Investigation and evaluation of zinc protoporphyrin as a diagnostic indicator in lead intoxication.

To evaluate the utility of zinc protoporphyrin (ZPP) as an indicator of lead exposure, we examined 128 workers employed at a battery storage plant and two smelters, 343 persons who lived within 200 m of the plants, and 217 controls. Based on Chinese criteria, the "normal" ZPP value among inhabitants of Shaanxi Province was determined to be 85 micrograms/100 ml. ZPP proved to be a more sensitive and specific indicator of lead exposure, at both high and lower levels, than PbB or PbU. Among 115 patients who underwent chelation therapy for lead poisoning, ZPP also proved to be a valid index of recovery.