Induction of sarcomas in rats by solid and fragmented polyethylene: Experimental observations and clinical implications

Abstract

Polyethylene plastic was implanted into the subcutaneous tissues of 40 young male rats: 20 received a solid segment of polyethylene (average weight 622 mg.) and 20 received shredded plastic (average weight 527 mg.) enclosed in a gelatin capsule. A sham operation, without implantation of plastic or capsule, was performed on 20 animals, and empty gelatin capsules were implanted into 20 control rats. Tumours at the site of implantation occurred only in animals which received the plastic. Seven rats with solid polyethylene implants developed local tumoursone carcinoma and six sarcomas-with a latent period of induction of 48 to 79 weeks (mean 52 weeks). Five sarcomas developed in rats in association with implants of shredded plastic, their latent period of induction ranging between 41 and 77 weeks with a mean of 60 weeks. The sarcomas in the two groups were similar in appearance and behaviour. Metastases were found in two animals. The incidence of other tumours, and of non-neoplastic pathological changes, was similar in test and control rats. Current theories of carcinogenesis by plastics are discussed in the light of these observations. The use of polyethylene in clinical medicine is also considered and the possible hazards associated with large amounts of the material, particularly in thoracic surgery, are emphasised. © 1969, The British Empire Cancer Campaign for Research. All rights reserved.