Half life of lead in bone is:
The half-life of lead compounds in the human body is, as a general rule, long, but it varies according to the tissue. Besides, it is almost impossible to determine its elimination rates, since the bones may have a large quantity ready to mobilize into the blood stream. Neveheless, some halflives are known for blood (3-4 weeks) and bones (20-27 years). Ref:
1 year
10 years
20 years
None of the above