EXPERIMENTAL FLUORIDE ACCUMULATION AND TOXICITY IN THE SHORT-TAILED FIELD VOLE (MICROTUS-AGRESTIS)

Vegetation established naturally on three industrial sites contaminate d by either airborne or soilborne fluorides was used to formulate diet ary feed for a laboratory-reared population of field voles (Microtus a grestis L.), an herbivorous species indigenous to ail three locations. Animals exposed to laboratory diets containing 100-300 mg F kg(-1) de rived from vegetation from around the aluminium smelter and fluorochem ical works showed reduced live weight gain, between 40 and 100% mortal ity and developed marked dental lesions. These comprised banding of th e enamel, loss of colour and erosion of the cutting surfaces of the in cisors, and dentine cavitation and erosion of the grinding faces of th e molar teeth. These morphological changes were accompanied by excessi ve accumulation of fluoride in the teeth. Voles consuming a diet of ve getation from the mine tailings site with a similar level of fluoride (100 mg kg(-1)) as for the other industrial locations, showed only sli ght dental changes and no weight loss or early mortality. This pattern for laboratory-bred voles is similar to that experienced in populatio ns of this species in the wild, and the contrast in the severity of th e dental lesions is ascribed to intersite differences in the chemical speciation and bioavailability of fluoride.