Absorption through skin depends on multiple factors; which option lists the correct set?

• A. Only the chemical type
• B. Only the exposure extent
• C. The chemical, extent of exposure, product formulation, area of skin exposed, and skin condition
• D. Only the area of skin exposed

Answer: (C)

Absorption through the skin depends on several interacting factors, not a single determinant. The chemical’s properties—such as lipophilicity, molecular size, and concentration—affect how readily it can cross the skin barrier. The extent of exposure matters because both how long the skin is in contact with the product and how large the exposed area is will influence the total amount absorbed. Product formulation plays a role because solvents, surfactants, and other ingredients can act as carriers or barriers, altering the rate and extent of absorption. The area of skin exposed matters since different skin sites have different permeability, and larger exposed areas can lead to more overall absorption. Skin condition is also critical: damaged, dry, cracked, or irritated skin compromises the barrier and increases absorption, with temperature and sweating further modifying permeability.

Therefore, the complete set includes the chemical, extent of exposure, product formulation, area of skin exposed, and skin condition.