Lead, cadmium, mercury, and arsenic are common environmental pollutants in industrialized countries, but their combined impact on children’s health is little known. We studied their effects on two main targets, the renal and dopaminergic systems, in > 800 children during a cross-sectional European survey. Control and exposed children were recruited from those living around historical nonferrous smelters in France, the Czech Republic, and Poland. Children provided blood and urine samples for the determination of the metals and sensitive renal or neurologic biomarkers. Serum concentrations of creatinine, cystatin C, and β2-microglobulin were negatively correlated with blood lead levels (PbB), suggesting an early renal hyperfiltration that averaged 7% in the upper quartile of PbB levels (> 55 μg/L; mean, 78.4 μg/L). The urinary excretion of retinol-binding protein, Clara cell protein, and N-acetyl-β-d-glucosaminidase was associated mainly with cadmium levels in blood or urine and with urinary mercury. All four metals influenced the dopaminergic markers serum prolactin and urinary homovanillic acid, with complex interactions brought to light. Heavy metals polluting the environment can cause subtle effects on children’s renal and dopaminergic systems without clear evidence of a threshold, which reinforces the need to control and regulate potential sources of contamination by heavy metals.

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The authors performed neurological, visual evoked potentials (VEP) and electroneurography (ENG) examinations on three groups of workers with occupational exposure to mercury vapors (Hg(0)), and on a control group. The exposure of dental professionals (n = 36) was mild, that of chloralkali plant workers (n = 36) was intermediate, and that of workers from mercury works (n = 77) was very high. Symptoms and signs of micromercurialism were observed only in the group with the highest exposure to Hg(0). In comparison with the control group, a shortening of VEP latency and a decrease in amplitude were found in the exposed groups. The VEP changes correlated with Hg(0) excreted in urine after administration of a chelating agent - sodium 2,3-dimercapto-1-propan sulfonate (DMPS). The frequency of abnormal VEP results increased with increasing levels of exposure. ENG changes were observed only in the group with the highest exposure to Hg(0). An isolated decrease of sural nerve conduction velocity was observed in 18% of total workers. In 70% of the cases, this was associated with an abnormality in VEP. The combination of a decrease in sural nerve conduction velocity and an abnormality of VEP seems to be a characteristic pattern of electrophysiological changes in persons exposed to mercury vapors.

Cikrt, M. (1972). Brit. J. industr. Med., 29,[74][75][76][77][78][79][80]. Biliary excretion of 203Hg, 64Cu, 52Mn, and 210Pb in the rat. The biliary excretion of 52Mn, 64Cu, 203Hg, and 210Pb after intravenous administration of 52MnCI2, 64CuC12, 203HgCl2, and 210Pb (NO3)2 in non-toxic doses was studied in rats. Cumulative biliary excretion reached by 24 hours after administration in the case of 64Cu 31-06%, of 52Mn 26-7%, of 203Hg 3-8%, and of 210Pb 6-7% of the administered dose. The excretion curve for 203Hg differed significantly from those of the other three metals. The maximum rate of excretion was reached at different periods after administration for each metal. The excretion of the metals via the wall of the gastrointestinal tract during 24 hours after administration was also studied. The excretion into faeces occurred mainly via the bile; to a lesser extent there was excretion through the wall, probably chiefly of the upper segments of the digestive tract.The gastrointestinal tract has repeatedly been shown to be one of the main pathways of excretion of heavy metals. Little isknown of the mechanisms responsible for the transport of metal into the intestinal lumen. In principle, there are two origins of the metal detected in faeces after parenteral administrationthe bile or pancreatic fluid, and the intestinal wall.

Biliary excretion of iron after administration of pyridoxal isonicotinoyl hydrazone (PIH), a recently identified effective iron-chelating agent, was investigated in rats. PIH administered both intraperitoneally and orally was shown to increase significantly 59Fe excretion into bile of rats which had previously been injected with 59Fe-transferrin to label hepatic parenchymal cells. 59Fe-PIH appears in bile as early as 15 min after chelator administration and the peak of 59Fe-radioactivity in bile is seen 1--5 h following intraperitoneal PIH injection. PIH, administered intraperitoneally, 125--250 mg/kg, increased 24 h biliary radioiron excretion about 35 times and in addition increased urinary and faecal iron excretion. When PIH was given immediately before 59Fe-transferrin, 24 h cumulative biliary 59Fe excretion was even higher. PIH was also demonstrated to increase biliary excretion of radioiron released from 59Fe-haemoglobin catabolysed in reticuloendothelial cells. The effect of PIH was confirmed by estimation of biliary iron concentration using the method of atomic absorption spectrophotometry. Repeated PIH administration to rats decreased 59Fe radioactivity in liver and kidney and increased urinary and faecal iron excretion.

The area around the Pribram lead smelter has been recognized to be heavily contaminated by lead (Pb). In the early 1970s, several episodes of livestock lead intoxication were reported in this area; thereafter, several epidemiological and ecological studies focused on exposure of children. In contrast to earlier studies, the recent investigation (1992-1994) revealed significantly lower exposure to lead. From 1986-1990, recorded average blood lead levels were about 37.2 micrograms lead (Pb)/100 ml in an elementary school population living in a neighborhood close to the smelter (within 3 km of the plant). The present study, however, has found mean blood lead levels of 11.35 micrograms/100 ml (95% CI = 9.32; 13.82) among a comparable group of children. In addition to blood lead, tooth lead was used to assess exposure among children. Statistically significant differences (p < 0.05) were observed between the geometric mean tooth lead level of 6.44 micrograms Pb/g (n = 13; 95% CI = 3.95; 10.50) in the most contaminated zone and 1.43 micrograms Pb/g (n = 35; 95% CI = 1.11; 1.84) in zones farther away from the point source. Both biomarkers, blood and tooth lead levels, reflect a similar pattern of lead exposure in children. This study has attempted a quantitative assessment of risk factors associated with elevated lead exposure in the Czech Republic. Content of lead in soil, residential distance from the smelter, consumption of locally grown vegetables or fruits, drinking water from local wells, the mother's educational level, cigarette consumption among family members, and the number of children in the family were factors positively related (p < 0.05) to blood lead levels. The resulting blood lead level was found to be inversely proportional to the child's age.ImagesFigure 1.

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Exposure to chemical substances at the workplace was relatively low, the limits being exceeded only sporadically (each such case was investigated at the workplace), and the level of exposure continues to decrease gradually over the years. Considering the fact that the exposed individuals are expected to work for 23 additional years on average, we feel that long-term monitoring of selected health-related parameters, not including tumor markers, appears desirable. The examination of tumor markers has not contributed to the problem evaluation for a number of false-positive results.