A Practical Study in Laboratory and Workplace Permeation Testing

Abstract

Persistent dermal exposure of workers and facility contamination by meta-phenylenediamine (MPDA) during a research project precipitated a concentrated testing program to evaluate protective gloves, clothing, and usage procedures. The objective of this work was to determine the proper gloves and procedures needed to protect workers from dermal exposure to chemicals which were potential carcinogens.

MPDA is a very sensitive indicator of contamination because it readily discolors on exposure to air. It is not unique in its permeation characteristics; other chemicals only differ in relative rates of permeation. Therefore, the results obtained are applicable to other situations with different chemicals.

In our operation, MPDA was present in an amine hardener mixture. An epoxy resin was also a test material, and acetone was used as a solvent. Glove manufacturers' recommendations and breakthrough time data for these and similar compounds conflicted with the experiences in our operation. In addition, limited permeation rate and breakthrough time data are available for mixtures. Available computer models were not satisfactory in predicting suitable protective materials. Therefore, procedures were developed for evaluating protective materials qualitatively and quantitatively in the laboratory and the workplace based on MPDA's staining characteristic.

The relative performance of various glove and protective materials was determined in the laboratory. A barrier cream was also evaluated. The performance of selected gloves was evaluated in actual work operations by observing for MPDA stains on inner cotton gloves. Factors including breakthrough time and residue migration were evaluated as well as the influence of certain work operations, tools, and equipment.

The laboratory studies demonstrated the relative performance of the protective materials tested with the specific test chemicals. Workplace test results demonstrated significantly shorter breakthrough times than determined in the laboratory and from what might be implied from manufacturers' breakthrough tables. Manipulative operations and tasks involving exertion of pressure by the gloved hand were found to severely affect glove effectiveness. Butyl and nitrile gloves used alone and in combination were found to be satisfactory for our operations. However, their effectiveness was limited to specific operations, and they had to be discarded directly after completing tasks of less than 2 hours. Gloves were changed every 2 hours, regardless of activity. The barrier cream was not found to be effective.