Importance of Contaminated Soils in Supplying Bioaccessible Fluoride to Grazing Animals From the Historic Metalliferous Mining Areas of the UK

Abstract

Soil-plant-animal and soil-animal pathways are the principal routes through which trace element e.g fluorine (F) enters the animal body systems. It is believed that soils and herbage contaminated with such trace elements may, eventually, reflect in the bones and other animal tissues. However, the correlationship between soil F and Bone F among grazing animalshas not been substantially, established. This study aimed at investigating the association between F concentration in soil to those found in the bones of sheep and cattle reared in metalliferous mining areas of the United Kingdom. The study area included Derbyshire, a site of fluorite (CaF2) mineralization; Ceredigion and Mendips, sites of mostly galena (PbS) mineralization, the latter two sites used as control sites for this study. The analytical approach involved alkali fusion, perchloric acid digestion and sequential extraction procedures in determining total soil F, total bone F and soil bioavailable F, respectively. The spectrophotometric technique was then used to determine soil F from solution extracts. The results showed mean total soil F concentrations of 302.3 mg/kg, 175.4 mg/kg and 70.8 mg/kg in Derbyshire, Mendips and Ceredigion respectively. The same order was observed for bone F with as high as 218.3 mg/kg, 118.1 mg/kg and 88.9 mg/kg found in Derbsyhire, Mendips and Ceredigion respectively. Analysis of Spearman rank coefficients established that there is a moderate association between soil bioavailable F and bone F (rs=0.571), significant at p < 0.1; a conclusion suggesting possible high risk from F on animals grazing within heavily contaminated areas affected by historical F mining