http://www.ag.ohio-state.edu/~news/story.php?id=1781

Every summer, I try not to think about rumors of cancer risks associated with barbecue-grilling food. Finally, I thought I'd better ask outright: Is grilling food safe?

As with any type of cancer-associated risk, the amount of potential carcinogens that you ingest affects the risk. People who eat a lot of grilled meat -- and "a lot" isn't really defined, unfortunately -- might want to take some precautions.

The problem, according to the American Institute for Cancer Research, comes in the form of compounds called heterocyclic amines (HCAs). Natural substances in red or white meat form HCAs when subjected to high heat, and HCAs have been linked with increased cancer risk in some animal studies. More HCAs form when the cooking time is longer and the cooking temperature is higher, whether the meat is grilled, broiled or pan-fried.

Other compounds, called polycyclicaromatic hydrocarbons (PAHs), are found in the charred parts of meat and in the smoke from juices and fat dripping on barbecue coals or stones. PAHs are mutagens, substances that can alter the genetic material of cells, and have been linked to cancer in animal tests. Like HCAs, however, a link between PAHs and human cancer hasn't been confirmed.

A recent study, reported in the Proceedings of the 92nd Annual Meeting of the American Association for Cancer Research, indicates some people may be at higher risk from substances formed in well-done red meat. Those people have specific genetic variations in which enzymes change the substances into cancer-causing agents. This could be why cause-and-effect is so hard to determine -- many other factors can come into play to make the compounds more risky, or less.