The skin, the largest organ of the human body, is the protective shield against many physical, chemical, and biological agents that would otherwise cause harm. However, it is not impervious to all possible environmental insults. Physical agents, e.g., heat, cold, ionized radiation, can all harm the skin. Many chemicals are toxic, even corrosive. Biological agents include some that induce toxic or allergic reactions in or on the skin, such as poison ivy, and some pathogenic organisms gain entry to the body through the skin. All these can be classified as dermal exposure.
Subjects: Public Health and Epidemiology.