The second expert report
by the World Cancer Research Fund (WCRF) and the American
Institute for Cancer Research (AICR), in 2007, informed that there
is a substantial amount of evidence that red meat and processed
meat are convincing causes of colorectal cancer. Nevertheless, this
report also noted that there was insufficient evidence to reach any
consensus for nitrates, nitrites, heterocyclic aromatic amines
(HAAs), nitrosamines, or polycyclic hydrocarbons as risk factors