Göran Ljungkvist

Exposure to Volatile Methacrylates in Dental Personnel

Abstract Dental personnel are exposed to acrylates due to the acrylic resin-based composites and bonding agents used in fillings. It is well known that these compounds can cause contact allergy in dental personnel. However, in the 1990s, reports emerged on asthma also caused by methacrylates. The main volatile acrylates in dentistry are 2-hydroxyethyl methacrylate and methyl methacrylate. The aim of this study was to quantify the exposure to these acrylates in Swedish dental personnel. We studied the exposure to 2-hydroxyethyl methacrylate and methyl methacrylate in five randomly selected public dental clinics and at the Faculty of Odontology at Göteborg University. In total, 21 whole-day and 46 task-specific short-term (1–18 min) measurements were performed. The median 8-hour time-weighted averages were 2.5 μ g/m3 (dentists) and 2.9 μ g/m3 (dental nurses) for 2-hydroxyethyl methacrylate, and 0.8 μ g/m3 (dentists) and 0.3 μ g/m3 (dental nurses) for methyl methacrylate. The maximum short-term exposure levels were 79 μ g/m3 for 2-hydroxyethyl methacrylate and 15 μ g/m3 for methyl methacrylate, similar in dentists and dental nurses. The observed levels are much lower than in complete denture fabrication. We found only one previous study in dentistry and it showed similar results (though it reported short-term measurements only). Irritant effects would not be expected in healthy people at these levels. Nevertheless, occupational respiratory diseases due to methacrylates may occur in dental personnel, and improvements in the handling of these chemicals in dentistry are warranted. This includes better vials for the bonding agents and avoiding evaporation from discarded materials.

Determination of ethane, pentane and isoprene in exhaled air using a multi-bed adsorbent and end-cut gas–solid chromatography

A method for the determination of exhaled ethane, pentane and isoprene was developed and validated. The method was based on pre-concentration of the analytes on a multi-bed solid adsorbent tube containing Tenax TA, Carboxen 569 and Carboxen 1000, thermal desorption and gas chromatography (GC) with flame ionisation detection (FID). A pre-column in an end-cut GC system was used to avoid problems with water and strongly retained substances. The detection limits were 5, 2 and 6 pmol per sample for ethane, pentane and isoprene, respectively, using a sample volume of 500 ml. The linearity was good for all analytes with correlation coefficients exceeding 0.999. The repeatability for exhaled air samples was 7, 10 and 12% for ethane, pentane and isoprene, respectively. Analysis of a certified reference material of ethane and pentane did not differ significantly from the certified values. Ethane and pentane levels were stable up to six days of storage in sample tubes. Isoprene levels were not stable during storage in the sample tubes used here, but using Carbopack X instead of Carboxen 569, levels were stable up to two days. The levels of exhaled ethane, pentane and isoprene in healthy subjects (n = 4) were 8.1+/-5.8 pmol l(-1), 11+/-5.8 pmol l(-1) and 2.4+/-0.90 mnol l(-1), respectively. The method could, with minor modifications, be used to determine other low-molecular hydrocarbons in exhaled air as well.

Characterization of exhaled breath particles collected by an electret filter technique.

Aerosol particles that are present in exhaled breath carry nonvolatile components and have gained interest as a specimen for potential biomarkers. Nonvolatile compounds detected in exhaled breath include both endogenous and exogenous compounds. The aim of this study was to study particles collected with a new, simple and convenient filter technique. Samples of breath were collected from healthy volunteers from approximately 30 l of exhaled air. Particles were counted with an optical particle counter and two phosphatidylcholines were measured by liquid chromatography-tandem mass spectrometry. In addition, phosphatidylcholines and methadone was analysed in breath from patients in treatment with methadone and oral fluid was collected with the Quantisal device. The results demonstrated that the majority of particles are  <1 μm in size and that the fraction of larger particle contributes most to the total mass. The phosphatidylcholine PC(16 : 0/16 : 0) dominated over PC(16 : 0/18 : 1) and represented a major constituent of the particles. The concentration of the PC(16 : 0/16 : 0) homolog was significantly correlated (p  <  0.001) with total mass. From the low concentration of the two phosphatidylcholines and their relative abundance in oral fluid a major contribution from the oral cavity could be ruled out. The concentration of PC(16 : 0/16 : 0) in breath was positively correlated with age (p  <  0.01). An attempt to use PC(16 : 0/16 : 0) as a sample size indicator for methadone was not successful, as the large intra-individual variability between samplings even increased after normalization. In conclusion, it was demonstrated that exhaled breath sampled with the filter device represents a specimen corresponding to surfactant. The possible use of PC(16 : 0/16 : 0) as a sample size indicator was supported and deserves further investigations. We propose that the direct and selective collection of the breath aerosol particles is a promising strategy for measurement of nonvolatiles in breath.

Specific determination of benzene in urine using dynamic headspace and mass-selective detection.

A method for the determination of benzene in urine was developed, based on dynamic headspace and preconcentration of the analyte on a solid sorbent. The subsequent analysis by thermal desorption of the sorbent, capillary gas chromatography and mass-selective detection ascertained a low limit of detection (6.5 ng/l) and a highly specific determination. The limit of detection is an order of magnitude lower than that reported earlier and allows reliable quantitation of occupational exposure and of most environmental exposures. Samples could be stored frozen for at least a month without significant loss.

Analysis of manganese and iron in exhaled endogenous particles

Background: many full-time welders experience some sort of respiratory disorder e.g., asthma, bronchitis and metal fume fever. Thus, welding aerosols are thought to cause airway inflammation. There is a need for markers of welding aerosols in exposure assessments, and as most welding aerosols contain manganese and iron, these metals may possibly be used as an indicator. We have previously developed a novel non-invasive technique to collect endogenous particles in exhaled air (PEx). This study is designed to (i) develop a method for analysis of manganese and iron in PEx and (ii) investigate whether the manganese and/or iron content of PEx changes after exposure to welding aerosols. Methods: nine individuals were experimentally exposed to welding fumes. PEx was collected at three time points for each individual; before, after and 24 hours after exposure. Analyses of PEx samples were performed using Inductively Coupled Plasma Mass Spectrometry (ICP-MS). Results: four out of nine individuals showed an increase in manganese and iron levels after exposure to welding aerosols. The mean manganese and iron concentration increased from, <LOD to 82–84 pg L−1 (range from 0 to LOD for values <LOD) and 20–86 to 2600 pg L−1 of exhaled air respectively. Conclusions: an ICP-MS method for analysis of manganese and iron in PEx has been developed. The method could easily be expanded to include other trace metals of interest, such as cadmium, nickel or chromium. This first attempt to evaluate PEx as a tool for exposure assessments of airborne metals indicates that the method has potential.

Determination of low concentrations of benzene in urine using multi-dimensional gas chromatography

A method for the determination of benzene in urine of occupationally or environmentally exposed persons was developed. The method was based on dynamic headspace, preconcentration on a solid sorbent, followed by thermal desorption and gas chromatographic determination. To achieve sufficient selectivity, we used multi-dimensional gas chromatography in combination with the inexpensive and robust flame ionisation detector. The limit of detection was 7 ng l-1 and the limit of quantification was 23 ng l-1. The linearity was good (correlation coefficient 0.999) in the range examined (20-4000 ng l-1) and the repeatability was 9%. The average recovery at low concentrations (20-400 ng l-1) was 86%. Analysis of a certified reference material of benzene in water, traceable to NIST, did not differ significantly from the certified value. Samples, frozen (-20 degrees C) in glass bottles sealed with Teflon-silicon septa, were stable for 1 year and refrigerated samples (4 degrees C) for at least 1 week. Loss of benzene during the collection and transfer of urine was investigated and found to be acceptable. The method is a cost effective and robust alternative to GC-MS and permits reliable quantification of occupational exposure and, in most cases, also of urine concentrations that can be expected from environmental exposure.

Supercritical fluid extraction (SFE) for determination of metalworking fluid aerosols

A common methodology for analyzing metalworking fluid (MWF) aerosols in workplace air is based on gravimetry before and after organic solvent extraction of the MWFs from a suitable collection filter. Because MWFs have different chemical and physical properties, various mixtures of organic solvents have been used to extract the MWFs from their collection device. An alternative to organic solvents, used in the work presented in this article, is the use of a supercritical fluid. The efficiency of supercritical fluid extraction (SFE) was investigated by weighing conditioned filters before and after extraction of samples spiked with MWFs at different concentrations using the American Society for Testing and Materials method. For three common straight oil MWFs spiked on filters, supercritical carbon dioxide gave recoveries of 92–101% with a low standard deviation (0.2–1.9%). For semisynthetic MWFs, carbon dioxide had to be mixed with methanol to obtain recoveries above 80%. With the optimized method using 7% methanol in carbon dioxide, the 10 investigated MWFs could be extracted in 30 min with a recovery of 90–98%. The amount of MWFs spiked on the filters varied between 0.10–1.65 mg. In Sweden, the limit value for MWFs is 1 mg/m3. Thus, our spike level is in the range of 10–200% of the limit value if sampling for 8 hours with 2 L/min. The use of SFE methodology results in small volume extracts (3 mL) with concentrations at such high levels that analysis of chemical components in the MWF can be carried out without further volume reduction.

Two techniques to sample non-volatiles in breath—exemplified by methadone

The particles in exhaled breath provide a promising matrix for the monitoring of pathological processes in the airways, and also allow exposure to exogenous compounds to be to assessed. The collection is easy to perform and is non-invasive. The aim of the present study is to assess if an exogenous compound-methadone-is distributed in the lining fluid of small airways, and to compare two methods for collecting methadone in particles in exhaled breath. Exhaled particles were collected from 13 subjects receiving methadone maintenance treatment. Two different sampling methods were applied: one based on electret filtration, potentially collecting exhaled particles of all sizes, and one based on impaction, collecting particles in the size range of 0.5-7 μm, known to reflect the respiratory tract lining fluid from the small airways. The collected samples were analyzed by liquid chromatography mass spectrometry, and the impact of different breathing patterns was also investigated. The potential contribution from the oral cavity was investigated by rinsing the mouth with a codeine solution, followed by codeine analysis of the collected exhaled particles by both sampling methods. The results showed that methadone was present in all samples using both methods, but when using the method based on impaction, the concentration of methadone in exhaled breath was less than 1% of the concentration collected by the method based on filtration. Optimizing the breathing pattern to retrieve particles from small airways did not increase the amount of exhaled methadone collected by the filtration method. The contamination from codeine present in the oral cavity was only detected in samples collected by the impaction method. We conclude that methadone is distributed in the respiratory tract lining fluid of small airways. The samples collected by the filtration method most likely contained a contribution from the upper airways/oral fluid in contrast to the impaction method.

Lipid composition of particles in exhaled air (PEx) from workers exposed to welding fumes

More than two million workers are exposed to pneumotoxic welding aerosols and there is a need for biomarkers of effects on the respiratory system. The lipid composition of the respiratory tract lining fluid (RTLF) is such a potential marker. The most abundant pulmonary surfactant phospholipid is dipalmitoylphosphocholine (DPPC). It is specific for the airways, while palmitoyloleoylphosphatidylcholine (POPC) is a common lipid in tissues and body fluids. We hypothesize that the amounts of or ratio between DPPC and DOPC are changed due to short term and/or long term exposure to welding fumes. We have developed a method for the collection of PEx, based on counting of the exhaled particles and subsequent collection by impaction on a teflon membrane. We have also developed a method for analysis of lipids in PEx based on LC/MS. We measured the exposure to iron, manganese, chromium and nickel of 18 stainless steel welders and also analyzed DPPC and DOPC in PEx samples taken at the end of the exposure measurement day. The welders working history was also recoded and summarized as welding years. Spirometry and nitrogen multiple breath wash out were also measured but the results are not yet evaluated. There were no significant correlations between the short term exposure to either iron, manganese, chromium or nickel and the fraction of DPPC in PEx or the ratio DPPC/DOPC. However, there was a tendency of correlation (Spearman correlation coefficient= 0.407 with p-value 0.09) between welding years and the DPPC/DOPC ratio. In this pilot study we could not establish short term effects of welding exposure on the RTFL lipid composition but a tendency of change due the long time exposure.