Renal alterations in female rats following subchronic lead exposure

Female Wistar rats were given 1% or 0.1% lead acetate in drinking water for 2 or 4 months, respectively. Urinary beta 2-microglobulin, N-acetyl-beta-D-glucosaminidase, lactate dehydrogenase and lysozyme were used as markers of tubular dysfunction. Excretion of albumin and glomerular filtration rate were used as indicators of glomerular impairment. Kidney and body weights and morphological changes in the kidney were also studied. Exposure to 1% lead acetate induced a mean blood lead level of 1730 micrograms l-1 and caused only an increase of beta 2-microglobulin excretion and relative kidney weight. Light microscopy of kidney revealed morphological changes mainly in the epithelial cells of the proximal tubules. The role of acetate or reduced water intake on kidney function was excluded because 1% sodium acetate or the restriction of water intake to the volume consumed by the rats of the lead-exposed group was ineffective. Exposure to 0.1% lead acetate induced a blood lead level of 376 micrograms l-1, corresponding to the current level in industry workers, without any sign of nephrotoxicity. Comparison of this study with the results of a previous study on male rats indicates no sex difference in the nephrotoxicity of lead.

Urinary N-acetyl-beta-D-glucosaminidase activity in lead-exposed workers

The adverse effects of long-term exposure to lead dust on renal tubular functions were studied in 39 male and 7 female workers in a secondary lead refinery. Laboratory examinations showed low or moderate lead absorption levels. The N-acetyl-beta-D-glucosaminidase (NAG) activity in urine showed significant correlation with each of the lead exposure indices. NAG activity increased remarkably in lead workers with blood lead (PbB) above 80 micrograms 100g-1. Blood urea nitrogen (BUN) showed significant correlation with PbB and logarithmic urine delta-amino-levulinic acid (log(ALAU)), but not with urine lead (PbU) and logarithmic urine coproporphyrin (log(CPU)). All the other indices of renal function were almost within the normal range and showed no correlation with lead indices. This study suggests that moderate lead absorption may cause renal tubular impairment, and NAG can be one of the most sensitive indices for estimating renal dysfunction due to lead poisoning.

Urinary mercury levels and early changes in kidney function in dentists and dental assistants

Mercury exposure and renal function parameters were examined in 68 dentists and 64 dental assistants. The levels of mercury in urine were low: only three individuals exceeded 20 micrograms/l. Increased excretion of urinary proteins and increased activity of urinary enzymes were observed. This enhanced prevalence of renal function changes appeared not to be related to the mercury urine level, age, sex, or smoking and drinking habits. Only for men was a positive relation between the level of mercury in urine and the activity of beta-galactosidase found. The proteinuria may be due to one or more potential nephrotoxic agents used in dental practice.