Long-term histological response to subcutaneously injected Polytef and Bioplastique in a rat model

Abstract

<h4>Objective</h4>To compare the long-term carcinogenic effect of Polytef and Bioplastique in the subcutaneous space of the rat.<h4>Materials and methods</h4>One hundred Sprague Dawley rats received a subcutaneous injection of one of two particulate plastics; subsequently 48 of those injected with Polytef paste containing polytetrafluoroethylene, 48 injected with silicone containing Bioplastique, and 48 control animals were available for assessment. Animals were killed when they became unwell, developed a tumour, or were 2 years of age. The injection site and all major organs and tumours were examined histologically.<h4>Results</h4>One or more tumours were found in 30 Polytef-injected rats, 34 Bioplastique-injected animals and 36 of the controls. The majority of the tumours were breast and pituitary adenomas with a similar incidence in each group. No tumours were found at the injection site of the Polytef-injected animals. Four poorly differentiated sarcomas were found on the back of Bioplastique-injected rats; three were intimately associated with silicone particles, whereas the fourth was separate from the injection site.<h4>Conclusion</h4>This study would suggest that the carcinogenic risk from injectable plastics is low, but further work should be conducted with the larger particles, to ensure that their use in humans is safe.