Renal Dysfunction in Workers Exposed to Inorganic Lead

ABSTRACT

Introduction: We studied the relationship between renal dysfunction and occupational lead exposure in a local factory.

Materials and Methods: A cross-sectional study with a cohort component was conducted with 55 male workers of a factory producing PVC stabilisers as subjects. Workers from this factory have been followed up with 6-monthly blood lead measurements since 1982. Two indices of overall lead exposure, i.e. the number of times a worker’s blood lead exceeded 40 µg/dL (PbB40) and cumulative blood lead index (PbBint), were obtained from this data. Recent blood lead concentration (PbB) was measured. 4-hour creatinine clearance and various other urinary and serum markers of renal dysfunction were used as effect indices.

Results: There was no relationship between PbB and any of the renal markers. However, creatinine clearance decreased significantly (P <0.001) with increasing PbB40 and PbBint after adjustment for age and smoking habits. Urinary albumin (Ualb), urinary α-1 microglobulin (Uα1m), urinary β-2 microglobulin (Uβ2m) and urinary retinol-binding protein (URBP) increased significantly with both increasing PbB40 and PbBint. Total urinary activity of N-acetyl-β-D-glucosaminidase (NAG-T) and its heat-stable isoenzyme (NAG-B) increased significantly with increasing PbB40. A significant difference in renal parameters occurred when PbB40 was 1 or more.

Conclusions: We have found a positive association between overall lead exposure and renal dysfunction. The renal parameters were significantly higher among those who had at least one episode of blood lead above 40 µg/dL. Our findings also strengthen the case for the use of Ualb, Uα1m, Uβ2m, URBP, NAG-T and NAG-B as early markers of lead nephropathy.

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