Decrease of skeletal lead levels in man after end of occupational exposure.

Lead levels in finger bone were monitored using an in vivo X-ray fluorescence technique in retired lead workers. Eight subjects followed for 2-5 yr directly after end of exposure all displayed a decrease. Their average half-time was 7 (range 3-15) yr. In a second group of six persons, followed from year 7 to year 13 after finishing lead work, a decrease was seen in all but one. The average half-time for this group was 8 (range 2 infinity) yr. The mean value for both groups was 7 yr. The results show that there is a decrease of lead in bone after the end of exposure and that it is considerably faster than estimated earlier from various data on lead metabolism.