Chemicals in Meat Cooked at High Temperatures and Cancer Risk - National Cancer Institute 
Heterocyclic amines (HCAs) and polycyclic aromatic hydrocarbons (PAHs) are chemicals formed when muscle meat, including beef, 
or pork, fish, or poultry, is cooked using high-temperature methods, such as pan frying or grilling directly over open flame.

In laboratory experiments, HCAs and PAHs have been found to be mutagenic—that is, they cause changes in DNA that may increase the risk of cancer.