PARIS -- It's official: Ham, sausage and other processed meats can lead to colon, stomach and other cancers - and red meat is probably cancer-causing, too.

While doctors have long warned against eating too much meat, the World Health Organization's cancer agency gave the most definitive response yet Monday about its relation to cancer - and put processed meats in the same danger category as cigarettes or asbestos.

A group of 22 scientists from the WHO's International Agency for Research on Cancer in Lyon, France evaluated more than 800 studies from several continents about meat and cancer.

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Based on that evaluation, they classified processed meat as "carcinogenic to humans" and red meat as "probably carcinogenic."

Meat industry groups protest the classification. The North American Meat Institute argued in a statement that "cancer is a complex disease not caused by single foods" and stressed the importance of lifestyle and environmental factors.

Doctors have warned that a diet loaded with red meat is linked to cancers, including those of the colon and pancreas. The American Cancer Society has long urged people to reduce consumption of red meat and processed meat.

Dr. David Agus, one of the world's leading cancer specialists and a CBS News medical contributor, told "CBS This Morning" Monday that processed meats can "slightly increase your risks," predominantly for colon cancer.

"To put this in perspective, the lifetime risk of colon cancer is 5 percent," Agus said. "If you have a hot dog every day, your risk goes to 6 percent."

Examples of processed meats include bacon, hot dogs, ham, sausages, corned beef, beef jerky and canned meats - any meat transformed to improve its flavor or preserve it through techniques like salting, curing or smoking.

"We've always known, processed meats - too much is bad," Agus said. "Processed meats aren't good for blood pressure, have a slight increase in colon cancer risk, potentially a slight increase in prostate and pancreatic cancer [risk]. They're very small. But the key is what grandma used to say: moderation."

He said research shows that three and a half servings of regular meat per week appears to have no negative health consequences.

Dana White, an clinical assistant professor of athletic training and sports medicine at Quinnipiac University, in Connecticut, concurred with the message on moderation. "As a registered dietitian I like to look at the big picture of the overall diet," she said. "Red meat can provide important nutrients such as essential amino acids, iron and vitamin B12. When lean cuts are consumed in moderation, it can still fit into a healthy diet."

The WHO report noted that red meat contains important nutrients but said it was associated with some cancers in several studies. Their report said grilling, pan-frying or other high-temperature methods of cooking red meat produce the highest amounts of chemicals suspected to cause cancer.

While the WHO report classifies processed meats as "carcinogenic to humans" - the same category as tobacco smoking and asbestos - it points out this does not mean such foods are as hazardous as cigarettes. The classifications "describe the strength of the scientific evidence about an agent being a cause of cancer, rather than assessing the level of risk," it explains. "This classification is based on sufficient evidence from epidemiological studies that eating processed meat causes colorectal cancer."

The report comes on the heels of another study that revealed surprising findings about the contents of hot dogs. Clear Foods, which "uses genomic technology to analyze the world's foods at a molecular level, ingredient by ingredient," released a report recently that it said was designed to look at the accuracy of the content labels of several major hot dog brands.

The company analyzed 345 hot dog and sausage products from 75 brands and 10 retailers, and said they found "human DNA in 2% of the samples, and in 2/3rds of the vegetarian samples."

Additionally, 10 percent of all vegetarian products appeared to contain meat.