate-co-ethylene dimethacrylate (BMA-co-EDMA)) monolith column were pyrolyzed at 450°C with poly(ethyl methacrylate) as a non-volatile internal standard. The monomer conversions were estimated from the corresponding relative peak intensities in the pyrogram. It was determined that the conversion of EDMA was significantly greater than that of BMA in a low-conversion UV-polymerized poly(BMA-co-EDMA) monolithic capillary column.

Pre-packed vacuum bone cement mixing systems. A further step in reducing methylmethacrylate exposure in surgery.

OBJECTIVES: Polymethylmethacrylate bone cements are widely used in orthopaedic and trauma surgery as well as in dentistry. The toxic side effects of inhaled methylmethacrylate (MMA) fumes generated during mixing have been well studied. Vacuum cement mixing systems have been shown to reduce the risk of airborne MMA significantly compared to handmixing. In an effort to further reduce MMA exposure, the latest generation of mixing devices are pre-packed with the ingredients and thus allow preparation in nearly closed circuits. Until now, there has been no study proofing the efficacy of those systems in protecting theatre staff from MMA vapours. METHODS: A pre-packed vacuum mixing system (Optipac®) was compared with two standard systems (Palamix® and Easymix®) regarding MMA emission. The latter systems require loading with the bone cement compounds prior to mixing. Following a standardized procedure, 10 mixes were performed with each system and the emission of MMA vapours in the breathing zone was recorded using photoionization detection over a period of 3 min. RESULTS: The mean MMA exposure was reduced when using the pre-packed system compared to the devices that require filling with the components. The highest emission peaks were recorded during the mixing and preparation steps in all systems. CONCLUSIONS: Modern pre-packed vacuum mixing systems further help to reduce the occupational hazards created by bone cement preparation. However, MMA fumes can still be detected using this technique. Although this is an important step in reducing MMA exposure in the operating theatre, further technical effort has to be taken to eliminate the continuous leakage of monomer from the devices while mixing and to minimize necessary manipulation for final delivery.

Effect of additive metals, Sn, Ga, and In in Ag-Pd-Au-Cu alloys on initial bond strength of 4-META adhesive cement to these alloys.

The purpose of this study was to investigate the effects of three additives, Sn, Ga, and In, as well as the main constituents, Pd and Cu, of Ag-Pd-Au-Cu alloys on the initial bond strength of 4-META adhesive cement to these alloys. The Ag-Pd-Au-Cu alloys consisted of 20%, 30% or 40% Pd, and 10%, 15% or 20% Cu, 20% Au, and Ag as balance. Besides, additive metals (Sn, Ga, and In) of 2% and 4% were added to these compositions. The addition of three additives, in general, increased the initial bond strength of the cement in comparison to the mother compositions (0% additives), although the degrees of effectiveness of the three additives were different and varied with their contents. Among these additives, a remarkable increase in bond strength was observed with the addition of In. The increase in Cu content, in many cases, resulted in an increase in bond strength at high Pd contents (30% and 40%), but a decrease at low Pd content (20%) in some cases. The positive effects of the three additives and Cu could be due to the formation of a suitable oxide layer for strong bonding with 4-META.

Residual monomer of autopolymerized acrylic resin according to different manipulation and polishing methods. An in situ evaluation.

OBJECTIVE: To test the hypothesis that no difference exists in the in situ levels of residual monomer of an autopolymerized acrylic resin, irrespective of the method of manipulation and polishing. MATERIALS AND METHODS: Forty volunteers received the test specimens. The residual monomer was evaluated by means of gas chromatography using methylethylketone as extraction solvent. The samples of autopolymerized acrylic resin were submitted to two methods of manipulation--mass and addition--as well as to two types of polishing-mechanical and chemical. Four test groups were determined according to manipulation and polishing techniques: mass-mechanical; mass-chemical; addition-mechanical; addition-chemical. The data obtained were analyzed by the Student's t-test for paired samples as well as by analysis of variance. RESULTS: Residual methylmethacrylate was verified in high concentrations in the beginning of the testing as well as 24 hours after the test specimens had been worn. Mechanical polishing was associated with lower levels of residual monomer. The mass-mechanical group showed the lowest values. Mechanical polishing was associated with the lowest levels of residual monomer, and the lowest level of all occurred in mass-mechanical group. CONCLUSIONS: The hypothesis is rejected. Variations of residual polymer were associated with variations in the manipulation and polishing, but high concentrations of residual monomer were present in all groups. These concentrations were reduced after 24 hours.

Analysis of residual monomers in dendritic methacrylate copolymers and composites by HPLC and headspace-GC/MS.

OBJECTIVES: The aim of this study was to analyze the residual monomer content of photopolymerized dendritic methacrylate copolymers and particulate filler composites. Headspace-gas chromatography/mass spectrometry (HS-GC/MS) was compared with high performance liquid chromatography (HPLC). METHODS: The resin mixtures consisted of a dendritic methacrylate monomer, methyl methacrylate and acetoacetoxyethyl methacrylate in varied proportions. In addition, one of the composites contained 1,4-butanediol dimethacrylate. Camphorquinone and 2-(N,N-dimethylamino)ethyl methacrylate were used as the light-activated initiator system. The content of residual methyl methacrylate and acetoacetoxyethyl methacrylate after 40 s photopolymerization were analyzed with HPLC and HS-GC/MS. RESULTS: The content of residual methyl methacrylate decreased and residual acetoacetoxyethyl methacrylate increased with increasing concentration of acetoacetoxyethyl methacrylate in the resin mixture. The results with both methods had the same trend. SIGNIFICANCE: The addition of acetoacetoxyethyl methacrylate enhanced the copolymerization of methyl methacrylate, but did not decrease the total residual monomer content. The HS-GC/MS method was found to be a feasible method in the analysis of low-boiling residuals in dental polymers.

A potentiostatic study of oxygen transport through poly(2-ethoxyethyl methacrylate-co-2,3-dihydroxypropylmethacrylate) hydrogel membranes.

The oxygen permeability and diffusion coefficients of hydrogel membranes prepared with copolymers of 2-ethoxyethyl methacrylate (EEMA)/2,3-dihydroxypropylmethacrylate (MAG) with mole fraction of the second monomer in the range between 0 and 0.75 are described. Values of the permeability and diffusion coefficients of oxygen are determined by using electrochemical procedures involving the measurement of the steady-state current in membranes prepared by radical polymerization of the monomers. The results obtained for the transport properties were analyzed taking into account the fractional free volumes, the cohesive energy densities and the glass transition temperatures of the hydrogels.

Residual methyl methacrylate monomer, water sorption, and water solubility of hypoallergenic denture base materials.

STATEMENT OF PROBLEM: Denture base materials have the potential to cause irritation and allergic reaction to the oral mucosa. Water sorption and water solubility of denture base resins affect dimensional behavior and denture stability. A correlation between residual monomer and water sorption exists. PURPOSE: This in vitro study compared the amount of residual monomer, quantity of water sorption, and solubility of 4 denture base materials purported to be hypoallergenic with those of a polymethyl methacrylate-based (PMMA) heat-polymerizing acrylic resin. MATERIAL AND METHODS: The denture base resins Sinomer (heat-polymerized, modified methacrylate), Polyan (thermoplastic, modified methacrylate), Promysan (thermoplastic, enterephthalate-based), and Microbase (microwave polymerized, polyurethane-based), which are purported to be hypoallergenic, and Paladon 65 (heat-polymerized, methacrylate, control group) were examined. Specimens of each material were tested for residual methyl methacrylate (MMA) monomer (% wt, n=3), amount of water sorption (microg/mm3, n=5) and water solubility (microg/mm3, n=5), according to ISO 1567:2000. The residual MMA monomer concentrations were determined by gas chromatography (GC). The data were analyzed with 1-way ANOVA and the Bonferroni-Dunn multiple comparisons post hoc analysis for each test variable (alpha=.05). RESULTS: Significantly lower residual MMA monomer was shown for Sinomer and Polyan compared to the PMMA control group (0.90 +/- 0.20% wt, P<.05). Sinomer contained 0.31% +/- 0.00% wt MMA monomer, and Polyan exhibited residual MMA monomer content of 0.44% +/- 0.01% wt. Promysan and Microbase did not contain detectable residual MMA. Water sorption of Promysan (16.21 +/- 0.96 microg/mm3) was significantly lower than Paladon 65 (23.04 +/- 3.13 microg/mm3, P<.0001), whereas water solubility of the hypoallergenic denture base materials (0.34-0.84 +/- 0.05-0.09 microg/mm3) was not significantly lower than the PMMA material (0.40 +/- 0.06 microg/mm3, P>.05). Except for Sinomer, the tested denture base resins passed the requirements of ISO 1567 regarding residual MMA monomer (<2.2% wt). Sinomer failed to comply with the requirements for residual MMA monomer because the manufacturer claimed that the material did not contain any MMA. The tested denture base materials fulfilled the requirements regarding water sorption (<32 microg/mm3) and solubility (<1.6 microg/mm3). CONCLUSION: The tested hypoallergenic denture base materials exhibited significantly lower residual monomer content than PMMA. Promysan and Microbase showed no detectable residual MMA.

High pressure liquid chromatography of dentin primers and bonding agents.

OBJECTIVE: The purpose of this study was to analyse the composition of representative dentin primers and bonding agents, and to investigate the relationship between chromatographic retention times and partition coefficient (log P) values. METHODS: Dentin bonding systems (DBS) were analysed with reversed phase high-performance liquid chromatography (HPLC). The log P values were obtained computationally with the advanced chemistry development software. RESULTS: The DBS were analysed and the monomers were identified. The log P values were calculated and the relationship between log P and retention times for the monomers was described by the equation: log P = 2.436R(t) - 3.636, with a correlation value (r) of r = 0.9095. SIGNIFICANCE: The components of the DBS were successfully resolved and identified, thus illustrating the analytical power of HPLC regarding those systems. Also the log P values correlated with the retention times of monomers. Thus, they can be used as a prediction tool in future analysis. These findings are important for a mechanistic understanding of Primer and Adhesive actions in the bonding to the dentin.

[Identification of synthetic adhesives by simultaneous pyrolysis methylation gas chromatography].

At present, pyrolysis gas chromatography (Py-GC) is an effective analytical method for trace synthetic adhesives. Synthetic adhesives are usually composed of polar components. Thus, the polar pyrolysis products are normally difficult to measure by Py-GC due to their partial or complete adsorption in the pyrolysis zone, injection system or capillary column and the accuracy of results is seriously affected. Simultaneous pyrolysis methylation gas chromatography (Py-Me-GC) is a fast analytical method which was developed in recent years for polar compounds. The five synthetic adhesives have been identified by using Py-Me-GC in our study. Analytical conditions were: filament pyrolysis apparatus, flame ionization detector (FID), gas chromatograph, FFAP capillary column (30 m x 0.25 mm i.d.) and a quaternary ammonium salt as methylating agent. Major peaks of the products of pyrolysis were analysed qualitatively by GC/MS and comparisons were also made between the results by Py-Me-GC and those by Py-GC. The information gained from the components of substances by Py-Me-GC is more than that by Py-GC. The method is suitable for identifying synthetic adhesives of trace evidence in forensic science.

Evaluation of exposure to methyl methacrylate among dental laboratory technicians.

Following the diagnosis of two cases of occupational asthma among dental technicians, an industrial hygiene survey was conducted in two dental laboratories to determine time-weighted average and peak concentrations of methyl methacrylate vapor and time-weighted average concentration of acrylic dust. The time-weighted average concentrations of methyl methacrylate vapor were 0.7 ppm and 1.6 ppm and average peak concentrations were 9.3 ppm and 9.7 ppm for the first and second laboratory, respectively. The use of a local exhaust ventilation system was significant in reducing the peak concentration of methyl methacrylate vapor in the breathing zone of dental technicians. However, the local exhaust ventilation was not efficient in reducing the concentration of airborne acrylic dusts. Occupational exposure of dental technicians to dental materials, in particular to methyl methacrylate, requires further investigation. Local exhaust ventilation systems can reduce the concentration of methyl methacrylate in the dental laboratories to a significant extent if installed and used properly.

Effect of polymerization temperature and time on the residual monomer content of denture base polymers.

The aim of this study was to investigate the effect of polymerization time and polymerization temperature on the residual methyl methacrylate (MMA) content of two heat-cured and two autopolymerized denture base polymers. Gas chromatography was used to determine the residual MMA content of three test specimens of each type of polymer. Increasing the polymerization temperature for the autopolymerized denture base resins from 30 degrees C to 60 degrees C decreased the residual MMA content of the polymer from an average of 4.6 wt% to 3.3 wt%. With the heat-cured denture base resins, a curing cycle at a polymerization temperature of 70 degrees C followed by a period at 100 degrees C significantly reduced the residual monomer content of the polymer when compared with a resin cured at 70 degrees C only. Polymerizing the heat-cured denture base resin at 100 degrees C only for various lengths of time significantly affected the residual MMA content of the polymer. The lowest residual MMA content (0.07 wt%) was obtained by polymerizing the heat-cured denture base resin at 100 degrees C for 12 h. The results of this study suggest that the polymerization temperature and polymerization time considerably affect the residual MMA content of denture base polymers.

Pulmonary effects of fixation of a fracture with a plate compared with intramedullary nailing. A canine model of fat embolism and fracture fixation.

UNLABELLED: Fat-embolism syndrome and pulmonary dysfunction may develop in multiply injured patients who have a fracture of a long bone. Although early fixation of a fracture is beneficial, intramedullary nailing may exacerbate pulmonary dysfunction by causing additional embolization of marrow fat. We examined the pulmonary effects of the timing and method of fixation of a fracture in a canine fat-embolism model. Fat embolism was induced in forty-one adult dogs by reaming the ipsilateral femur and tibia followed by pressurization of the intramedullary canal. The animals were divided into a control group of eight dogs that had induction of fat embolism alone and an experimental group of thirty-three dogs that had induction of fat embolism and internal fixation of a transverse fracture of the middle of the contralateral femoral shaft. In the control group, four dogs each were killed four hours and twenty-four hours after induction of fat embolism. In the experimental group, a femoral fracture was created and fixation was performed four hours after embolic showering in fifteen animals and twenty-four hours after embolization in eighteen animals. The two experimental groups were subdivided according to the method of fixation of the fracture: eleven dogs each had application of a plate, nailing without reaming, and nailing with reaming. The pulmonary arterial pressure and the alveolar-arterial gradient were measured preoperatively, during induction of fat embolism, and as long as one hour after fixation of the fracture but before the animal was killed. The lungs, brain, and kidneys were examined for pathological and physiological evidence of intravascular fat. The intravascular fat persisted for twenty-four hours after induction of pulmonary fat embolism. Pulmonary arterial pressure remained elevated at four hours after the embolic showering, before creation and fixation of the fracture. By twenty-four hours after the induction of fat embolism, pulmonary arterial pressure had returned to the baseline level. Neither the creation nor the fixation of the fracture affected pulmonary arterial pressure. In the animals that had fixation of a fracture four hours after embolization, both nailing with reaming and nailing without reaming produced alveolar-arterial gradients that were higher than the baseline values, whereas fixation with a plate did not change the alveolar-arterial gradient significantly from the baseline value. In addition, the alveolar-arterial gradients in the animals that had nailing with reaming and nailing without reaming four hours after embolization were, respectively, four and 3.5 times higher than that in the animals that had fixation of the femur with a plate. In the animals that had fixation twenty-four hours after embolization, none of the methods for fixation affected the alveolar-arterial gradient. The amount of embolic fat in the lungs, brain, and kidneys was not affected by fixation of the fracture when it was performed at either the four-hour or the twenty-four-hour time-interval. Scores for pulmonary edema were increased by fixation of the fracture, but there was no difference among the scores associated with the three methods of fixation. CLINICAL RELEVANCE: The findings of the present study indicated that the amount of intravascular fat persisting in the lungs, kidneys, and brain twenty-four hours after pressurization of the intramedullary canal is not affected by the method of fixation of the fracture. Fixation of a fracture is associated with minimum evidence of acute inflammation and has no effect on pulmonary artery pressure. The development of pulmonary dysfunction from fat emboli depends on other factors, not just on the presence of fat in pulmonary vessels. It appears that the method of fracture fixation has little influence on the outcome of treatment.

Estimation of monomer content in polymethyl methacrylate contact lens materials by Raman spectroscopy.

Polymethyl methacrylate is the most commonly used contact lens material due to its excellent optical properties. However the presence of residual monomer in the structure alters its transparency as well as its biocompatibility, thus, there is a need to detect any remaining methyl methacrylate. Raman spectroscopy is a rapid, sensitive, and non destructive method as compared to other spectroscopic, chromatographic or polarographic methods. In this study, the spectra of some lens materials (prepared from methyl methacrylate, 2-hydroxy ethyl methacrylate, Hexamethyl disiloxane and polypropylene glycol with or without the addition of crosslinker ethylene glycol dimethylacrylate) were obtained by Raman spectroscopy. It was observed that an amount of crosslinker present in the structure proves effective for the unpolymerized monomer content. None of the samples, except those containing nexamethyl disiloxane, demonstrated any monomer residue.

Control of ethyl methacrylate exposures during the application of artificial fingernails.

In 1990 six cases of physician-diagnosed occupational asthma in cosmetologists working with artificial fingernails prompted the Colorado Department of Health to request the assistance of National Institute for Occupational Safety and Health (NIOSH) researchers in the evaluation and control of nail salon technician exposure. A commercially available recirculating downdraft table with charcoal filters was purchased and evaluated. Researchers from NIOSH made modifications to the table that included increasing the downdraft air volume; enlarging the plenum for more consistent airflow rates at the face of the table; removing the charcoal filters while incorporating a ventilation system to the outdoors; and putting an extension around the duct leading to the perforated plate at the downdraft face of the table. An evaluation was performed using the following two configurations: the modified table with the downdraft ventilation on (vented) and without the downdraft ventilation on (unvented). Each of the two configurations was sampled for 3 days in random order. Testing included the use of XAD-2 solid sorbent tubes for determining ethyl methacrylate and methyl methacrylate concentrations. Relative concentrations of organics were examined and used to analyze work practices. The geometric mean ethyl methacrylate exposure for personal breathing zone samples when using the modified table for approximately 6 hours was 0.6 ppm; when using the unventilated conventional table, the geometric mean exposure was 8.7 ppm. The difference in the values is statistically significant (p = 0.0045). Methyl methacrylate concentrations were nondetectable on all sorbent tubes.

Release of residual methyl methacrylate into water from glass fibre-poly(methyl methacrylate) composite used in dentures.

The aim of this study was to determine the release of residual methyl methacrylate (MMA) into water from heat-cured and chemical-cured test specimens of continuous glass fibre-poly(methyl methacrylate) (PMMA) composite fabricated from experimental glass fibre reinforcement. The glass fibre concentration of the test specimens was 12% by weight. The residual MMA was extracted from the storage water of the test specimens (n = 5 per group) and its concentration was determined by high-performance liquid chromatography. The results revealed that release of residual MMA from heat-cured test specimens with glass fibre reinforcement was significantly higher than that from unreinforced test specimens (P = 0.003), while in chemical-cured test specimens with and without glass fibre reinforcement the amount of MMA released did not differ (P = 0.501). In general, however the test specimens made from chemical-cured PMMA released more residual MMA than specimens made from heat-cured PMMA (P < 0.001). This study suggests that the use of glass fibre reinforcement in heat-cured denture PMMA statistically increases the release of residual MMA from the material, but it is questionable whether it has clinical significance.

Methylmethacrylate and bone screw repair of seventh lumbar vertebral fracture-luxations in dogs.

Fracture-luxations of the seventh lumbar vertebrae in two large dogs were stabilised with bone screws and methylmethacrylate. Screws inserted bilaterally into the bodies of the lumbar vertebrae and ilial wings were left protruding by about 2 cm, and embedded in methylmethacrylate bone cement. Implant failure occurred in one dog six days after surgery, necessitating a revision of the fixation. Fracture healing and return of normal ambulation occurred in both dogs. Implants were removed in one dog because of screw loosening and discomfort.

The effect of surface treatment of denture acrylic resin on the residual monomer content and its release into water.

The test specimens were processed by autopolymerizing poly(methylmethacrylate) (PMMA), and their surfaces were untreated, polished in a conventional manner with a rag wheel, or coated with a light-curing resin. The residual methylmethacrylate (MMA) content and its release into water from the specimens were measured with high-performance liquid chromatography. The light-curing resin coating reduced most effectively the release of residual MMA into water during a 2-day storage, but conventional polishing of the PMMA surface had a similar effect when the mean values of groups were tested by means of one-way ANOVA (p < 0.001). The residual MMA content was lowest in the test specimens coated with a light-curing resin, whereas only a slight difference was seen when the untreated and polished test specimens were compared. This study suggests that not only light-curing resin coating but also the conventional polishing of the denture PMMA reduces residual MMA release into water in vitro.

[Chemical analysis of compounds released after damage of the intraocular lens with the Nd: YAG laser]. / Chemiczna analiza uwalnianych zwiazków po uszkodzeniu sztucznej soczewki wewnatrzgalkowej laserem Nd: YAG.

PURPOSE: To evaluate the amount of releasing chemical compounds after laser Nd: YAG damage of PMMA intraocular lenses. MATERIAL AND METHOD: The study was undertaken in vitro condition. In two chemical vials filled with aqua humor-like solution 7 intraocular lenses in each were installed. One vial was the control group. 500 exposures to the laser Nd: YAG were performed focusing the beam on intraocular lenses in second vial. The aqua humor-like solution was analysed by gas chromatography in period of 1, 5 and 10 weeks. RESULTS: Methylmethacrylate was present in vial with damaged intraocular lenses in the first week after laser exposition, the other chemical compounds were observed after this period. CONCLUSIONS: 1. Laser Nd: YAG provokes depolymerisation of PMMA to methylmethacrylate just in time when damaging factor occurs. 2. Methyl alcohol and formaldehyde present in a longer time after damage of PMMA are the products of methylmethacrylate reactions. 3. The amount of released chemical compounds is so small and seems not to have the toxic properties.

Effect of light-exposure duration on the amount of leachable monomers from light-activated reline material.

Leaching of monomers from light-activated direct intraoral reline material (Lebaron LC) was determined by means of high-pressure liquid chromatography analysis. This study evaluated the effects of exposure duration and thickness to determine appropriate curing conditions that reduce the levels of unreacted monomeric components. Prolonged duration of exposure (30 minutes) reduced the amount of leached monomer. However, the results of this study indicated that the amount of leached monomeric components increased with an increasing reline material thickness. The results suggest that the light-activated reline material should be cured for sufficient prolonged exposure duration.