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Dermal Exposures
Assessment and Control Techniques

Employers today face requirements to assess and control employee exposures to a wide range of hazardous conditions. Emphasis is often placed on the obvious exposure pathways, inhalation and ingestion. Dermal exposure pathways are less easily measured and lack the exposure guidelines or thresholds commonly used to assess other chemical or physical agents. Interestingly, of the 264 OSHA regulated substances, over 60% carry skin notations. The ACGIH lists 179 compounds with a skin notation, referring to the substance’s potential to significantly contribute to the overall exposure by the cutaneous route. In a 1984 annual survey, the Bureau of Labor Statistics (BLS) estimated that 34% of all reported cases of chronic occupational diseases were dermatological disorders. In 1985 BLS and the Department of Labor found that 66% of the 125,000 new cases of occupational illnesses involved skin disease or disorders associated with repeated trauma. These facts confirm the importance of assessing dermal hazards in the work environment.

The skin is the largest organ of the human body. It’s surface area, approximately 20 square feet (1.8 m2), is second only to that of the lungs (70-100 m2) in available exposure pathways. The significance of dermal absorption is commonly underestimated. For example, a fully absorbed dermal exposure of one drop (35 mg) of MDI (diphenylmethane-4,4 diisocyanate) is estimated to be the equivalent of 62 consecutive days of 8 hour inhalation exposure at the 5 PPB threshold limit value!

OSHA has long recommended the use of "wipe sampling" to screen working surfaces for contamination by suspected carcinogenic agents like the Aromatic Amines. Some standards, such as 1910.1050 for Methylenedianiline (MDA), require the employers to make routine inspections of employee hands, face and forearms potentially exposed to MDA. Other potential dermal exposures reported by the employee must be referred to the appropriate medical personnel for observation.

In a document recently released by OSHA’s Salt Lake City, Directorate of Technical Support, a comparison of the performance of easy-to-use field indicators called "SWYPE’s" and "PERMEA-TEC Pads" to the existing OSHA wipe methods was done to evaluate the specificity and lower detection limits of these indicators to the amines group. These colorimetric indicators provide reliable direct reading indications of surface contamination and glove breakthrough. The report determined that such indicators could have wide applicability under present regulations for MDA.

Controlling dermal hazards once they are recognized often relies on effective skin cleaning. Most MSDS information recommends "soap and water" decontamination of the skin even though many of these contaminants are non-soluble. Cleaning products should be evaluated for pH, and the presence of abrasives, emollients or lanolin which may enhance the absorption of skin contaminants.

Written by:

Timothy Kearney, CSP
Vice President, Argus Group

Article Provided by: The Argus Group

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