Comparison of the Carcinogenic Actions of Subcutaneous Implants of Iron and Aluminum in Rodents

Summary

Subcutaneous implants of aluminum foil induced sarcomas in 8 of 18 NIH Black rats. However, no sarcomas were obtained in 25 rats similarly implanted with rough-surfaced iron discs during an observation period of 25 months. The iron discs or scales were obtained from chips of the partly oxidized inner surface of a cooking pot used by a Bantu family, 2 members of which died of esophageal cancer. Possible reasons for the different responses of the iron and aluminum implants are discussed and it is tentatively concluded that a smooth surface on the implant expedites the induction of sarcomas. An additional group of rats received 3 subcutaneous injections of a suspension of powdered iron scales, and 1 of 24 developed a sarcoma at the injection site. NIH General Purpose mice received a single injection of powdered iron scales as newborns and did not differ materially from control mice after an observation period of 21 months. It is concluded that iron is only weakly carcinogenic to the rodent.