If you are interested in knowing a rough range of Pb, you may use Pb level indicator paper meant for testing water samples which may be available or supplied by some firms like E Merk etc. These papers may be used on blood serum or tissue sap. This may give a rough range only. The precise level of Pb in these samples can be determined by digesting the bloods serum or tissue in di-acid mixture and aspirating the digest in AAS or ICP-OES or ICP-MS.
I believe mines are using ASV such as the PDV6000+ built by B3 electronics to investigate lead levels in miners in Western Australia. Cogent used to be the manufacturer of this atomic striping voltametric equipment. We use it for water analysis at B Hochwimmer & Associates Pty Ltd, but for blood tissues there are some extra steps of denaturing, possibly including UV. The manufactures will know more.