Fluoride excretion in urines of schoolchildren living close to an aluminum refinery in the Netherlands

The concentration of fluorides in urines of schoolboys, 9–11 years old, was used for biological monitoring of the fluoride exposure in an area of the Netherlands with two important sources of fluoride emissions. There were no indications of an abnormal uptake of fluorides at that time. The vegetables in the most polluted area contained approximately 40 ppm of fluorides and caused at most an incidental daily intake of 1.70 mg of fluorides, the ambient air an intake of 0.040 mg. The concentrations in the urine were in accordance with this finding. Biological monitoring of this type at 3–5 year intervals seems indicated to detect undesirable uptake in coming years.