ABSTRACT
There are numerous methods which have been employed to assess the
percutaneous absorption of toxic chemicals using both in vitro and in vivo animal
models. There is little debate that in vivo human studies are optimal for predicting
the absorption of topically applied chemicals in man. However, for highly toxic
or carcinogenic chemicals, ethics preclude conducting such studies when a risk
analysis is to be conducted. Similar considerations apply to the humane use of
animal surrogates. For chemicals which pose little direct adverse risk to man or
animals, experimental design and sampling limitations often apply to any
in vivo study. An important limitation is the inability to noninvasively sample
the venous drainage of a topical application site to determine the true cutaneous
flux for use as an input into systemic risk assessment models. Similarly, extensive
biopsies may not be taken to quantitate subtle, pre-clinical morphological or
biochemical manifestations of dermatotoxicity.