1 Center for Disease Control, Atlanta, Georgia 30333
Piomelli et al.1 have presented an extensive experience in comparison of free erythrocyte porphyrin (FEP) levels with blood lead concentrations. Their finding that an FEP
250µg/100 ml RBC was invariably associated with a blood lead concentration
6Oµg/100 ml is consistent with data obtained in our laboratory2 using a somewhat different microfluorometric method for FEP determination.3
We must, however, take issue with the conclusion of Piomelli et al.1 that only FEP levels above 250µg/100 ml RBC should be considered "positive."