Just like any assessment of exposure to airborne hazards
there are a number of exposure parameters that should be
measured to characterise dermal exposure and to determine
uptake. The exposure intensity and the surface area exposed
together with the duration of skin contact and frequency of
skin cleaning or repeated exposure are all required to
understand the mass of substance likely to be absorbed.
Measurement of dermal exposure has developed in a
piecemeal and often chemical or use specific manner with
much of the methodology centred around measurement of
pesticide residues on the skin. Current methods can be
divided into five main types.16 Surrogate skin and patch
methods use whole body suits or representative patches to
capture the potential exposure. Removal methods use
washing, wiping, or skin stripping techniques to determine
the amount of material on the skin at a given time point.
Visualisation uses fluorescence to determine the area of
exposure and quantify the mass deposited on the skin. Biomonitoring
can be used to indirectly determine the amount
of dermal uptake and from this provide an estimate of the
amount of actual exposure. Dermal exposure modelling
utilises statistical or deterministic methods to help estimate
the amount of chemical likely to be deposited on the skin.
A review by Soutar and co-workers17 describes the range of
surrogate skin and patch methods in use for the assessment
of dermal exposure. The two most commonly used sampling
protocols are published by the World Health Organisation
(WHO) and the Organisation for Economic Cooperation and
Development (OECD).