[Dose-effect relationships between blood lead and free erythrocyte protoporphyrin or zinc protoporphyrin].Zhonghua Yu Fang Yi Xue Za Zhi. 1989 Sep; 23(5):279-82.ZY
Studies on dose-effect relationships between blood lead (PbB) and free erythrocyte protoporphyrin (FEP) or zinc protoporphyrin (ZPP) in 583 workers (male 326, female 257) was conducted. Good dose-effect relationships and S-shaped curves between PbB and logFEP, logZPP or log (ZPP/Hb) were established. Sectioned linear regression showed that linear correlation was obtained while PbB between 0.48 (10 micrograms/dl) and 3.36 mumol/L (70 micrograms/dl) (male) or 0.48 (10 micrograms/dl) and 2.88 mumol/L (60 micrograms/dl) (female). However, while PbB below 0.48 mumol/L (10 micrograms/dl), there was no linear correlation. The increasing of FEP, ZPP slowed down remarkably as PbB were beyond 3.36 mumol/L (70 micrograms/dl) (male) or 2.88 mumol/L (60 micrograms/dl) (female). Therefore, the degree of lead poisoning can't be classified by the values of FEP, ZPP among plumbism.