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Research for investigating the effectiveness of solid sorbents in detecting small levels of permeating low-volatility organic chemicals.
NIOSH 2005 Dec; :1-65
The selection of chemical protective gloves is based on many factors, including barrier performance against chemicals, physical hazard resistance, effect on hand function, and cost. In nearly all instances of use, significant tradeoffs between worker protection and productivity are involved for any glove use as the wearing of gloves diminishes worker dexterity and tactility as well as significantly reducing hand comfort. These tradeoffs can often result in improper wearing practices and failure to use gloves, when needed. Therefore, it is critically important that gloves provide the best fit, offer the greatest comfort, and create the least interference with hand function. The appropriate selection of gloves must therefore involve optimizing the human factor aspects for gloves against the need for providing minimum protection. Part of the optimization process for glove selection must account for choosing the appropriate barrier protection against chemical exposure. The current practices for measuring glove material permeation resistance according to those established by test method American Society for Testing and Materials (ASTM) F739 do not always reflect this perspective of optimization. This is because this test method involves conditions that do not replicate actual wearer exposures and the types of measurements typically reported to do not allow end users to assess exposure. Instead, permeation testing is most often performed with 'neat' chemical over a relatively long-term exposure (usually up to 8 hours) and the testing does not entail evaluating all aspects of the glove performance, particularly as related to evaluating the entire exposure area accounting for repeated flexing, surface contact, and wearing degradation of gloves during use. Limited research has shown that glove performance in use can be dramatically different than predicted by permeation testing. Measurements of breakthrough time commonly used to support glove selection decisions through permeation testing are an arbitrary means to compare glove material performance against specific chemicals but offer no information about skin exposure to chemicals. A more useful measurement to report would be the cumulative permeation of a chemical that occurs over a given exposure period. This measurement can then be related to levels of skin contact that could be permitted specific to the chemical. The evaluation of glove performance from in-use measurements of permeation may offer a more appropriate means for determining the minimum necessary barrier performance of gloves and glove materials. This is especially true for organic chemicals that are not easily detected in conventional permeation tests. Many of these chemicals have low water solubility and low volatility but yet have been observed to permeate many types of gloves. Thus, the availability of techniques to measure permeation of low volatile, low water soluble chemicals through gloves under conditions of actual use can offer the potential for not only monitoring worker exposure, but also provide the basis for determining the appropriate minimum protection. This final report covers specific work requested by the National Institute for Occupational Safety and Health (NIOSH) for evaluating the effectiveness of absorbent materials used under gloves against specific chemicals and under defined exposure conditions, including the application of pressure. It is part of a comprehensive series of investigations sponsored by NIOSH to examine the use of solid sorbents and colorimetric indicators as a means for measuring glove material permeation resistance. This study was able to demonstrate that different solid sorbents can be used for the efficient detection of semi-volatile chemicals, having vapor pressures below 5 mm Hg. The selected sorbents offer potential for use under protective clothing based on their design and prior demonstrated use for measuring chemical permeation. The relative effectiveness of the solid sorbents was characterized with the 3M Empore C18 extraction disks providing the greater consistency of results over the spiked volume range used in the study (0.2 to 5 µL). The analytical techniques developed to extract and quantify the selected analytes proved linear with increasing volume. The study showed that increasing pressure (up to 200 g/cm2, consistent with tool use) increases the ability of the selected sorbents to detect semi-volatile chemicals. While the mechanism for these observations has not been fully investigated, it is suspected that the increased pressure provides more uniform contact of the permeating chemical with the sorbent material. In comparing the performance of the selected solid sorbents with commercially available colorimetric indicators, correspondence was generally achieved between solid sorbent and colorimetric indicators for detection of permeating chemical. Exceptions included the colorimetric indicator that did not show detection of the selected solvent (2-ethoxyethanol). In this case, the indicator sensitivity to the chemical may have been at higher level than achieved in the permeation of the sample glove material. However, colorimetric detectors showed indications of permeation in all cases for the selected aromatic amine (aniline) and phenolic chemical (mcresol). While the findings of this study are limited to a few chemicals and solid sorbents under specific conditions, the results suggest the potential for using solid sorbents and colorimetric indicators as an effective media under protective clothing to quantify or indicate permeation, respectively. A practice of using solid sorbents can provide a more meaningful basis for measuring permeation in terms of cumulative dose to the individual worker under the conditions of use.
Gloves; Protective-clothing; Protective-equipment; Work-clothing; Personal-protection; Personal-protective-equipment; Analytical-processes; Analytical-methods; Laboratory-techniques; Laboratory-testing
Final Contract Report
National Institute for Occupational Safety and Health
International Personnel Protection, Inc.
Page last reviewed: September 2, 2020
Content source: National Institute for Occupational Safety and Health Education and Information Division