Formation and Elution of Toxic Compounds from γ-Ray Sterilized Medical Products: Toxic Compound Formation and Ames test of Eluted Components

Abstract

No formation of MDA was observed in chain-extended thermoplastic polyurethane (PU) when sterilized by autoclave 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 sterilized by 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 is 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 presented mutagenicity in the absence of metabolic activity (S9Mix). MDA presented mutagenicity in the presence of metabolic activity; therefore MDA was not the major mutagenic candidate. The chemical and biological characteristics of the specific mutagens required to identify in a further study. Negative promotion of MDA formation and a lesser presence of mutagen in autoclave sterilized potting material indicated that autoclave sterilization was preferable if the material is tolerable to heating.

Ethylene Oxide Gas Sterilization of Medical Devices

“…Because moist heat sterilization procedures are simple and no toxic residues. Other methods such as EOG or gamma-ray irradiation sterilization has a problem of toxic gas residue or degradation of medical devices, respectively Shintani and Nakamura, 1991a;Shintani and Nakamura, 1991b;Shintani, 1991c;Shintani, 1992;Shintani, 1995a: Shintni 1995bShintani, 1996a;Shintani, 2001a;Shintani, 2004a: Shintani, 2012Shintani, 2014a . This means EOG sterilization was not positively recommended.…”