There's a court case in the US where the plaintiffs are suing the EPA for not regulating fluoride added to drinking water. I think this is the second such case, but there was a recent ish bipartisan law passed that puts the plaintiff at higher odds of success if they present their case well. Typically these cases are stacked for the government agency being sued (must prove the agency is acting in an arbitrary or capricious manner), the new law means they only have to successfully prove fluoride has potential to cause health damages and the judge could force the EPA to look closer at fluoride or he could order them to ban adding it to water supplies altogether.