Those aren't really great examples, considering that Arsenic and Asbestos have been known to be harmful for centuries/millennia.

Thalidomide never even made it to use in the USA.

Fluoride being good for teeth was discovered by fluoride naturally being in the water already

Can't speak for the other two, but I hope you're not basing your fears on stuff like that.

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FireBeyond an hour ago | parent [-]

> Thalidomide never even made it to use in the USA.

What? It was initially blocked by the FDA, but was later approved for use in cancer, where it is in fact a front line drug for some myelomas, albeit with significant usage warnings.

	▲	atrus 40 minutes ago \| parent \| next [-]
		Fair, I was talking more the initial pregnancy use, but even still that further pushes my point that those examples have either never been considered perfectly safe, or have been in active normal usage for so many years that you really have to squint to say it's unsafe.
	▲	tptacek 35 minutes ago \| parent \| prev [-]
		It was never approved in the US for the on-label use for which it gained its reputation (it's a potent teratogen and was prescribed --- never officially in the US --- for morning sickness).