Fluoride in moles, shrews and earthworms near an aluminium reduction plant

Abstract

Moles (Talpa europaea) and common shrews (Sorex araneus) were trapped in 1977 at three 5 km intervals on two transects radiating NE and SE from an aluminium reduction plant on the island of Anglesey, North Wales. Earthworms (Lumbricidae) were collected from the same transect locations. Materials were also obtained from elsewhere for comparison. For all materials, highest fluoride concentrations were found within 1 km radius of the reduction plant.

Moles from within 1 km of the reduction plant had a mean bone fluoride content of 7740 μg g⁻¹ (range 5160-11 100 μg g⁻¹); elsewhere on the island the overall mean was 1294 μg g⁻¹ (range 42 to 3125 μg g⁻¹). With the exception of animals within 1 km of the reduction plant, bone fluoride in moles showed no relationship to distance from the plant along either transect (P > 0·7 at least). Moles from areas more than 15 km from the reduction plant had a mean bone fluoride concentration of 971 μg g⁻¹ (range 40 to 2200 μg g⁻¹). Tooth wear index in this sample was only half that found in moles from within 15 km of the reduction plant (P < 0·001).

Common shrews had an overall mean bone fluoride concentration of 1404 μg g⁻¹ (range 82 to 8600 μg g⁻¹). Concentrations decreased with distance from the reduction plant, consistent with airbone carriage of fluoride from the stack at the plant (P < 0·05).

Apart from the immediate vicinity of the reduction plant, total fluoride concentration in earthworms showed no relationship to distance from the plant. Their fluoride content was considered to be largely due to soil contained in the gut.