Solvent and vehicle effects on the skin.
Roberts-MS; Gierden-A; Riviere-JE; Monteiro-Riviere-NA
Dermal Absorption and Toxicity Assessment, 2nd ed. Roberts MS, Walters KA, eds., New York: Informa Healthcare, 2007 Dec; :433-447
The effects of solvents and vehicles on the skin are important since skin is the largest organ of the human body and provides protection against the external environment. In addition, the skin enables us to maintain a state of homeostasis. However, skin and its barrier properties may be altered when exposed to various chemical agents. Exposure to solvents and vehicles can occur after occupational or accidental spillage, topical application of cosmetics, sunscreens, insect repellents, as well as following the topical application of drugs for therapeutic purposes. This chapter provides an update on our earlier work (1). As discussed earlier in this book, the outermost layer of the skin, the stratum corneum (SC) is the main skin barrier and is composed of keratinized dead epidermal cells that are thin, less than 1 microm, and 30 to 40 microm in diameter. Figure 1 shows a transmission electron microscopy (TEM) image of the SC (1). The lipid bilayers between the cells can be easily visualized by after fixing in Trump's fixative and postfixing in phosphate-buffered ruthenium tetroxide prior to being processed for TEM. Desmosomes are evident in lipid bilayers, especially in areas associated with friction in the environment. Disintegration of the desmosomes, most evident in the outermost SC, is frequently associated with the creation of lacunae (1). Desmosomes usually span the entire width of the intercellular space but, with jet fuel JP-8 + 100 treatment, desmosomes are degraded and separated from the central core leaving a space (lacunae) between the desmosomes (2), similar to what was found for hydrocarbon solvents in our earlier work (1). The lacunae are probably also due to the extracted lipid lamellae (1). The main lipids in the SC are ceramides, cholesterol, and free fatty acids (3).
Skin-exposure; Skin-absorption; Absorption-rates; Chemical-kinetics; Chemical-properties; Dermatology; Physiological-factors; Physiological-effects; Physiological-response; Sunscreening-agents; Solvents; Cosmetics; Hydrocarbons; Insect-repellents
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Disease and Injury: Allergic and Irritant Dermatitis
Dermal Absorption and Toxicity Assessment, 2nd ed.
North Carolina State University, Raleigh, North Carolina