LONG-TERM HISTOLOGICAL RESPONSE TO SUBCUTANEOUSLY INJECTED POLYTEF AND BIOPLASTIQUE IN A RAT MODEL

Objective To compare the long-term carcinogenic effect of Polytef and Bioplastique in the subcutaneous space of the rat. Materials and metho ds One hundred Sprague Dawley rats received a subcutaneous injection o f one of two particulate plastics; subsequently 48 of those injected w ith Polytef paste containing polytetrafluoroethylene, 48 injected with silicone containing Bioplastique, and 48 control animals were availab le for assessment. Animals were killed when they became unwell, develo ped a tumour, or were 2 years of age, The injection site and all major organs and tumours were examined histologically. Results One or more tumours were found in 30 Polytef-injected rats, 34 Bioplastique-inject ed animals and 36 of the controls. The majority of the tumours were br east and pituitary adenomas with a similar incidence in each group. No tumours were found at the injection site of the Polytef-injected anim als. Four poorly differentiated sarcomas were found on the back of Bio plastique-injected rats; three were intimately associated with silicon e particles, whereas the fourth was separate from the injection site. Conclusion This study would suggest that the carcinogenic risk from in jectable plastics is low, but further work should be conducted with th e larger particles, to ensure that their use in humans is safe.