Lead was used way past discovering it was dangerous, and is still used enough to cause problems in specific populations. Just like cigarettes. If there is a large moneymaking industry and it suddenly comes to light that what it is producing is dangerous, they have a lot of motivation to put money behind keeping that knowledge from getting out or, when it does, keep it from affecting law. They lobby/bribe, they abuse the legal system, whatever they can to avoid going under. As such, it’s not safe to assume that something is not dangerous simply because it hasn’t been banned.