Dead in the water: comment on “Development of an aquatic exposure assessment model for imidacloprid in sewage treatment plant discharges arising from use of veterinary medicinal products”

Abstract

Anthe et al. (Environ Sci Eur 32:147, 2020. 10.1186/s12302-020-00424-4) develop a mathematical model to calculate the contribution of veterinary medicinal products (VMPs) to the levels of imidacloprid observed in the UK water monitoring programme. They find that VMPs make only a very small contribution to measured pollution levels, and that the estimated concentrations do not exceed ecotoxicological thresholds. However, shortcomings in methodology—including the implicit assumption that imidacloprid applied to pets is available for release to the environment for 24 h only and failure to incorporate site-specific sewage effluent data relating to measured levels—raise questions about their conclusions. Adjusting for these and other deficiencies, we find that their model appears consistent with the conclusion that emissions from VMPs may greatly exceed ecotoxicological thresholds and contribute substantially to imidacloprid waterway pollution in the UK. However, the model utilises imidacloprid emissions fractions for animals undergoing the different scenarios (for example, bathing) that are extrapolated from unpublished studies that do not clearly resemble the modelled scenarios, with insufficient evidence provided to support their derivation. As a result, we find that the model presented by Anthe et al. provides no reliable conclusions about the contribution of veterinary medicinal products to the levels of imidacloprid in UK waterways.

The Effects of Wastewater Treatment Plant Failure on the Gulf of Gdansk (Southern Baltic Sea)

“…The second-largest threat to the aquatic ecosystems after wastewater discharge is reducing the dissolved oxygen content caused by the oxygen intake by organic matter. All of the changes mentioned above were identified as hazardous due to their accelerating effects on the eutrophication process, causing a further imbalance to the entire ecosystem [ 30 ]. However, in most cases, the long-distance sampling is not performed and the changes in those parameters on a distant stretch of rivers remain unknown.…”

Authors’ response on Perkins et al. (2021) “Dead in the water: comment on “Development of an aquatic exposure assessment model for imidacloprid in sewage treatment plant discharges arising from use of veterinary medicinal products”

“…Perkins et al dismiss, without any validation, other potential sources of imidacloprid found in UK rivers [2]. We believe that most of the arguments in the Perkins et al commentary relates to exposure pathways without a consideration of their plausibility, relevance or significance.…”

“…Perkins et al [2] seem to question the validity of the well-established biocide modelling approach that is set out by the Authorities responsible for regulating biocides in the EU (such as the use of default values) [3]. The model is based on the principles of the environmental risk assessment for Biocidal Products, which provide protection over an extended period (e.g.…”

“…The resulting average river concentration for a month of highest use has been compared with the lowest Predicted No Effect Concentration (PNEC) for aquatic chronic exposure in use by the European Commission, as well as the annual average surface water concentrations measured at different locations in the UK. The critique from Perkins et al [2] stipulating that the model implies Imidacloprid is released from pets into the environment for 24 h only, is incorrect. The calculations are detailed in the section "Materials and Methods-Emission calculations" [1] with an example calculation given by the authors in the Additional File 1 (https:// enveu rope.…”

Advanced Treatment of Urban Sewage Sludge by Upflow Aerated Biological Filter

“…Organic matter, often forming a facultative anaerobic environment. Here, bacteria are permanently present, have poor adhesion to the material, and are easily released [14][15].…”