Gastrointestinal tract and skin permeability of chemicals in consumer products using parallel artificial membrane permeability assay (PAMPA)

Some chemicals commonly used in personal care products, household items, food vessels, cosmetics, and other consumer products are potentially harmful, and several reviews of epidemiological studies have suggested the associations between the chemical exposure from consumer products, and respiratory diseases, skin sensitization, and reproductive problems. Therefore, risk assessment is essential for management of consumer products safety. Necessarily, the estimation of human exposure is an essential step in risk assessment, and the absorption rate of those chemicals via the gastrointestinal tract, respiratory tract, and skin are very critical in determining the internal dose of the exposed chemicals. In this study, parallel artificial membrane permeability assays (PAMPA) for the gastrointestinal tract and skin were performed to evaluate the permeability of parabens (4-hydroxybenzoic acid, methyl-, propyl-, and butyl paraben), bisphenols (bisphenol A, bisphenol F, and bisphenol S), isothiazolinones (methyl-, chloromethyl-, benz-, octyl-, and dichlorooctyl isothiazolinone), and phthalates [diethyl-, dibutyl-, Di-isononyl-, and bis(2-ethylhexyl) phthalate]. Lipid solubility of test chemicals indicated by log P values was shown as the most critical factor and showed a positive association with the permeability of parabens, bisphenols, and isothiazolinones in PAMPA assay. However, phthalate showed a reverse-association between lipophilicity and permeability. The permeability of all the tested chemicals was higher in the gastrointestinal tract membrane than in the skin membrane. The pH in donor solution did not show significant effects on the permeability in all the chemicals, except the chemicals with a free hydrophilic moiety in their chemical structures.