Skin permeation and metabolism of di(2-ethylhexyl) phthalate (DEHP).

Toxicology letters (2013-10-22)
N B Hopf, A Berthet, D Vernez, E Langard, P Spring, R Gaudin
ABSTRACT

Phthalates are suspected to be endocrine disruptors. Di(2-ethylhexyl) phthalate (DEHP) is assumed to have low dermal absorption; however, previous in vitro skin permeation studies have shown large permeation differences. Our aims were to determine DEHP permeation parameters and assess extent of skin DEHP metabolism among workers highly exposed to these lipophilic, low volatile substances. Surgically removed skin from patients undergoing abdominoplasty was immediately dermatomed (800 μm) and mounted on flow-through diffusion cells (1.77 cm(2)) operating at 32°C with cell culture media (aqueous solution) as the reservoir liquid. The cells were dosed either with neat DEHP or emulsified in aqueous solution (166 μg/ml). Samples were analysed by HPLC-MS/MS. DEHP permeated human viable skin only as the metabolite MEHP (100%) after 8h of exposure. Human skin was able to further oxidize MEHP to 5-oxo-MEHP. Neat DEHP applied to the skin hardly permeated skin while the aqueous solution readily permeated skin measured in both cases as concentration of MEHP in the receptor liquid. DEHP pass through human skin, detected as MEHP only when emulsified in aqueous solution, and to a far lesser degree when applied neat to the skin. Using results from older in vitro skin permeation studies with non-viable skin may underestimate skin exposures. Our results are in overall agreement with newer phthalate skin permeation studies.

MATERIALS
Product Number
Brand
Product Description

Sigma-Aldrich
Dioctyl phthalate, ≥99.5%
Supelco
Bis(2-ethylhexyl) phthalate, PESTANAL®, analytical standard
Supelco
Bis(2-ethylhexyl) phthalate, certified reference material, TraceCERT®
Supelco
Bis(2-ethylhexyl) phthalate, Selectophore
Supelco
Bis(2-ethylhexyl) phthalate solution, certified reference material, 2000 μg/mL in methanol