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Earlobe sampling for lead surveillance: an evaluation of this sampling technique with occupationally-exposed adults.

Taylor-L; Kevin-A; Deddens-J; Jones-R; Kwan-L
American Industrial Hygiene Conference and Exposition, June 1-6, 2002, San Diego, California. Fairfax, VA: American Industrial Hygiene Association, 2002 Jun; :66
Employees who are monitored for lead exposure must routinely have a venipuncture sample taken, which is both uncomfortable and normally collects more blood than needed for analysis. Capillary sampling is less invasive but introduces the possibility of surface contamination. The objective of this study was to compare venous and capillary (earlobe) blood lead samples obtained from occupation- ally exposed individuals. Phlebotomists with specific training for the collection of blood lead samples, collected two venous blood samples and two capillary earlobe samples from each participating employee. Prior to the capillary draw, the employee's earlobe was cleaned with an alcohol wipe in an effort to remove potential lead contamination. A second alcohol wipe was then used to sterilize the lancing area and was retained for lead analysis. Both the venous and capillary blood lead samples were analyzed by graphite furnace atomic absorption spectrometry (GFAAS) in a CDC laboratory. The venous blood lead results were considered the reference collection method. A total of 126 paired, earlobe and venous samples were collected and analyzed. Capillary earlobe sampling was preferred to venous sampling by 54% of the employees. The mean difference between the capillary and venous results was 38.8 mg/dL +/- 48.1. Earlobe blood lead concentrations were more than twice the venous results in over half (64/126) the samples. Despite a simple cleaning with an alcohol wipe and no visible lead contamination, 94% of the earlobe wipe samples contained lead contamination greater than 0.3 mg lead per wipe sample. Even low levels of contamination significantly alter the blood lead concentration as a sample contamination of 0.3mg lead in a 200mL blood sample would cause a 150mg/dL elevation. Until satisfactory cleansing techniques are identified and evaluated, this study suggests capillary earlobe sampling should be avoided as a means for occupational blood lead surveillance.
Sampling; Surveillance-programs; Occupational-exposure; Blood-analysis; Blood-samples; Lead-compounds; Workers
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Work Environment And Workforce; Research Tools and Approaches; Other Occupational Concerns
Source Name
American Industrial Hygiene Conference and Exposition, June 1-6, 2002, San Diego, California