The thing I remember about lead paint abatement was that it can be put into the air, like when somebody is arc welding on a beam that has lead paint.
They also said that you can have it on your clothing and expose whoever does your laundry to lead.
If it is a pregnant women or one about to become pregnant they said that was not good.
Or any young children around it.
Or anything that puts the paint dust into the air, such as grinding or sand through lead paint.
It also seems to be a material that can add up in your system.
So it must accumulate in your body and doesn't leave your system very rapidly.
I have read that soldering with lead based solder doesn't really put lead in the air but handling it can get it into your body.
And, I'm pretty sure breathing the fumes is not a healthy thing to do.
I usually hold my breath while leaning over the iron.
So those classes about lead and asbestos (which I have been around a lot) are enough to scare anybody away from working on old buildings.