[en] Cytotoxicity testing (cell growth inhibition, LDH-assay) has shown that RVNRL materials are considerably less cytotoxic than sulphur-vulcanised materials. Also the effect of applying different leaching times during the production process was investigated and gave interesting results. Protein testing (BCA - comparable to a Lowry assay ) has shown that some, but not all proteins are destroyed during irradiation. For the total protein content of the materials as determined in this way, the effect of leaching proved to be very important. This was also checked by; SDS-PAGE assays: After irradiation a smear is observed with SDS-PAGE; when the irradiated material has been leached, most of the smear has disappeared. An important protein (14 kD) is still present and seems hardly to be affected. The materials have also been evaluated clinically, using well characterised patient sera (Western blotting) in order to determine whether the remaining proteins are allergenic