Hot dogs, bacon and other processed meats raise the risk of colon, stomach and other cancers, the World Health Organization (WHO) has said.
Monday's announcement follows studies which looked at more than a dozen types of cancer in populations with diverse diets over the past 20 years.
The findings back what many doctors have been warning for years, and will anger the meat industry which has been rallying against putting processed meats in the same danger category as smoking or asbestos.
A group of 22 scientists from the WHO's International Agency for Research on Cancer (IARC) in Lyon, France, evaluated more than 800 studies from several continents about meat and cancer.
Based on the results, the IARC classified processed meat as "carcinogenic to humans".
With regard to red meat, the report said it contained some important nutrients, but still labelled it "probably carcinogenic", with links to colon, prostate and pancreatic cancers.
The agency said it did not have enough data to define how much processed meat is dangerous, but said the risk grows with the amount consumed.
Analysis of 10 of the studies suggested that a 50-gramme portion of processed meat daily increases the risk of colorectal cancer over a lifetime by about 18 percent.
The WHO's findings can influence public health recommendations around the globe.
Doctors, especially in rich countries, have long 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 eat less processed and red meat.
"For an individual, the risk of developing colorectal cancer because of their consumption of processed meat remains small, but this risk increases with the amount of meat consumed," Dr Kurt Straif of the IARC said in a statement.
"In view of the large number of people who consume processed meat, the global impact on cancer incidence is of public health importance."
The cancer agency noted research by the Global Burden of Disease Project suggesting that 34,000 cancer deaths per year worldwide are linked to diets heavy in processed meat - compared with one million deaths a year linked to smoking, 600,000 a year to alcohol consumption and 200,000 a year to air pollution.