I did research on it and posted it here in "DNP for Dummies," collecting peer-reviewed medical reports finding that DNP is not toxic to any body part, and is not carcinogenic...in fact, DNP *attacks* cancers, tumors, and resistant bacteria. It can be used as a stain in tumor detection because it will bind to, and suffocate, tumors without changing the chromosomes or health of surrounding healthy cells. It also attacks breast cancers.
Yet it is classified as a carcinogen and a toxin by the EPA. The first label is obviously false, and is based on the syllogism that "other phenols are carcinogenic, so a dinitro probably would be, too!" Is it a toxin? In the sense that too high a dose is deadly, yes--just like salt.
The worst damage seems to be free radicals released by fat cells. Well-researched approaches to antioxidant inclusion will mitigate this, and I use a product that my source caps with a blend of four antioxidants, not corn starch, anyway.
Frankly, I think it is remarkably safe, and remarkably effective, and remarkably uncomfortable.