Lead is toxic; hence, the shift to lead-free petrol, a move indicative of a growing concern about inadvertent poisoning by a widely-used element. Health authorities and employers are generally aware of the dangers of lead in the environment. They have acted to reduce the risk of poisoning from eating food high in lead or from breathing in lead-rich dust. Less often considered is a third route of entry, the skin. Skin usually forms a fairly efficient barrier to the entry of chemicals and microorganisms. Certain compounds, especially if they are fat-soluble, can pass across it.