I certainly can't be sure - I don't know that much about fluoride itself and the limits that are on it nor exactly what research has been done. It seems the main concerns with fluoride is getting too much of it along with some environmental damage. I doubt testing for all values of x is prudent: simply the ingredients compared to the allowed amount of fluoride allowed (there is a limit in amount in the over the counter stuff). I'd think at minimum, he should be able to send a sample to the FDA or independent company for analysis to compare it with research already on file. Or be able to cross reference the ingredients himself. So long as his stuff is within the tested parameters, he'd be allowed to go ahead.

Of course, it might also be prudent to get certified to handle fluoride as well as manufacture toothpaste with it and other such things.

But then again, caffeine is a drug occasionally as well. Excedrine has to list it on their FDA required product information: No-Doz (caffeine pills) has the same sort of label. Granted, it might be more benign than fluoride - yet the FDA sees no problem with it being in toothpaste so long as he doesn't have the fluoride.

I don't know all the details, mostly because I've never wanted to manufacture toothpaste. But it seems there should be a simple way of doing this stuff with simple tests in most cases, and that the information should be easily accessible.