EFFECT OF LOW BLOOD LEAD LEVELS ON ANAEMIA INDICATORS AND CREATININE CLEARANCE RATE OF WORKERS OCCUPATIONALLY EXPOSED TO LEAD

Abstract

Background and Objectives: Although recognized and written about centuries, lead toxicity remains an occupational and public health problem of global dimensions. Several studies have demonstrated that clinical and sub clinical effects of lead toxicity at the blood lead levels considered as safe, i.e., below 30 μg/dl in adults and 10 μg/dl in children. Such studies have received scant attention in the case of lead occupational workers due to the presumption of high blood lead levels in accordance with occupation. In the present study, therefore an attempt was made to investigate the effect of low blood lead levels on indicators of anaemia and renal impairment. Methods: A cohort of 690 subjects who had been occupationally exposed to lead was studied using stratified random sampling design. The markers of anaemia included changes in Haematocrit value, Haemoglobin and Erythrocyte count where as renal health was judged from changes in creatinine clearance rate. The controls were derived from similar socioeconomic background and matched in age and sex with subjects. Blood lead levels were determined by graphite furnace atomic absorption and biochemical determinations carried out using standard procedures. Results: Blood lead levels in the range 10–40 μg/dl had significant effect on anaemia indicators and resulted in inverse co relationship. (Pearson’s correlation coefficient r= -0.65, -0.71 and -0.58 respectively for haematocrit, erythrocyte count and haemoglobin). The creatinine clearance rate estimated after adjustment for body mass index and age factors was found to depend on blood lead level and duration of exposure of subjects. These effects were statistically significant in the subjects having age in the range 15–30 years. Conclusion: Low lead levels in blood have high potential of inducing lead related anaemia by disturbing the pathway of heme synthesis at either ferrochelatase stage or inhibiting the aminolevulinate dehydratase activity. Though creatinine clearance rate did not prove as reliable marker of renal health at low PbB levels but it was successfully used in the case of high PbB levels whereby it could be used to predict the PbB values and vice versa.