Lead poisoning from retained missiles. An experimental study.

The problem of lead poisoning from bullets has been investigated by surgically implanting discs of lead, each enriched in a different natural isotope, into the tissue of two mongrel dogs and monitoring by mass spectrometry the release of the lead into each animal's blood over the course of 3 years. Lead placed in the knee underwent vigorous attack by the synovial fluid, far in excess of what would be expected from corrosion theory, and reached a maximum concentration in blood 4-6 months after operation. Thereafter, lead concentration exponentially declined as the remaining fragments became encapsulated. The disc placed in muscle was sparingly soluble immediately following implantation. It is concluded that the greatest danger of lead poisoning from an injury involving many fragments having collectively a large surface area will occur within a month, and that the cases of lead poisoning resulting from bullets in joints that occur 5 or more years after injury are caused by continual wear of metal on a joint surface, storage of lead so released in the skeleton, and its subsequent resorption during a change in osteocyte activity.