A client and good friend was a firearms instructor at our State Police training institute, and when tested for lead, showed high enough that they took him off the range, and put him in the classrooom. A year later, his blood tests showed he was back to normal lead levels. Subsequent yearly testing showed no changes upward.
All that you say can happen, but in infants and small children, where they are still growing bone tissues. It also gets into the fatty tissue of the brain, which is where it causes mental problems. I have heard of NO empirical evidence that lead collects in the bones of mature adults, or that it poses the same risk to adults' brains. Obviously, if you are breathing in lead particles, it first affects the soft lung tissue, and lead is not going to do your lungs any good. That in itself justifies taking precautions when casting lead to make sure the area is well ventilated, and that fumes are not allowed to blow into your face. Washing the skin, and showering to get any lead dust out of your hair is smart, because the second way to get lead into your body is by ingesting it. If lead gets on your hands, and then you transfer this to a sandwich or other food you are eating, you are going to eat lead, too.
This matter came up more than 20 years ago when I represented our local Public Housing Authority, and it received a request from HUD to do a survey of its buildings to see what lead abatement needed to be done. The staff and the Board of Commissioners was all concerned about lead poisoning, until the Board was told that lead abatement had begun back in the 1950s, , that all lead based paint that could be reached by small children, were removed, and that as part of ordinary maintenance, in the 1960s, the rest of the lead based paint that kids could not reach was also removed. An expert with all the testing equipment showed up From HUD, and after testing the apartments, was shocked to find out that we had no lead problem that needed further abatement. ( Well, actually, we were having nightly shootings in our family projects, but he was not qualified to do anything about that lead pollution!)
I am not trying to minimize the dangers of lead toxicity, but I also don't believe that you have been given the best information about the affects of lead on Adults. The liver, and kidneys remove heavy metals from the digestive track all the time. They exit the body in the lower Large Intestine. I believe that adults can and do filter out certain amount of lead, along with other metals, all the time. You just don't want kids around when you are casting.