It’s an opinion piece by a geneticist (so not a chemist or biologist or a field that could be related) and she ignores all the direct evidence that every city and county that added fluoride started having fewer cavities than neighboring areas that hadn’t yet added it.
She then further points out that it only causes health issues in much higher concentrations than what the US was getting our water supply up to. You know, like literally anything that you get too much of is bad for you. You can literally die from drinking too much plain water. Too much of anything will kill you.