Getting under the skin

For a long time, the skin was considered to be an impermeable layer that protected the underlying tissues from adverse effects by chemical substances. Although it was recognized that some substances - for instance insecticides which were deliberately designed to penetrate insect skin - could readily pass the human skin as well and cause toxicity, this was thought to be an exception rather than the rule. A good example of this mindset is the perception that the dermal penetration of benzene is in general negligible. This thought is found in some text books and also in the USA Environmental Protection Agency (US EPA) Integrated Risk Information System (IRIS), where it is stated that "absorption of benzene via the dermal route of exposure is usually