Evaluation of dermal exposure to phthalates and parabens resulting from the use of hair relaxers.

Abstract

Hair relaxers have been suggested as a source of exposure to parabens and phthalates. However, dermally absorbed doses of these chemicals resulting from consumer use of hair relaxers have yet to be quantified, and results from epidemiological studies have consistently demonstrated that there is no increased risk for hormone-sensitive, reproductive cancers associated with use of hair relaxers among Black women. Therefore, dermal absorption of parabens and phthalates associated with hair relaxer use for several commercially available hair relaxer kits was modeled using IH SkinPerm™. The chemicals detected in the hair relaxer kits included methylparaben (MP), ethylparaben (EP), butylparaben (BP), diethyl phthalate (DEP), bis(2-ethylhexyl) phthalate (DEHP), and the phthalate substitute bis(2-ethylhexyl) adipate (DEHA). The daily absorbed dose ranges (mg/kg/day), standardized over a year of product use, were as follows: 8.64 × 10^-5-0.00116 MP, 2.30 × 10^-8-3.07 × 10^-6 EP, 3.24 × 10^-8-4.33 × 10^-6 BP, 8.65 × 10^-9-1.15 × 10^-6 DEP, and 8.94 × 10^-7-0.000119 DEHP for Kit #1; 8.44 × 10^-5-0.00113 MP and 7.91 × 10^-5-0.00106 DEP for Kit #2; and 2.49 × 10^-6-3.33 × 10^-5 MP, 1.52 × 10^-8-2.03 × 10^-6 EP, 3.29 × 10^-9-4.39 × 10^-7 DEP, and 3.11 × 10^-6-4.14 × 10^-5 DEHA for Kit #3. These absorbed doses were well below applicable health-based guidance values, indicating consumer exposure from product use is not expected to pose a health risk. These results provide valuable information for health risk evaluations for hair relaxer use.