标题：Reappraisal of Blood Lead Levels and Relation to Delta-Aminolevulinic Acid Dehydratase, Zinc Protoporphyrin and Urinary ALA Level in Thai Normal Adults and Lead Exposed Workers
出版社：Thai Society of Higher Eduction Institutes on Environment
摘要：All studied participants of 65 lead-exposed workers and 52 non lead-exposed persons who voluntarily participated and signed consents were interviewed about their working duration, type of work, risk behavior and personal data. Blood and urine samples were drawn for PbB, d-ALAD, ZPP and ALAU analysis respectively. The mean PbB level for workers in lead smelters, 22.4 +/- 17.9 microgram/dl (range 1.3-67.2 microgram/dl) was found higher than that for the non-exposed persons (mean = 5.0 +/- 2.4 microgram/dl, range 2.0-13.2 microgram/dl). In relative to previous studies, mean PbB concentration found in the unexposed persons tended to decreased follows the reduced use of leaded gasoline in 1996 in Thailand. A highly significant negative correlation (R2 = 0.86) was observed between PbB concentration and d-ALAD activities among lead exposed persons. Statistical analysis showed that d-ALAD activities significantly decreased (p<0.05) when PbB level surpassed 10 microgram/dl. ZPP level increases slowly with increasing PbB concentration from 10-40 microgram/dl and can be distinguished from normal when the PbB concentration surpasses 40 microgram/dl. Whereas significant relationship between ALAU levels & PbB concentrations did not observed in lead exposed persons as well as non-lead exposed persons. The mean PbB level of 5.0 +/- 2.4 microgram/dl and range of 2.0-13.2 microgram/dl could be regarded as the current reference values for the general population of the country. Determination of d-ALAD activity in erythrocytes is a useful method for evaluating lead exposure in high blood lead level persons (PbB>10 microgram/dl). ZPP measurement is simple and inexpensive, but less sensitive and could be used for screening only in those high lead contaminated persons (PbB>40 microgram/dl). ALAU measurement cannot be served as early biochemical indices of lead exposure both in lead exposed and non-lead exposed persons.
