EFFECTS OF ACUTE AND SUBCHRONIC EXPOSURE OF TOPICALLY APPLIED FULLERENE EXTRACTS ON THE MOUSE SKIN

The recent discovery that fullerenes (C60) can be produced in macrosco pic quantities has sparked much interest in the chemistry of this unus ual molecule. Concerns have also arose about the potential carcinogeni c effects of this molecule. We have addressed the potential acute and subchronic toxic effects of fullerenes applied in benzene on the mouse skin. The acute toxic effects measured in this study included epiderm al DNA synthesis and the induction of ornithine decarboxylase activity in the epidermis. At the topical dose of fullerenes used in these stu dies (i.e., 200 ug), we found no effect on either DNA synthesis or orn ithine decarboxylase activity over a 72 hour time course after treatme nt. The subchronic effects of the fullerenes as a mouse skin tumor pro moter was assessed by repeatedly applying the chemical to the skin aft er initiation with the polycyclic aromatic hydrocarbon, 7,12-dimethlyb enzanthracene (DMBA). Repeated administration of the fullerenes for up to 24 weeks post-initiation did not result in either benign or malign ant skin tumor formation, whereas promotion with the phorbol ester, 12 -O-tetradecanoyl-phorbol-13-acetate (TPA) resulted in the formation of benign skin tumors. Our data indicate that fullerenes applied in benz ene at a likely industrial exposure level do wt cause acute toxic effe cts on the mouse skin epidermis.