They re lurking in your favorite foods barbequed chicken, smoky ribs, hamburgers. Even gravy is suspect. A good dose will give a rat cancer within weeks. Heterocyclic amines are brought to us by the same chemistry that gave us free radicals, and they're just about as welcome. These little molecules are created when heat breaks up amino acids and creatinine.
High heat is the worst.
HCAs are not free radicals themselves, but they provoke them. And they do things just as bad or worse. There's a bunch of different types, and researchers are beginning to think that these little devils are one reason meat-eaters are at risk for certain types of cancer. HCAs cause DNA mutations, especially in the colon. The liver and breasts are other well-studied targets for HCAs, but any organ is susceptible.