title: Plasma-lead concentration: investigations into its usefulness for biological monitoring of occupational lead exposure.
abstract: BACKGROUND
  The lead concentration in plasma is correlated to that in whole blood with a two to fourfold variation. It has never been investigated if this variation is inter-individual.
  
  
  METHODS
  Lead and hemoglobin were determined in blood and plasma from 13 lead workers with a history of relatively high blood-lead concentrations, sampled three times during 1 day. The variation in the distribution of lead between cells and plasma was studied, but not the variation in the lead concentrations as such.
  
  
  RESULTS
  Blood hemoglobin decreased with rising plasma lead (0.9-3.0 microg/L). Regarding the distribution of lead, no effect of current exposure during the day or of recent meals appeared. As much as 84% of the overall variance of the distribution of lead between cells and plasma could be attributed to individual factors. After adjustment for erythrocyte volume fraction this decreased to 67%. Plasma samples with elevated hemoglobin concentrations (due to in vitro hemolysis) had somewhat elevated lead concentrations.
  
  
  CONCLUSIONS
  Plasma lead is not significantly altered by variation in a single day's exposure and, therefore, the choice of time of the day is not critical for sampling. However, plasma lead is negatively correlated to blood hemoglobin and mild hemolysis (not visible by the eye) in a sample may increase plasma lead with up to 30%. Finally, plasma provides lead exposure information that differs from whole blood, but it is not clear which one of these is the biomarker with the closest relation to exposure and/or effects.
authors.affiliation: Occupational Medicine, Department of Public Health and Clinical Medicine, Umeå University, Umeå, and Sahlgrenska University Hospital, Gothenburg, Sweden. ingvar.bergdahl@envmed.umu.se
authors.forename: Ingvar A
authors.initials: IA
authors.lastname: Bergdahl
authors.forename: Lars
authors.initials: L
authors.lastname: Gerhardsson
authors.forename: Ingrid E
authors.initials: IE
authors.lastname: Liljelind
authors.forename: Leif
authors.initials: L
authors.lastname: Nilsson
authors.forename: Staffan
authors.initials: S
authors.lastname: Skerfving
mesh_terms: D000328:Adult; D004784:Environmental Monitoring / Q000379:methods*; D004912:Erythrocytes; D006454:Hemoglobins / Q000032:analysis*; D006801:Humans; D007854:Lead / Q000097:blood* / Q000633:toxicity; D008297:Male; D008669:Metallurgy; D016273:Occupational Exposure / Q000009:adverse effects / Q000032:analysis*; D010949:Plasma
chemical_list: D006454:Hemoglobins; D007854:Lead