Scintigraphic assessment of renal function in steel plant workers occupationally exposed to lead

Objectives: Occupational exposure to lead may produce kidney damage, but existing data on the dose range associated with nephrotoxicity are inconclusive. We here assessed renal function under conditions of low to moderate lead exposure using renal scintigraphy. Methods: Fifty-three male foundrymen (exposed group) and fourty male office workers (control group) from a steel plant were included in the study. Glomerular and tubular renal function were assessed by means of Tc-99m-DTPA and Tc-99m-EC clearance, respectively. Urinary markers of glomerular dysfunction (albumin) and tubular damage (alpha(1)-microglobulin (alpha M-1), beta(2)-microglobulin (beta M-2), retinol-binding protein (RBP), N-acetyl-beta-glucosaminidase (NAG) activity) were determined using latex beads tests or colorimetry. The lead concentration in blood was measured with atomic absorption spectrometry. Results: The blood lead concentrations were 145.8 (121.3-175.3) and 39.3 (35.1-44.1) mu g/l (geometric mean, 95th CI, p<0.001) in the exposed and control groups, respectively. Subjects exposed to lead presented with increased Tc-99m-DTPA clearance (158.3 (148.4-168.8) vs. 135.9(127.9-144.4) m//min; p<0.01) and urinary albumin excretion (7.61 (6.28-9.22) vs. 4.78 (4.05-5.65) mg/g creatinine; p<0.001). Tc-99m-EC clearance and excretion of alpha M-1, beta M-2, RBP and NAG were not significantly different between the groups. Significant correlations between Tc-99m-DTPA clearance and blood lead concentrations (r=0.45; p<0.01) and between urinary albumin excretion and blood lead concentrations (r=0.71; p<0.001) were noted. Conclusions: Use of renal scintigraphy in present study revealed measurable alterations of renal function under the conditions of low-level lead exposure and suggest that increased glomerular filtration may be an early indicator of kidney damage in subjects occupationally exposed to lead.