In fact, there is nothing wrong with alchemy. As long as the prescription can be used, many Taoist priests are experts and have high pharmacological knowledge. After all, in order to prolong life, they will refine some pills to take, so "Dan" is actually not a big problem, but the people with problems are the people who test and take "Dan".
In ancient times, the emperor's things needed all kinds of attention and perfection, even if it was soup and medicine, it was effective anyway, but "Dan medicine" was different. It comes from Taoism, and in all kinds of legends and literary works, it has a name, which is as true as it is-the elixir is Xiaohong.
"Shi Tian" is impatient. Good things are all black, chocolate, or yellow, but none of these colors of Dan medicine can pass the trial, not to mention the emperor himself, and even the little eunuch who sent water refused to see it. But the emperor has to have a job if he wants to eat these things.
Therefore, these Tianshi are also very helpless. Add it, add it and make it red. Anyway, the emperor doesn't eat good food, so give him what he can accept and reward him for meritorious service. He won't die right away anyway. Therefore, those good prescriptions are all marked with a lot of cinnabar by these heavenly teachers.
Now that we know the chemical composition of cinnabar, we know that it is mercury sulfide. Although it is not highly toxic, the chronic poison has not escaped. Imagine that these little pills were given to the emperor like vitamins from the moment he ascended the throne. They live well in their thirties, and it is normal for them not to live to 40.