ADVERSE-EFFECTS OF CHRONIC LOW-LEVEL LEAD-EXPOSURE ON KIDNEY-FUNCTION- A RISK GROUP-STUDY IN CHILDREN

Background. Children have been considered a risk group for lead (Pb) t oxicity, mainly because of neurophysiological or neuro-cognitive defic its following rb exposure. Blood Pb levels (b-Pb) of 100 mu g/l curren tly have been defined as the lowest adverse effect level. The aim of t his study was to compare, with the help of urinary markers, the kidney function of children with b-Pb just above this threshold with that of unexposed children, to assess from a nephrological point of view whet her the current threshold is justified and whether children really are a particularly vulnerable risk group in terms of Pb-induced kidney da mage. Methods. In a cross-sectional study, 112 children, either from u nexposed areas (controls, n = 50) or Pb-contaminated areas (n = 62), t he latter partly with a known history of elevated b-Pb, were examined. Twenty nine urinary or serum markers mostly related to the function o r integrity of specific nephron segments were determined (e.g. filtere d plasma proteins, tubular enzymes, tubular antigens, eicosanoids). Re sults. b-Pb were 39 +/- 13 mu g/l in controls and 133 +/- 62 mu g/l in exposed children. The main findings were increased excretion rates of prostaglandins and thromboxane B-2, epidermal growth factor, beta(2)- microglobulin and Clara cell protein in the exposed children. A relati onship between b-Pb and the prevalence of values above the upper refer ence limits was observed. Conclusions, With the help of urinary marker s, nephron segment-specific effects of chronic low-level Pb exposure c ould be detected in children. The pattern of effects on glomerular, pr oximal and distal tubular and interstitial markers was similar to that previously observed in adults. The changes, however, occur at lower b -Pb levels than in adults. The current threshold appears to be justifi ed also from a nephrological point of view, and children can indeed be considered a special risk group.