Environmental risk assessment of ivermectin: A case study

Abstract

The veterinary parasiticide ivermectin was selected as a case study compound within the project ERAPharm (Environmental Risk Assessment of Pharmaceuticals). Based on experimental data generated within ERAPharm and additional literature data, an environmental risk assessment (ERA) was performed mainly according to international and European guidelines. For the environmental compartments surface water, sediment, and dung, a risk was indicated at all levels of the tiered assessment approach. Only for soil was no risk indicated after the lower tier assessment. However, the use of effects data from additional 2-species and multispecies studies resulted in a risk indication for collembolans. Although previously performed ERAs for ivermectin revealed no concern for the aquatic compartment, and transient effects on dung-insect populations were not considered as relevant, the present ERA clearly demonstrates unacceptable risks for all investigated environmental compartments and hence suggests the necessity of reassessing ivermectin-containing products. Based on this case study, several gaps in the existing guidelines for ERA of pharmaceuticals were shown and improvements have been suggested. The action limit at the start of the ERA, for example, is not protective for substances such as ivermectin when used on intensively reared animals. Furthermore, initial predicted environmental concentrations (PECs) of ivermectin in soil were estimated to be lower than refined PECs, indicating that the currently used tiered approach for exposure assessment is not appropriate for substances with potential for accumulation in soil. In addition, guidance is lacking for the assessment of effects at higher tiers of the ERA, e.g., for field studies or a tiered effects assessment in the dung compartment.

Fate and effects of ivermectin on soil invertebrates in terrestrial model ecosystems

“…Based on good experiences in tests with pesticides (Förster et al 2006;Knacker et al 2004) the Terrestrial Model Ecosystem (TME) method was selected for studying the effects of ivermectin on structural (abundance and species composition of soil organisms) and functional (bait-lamina test) endpoints. While there are many ecotoxicological data available for this compound regarding single species tests (for review see Liebig et al 2010), it has never been tested in a comparable semi-field test so far.…”

Introduction to the special issue on environmental risk assessment of pharmaceuticals

“…A considerable amount of work within the project focused on 3 case studies; 2 focused on human pharmaceuticals, the b-blocker atenolol (Kü ster et al 2010) and the antidepressant fluoxetine (Oakes et al 2010), and the third on a veterinary parasiticide, ivermectin (Liebig et al 2010). For these 3 compounds, environmental risk assessments were performed to evaluate and highlight the strengths and weaknesses of the existing European guidelines on environmental risk assessment of pharmaceuticals.…”

Human Pharmaceuticals in the Aquatic Environment: A Review of Recent Toxicological Studies and Considerations for Toxicity Testing

“…Ecotoxicological data, published either in the peer-reviewed literature or in ecotoxicological databases (ECE TOX in EU; ECOTOX in USA) (EU 2001 ;Jones et al 2002 ;Sanderson et al 2003 ;Stuer-Lauridsen et al 2000 ) , are currently available for <10% of the currently prescribed pharmaceuticals. It is also disconcerting that only a few pharmaceuticals have been subjected to ecological risk assessments (Henschel et al 1997 ;Emblidge and DeLorenzo 2006 ;Hernando et al 2006 ;Küster et al 2010 ;Oakes et al 2010 ;Liebig et al 2010 ). Furthermore, the majority of aquatic toxicity studies performed on pharmaceuticals address the effects of individual-substance exposures in laboratory waters (or a few with sediments), rather than effl uent matrices that refl ect how pharmaceuticals are typically discharged to surface waters.…”