Smaller particles can reach deeper in the lungs and from there be absorbed into the bloodstream. This means that when there is burning or welding on lead-painted surfaces, the lead fumes can be especially dangerous. The small particles created as a fume will reach the blood if they are inhaled. Lead that is stored in the bones can leave them and enter the blood and then the soft tissue. This can damage the organs or the blood's ability to make red blood cells.
Lead stays in the body for different periods of time, depending on where it is.
In soft tissues, it takes 40 days for half of the lead to be excreted. In bones and teeth it takes much longer, up to 10 years or longer. It can take months or years for the body to get rid of lead. A person will continue to be exposed to lead internally even after the actual exposure to lead stops. Blood tests to measure the amount of lead circulating in the body were developed over 60 years ago.