Biomarkers Potency to Monitor Non-target Fauna Poisoning by Anticoagulant Rodenticides

Abstract

The widespread use of pesticides to control agricultural pests is a hot topic on the public scene of environmental health. Selective pest control for minimum environmental impact is a major goal of the environmental toxicology field, notably to avoid unintended poisoning in different organisms. Anticoagulant rodenticides cause abnormal blood coagulation process; they have been widely used to control rodents, allowing inadvertent primary and secondary exposure in domestic animals and non-target predatory wildlife species through direct ingestion of rodenticide-containing bait or by consumption of poisoned prey. To report toxic effect, the most common approach is the measurement of liver or plasma residues of anticoagulant rodenticides in dead or intoxicated animals showing clinical symptoms. However, one major challenge is that literature currently lacks a hepatic or plasma concentration threshold value for the differentiation of exposure from toxicity. Regarding the variation in pharmacology properties of anticoagulant rodenticides inter- and intra-species, the dose-response relationship must be defined for each species to prejudge the relative risk of poisoning. Beyond that, biomarkers are a key solution widely used for ecological risk assessment of contaminants. Since anticoagulant rodenticides (AR) have toxic effects at the biochemical level, biomarkers can serve as indicators of toxic exposure. In this sense, toxicological knowledge of anticoagulant rodenticides within organisms is an important tool for defining sensitive, specific, and suitable biomarkers. In this review, we provide an overview of the toxicodynamic and toxicokinetic parameters of anticoagulant rodenticides in different animal species. We examine different types of biomarkers used to characterize and differentiate the exposure and toxic effects of anticoagulant rodenticide, showing the strengths and weaknesses of the assays. Finally, we describe possible new biomarkers and highlight their capabilities.

White-Tailed Eagles’ (Haliaeetus albicilla) Exposure to Anticoagulant Rodenticides and Causes of Poisoning in Poland (2018–2020)

“…The obtained results represent the first report about white-tailed eagles' (Haliaeetus albicilla) exposure to AR in Poland. If we take into consideration different species of birds of prey, the situation is similar to other countries, concluding that the main hazards from AR are SGARs, including bromadiolone and brodifacoum [1,8,11,15,18,34]. In Finland, in addition to the SGARs, coumatetralyl (the only FGAR) was detected in 48% of the samples tested; however, its measured concentrations were low, linked to its short elimination half-life and high concentration in available products [11].…”

“…Widespread deratization influences rodent behavior, making them easy prey for predators [12], whose primary task in ecosystems is to eliminate weak and sick individuals. By looking from the other side, we should assess the not-thoroughly-investigated impact of AR on the health and behavior of birds of prey [34]. However, some areas of AR impact are challenging to define.…”

“…However, some areas of AR impact are challenging to define. It is difficult to determine the long-term effects on health from exposure to even low concentrations of AR over time [34]. Even a relatively small increase in blood vessel permeability can result in bruises at a much higher rate than normal.…”

Comparative pharmacokinetics of difethialone stereoisomers in male and female rats and mice: development of an intra- and inter-species model to predict the suitable formulation mix

“…This might seem to be a disadvantage, but it could also be a sign of the selectivity that this stereoisomer would allow. Indeed, if this mouse specificity is shared with other small mammals that are often victims of primary intoxication to ARs 11,28 , this would provide the way to the creation of ARs effective on rats but with limited primary and secondary ecotoxicity on non-target fauna. Further investigations on non-target species should be implemented to explore this In conclusion, and despite the biases of our study, we highlight that studies on anticoagulants must necessarily integrate research on the effect of gender and species both on efficacy (which is already done in regulatory tests), but also with regard to the ecotoxicity of these molecules.…”

“…In addition, intoxication of non-target animals is the most serious drawback of SGARs. Indeed, direct access of domestic or wild animals to the poisoned bait or repeated consumption of poisoned rodents by some predators and scavengers lead to fatal poisonings [9][10][11] . Although ingestion of intoxicated rodents does not lead systematically to the death of the animal, many predators and scavengers have been shown to be chronically exposed to SGARs due to the long tissue-persistence of these molecules and the consequences of this exposure on populations are not fully understood 12,13 .…”