Dermal Exposure

Dermal Exposure Menu Workers' Rights

Evaluating Exposure

A variety of methods exist for estimating dermal exposure. Hand rinses, dermal/surface wipes, and skin patches are some of the tools which can be used to determine the effectiveness of gloves or the extent of the contamination in "clean" work areas, such as break rooms and lunch rooms. Biological monitoring results are also a very valuable means of determining if dermal exposure is a major route of exposure. Presently, there are a limited number of guidance values for chemicals measured in the body, that is the biological exposure indices (BEIs) which are published by the American Conference of Governmental Industrial Hygienists (ACGIH). In addition, there are many studies published in peer-reviewed literature which report chemical exposure levels for workers in a variety of different occupations and different industries.

  • While "Skin" notation is an alert, the means to evaluate the magnitude of dermal exposure, its importance relative to airborne exposure, and the effectiveness of preventive controls, are limited.
  • Limits for biological response, called Biological Exposure Indices (BEIs) by the ACGIH, have been set for 36 chemicals or chemical groups(2); however, only 15 of these chemicals have a "Skin" notation, suggesting that less than half of these BEIs are for chemicals that are significantly absorbed through the skin. Biomonitoring methods are discussed at greater length elsewhere. (27-28)
Monitoring and Evaluation Methods

Dermal exposure evaluation methods have been broadly categorized into direct and indirect methods.

Direct

  • Direct means assessing what is deposited onto the skin.
    • The most common direct method is the use of dermal dosimeters in the form of either patches(3-17) or whole body suits.(3,12) Other direct evaluation methods include skin washes and wipes,(3,10,11,13) and the video detection of fluorescent tracers.(3,8,11,13,15)

Indirect

  • Indirect means estimating dermal dose either as attributable to some biologic indicator that is actually measured or that which could potentially result from a contaminant measured on an accessible surface.(3)
    • Indirect methods refer primarily to measuring a biologic response such as cholinesterase activity in blood(5,6,14) or urinary excretion(5-7,9,12,14,15), but also include measuring surface contamination.(3,5,6,11,18-20)

Monitoring surfaces for contamination is an old method frequently used in the radiation health field where control is based on keeping exposure as low as reasonably achievable. In comparison, chemical hazards allow exposures to define limits or thresholds of exposure. The problem is defining a relationship between surface contamination and dose that would be used to set a surface contamination threshold. Most reviewers have found poor correlations between the two. (11,18,19) For instance, Caplan concluded there is no correlation between surface contamination levels as determined by wipe sampling and air concentration levels; however, wipe sample levels can be useful in estimating dermal exposure if skin absorption data is available.(18) In the area of pesticide foliar residues, this relationship has been called a "transfer coefficient."(3) There are currently no OSHA standards that specify surface contamination criteria. However, several standards do require appropriate provision of personnel protective equipment (PPE), housekeeping, decontamination, and related procedures to control surface contamination hazards.

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