Group 1 carcinogens

Thomas Lumley at Stats Chat blogs a quote from Professor Doug Sellman:

The ethanol in alcohol is a group one carcinogen, like asbestos

Now I have to say I had no idea what a group one carcinogen is, but Prof Sellman makes it sound like something very very nasty and fatal.

Prof Lumley explains:

Many of the readers of this story won’t know what a “group one carcinogen” is.  Given the context, a reader might well assume that “group one carcinogens” are those that carry the largest risks of cancer, or cause the most serious cancers. In fact, all it means is that an additional hazard of cancer, whether high or low, has been definitely established, because that’s all the IARC review process tries to do.

So it is a fancy name for some risk, not high risk.

Some group 1 carcinogens, such as tobacco and hepatitis B, are responsible for large numbers of cancer deaths worldwide. Others, such as plutonium and diethylstilbestrol, are responsible only for small numbers of deaths. Some group 1 carcinogens cause aggressive, untreatable tumours; for others, such as human papillomavirus, disease is largely preventable by screening; still others, such as sunlight, sometimes cause serious disease but mostly cause relatively minor tumours.

The phrase “group one carcinogen” is only relevant in an argument over whether the risk is zero or non-zero. Its use in other contexts suggests that someone doesn’t know what it means, or perhaps hopes that you don’t.

I am sure Prof Sellman knows exactly what it means.