Public health implications of environmental exposure to cadmium and lead: an overview of epidemiological studies in Belgium. Working Groups.

The CadmiBel Study was a cross-sectional population study that investigated the health effects of environmental exposure to cadmium and lead. The 2327 participants constituted a random sample of the population of four Belgian districts, chosen in order to provide a wide range of environmental exposure to cadmium. After adjustment for confounding factors, such as smoking and occupational exposure, the urinary cadmium excretion, a measure of lifetime exposure, was nearly 30% higher in the polluted areas. The CadmiBel Study produced evidence inconsistent with the hypothesis that environmental exposure to cadmium and lead would lead to an increase in blood pressure and to a higher prevalence of hypertension and other cardiovascular diseases. On the other hand, the serum alkaline phosphatase activity and the urinary excretion of calcium were significantly and positively correlated with urinary cadmium in both sexes. These findings suggested that the homeostasis of calcium was gradually affected as cadmium accumulated in the body. Furthermore, several markers of renal tubular dysfunction (urinary excretion of retinol-binding-protein, N-acetyl-beta-glucosaminidase, beta 2-microglobulin and amino acids) were significantly and positively associated with urinary cadmium. Across 10 small areas of which six were polluted with cadmium, an inverse association existed between the creatinine clearance and several indexes of environmental exposure to cadmium (cadmium concentration in the soil, cadmium content of locally grown vegetables, the inhabitants' 24 h urinary cadmium excretion). In the CadmiBel Study, the creatinine clearance was also inversely correlated with the concentrations of lead and zinc protoporphyrin in the blood. Thus, environmental exposure to cadmium and lead was associated with alterations in renal function. The significance in terms of morbidity and mortality of the functional disturbances observed in the CadmiBel Study, and the possible strategies to prevent the transfer of cadmium from the environment to man are under investigation in the prospective PheeCad Study in which half of the Cadmibel participants have been enrolled (participation rate 80%).