Blood lead and plasma homocysteine in petrol pump workers in Karachi: Role of vitamins B6, B12, folate and C

Vehicle population in Karachi has increased significantly. Therefore, workers at petrolpumps would be at a risk of developing lead poisoning. Present study was undertaken to determine if petrol-pump workers in Karachi have high levels of blood lead and plasma homocysteine, and to find out the role of vitamins-folate, B12, B6 and C in influencing levels of blood lead and homocysteine in study population. In a comparative pilot study, 35 males working at petrol-pumps and SO age-matched males working in the Aga Khan University (AKU) were enrolled. Fasting blood was analyzed for lead, while plasma/serum was analyzed for homocysteine, folate, vitamin-B12, pyridoxal phosphate (PLP, coenzymic form of vitamin-B6) and vitamin-C. Mean levels of blood lead and plasma homocysteine in petrol-pump workers and AKU-employees were not found to be significantly different (12.9 ± 3.7 μg/d1, 25.35 ± 17 μmol/l, 14.5 ± 6.1 μg/d1, 23.8 ± 18 μmol/1, respectively). Vitamin-C and folate levels in serum of petrol-pump workers were, however, found to be significantly decreased compared to AKU employees (P = 0.018 for vitamin-C and P = 0.009 for folate). Percent deficiencies of folate, vitamin-B12, PLP and vitamin-C in the study population were found to be 22.4 %, 16.4 %, 29.4 % and 10.2 %, respectively. Correlation analysis of the data revealed a moderate positive association between blood lead and plasma homocysteine (Pearson's r = 0.24; P = 0.01) and an inverse relationship between blood lead and serum folate (Pearson's r =-0.300; P = 0.006). Folate deficiency and moderately elevated levels of lead could be contributing to hyperhomocysteinemia in Karachi population. Introduction of unleaded petrol might have decreased blood lead in this population.