Validation of the exposure assessment for veterinary medicinal products

Abstract

Under the EU Directive 2004/28/EC, an environmental risk assessment of new veterinary medicinal products is required. Given the nature of risk assessment for new applications, there is a need to model exposure concentrations. Critical evaluations are essential to ensure that the use of models by regulators does not result in the propagation of misleading information. The empirical validations of soil exposure models, previously discussed in this journal, indicate that it is impossible to analyse the contribution of every model parameter to the variability in the predictions. In particular, the prediction of the slurry concentration is challenged by uncertainties concerning dilution, mixing and dissipation of residues. Surface water and groundwater models generated highly deviating results compared to the field results, questioning the usefulness of the available screening models. Animal husbandry, slurry handling and environmental conditions throughout Europe are considered in order to define realistic worst case scenarios, to be used in conjunction with distribution models for the environmental risk assessment of veterinary medicinal products at registration. Given the variability in manure management practice throughout Europe, a deterministic approach for the manure-to-soil model was selected. Both worst case and best case scenario were developed. Several modelling assumptions applied in the surface water exposure model for fish nursery effluent were validated against newly available data. Since the available data give no proof that a settling tank contributes to the removal of pesticides from waste water, it is recommended for risk assessment purposes to consider the contribution of the settling tank to removal of pesticides and medicines to be negligible. Surface water dilution factors may be considered to be rather small, a factor of 2, for low flow situations.

Eco-toxic effects of sulfadiazine sodium, sulfamonomethoxine sodium and enrofloxacin on wheat, Chinese cabbage and tomato

“…Like other veterinary pharmaceuticals, sulfadiazine sodium (SDS) and sulfamonomethoxine sodium (SMMS) entered agricultural soils mainly by fertilizing, grazing (Jørgensen and Halling-Sørensen 2000;Dagnac et al 2002;Haller et al 2002), transporting through soil (Christian et al 2003;Hamscher et al 2005;Wojciech et al 2006), surface runoff (Davis et al 2006) and uptake by plants (Dolliver et al 2007). Besides possible adverse effects on microorganisms, the major risk of these antibiotics entering the environment is probably the development and spreading of resistant pathogens (Paul et al 2005;Montforts 2006;Heuer and Smalla 2007;Nicole 2008).…”

Sales data as a measure of antibiotics usage: Concepts, examples and discussion of influencing factors

“…The countries also provide information on name and concentration TA B L E 1 Average animal weights at typical age of treatment (European Medicines Agency, 2009;Montforts, 2006)…”

Organic Xenobiotics

“…For a risk assessment of antibiotics it is necessary to calculate realistic worst-case concentrations in slurry and soils. Following this approach, Montforts (2006) calculated a soil concentration of 207 µg OTC per kg dry weight in the upper 30 soil cm when pig slurry was applied. This value was confirmed by field measurements .…”