They fall into one of five classifications, according to the strength of the evidence: agents or activities that definitely, probably, or possibly cause cancer in humans; those that probably don’t cause cancer; and those for which the evidence is inconclusive.

It’s important to note that the agents at the top aren’t necessarily the most dangerous. They’re the ones with the clearest evidence of hazard. WHO seeks to identify carcinogens “even when risks are very low at the current exposure levels, because new uses or unforeseen exposures could engender risks that are significantly higher,” the agency says. In other words, even though WHO has determined that red meat is a carcinogen, the report doesn’t quantify how much meat it would take to cross into the danger zone.