> We have analyzed the hair of lead smelter workers and found there is too much contamination, unable to be removed from washing, to be able to infer blood lead

> We have analyzed the hair of lead smelter workers and found there is too much contamination, unable to be removed from washing, to be able to infer blood lead concentrations Well yeah, lead smelters probably have a higher lead concentration in their hair than in their blood. However, if you ingest the lead and it shows up in your hair, it's probably safe to say that the blood concentration must have been pretty high (although it's not possible to infer the exact number of course).