Proposal for a Monitoring Concept for Veterinary Medicinal Products with PBT Properties, Using Parasiticides as a Case Study

The aim of this work is to prepare a proposal for the post-authorization monitoring (PAM) of veterinary medicinal products (VMP), in particular parasiticides. Such a monitoring might especially be useful for parasiticides identified as Persistence Bioaccumulation Toxicity (PBT) substances, i.e., chemicals that are toxic (T), persist in the environment (P) and bioaccumulate (B) in food chains and, thus, pose a hazard to ecosystems. Based on a literature search, issues to be considered when performing such a PAM are discussed (e.g., residue analysis, compartments to be included, selection of organisms and the duration of monitoring studies). The outcome of this discussion is that—and despite that there are huge challenges in detail (e.g., in terms of analytical chemistry or taxonomy)—the technical performance of such a PAM is not the main problem, since most of the chemical and biological methods to be used are well-known (partly even standardized) or could be adapted. However, it is very difficult to define in detail where and when a monitoring should be performed. The main problem is to link exposure to effects of a certain parasiticide in a way that any impact can directly be related to the use of this parasiticide. Therefore, a “Targeted Environmental Monitoring” (TEM) is proposed, which is essentially a combination between a field study and a PAM.