Bone fluorine concentrations in Canda geese (Branta canadensis) from areas with different levels of fluoride pollution

The concentration of fluorine in bone ash was measured in tarsometatarsi of 30 Canada geese in total. Nine birds originated from Sunndal and 11 birds from Husnes. These areas, both located in western Norway, are exposed to fluoride emissions from aluminium reduction plants. Ten birds orginated from Naustdal in western Norway and represented a reference population not exposed to any industrial fluoride emissions. The median fluorine concentrations were 3374, 1450, and 1334 mg F/kg bone ash in birds from Sunndal, Husnes and Naustdal, respectively. The bone fluorine concentration in Canada geese from Sunndal was significantly higher than in birds from Husnes (P < 0.01) and Naustdal (P = 0.01). Thus, the Canada goose population in Sunndal showed evidence of accumulation of fluoride due to fluoride emissions from the aluminium smelter, whereas birds from Husnes did not seem to be affected by emissions from the local aluminium plant. No gross osteofluorotic lesions were demonstrated in the birds examined. Due to difficulties with age assessment, varying sedentariness and a wide range in background fluorine concentrations, the Canada goose is not well suited for use as a bioindicator for monitoring fluoride exposure.