The major barrier to dermal absorption of toxicants is the horny layer. Arrange the following in the increasing order of skin permeability to toxicants:
(A) Genital area (B) Abdomen (C) Arms (D) Palms
Choose the correct answer from the options given below:

Correct option is C

Skin Permeability and the Horny Layer:
· The stratum corneum (horny layer) is the outermost layer of the skin and acts as the primary barrier to chemical penetration.
· Permeability varies based on the thickness of the stratum corneum and regional differences in skin.
Order of Permeability:
· (D) Palms: Least permeable due to the thick and dense stratum corneum.
· (B) Abdomen: Moderately permeable due to thinner skin than the palms but thicker than other areas.
· (C) Arms: Higher permeability due to relatively thin skin.
· (A) Genital Area: Most permeable due to very thin skin and rich vascularization, making it highly susceptible to toxicant absorption.
Information Booster: 1. Factors Affecting Skin Permeability:
· Thickness of the Stratum Corneum: Thicker skin reduces permeability.
· Regional Differences: Certain areas like the genital area are more permeable.
· Chemical Properties: Lipid solubility and molecular size of the toxicant influence absorption.
2. Applications in Toxicology and Pharmacology:
· Understanding skin permeability is critical in designing topical medications and evaluating exposure risks to chemicals.
3. Examples:
· Palms resist absorption due to their thick skin, whereas the genital area readily absorbs due to thin skin and increased blood flow.