Background: Para-Phenylenediamine (PPD) is a commonly used dye intermediate in permanent hair dye formulations, and exposure to PPD has been associated with allergic contact dermatitis at certain doses.
Purpose: Determine the concentration of PPD in a survey of self-application permanent hair dye products, and perform a quantitative risk assessment to determine the risk of skin sensitization induction following application of these products.
Methods: Consumer exposure levels (CELs) to PPD following application of hair dye products were estimated using the maximum amount of hair dye that can adhere to the surface area of the scalp, the measured concentration of PPD in the hair dye product, a retention factor, the dermal absorption of PPD, and the surface area of the scalp. CELs were calculated for various exposure scenarios, and were stratified by hair dye shade.
Results: All estimated CELs did not exceed the acceptable exposure level. Specifically, margins of safety ranged from 2.3 to 1534 for black dyes, 2.9 to 5031 for brown dyes, and 26 to 5031 for blonde dyes.
Conclusions: Findings suggest that use of the evaluated permanent hair dyes, under the evaluated exposure scenarios, would not be expected to induce skin sensitization due to PPD exposure at concentrations ≤0.67%.
Keywords: PPD; Para-Phenylenediamine; dermal exposure; hair dye; quantitative risk assessment; skin sensitization.