Irritation effects of residual products derived from poly(2-hydroxyethyl methacrylate) gels. I. Testing of some model...

2-Hydroxyethyl methacrylate (HEMA) monomer and sodium benzoate, diluted with saline in the range 0-20%, were tested for intradermal irritation in rats. Radioactive indicator (113mIn) was used to quantify this biological response. At low concentrations (up to 1%) only a little irritation was recorded, while at higher levels (5% or more) a significant adverse reaction developed. The degree of irritation was dose dependent. In the concentration range 0-10%, the response was exponential. Model decomposition products derived from three different polymerization initiators were also tested. How the results obtained with the model irritants relate to real polymerization systems is discussed.