However much they want and can afford to buy.
Somewhere between "none" and "a lot". Lead is not biologically necessary, so it's up to you how much of it you use and what you use it for.
What is the maximum quantity of lead that a human can consume without dying
For animal parts such as gull blatters for human use.
Lead is a heavy metal and poisonous to the human body. Use of lead pipes leads to a build up of lead in the system which affects the nervous system and can lead to brain damage and death.
You don't use lead in cooking measurements.
10%
appox 20 %
I would HIGHLY advise against it. Human medicine is made for humans. Cats are much smaller than humans, so giving a cat human medicine can easily lead to an overdose which can ultimately kill the cat. If your cat needs treatment, take it to a vet where they can prescribe medicine that is safe to use on your cat.
2%
97%
The average human is to at least use or waste over a whole tree or more!!
for a human. the human supply water usage is 3%. ONLY 3 PERCENT IS DRINKABLE TO HUMANS