Blood lead, cadmium and mercury among children from urban, industrial and rural areas of Fez Boulemane Region (Morocco): Relevant factors and early renal effects

Objectives: To describe blood lead (Pb-B), cadmium (Cd-B) and mercury (Hg-B) levels in children living in urban, industrial and rural areas in Fez city (north of Morocco) and to identify the determinants and some renal effects of exposure. Material and Methods: The study was conducted from June 2007 to January 2008 in 209 school children (113 girls, 96 boys), aged 6-12 years, from urban, industrial and rural areas in Fez city. Interview and questionnaires data were obtained. Blood and urinary samples were analyzed. Results: The mean of blood lead levels (Pb-B) in our population was 55.53 μg/l (range: 7.5-231.1 μg/l). Children from the urban area had higher blood lead levels (BLLs) mean (82.36 μg/l) than children from industrial and rural areas (48.23 and 35.99 μg/l, respectively); with no significant difference between boys and girls. BLLs were associated with traffic intensity, passive smoking and infancy in the urban area. The mean of blood cadmium levels (BCLs) was 0.22 μg/l (range: 0.06-0.68 μg/l), with no difference between various areas. Rural boys had higher BCLs mean than rural girls, but no gender influence was noticed in the other areas. BCLs were associated with the number of cigarettes smoked at children's homes. The blood mercury levels (BMLs) mean was 0.49 μg/l (range: 0.01-5.31 μg/l). The BMLs mean was higher in urban and industrial areas than in the rural area with no gender-related difference. BMLs were associated with amalgam fillings and infancy in the urban area. About 8% of the children had BLLs ≥ 100 μg/l particularly in the urban area, microalbuminuria and a decrease in height were noticed in girls from the inner city of Fez and that can be related to high BLLs (89.45 μg/l). Conclusions: There is a need to control and regulate potential sources of contamination by these trace elements in children; particularly for lead

Markers of Early Renal Changes Induced By Industrial Pollutants .1. Application To Workers Exposed To Mercury-vapor

Several markers of renal changes have been measured in a cohort of 50 workers exposed to elemental mercury (Hg) and in 50 control workers. After application of selection criteria 44 exposed and 49 control workers were retained for the final statistical analysis. Exposed workers excreted on average 22 mug Hg/g creatinine and their mean duration of exposure was 11 years. Three types of renal markers were studied-namely, functional markers (creatinine and beta2-microglobulin in serum, urinary proteins of low or high molecular weight); cytotoxicity markers (tubular antigens and enzymes in urine), and biochemical markers (eicosanoids, thromboxane, fibronectin, kallikrein, sialic acid, glycosaminoglycans in urine, red blood cell membrane negative charges). Several blood-borne indicators of polyclonal activation were also measured to test the hypothesis that an immune mechanism might be involved in the renal toxicity of elemental Hg. The main renal changes associated with exposure to Hg were indicative of tubular cytotoxicity (increased leakage of tubular antigens and enzymes in urine) and biochemical alterations (decreased urinary excretion of some eicosanoids and glycosaminoglycans and lowering of urinary pH). The concentrations of anti-DNA antibodies and total immunoglobulin E in serum were also positively associated with the concentration of Hg in urine and in blood respectively. The renal effects were mainly found in workers excreting more than 50 mug Hg/g creatinine, which corroborates our previous estimate of the biological threshold of Hg in urine. As these effects, however, were unrelated to the duration of exposure and not accompanied by functional changes (for example, microproteinuria), they may not necessarily represent clinically significant alterations of renal function

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) toxicity, mainly because of neurophysiological or neuro-cognitive deficits following rb exposure. Blood Pb levels (b-Pb) of 100 mu g/l currently have been defined as the lowest adverse effect level. The aim of this 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 whether the current threshold is justified and whether children really are a particularly vulnerable risk group in terms of Pb-induced kidney damage. Methods. In a cross-sectional study, 112 children, either from unexposed areas (controls, n = 50) or Pb-contaminated areas (n = 62), the latter partly with a known history of elevated b-Pb, were examined. Twenty nine urinary or serum markers mostly related to the function or integrity of specific nephron segments were determined (e.g. filtered plasma proteins, tubular enzymes, tubular antigens, eicosanoids). Results. 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 relationship between b-Pb and the prevalence of values above the upper reference limits was observed. Conclusions, With the help of urinary markers, nephron segment-specific effects of chronic low-level Pb exposure could be detected in children. The pattern of effects on glomerular, proximal 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 justified also from a nephrological point of view, and children can indeed be considered a special risk group

Markers of Early Renal Changes Induced By Industrial Pollutants .1. Application To Workers Exposed To Mercury-vapor

Several markers of renal changes have been measured in a cohort of 50 workers exposed to elemental mercury (Hg) and in 50 control workers. After application of selection criteria 44 exposed and 49 control workers were retained for the final statistical analysis. Exposed workers excreted on average 22 mug Hg/g creatinine and their mean duration of exposure was 11 years. Three types of renal markers were studied-namely, functional markers (creatinine and beta2-microglobulin in serum, urinary proteins of low or high molecular weight); cytotoxicity markers (tubular antigens and enzymes in urine), and biochemical markers (eicosanoids, thromboxane, fibronectin, kallikrein, sialic acid, glycosaminoglycans in urine, red blood cell membrane negative charges). Several blood-borne indicators of polyclonal activation were also measured to test the hypothesis that an immune mechanism might be involved in the renal toxicity of elemental Hg. The main renal changes associated with exposure to Hg were indicative of tubular cytotoxicity (increased leakage of tubular antigens and enzymes in urine) and biochemical alterations (decreased urinary excretion of some eicosanoids and glycosaminoglycans and lowering of urinary pH). The concentrations of anti-DNA antibodies and total immunoglobulin E in serum were also positively associated with the concentration of Hg in urine and in blood respectively. The renal effects were mainly found in workers excreting more than 50 mug Hg/g creatinine, which corroborates our previous estimate of the biological threshold of Hg in urine. As these effects, however, were unrelated to the duration of exposure and not accompanied by functional changes (for example, microproteinuria), they may not necessarily represent clinically significant alterations of renal function

Nephropathies and exposure to perchloroethylene in dry-cleaners

Even in specific risk groups, the relation between exposure to organic solvents and chronic renal diseases remains controversial. Thus, in a collaborative European study, we assessed the renal effects of occupational exposure to perchloroethylene (PCE) in dry-cleaners compared with matched controls who were simultaneously examined. Single high and low molecular weight proteins, kidney-derived antigens and enzymes, and prostanoids were measured in urine. Beta-2-microglobulin, creatinine, laminin fragments, and anti-glomerular basement membrane antibodies were also measured in serum. A canonical function based on 23 such variables correctly classified 93% of individuals as either PCE-exposed or controls; with 13 markers, group membership was identified in 87% of subjects. Increased high molecular weight protein in urine was frequently (17/50 vs 1/50, p < 0.0001) associated with tubular alterations. Changes were consistent with diffuse abnormalities along the nephron in workers exposed to low levels of PCE (median 15 parts per million). Generalised membrane disturbances might account for the increased release of laminin fragments, fibronectin, and glycosaminoglycans, for high molecular weight proteinuria, and for the increased shedding of epithelial membrane components from tubular cells with different location along the nephron (brush-border-antigens and Tamm-Horsfall glycoprotein). These findings of early renal changes indicate that solvent-exposed subjects, especially dry-cleaners, need to be monitored for the possible development of chronic renal diseases

Nephropathies and exposure to perchloroethylene in dry-cleaners

Even in specific risk groups, the relation between exposure to organic solvents and chronic renal diseases remains controversial. Thus, in a collaborative European study, we assessed the renal effects of occupational exposure to perchloroethylene (PCE) in dry-cleaners compared with matched controls who were simultaneously examined. Single high and low molecular weight proteins, kidney-derived antigens and enzymes, and prostanoids were measured in urine. Beta-2-microglobulin, creatinine, laminin fragments, and anti-glomerular basement membrane antibodies were also measured in serum. A canonical function based on 23 such variables correctly classified 93% of individuals as either PCE-exposed or controls; with 13 markers, group membership was identified in 87% of subjects. Increased high molecular weight protein in urine was frequently (17/50 vs 1/50, p < 0.0001) associated with tubular alterations. Changes were consistent with diffuse abnormalities along the nephron in workers exposed to low levels of PCE (median 15 parts per million). Generalised membrane disturbances might account for the increased release of laminin fragments, fibronectin, and glycosaminoglycans, for high molecular weight proteinuria, and for the increased shedding of epithelial membrane components from tubular cells with different location along the nephron (brush-border-antigens and Tamm-Horsfall glycoprotein). These findings of early renal changes indicate that solvent-exposed subjects, especially dry-cleaners, need to be monitored for the possible development of chronic renal diseases