Influence of water dilution on in vivo and ex vivo percutaneous absorption of [14C]-N-vinyl-2-pyrrolidone in rats

N-vinyl-2-pyrrolidone (NVP) is mainly used as monomer in the production of polyvinylpyrrolidone or copolymers. Percutaneous absorption is an important source of exposure in the work environment. However, literature on this route of absorption is poorly documented.
In this study, percutaneous NVP absorption of neat or aqueous solutions was measured in vivo in rats, and ex vivo in rats and humans. Following in vivo exposure to neat NVP, penetration and absorption fluxes were very close (respectively 0.50 and 0.40 mg/cm²/h) indicating that there was no or small accumulation in the skin throughout exposure. Exposing rats to a 50% aqueous solution of NVP resulted in a threefold increase of both fluxes (respectively 1.48 and 1.55 mg/cm²/h). Ex vivo in rats, the absorption flux rose from 10% to 50-75% of NVP and then remained relatively constant over this point. There was no significant difference between neat and 50% NVP. In similar exposure conditions, the same occurred on human skin, where the flux rose between 10% and 50 % (respectively 0.40 and 1.60 mg/cm²/h) and was not significantly different between 50% and neat NVP (1.30 mg/cm²/h).