By now, bacon lovers everywhere have probably heard the sad news. Processed meats cause cancer.
I’m actually kind of shocked that anyone would think this is novel, but it’s actually not quite as simple as yesterday’s headlines make it seem. I fully admit I’m stealing plenty of content from The Atlantic on this one because Ed Yong does a great job explaining why yesterday’s news is so troubling.
The International Agency of Research into Cancer (IARC) is part of the World Health Organization, and as its name suggests, IARC is responsible for carefully assessing whether a substance causes cancer. The problem is that once the IARC makes such a finding, it reports it – and often poorly communicates those findings.
IARC’s working group of 22 scientists reviewed a large number of studies when they classified the consumption of red meats as “probably carcinogenic” (Group 2A) and processed meats as “carcinogenic to humans” (Group 1). IARC divides substances into five possible categories; Group 1 includes known carcinogens like asbestos, smoking, and alcohol. Group 2A (probably carcinogenic) and 2B (possibly carcinogenic) are where things get a little less clear. Group 3 is for substances that lack enough data, while Group 4 is for substances that are known to not be carcinogenic… like water.
The problem with the classification scheme is that it’s based no on the degree of risk, or how much of a substance is needed to cause cancer, but rather on the strength of the evidence out there in the scientific world that demonstrates whether the substance causes cancer or not. Two substances in Group 1 are both known to cause cancer, but to cause cancer, one might need to be exposed to 100 times the amount of substance A as opposed to substance B. If Substance C tripled the risk of cancer while substance D barely increased the risk of cancer – they would both fall into Group 1 since they both cause cancer. Substance C could cause many more types of cancer than Substance D, and yet since they both cause cancer, boom… Group 1! Two risk factors could be slotted in the same category even if one affects a greater swath of the population, and if it actually causes more cancers.
As Ed Yong explains,
these classifications are not meant to convey how dangerous something is, just how certain we are that something is dangerous.
Group 1 is billed as ‘carcinogenic to humans,’ which means that we can be fairly sure that the things here have the potential to cause cancer. But the stark language, with no mention of risks or odds or any remotely conditional, invites people to assume that if they specifically partake of, say, smoking or processed meat, they will definitely get cancer.
So yes – smoking and eating bologna will definitely cause cancer. The only remaining question here is how much bacon are you about to give up?