抄録
No formation of N,N’-methylene dianiline (MDA) was observed in chain-extended thermoplastic polyurethane (PU) when sterilized by autoclaving or γ-ray irradiation. No formation of MDA was observed in nonchain-extended thermoplastic PU when sterilized by γ-ray irradiation. Less than 1 ppm of MDA was produced in nonchain-extended thermoplastic PU subjected to autoclave sterilization. Autoclave sterilization did not produce MDA in thermosetting PU potting material. MDA formation in potting material was promoted by γ-ray irradiation and increased with increasing irradiation doses at a quadratic equation of regression. MDA formation at 100 kGy irradiation amounted to a few ppm and less than one ppm at 25 kGy irradiation: therefore, the potential risk to human recipients was not significant. The elution of compounds other than MDA from potting material was more problematic. Solvent extracts from potting material showed mutagenicity in the absence of metabolic activity (S9Mix). MDA showed mutagenicity in the presence of metabolic activity, therefore MDA was not the major mutagenic candidate. The chemical and biological characteristics of the specific mutagens should be identified in a further study. The lack of MDA formation and a smaller presence of mutagens in autoclave-sterilized potting material indicated that autoclave sterilization was preferable if the material is able to tolerate heating.
