Cadmium and other heavy metal concentrations in bovine kidneys in the Republic of Ireland

Abstract

In Ireland, an estimated 15% of Irish soils exceed the EU threshold limit for soil Cd of 1mg/kg. The aim was to determine the concentrations of Cd and other heavy metals (As, Hg and Pb) in kidneys collected from cattle at slaughter. Systematic sampling of eligible animals (animals that were born and reared until slaughter in the same Irish county) at the time of slaughter was conducted, until a threshold number of animals from all 26 counties and 6 age categories was reached. A predictive surface of soil Cd was generated, by kriging the Cd values of 1310 previously reported soil samples. A linear regression weighted model was developed to model kidney Cd concentration, using the risk factors of age, sex, breed, province and estimated soil Cd concentration. Kidney Cd (n=393) concentrations varied between 0.040 and 8.630mg/kg wet weight; while concentrations of As, Hg and Pb were low. The estimated weighted proportion of animals with a high (≥1mg/kg) kidney Cd concentration was 11.25% (95% CI: 8.63–14.53%). Key predictors for high kidney Cd concentration were soil Cd, animal age and province. At a soil Cd concentration of 1.5mg/kg, it was predicted that an age threshold to avoid exceeding a kidney Cd concentration of 1mg/kg in most animals would be ~3y in Connacht, >4y in Ulster, and >5y in Leinster and Munster. In naturally occurring areas of high Cd levels in soils in Ireland, the Cd level in bovine kidneys can exceed the current EU ML of 1mg/kg in older animals. Kidneys of most cattle under three years of age will conform with EU requirements.