Observations on the effects of powdered polymer in the carcinogenic process.

It has been shown that polymer powders, in contrast to polymer and other films, are noncarcinogenic when imbedded subcutaneously. An important difference in response between films and powders appears to be the fibrous pocket formed around the im bedded film. It is in the lining cells of this pocket that the tumors originate. No such pocket arises with powders. It was suggested that powder might perhaps induce tumors if presented directly to the cells of a pre-formed pocket. To test this hypothesis (1) polyethylene powder and (2) glass powder were inserted into pockets produced by imbedding glass films, both with and without the presence of the film. Results gave no evidence of any significant change in tumor incidence produced by the action of powder on the pocket cells. This was confirmed by histological observations, which showed a remarkable similar ity in response to powder whether imbedded in ordinary connective tissue or introduced into a pocket. A foreign-body reaction, with phagocytic giant cells, was found con stantly with imbedded powder.