"The Truth About Cancer"

[Aractus]

Fluoride toxicity causes fluorosis - it isn't known to cause cancer, but I suppose it's a perfectly plausible hypothesis.

Sure, but paired with everything else, I highly doubt he has much credible evidence for it.

Yeah I said it's a plausible hypothesis - there's no scientific evidence to support it that I'm aware of. Same with vaccinations.

The difference between them though is that in recent years fluoridation of water has had evidence supporting the theory that fluoridation does not improve bone and teeth health, or not by a lot if it does. If you look at the Australian data by State for example (see this report) it is really difficult to say conclusively that fluoridation has a large protective effect, however most health professions do believe it offers some protection, just less than was estimated 70 years ago. And it's worth noting that we don't do public health measures just because they have a massive effect - even a small reduction in dental caries is better than no reduction. It was estimated (in the 90's) that folic acid fortification in wheat-flour used in bread-making would reduce NTDs by only 10% (and the evidence has thus far suggested that even that figure may have been ambitious). But a limited benefit is better than no benefit, and the fact that it's limited isn't a reason not to undertake the health measure.

There is an ethical issue with it (both fluoride and folic acid), because in both cases it has an upper-limit (i.e. it can be consumed in toxic amounts, which in the case of fluoride causes fluorosis which is literally tooth decay).

Anyway to get back on point, dietary supplements (especially multivitamins) that are taken without the recommendation of a doctor, dietician, or registered nutritionist, can certainly cause harm to patients (see this article) - and probably can increase the risk of cancer:

    “We are not sure why this is happening at the molecular level but evidence shows that people who take more dietary supplements than needed tend to have a higher risk of developing cancer,” explains Byers, associate director for cancer prevention and control at the CU Cancer Center.
    ...
    “When we first tested dietary supplements in animal models we found that the results were promising,” says Byers. “Eventually we were able to move on to the human populations. We studied thousands of patients for ten years who were taking dietary supplements and placebos.”
    The results were not what they expected.
    “We found that the supplements were actually not beneficial for their health. In fact, some people actually got more cancer while on the vitamins,” explains Byers.
    (Source).

So as for whether fluoride taken in excess can be carcinogenic, I would suggest that until we know otherwise we certainly should assume that it could. But that said, it's still an essential mineral for bone and teeth health. So the key is to ensure that people are getting enough, but not too much.