Alcohol: Well known to be carcinogenic to humans. Despite this, a large proportion of the population drink it regularly. More surprisingly, whenever the International Agency for Research on Cancer updates its carcinogen classifications for other substances with a lower cancer risk, there’s often media fanfare. In recent years, the IARC has upgraded classifications for red meat and aspartame, leading to a spate of panicked articles. This republished and updated post takes a look at what the classification groups actually mean, and how worried we should be about a substance’s classification.