Temporal stability of blood lead concentrations in adults exposed only to environmental lead.

The temporal stability of blood lead concentrations of 21 healthy adults (14 men and 7 women) exposed only to environmental lead was assessed by analysis of 253 blood specimens collected serially over periods from 7 to 11 months. Improved analytical sensitivity allowed detection of small (less than 1.0 microgram/100 ml) changes in blood lead concentrations and both within- and between-run analytical errors were minimized by a strict internal quality control protocol. The women had lower blood lead concentrations (mean 8.5, range 7.4-10.8 micrograms/100 ml) than did the men (mean 12.2, range 8.6-15.8 micrograms/100 ml). These are within the expected ranges for non-occupationally exposed persons. Blood lead concentrations in the serial specimens from both men and women changed very little over the study period, with standard deviations of less than 0.5 micrograms/100 ml for the majority of individual mean concentrations: for all except two subjects the standard deviations were less than 0.8 micrograms/100 ml. Two subjects showed significant changes in blood lead concentrations during the study (standard deviations of mean greater than 1.0 micrograms/100 ml). A temporary increase in oral lead intake was identified for one of these subjects. In the absence of substantial changes in lead exposure blood lead levels in adults are remarkably stable and for their environmental monitoring a single blood lead concentration is an excellent biological indicator.