Evaluation of lead body burden in occupational workers by lead mobilization test.

OBJECTIVE To determine total lead body burden by the Lead mobilization test (LMT) by measuring 4 hours urinary lead excretion in the lead exposed as compared to unexposed industrial workers after administration of 10 mg/Kg of dimercaptosuccinic acid and correlate it with blood lead levels, at Wah district Rawalpindi. METHODS Total 149 males consisting of 87 lead exposed workers and 62 controls were included. Dimercaptosuccinic acid (DMSA), 10mg/kg body weight, was administered orally. Four hours urine specimens before and after DMSA administration were collected. Blood lead levels (BLL) were determined on 3010B ESA lead analyzer and urinary lead was measured on atomic absorption analyst 800 (Perkin Elmer). RESULTS The lead exposed workers had high BLL median (range) 291 (90-611) ug/L as compared to controls 108 (10-310) ug/L (p=0.01). The occupational workers also revealed high DMSA-chelated urinary lead excretion (DMSA Pb-U) median (range) 28 (1.7-268) ug/4h as compared to controls 6 (1-27) ug/4h (p<0.01). Four hours DMSA Pb-U was significantly correlated with BLL (r=0.67), baseline Pb-U (r=0.54) and DMSA Pb-U/creatinine ratio (r=.81) in the lead exposed group (p<0.001). Increased lead exposure was detected in 43% of the subjects by using the WHO criteria for BLL while 54% were identified with LMT. Thirteen (15%) lead exposed workers had BLL more than OSHA permissible limits. CONCLUSION Lead mobilization test is a more reliable diagnostic test than BLL for assessment of toxicologically active fraction of total lead body burden and imminent health risks in occupational workers.