Updating and expanding the scope of topics covered in the previous edition, this Fourth Edition supplies new chapters on topics currently impacting the field including cutaneous metabolism, skin contamination, exposure to protein allergens, in vitro absorption methodology, the percutaneous absorption of chemical mixtures, the penetration of chemicals through the hair follicles, dermal drug delivery, mechanisms of absorption, nanoparticles and dermal absorption, the absorption of drugs and cosmetic ingredients, nail penetration, and other current research.