Lead concentration in bone indicates:: (A) Recent exposure, (B) Cumulative exposure, (C) Both of the above, (D) None of the above
Answer is B. The absorbed lead, both inhaled and ingested, is transpoed to the blood stream where a rapid equilibrium is established between plasma and red cells in a propoion of 1:16. From the blood stream, the lead is delivered to all organs, especially bones which may retain around 90% of the body's lead content. Therefore, while the blood lead concentration reflects the recent exposure, bone lead concentration reflects the cumulative exposure. Ref :