Narrator: This is Science Today. Toxicologists have long known that lead accumulates in the skeleton. This had been considered beneficial, since it was thought the toxic metal was out of the blood. But Donald Smith, a toxicology professor at the University of California, Santa Cruz found about half the lead present in our blood leeches out of our own bones.
Smith: And so the skeleton ends up being a very important internal reservoir for lead and 116 can be a very important internal source of lead exposure back to more lead sensitive target organs like the brain or the blood system and so on.
Narrator: Even though most people only have low levels of lead in their bones, Smith says it's still the predominant source of lead in the blood.
Smith: We're following up on that issue because the concern could be for people who are actually mobilized and are losing a relatively high amount of bone mineral over a short period of time. And two segments of the population that fit that relatively well are women going through menopause, becoming osteoporotic and women who become pregnant and nursing their infant.
Narrator: If you're concerned about past lead exposure, Smith recommends having a blood test. For Science Today, I'm Larissa Branin.