Masashi Kamiyama

The potential dermal irritating effect of residual (meth) acrylic monomers in pressure sensitive adhesive tapes

It is generally thought that residual unpolymerized (meth)acrylic monomers commonly found in pressure sensitive adhesive tapes for medical use may cause dermal irritation, but a systematic study has never been carried out. Therefore, we assessed the potential dermal irritating effect of residual (meth)acrylic monomers. We studied seven acrylic monomers, acrylic acid (AA), methyl acrylate (MA), ethyl acrylate (EA), n-butyl acrylate (n-BA), n-hexyl acrylate (n-HA), 2-ethylhexyl acrylate (2-EHA) and 2-hydroxyethyl acrylate (HEA), as well as three methacrylic monomers, methacrylic acid (MAA), methyl methacrylate (MMA) and 2-hydroxyethyl methacrylate (2-HEMA). We first examined their cytotoxic effect on a cultured dermis model using the MTT method to determine their EC50 and then performed a primary irritation test in rabbits using the monomers at three different concentrations (i.e., EC50 , one-tenth EC50 and 10 times EC50). Marked variations were found in cytotoxic and dermal irritating activities among the (meth)acrylic monomers tested. HEA exhibited the most potent dermal irritation having the lowest erythema dose (the concentration which gives a primary dermal irritation index of 1.00) of 460 ppm. But the other monomers exhibited less potent dermal irritation (lowest erythema doses ≥1000 ppm). For the monomers, significant correlation was found between cytotoxic activity and in vivo dermal irritating activity. Our results show that residual unpolymerized (meth)acrylic monomers in adhesive tapes are unlikely to induce skin irritation except for HEA. This study also suggests that cultured skin models are extremely useful as a screening method for chemical substances that could potentially cause dermal irritating activity.