[Studies on biological indicator values in diagnosis for lead poisoning]

Blood lead levels, urine lead levels, indicators of porphyrin metabolism and other biological indicators were determined in 330 workers exposed to lead and 100 unexposed controls with national standardized methods for quality assurance. Data were analyzed with modern statistical methods in a microcomputer with SAS software. Criteria values for blood lead and urine lead were formulated with curve fitting and discriminant analysis, and local normal upper limit values were 1.43 and 0.25 mumol/L for blood lead and urine lead, respectively, acceptable upper limit values 1.93 and 0.35 mumol/L, respectively, and diagnostic values for poisoning 3.02 and 0.56 mumol/L, respectively. Correlation between workplace air lead concentrations and biological indicators, between blood lead levels and other indicators, and their specificity, sensitivity, accuracy and underdiagnosis and misdiagnosis were evaluated at the same time to provide a reference database for revising the national diagnostic criteria for lead poisoning.