Isocyanate and VOC exposure analysis using Flexane®.

Flexane® 80 is a trowelable urethane product used in combination with cleaners and primers to effect rubber conveyor belt repairs. These products are of concern due to the potential for worker exposure to isocyanates and volatile organic compounds (VOCs). Small chamber experiments were used to identify chemicals liberated to the ambient air from each of the Flexane®-related products. A new sample collection method using treated cotton sleeves as a surrogate skin surface to assess potential dermal exposure to isocyanates during mixing and application of the Flexane® product was validated. Six simulations of a worst case scenario were performed by an experienced belt repair technician in a walk-in laboratory exposure chamber. Analysis of air samples from the large chamber simulations did not detect airborne isocyanates. The average airborne VOC concentrations were below established occupational exposure levels. Dermal sleeve samples detected intermittent and low levels of isocyanates from self-application while wearing gloves having surface residues of uncured Flexane®. The data strongly suggest that the normal and intended use of Flexane® putty, and its associated products under worst case or typical working conditions is not likely to result in worker VOC or isocyanate exposure levels sufficient to produce adverse health effects.

Measurement of respirable superabsorbent polyacrylate (SAP) dust by ethanol derivatization using gas chromatography-mass spectrometry (GC-MS) detection.

Superabsorbent polyacrylate (SAP) is an important industrial chemical manufactured primarily as sodium polyacrylate but occasionally as potassium salt. It has many applications owing to its intrinsic physical property of very high water absorption, which can be more than 100 times it own weight. SAP is commonly used in disposable diapers and feminine hygiene products and is known by a number of synonyms-sodium polyacrylate, superabsorbent polyacrylate (SAP), polyacrylate absorbent (PA), and superabsorbent material (SAM). Germany and The Netherlands have adopted a nonbinding scientific guideline value 0.05 mg/m³ (8-hr time-weighted average, TWA) as the maximum allowable workplace concentration for the respirable dust of SAP (<10 µm particle diameter). Three industry associations representing Europe, the United States, and Asia have adopted the German scientific guideline value of 0.05 mg/m³ (8-hr TWA) as a voluntary guideline. A new test method based on alcohol derivatization of the acrylate was developed and validated for the analysis of respirable superabsorbent polyacrylate dust collected on filter cassettes in the workplace environment. This method is an alternative to the commonly used sodium-based method, which is limited owing to potential interference by other sources of sodium from the workplace and laboratory environments. The alcohol derivatization method effectively eliminates sodium interference from several classes of sodium compounds, as shown by their purposeful introduction at two and six times the equivalent amount of SAP present in reference samples. The accuracy of the method, as determined by comparison with sodium analysis of known reference samples, was greater than 80% over the study range of 5-50 µg of SAP dust. The lower reporting limit of the method is 3.0 µg of SAP per sample, which is equivalent to 3 (µg/m³) for an 8-hr sampling period at the recommended flow rate of 2.2 L/min.

Method for the determination of perfluorooctanoic acid in air samples using liquid chromatography with mass spectrometry.

Perfluorooctanoic acid is a completely fluorinated carboxylic acid that is usually used in the ammonium salt form as a processing aid in the production of many fluoropolymers and fluoroelastomers. Ammonium perfluorooctanoate readily dissociates in water to give the ammonium and perfluorooctanoate ions. Perfluorooctanoate has been reported to be present in low levels in human serum in the United States and Europe. This study reports on the development and validation of a method for the determination of perfluorooctanoic acid in air samples. This method uses the Occupational Safety and Health Administration (OSHA) Versatile Sampler (OVS) with a nominal 0.3 micro m filter and polystyrene resin sorbent (XAD-2 or XAD-4) followed by determination of the perfluorooctanoate anion by liquid chromatography mass spectrometry. The method was validated in the range of 0.474 to 47.4 microg/m3 for a 480-L sample. Breakthrough studies showed samples could be collected at 1 L/min for 24 hours or at 15 L/min up to 8 hours without breakthrough. Extract storage stability tests showed that sample extracts in methanol remain stable in glass autosampler vials for up to 13 days following initial injection. Perfluorooctanoic acid stability on OVS tubes was unaffected at both refrigerated and ambient temperatures. The overall average retention efficiency was 92.1% with a pooled RSD95 of 5.8% at five concentration levels (0.474 microg/m3 to 47.4 microg/m3).

Sampling and analysis of butyltin compounds in air using gas chromatography and flame photometric detection.

Organotin compounds are used in a variety of applications including stabilizers, catalysts, antifouling agents, and biocides. Because of the widespread use of organotin compounds in industry and their wide range of toxic effects, it is important to measure worker exposure to specific organotin compounds. Three butyltin compounds were selected for this study--butyltin trichloride, dibutyltin dichloride, and tributyltin chloride. These three compounds are typically present in the same work environment; therefore, developing a sampling and analytical method that would allow all three butyltin compounds to be sampled and analyzed simultaneously was desired. A derivatization procedure using sodium tetraethylborate (STEB) was selected for study and validation. The validation study demonstrated that sampling using the Occupational Safety and Health Administration (OSHA) Versatile Sampler (OVS) with XAD-2 resin sorbent and analysis using gas chromatography/flame photometric detection (GC/FPD) can be used to evaluate worker exposures to specific butyltin chlorides over the range of 5 to 270 micrograms/m3 collected at a flowrate of 0.25 L/min over a 3-hour period for a 45-L air sample. Breakthrough studies at 1.5 times the occupational exposure guideline (OEG) of 0.05 mg/m3 showed that samples could be collected at flowrates up to 0.5 L/min for 12 hours without breakthrough. The 14-day storage stability study showed apparent degradation of tributyltin and monobutyltin within a 3-day storage period at both ambient and refrigerated temperatures. There was no further degradation from 3 to 14 days. The stability of dibutyltin was unaffected by storage condition over the 14-day storage study. Subsequent stability studies incorporating a spiking solution control sample were conducted extending the stability study out to 27 days. These data show that all three butyltins were stable at either ambient or refrigerated conditions.