Temporal Persistence of Bromadiolone in Decomposing Bodies of Common Kestrel (Falco tinnunculus)

State of the art, gaps and future perspectives on common kestrel ecotoxicology

Anthropogenic activities have caused a steady decline of common kestrel (Falco tinnunculus) since the 1980 s. Effects, especially sublethal effects of contaminants, need to be investigated to ensure the conservation of this species. Data about countries, biological material, contaminants classes, and methodological approaches were collected from scientific publications to highlight gaps on common kestrel toxicology and ecotoxicology. We found that most studies have been conducted in Europe and in the field, underlining a lack of in vitro studies. The studies investigated mainly contaminant levels, while sublethal effects, evaluation of emerging contaminants and use of non-invasive or low-invasive samples were scarce. This work shows important gaps on toxicological status of the common kestrel, highlighting the importance of developing a non-lethal approach that combines responses at different levels of biological organization, as well as data on chemical contamination and on the environment in which the different populations inhabit.

Interest of the faecal and plasma matrix for monitoring the exposure of wildlife or domestic animals to anticoagulant rodenticides

Anticoagulant rodenticides (ARs), particularly second-generation compounds (SGAR), are known to be a potential threat to unintended species due to their tissue persistence. The liver is the storage tissue of ARs and is a matrix of choice in diagnosing exposure and intoxication of non-target fauna. However, it is only available on dead animals. Blood and faeces can be used on living animals. These two biological matrices were compared in terms of their relevance to exposure to ARs. In addressing this question, we compared the faecal, plasma and liver concentrations of bromadiolone, one of the SGAR frequently implicated in wildlife exposure. We studied this comparison at the individual level and at the population level, considering three influencing factors: dose, sex and time. Our findings demonstrate that faecal analyses are more valuable than plasma analyses for monitoring AR exposure of domestic and wild animals, even if faecal concentrations cannot be correlated with liver concentrations.

Exposure of predatory and scavenging birds to anticoagulant rodenticides in France: Exploration of data from French surveillance programs

Wild raptors are widely used to assess exposure to different environmental contaminants, including anticoagulant rodenticides (ARs). ARs are used on a global scale for rodent control, and act by disruption of the vitamin K cycle that results in haemorrhage usually accompanied by death within days. Some ARs are highly persistent and bioaccumulative, which can cause significant exposure of non-target species. We characterized AR exposure in a heterogeneous sample of dead raptors collected over 12 years (2008-2019) in south-eastern France. Residue analysis of 156 liver samples through LC-MS/MS revealed that 50% (78/156) were positive for ARs, with 13.5% (21/156) having summed second-generation AR (SGAR) concentrations >100 ng/g ww. While SGARs were commonly detected (97.4% of positive samples), first-generation ARs were rarely found (7.7% of positive samples). ARs were more frequently detected and at greater concentration in predators (prevalence: 82.5%) than in scavengers (38.8%). Exposure to multiple ARs was common (64.1% of positive samples). While chlorophacinone exposure decreased over time, an increasing exposure trend was observed for the SGAR brodifacoum, suggesting that public policies may not be efficient at mitigating risk of exposure for non-target species. Haemorrhage was observed in 88 birds, but AR toxicosis was suspected in only 2 of these individuals, and no difference in frequency of haemorrhage was apparent in birds displaying summed SGAR levels above or below 100 ng/g ww. As for other contaminants, 17.2% of liver samples (11/64) exhibited Pb levels compatible with sub-clinical poisoning (>6 μg/g dw), with 6.3% (4/64) above the threshold for severe/lethal poisoning (>30 μg/g dw). Nine individuals with Pb levels >6 μg/g dw also had AR residues, demonstrating exposure to multiple contaminants. Broad toxicological screening for other contaminants was positive for 18 of 126 individuals, with carbofuran and mevinphos exposure being the suspected cause of death of 17 birds. Our findings demonstrate lower but still substantial AR exposure of scavenging birds compared to predatory birds, and also illustrate the complexity of diagnosing AR toxicosis through forensic investigations.

Developing a European network of analytical laboratories and government institutions to prevent poisoning of raptors

Many cases of wildlife poisoning in Europe have been reported causing population declines, especially in raptors. Toxicovigilance and risk assessment studies are essential to reinforce the knowledge of the number of illegal poisoning cases and the substances involved in these crimes. Many researchers and projects in different institutions have suggested the creation of a network to improve communication and share information between European countries. This article presents the results of the Short-Term Scientific Mission titled "Developing a Network of Analytical Labs and Government Institutions" supported by the COST Action European Raptor Biomonitoring Facility (CA16224), which aims to initiate a network of veterinary forensic toxicology laboratories, in order to improve communication among laboratories to prevent wildlife poisoning, especially in raptors. For this purpose, a questionnaire was designed and sent by email to 119 laboratories in Europe. It contained 39 questions on different topics (e.g. laboratory activities, analytical information). A total of 29 responses were received. Most participant laboratories work on veterinary forensic toxicology research and external cases at the same time, which provides a robust overview of the actual situation in the field. Analytical techniques and data collection methods should be harmonised, and communication between laboratories is encouraged to create a more effective network. The present study established contact between laboratories as an initial step to create a European network and compiled basic data to identify strengths and weaknesses that will help harmonise methodologies across Europe and increase pan-European capacities.

Wildlife poisoning: a novel scoring system and review of analytical methods for anticoagulant rodenticide determination

Anticoagulant rodenticides (ARs) are commonly used to control rodent populations and frequently involved in wildlife and domestic animal poisoning. These poisoning cases (especially for ARs) are a challenge for forensic toxicologists, and adequate post-mortem examination and toxicological analyses become essential for a proper diagnosis. Publications describing different analytical methods for AR analysis in biological samples are growing, and a clear compilation of the overall picture is needed to standardize methodologies in future research. This review aims to compile and compare the analytical procedures applied for AR determination in the literature. Using this information, a scoring system was developed for those techniques using liver and blood as matrices, and the techniques were ranked considering different criteria (i.e. sample amount required, recoveries, limits of quantification (LOQs), number of ARs analysed, points of the calibration curve and multi-class methods). This review shows an overview of the main methods used for AR analysis in forensic toxicology and will help to elucidate future directions to improve multi-residue techniques to detect the ARs involved in wildlife lethal poisoning.