From someone who has seen first hand the effects of mercury poisoning on a patient and the detrimental effect it had on their mental faculties due to taking a ayurvedic rasa shastra. The damage is causes is real. The reason these medicines have been around so long are not because they have heavy metals in them but the herbs and healthful properties that they impart. People should not take heavy metals ever. Even if people have taken it in the past there is no way of knowing how much they were dosed with so it is possible they did not show all the symptoms of heavy metal poisoning at once. Alternative therapies are important but just like anything thing else going into your body you should think about what effect it can have on you.