Estimation of veterinary drug concentrations in Canadian soils: Flexing the PECs with MECs

Estimation of veterinary drug concentrations in Canadian soils: Flexing the PECs with MECs Presented by: Sigrun Kullik, Ph.D., Environmental Impact Initiative Division, Health Canada The first L-SETAC Ottawa Pub Night of the 2015-2016 season was held on Wednesday, September 30th at the Clocktower Brew Pub. In a presentation entitled “Estimation of veterinary drug concentrations: Flexing the PECs with MECs”, Dr. Sigrun Kullik from Health Canada’s Environmental Impact Division discussed their development of a screening-level model for predicting Canadian environmental concentrations of veterinary drugs used in livestock. The model, adapted from the European Medicines Agency, estimates soil concentrations of veterinary drugs resulting from the application of manure to agricultural fields. Data on Canadian livestock breeds, production methods, and manure application practices were compiled for use as model inputs. For screening-level purposes, the model conservatively assumes that 1) the highest labeled use of the drug was administered, 2) the drug was not metabolized by the animal, and 3) no degradation of the drug occurred during storage of the manure. The model was validated by comparing predicted environmental concentrations (PECs) to measured environmental concentrations (MECs) published in the literature or obtained from researchers. The majority of PECs were well above MECs, indicating that the model was adequately conservative. However, when refinements were made to consider metabolism, degradation, and water dilution of manure, PECs were much closer to measured drug concentrations. Dr. Kullik noted that while several studies reported MECs for soils receiving pig manure, few studies were available for cattle and poultry. As a result, Dr. Kullik and her colleagues are collaborating with researchers to collect more MEC data from application of cattle and poultry manure. In addition, a model predicting veterinary drug concentrations in surface water from agricultural runoff is currently in the works. The Ottawa Pub Nights got off to a great start with Dr. Kullik’s engaging talk, and we’re looking forward to many others in the year ahead! -Submitted by Gillian Manning