THE EFFECT OF COSMETIC VEHICLES ON THE PENETRATION OF N-NITROSODIETHANOLAMINE THROUGH EXCISED HUMAN-SKIN

[摘要] Cosmetic products are frequently applied to the human skin but some contain compounds that are potentially toxic, if absorption through the skin is sufficient. Percutaneous absorption of N-nitrosodiethanolamine (NDELA) [an animal carcinogen], an impurity in many cosmetic products, was evaluated in diffusion cells using excised human skin. Nitrosamine was applied to the skin in vehicles with different solubility properties. Permeability constants for water (5.5 .times. 10-6 cm/h) and propylene glycol (3.2 .times. 10-6 cm/h) were small and similar. In isopropyl myristate the permeability constant increased .apprx. 250-fold to 1.1 .times. 10-3 cm/h. NDELA membrane:vehicle partition coefficients were determined using trypsin-treated stratum corneum as the membrane. These coefficients were 1.8 and 1.0, respectively, for water and propylene glycol and 230 for isopropyl myristate. Permeability of NDELA through skin was apparently greatly increased when applied from sufficiently lipoidal formulations; this was primarily due to the favorable partition coefficients for NDELA from such formulations. The amount of NDELA penetrating the skin from 3 types of cosmetic products was calculated based on their different conditions of use. Products applied over large areas of the body that remained on the skin for long periods of time (sun tanning lotion) resulted in the greatest absorption of NDELA if all other factors were equal.