The WHO's cancer research unit now classifies processed meat as "carcinogenic to humans" based on evidence from hundreds of studies, and linked it specifically to colon, or colorectal, cancer.
The report outlined that simply eating 50 grams of processed meat each day -- the equivalent of two slices of ham -- can increase the risk of such cancer by 18%. However, the authors say the risks are relatively small to begin with.
The organization defines processed meat as any type of meat that is salted, cured or smoked to enhance its flavor or preserve it. Processed meat generally contains pork or beef, but may also contain poultry.
The WHO now classifies processed meat in the same category as smoking and asbestos, based on its certainty of a link with cancer, but stressed that did not mean they were equally dangerous.
Unprocessed red meat such as steak and lamb shanks is classified as "probably carcinogenic."
Balancing risks and benefits
The WHO said the finding was important for public health since processed meat is so widely consumed. However, it said red meat still has "nutritional value."
"These results are important in enabling governments and international regulatory agencies to conduct risk assessments, in order to balance the risks and benefits of eating red meat and processed meat and to provide the best possible dietary recommendations," said Christopher Wild, head of the WHO's cancer agency, in a statement.
According to estimates cited by the WHO, about 34,000 cancer deaths per year worldwide can be attributed to diets that are high in processed meat. That's a small fraction of the 8.2 million deaths caused by cancer in 2012, according to the latest WHO data.
Meat industry cries foul
Meat industry groups slammed the WHO report as biased and misleading.
"They tortured the data to ensure a specific outcome," said Betsy Booren, vice president of scientific affairs at the North American Meat Institute.
The National Cattlemen's Beef Association said the scientists who issued the report were split on their decision to make an explicit link between red meat with cancer.
"As a registered dietitian and mother, my advice hasn't changed," said Shalene McNeill, an executive director at the National Cattlemen's Beef Association. "To improve all aspects of your health, eat a balanced diet, which includes lean meats like beef, maintain a healthy weight, be physically active and, please don't smoke."