I think OP is referring to carcinogenic effects linked to red meat - in some ways it‘s healthier because its iron is the easiest to absorb, in some ways it‘s not by giving you 20% or so higher risk of intestinal cancer if you consume more than a certain amount - don’t remember the details. My stance is, duh, everything at the right dose (like 30-50g per day on average would be my bet for red meat and red fish). Plenty of animal protein sources are AFAIK not linked to adverse effects as long as you‘re not overstressing your kidneys, i.e. eggs, white meat/fish, cheese.
There's also some evidence that high levels of iron are linked to intestinal cancer.[0] So maybe the meat is just a proxy of iron. My takeaway is that the links between X food and Y disease are still largely a mystery. The correlation may be there, but the cause is not understood.
There is some evidence suggesting an association between red meat consumption and colorectal cancers. I don't think the link is well-enough understood to suggest it's a causal one, but I also don't think it's any longer supported to flatly dismiss any possible links out of hand like that.
Perhaps OP was referring to bacon?
In that case, I would be better stated that nitrates are carcinogens not bacon itself.
And nitrates are likely only carcinogenic if cooked at very high heat, i.e don’t burn your bacon and best not to eat cured too often anyway.
Source: On Food and Cooking by Harold McGee
in which case the source of nitrates is plant or mineral. oh the irony