标题：THE DIAGNOSIS OF DIFFERENT DEGREES OF LEAD ABSORPTION; IN SPECIAL REFERENCES TO CHOICE AND EVALUATION OF VARIOUS PARAMETERS INDICATIVE OF AN INCREASED LEAD ABSORPTION
出版社：National Institute of Occupational Safety and Health
摘要：A series of 44 workers occupationally exposed to lead and 79 habitants naturally exposed to lead was investigated in order to define more clearly the clinical and biochemical criteria of lead exposure after grouping them into five according to the degree of lead exposure and also to the clinical evidence. The parameters used were hemoglobin (Hb), blood lead (Pb-B), urinary lead (Pb- U), urinary coproporphyrin (Copro), urinary δ-aminolevulinic acid (ALA), and ALA- dehydrase (ALA-D) activity in peripheral red blood cells (RBC) estimations. A statistically significant difference was found between mean values respectively for Pb-B and ALA-D of all five groups and also for Pb-U, ALA, Copro and Hb of three occupationally exposed groups. Furthermore, Pb-B correlated negatively with ALA-D in all five groups, and positively with Pb-U and ALA in three occupational groups. Negative correlations were also observed between ALA-D and each of Pb-U and ALA in three occupational groups. As for naturally exposed groups, a significant difference was found between the urban habitants and the rural habitants in regard to the values for Pb-B and ALA- D and, moreover, a close negative correlation was observed between Pb-B and ALA- D at these "normal" levels of Pb-B. Increased ALA excretions were observed when ALA-D activity was decreased to approximately 40% of normal levels. As for choice of a parameter, Pb-B and ALA were concluded to be of value for assessment of a heavy exposure and also for the clinical assessment, ALA-D for a minimum to slight exposure, and all the parameters including Hb and Copro for the comparison of the different lead exposure as a group. Pb-B above 65 μg/100 g and ALA above 17 mg/1 were almost always associated with symptoms and signs of lead poisoning and were therefore considered to be the upper limits of safe ranges. These levels corresponded to ALA-D activity of 0.250 μmole PBG/1 hr/1 ml RBC.
