UCLA

Human exposure to organic gunshot residues is a largely under researched topic in environmental and occupational health. This study aimed to examine how the components of a complex liquid blend affect the permeation behavior of its constituents. In the initial study, Hoppes No. 9 Gun Bore Cleaner, a firearm cleaning solvent, was chosen to test two types of disposable nitrile gloves from Kimberly-Clark’s Kimtech Science: the thinnest (Lavender) and thickest (Blue). Testing was conducted using the 1-inch diameter closed-loop ASTM F739 cell at 35℃ without recirculation with n-decane collection, and subsequent analysis via capillary gas chromatography-mass spectrometry to quantify the permeated compounds. Results showed that the thicker Blue glove resisted Hoppe’s permeation more than the thinner Lavender glove. The Lavender glove permeated 3.2 times more mass at 60 minutes despite having the same standardized breakthrough times (7.5 ± 2.5 min). Unexpectedly, the kerosene fraction permeated at a much higher rate than anticipated, appearing at the standardized breakthrough time for Hoppe’s, contrary to the Kimberly-Clark chemical resistance guide's listing for Sterling disposable nitrile glove material. Notably, components reported by the glove manufacturer to quickly permeate nitrile material, like ethanol, did not permeate slower than expected, hinting at a possible carrier function. A semiquantitative risk assessment confirmed the inadequacy of both gloves, suggesting that individuals using personal protective equipment may not receive the anticipated resistance to chemical permeation when dealing with complex mixtures, thus heightening exposure risk. Further research is necessary to develop improved glove testing measures to ensure worker safety and health.Additionally, this research examined how methyl centralite and ethyl centralite, two major gunshot residue components, simulated gunshot residues when permeating disposable nitrile glove material in three different solvents: Hoppe’s Gun Cleaning Solvent, n-decane, and an n-decane/ethanol 7:3 v/v mixture. The objective was to determine whether ethanol plays a key role in a carrier effect. Permeation testing followed a modified ASTM F739-20 standard method at 35.0 ± 0.1 ℃ with sample quantification conducted via GC-MS analysis. The findings indicate significant variations in permeation behavior across solvents. Hoppe’s solvent caused a type D permeation behavior characterized by a notable increase in permeation rate to a maximum post-standardized breakthrough time then followed by a lower SSPR. This was attributed to ethanol and other polar components. Conversely, the n-decane/ethanol mixture displayed a type A behavior with the SSPR being the maximum permeation rate, with markedly reduced permeation rates and total permeated analyte mass, indicating ethanol's likely pivotal role in the carrier effect. The study results emphasize the importance of considering the complete chemical composition of mixtures when assessing their interactions with protective equipment, and are suggestive of the need for comprehensive testing protocols in PPE selection. Limitations include the lack of prior research on firearm cleaning solvents' permeation through PPE and challenges in comparing study findings with manufacturer-reported glove effectiveness for individual components. The study suggests adjusting concentrations of analytes and solvent groups for future investigations. Overall, this research offers insights into the permeation behavior of complex chemical mixtures through disposable nitrile gloves, aiding in better protective equipment selection and testing methodologies, and thereby improving worker safety and health. Finally, this research examines how different glove materials affect the permeation of gunshot residue components compared to when these materials are used individually. Simulated gunshot residues containing methyl centralite and ethyl centralite dissolved in a 7:3 v/v mixture of n-decane and ethanol, mimicking gun cleaning solvent, were used to challenge two types of disposable glove materials: nitrile rubber and polyvinylchloride (PVC). Testing was again conducted using the closed-loop ASTM F739 cell without recirculation and n-decane collection at 35.0 ± 0.1 oC, followed by quantification of permeated compounds through capillary gas chromatography-mass spectrometry. Results showed that the combination of nitrile gloves alone exhibited the highest reduction in permeation. The next best reduction was observed with a combination of nitrile and vinyl gloves, with the vinyl side specifically facing the challenge solution. However, for Hoppe’s solvent, the kerosene components appeared at the standardized breakthrough time. Moreover, using vinyl-only glove material led to increased permeation of ethyl centralite compared to methyl centralite, while all other material combinations resulted in decreased permeation of ethyl centralite compared to methyl centralite. This suggests that the specific combination or orientation of glove materials used affected the expected resistance to chemical permeation and needs to be confirmed with different challenge chemicals and glove material combinations. Further research is necessary to develop improved glove testing measures to ensure worker safety and health, particularly when utilizing gloves with multiple types of materials such as laminated gloves.