Zinc protoporphyrin in the red blood cell. Analytical method and screening level for environmental lead exposure.

An appropriate method of measurement was established for zinc protoporphyrin (ZnP) in the red blood cell (RBC) and applied to Japanese rural and urban inhabitants as well as the workers exposed to lead (Pb). ZnP was sufficiently extracted by an acetone extraction method by spinning the blood sample at more than 10,000 rpm. The author set the upper fiducial limit of ZnP concentration at 70 micrograms/dl RBC for adult males and 90 micrograms/dl RBC for adult females for the persons who were not occupationally exposed to Pb. ZnP concentration in RBC was well correlated to blood Pb level among the workers exposed to relatively high level of Pb. The author's procedure for the measurement of ZnP level is useful for the control of occupational health in Pb exposure.