Evaluation of a Lower Tier Exposure Assessment Model for Veterinary Medicines

• Published in: Journal of agricultural and food chemistry 2005-03, Vol.53 (6), p.2192-2201
• Main Authors: Blackwell, Paul A, Boxall, Alistair B. A, Kay, Paul, Noble, Helen
• Format: Article
• Language: English
• Subjects: Animals; Anti-Bacterial Agents - adverse effects; Anti-Bacterial Agents - analysis; Anti-Bacterial Agents - chemistry; antibiotic residues; antibiotics; Biological and medical sciences; clay loam soils; drug residues; drug therapy; ecotoxicology; Environmental Exposure; environmental fate; General pharmacology; Kinetics; land application; liquid manure; Manure - analysis; manure spreading; Medical sciences; Miscellaneous; Oxytetracycline - analysis; Pharmacology. Drug treatments; pig manure; predicted environmental concentration; Risk Assessment; sandy loam soils; Soil - analysis; soil pollution; Sulfachlorpyridazine - analysis; Swine; Tylosin - analysis; veterinary drugs; Veterinary Drugs - adverse effects; Veterinary Drugs - analysis; Veterinary Drugs - chemistry
• ISSN: 0021-8561; 1520-5118
• DOI: 10.1021/jf049527b

Veterinary antibiotics are used in large quantities in the European Union, and one of the key environmental exposure routes is via the application of manure containing excreted antibiotics to arable land as fertilizer. It is a legal requirement to assess the environmental risk of veterinary medicines, and this is done in two stages. A key decision parameter in phase I of these assessments is the predicted environmental concentration (PEC) in soil, and if a trigger value of 100 μg/kg is exceeded, then further phase II studies on the fate, behavior, and effects are carried out. A widely used model to calculate manure and soil PECs is the Uniform Approach. This study evaluated the Uniform Approach in two ways:  first, by reviewing existing data, addressing data gaps by performing degradation studies, and then calculating soil and manure PECs for the veterinary antibiotics sulfachloropyridazine, oxytetracycline, and tylosin applied to arable land via liquid pig manure and comparing these data with the results from two field-scale fate studies; second, by collating monitoring data and making a comparison with modeled data. The data comparisons indicated that the Uniform Approach model performed conservatively, with initial PECs being up to 2 orders of magnitude greater than measured environmental concentrations, providing confidence in the use of the model in the risk assessment process, although the assumption of first-order degradation kinetics in the model may underestimate the environmental persistence of veterinary antibiotics. Keywords: Exposure assessment; model evaluation; veterinary medicines; environmental risk assessment; uniform approach