Anticoagulant Rodenticides Research Articles

Nest-boxes for raptors as a biological control system of vole pests: High local success with moderate negative consequences for non-target species

Biological control of rodents in agricultural areas, increasing avian predator abundance by nest-box provisioning, has been proposed during the last decades in several regions around the world as an alternative to the widespread use of anticoagulant rodenticides (AR) to protect crops. However these experiences have often lacked a “Before-After-Control-Impact” (BACI) experimental design providing evidence strong enough about their efficacy reducing vole abundance or crop damages. Furthermore, little is known about possible indirect effects on non-target species.Here we test the effectiveness of providing nest-boxes to common kestrels (Falco tinnunculus) and barn owls (Tyto alba) in reducing the abundance of two different vole species using indirect index methods to estimate rodent abundance in late spring (May). We monitored the abundance of both vole species in a treatment (with nest boxes) and control (without nest boxes) areas during three years in alfalfa fields, using a BACI design. We studied also the efficiency of this control method in three different crops (alfalfa, cereal and fruit-trees) during the last year of the experiment. We compare the results obtained in this study area in NE Spain with those obtained simultaneously in other three experimental areas in NW Spain. Finally we explored potential negative effects of this method on the abundance of several passerine birds present in our research area.Our results showed a clear-cut reduction in the abundance of the two vole species, the common vole (Microtus arvalis) and the mediterranean-pine vole (Microtus duodecimcostatus) in the experimental area after applying the treatment (nest box installation) in alfalfa crops. We also found a significant decrease in the presence of both species of voles on fruit-tree plantations and alfalfa crops but we did not find significant effects in the cereal fields, where voles were in general very scarce. These results suggest higher efficacy of biological control in this study area than in some areas of NW Spain, what could be explained by several non-exclusive hypotheses presented in the discussion.For other species, we found a negative effect of nest-boxes on the abundance of a limited number of common bird species, but also positive effects over other species using poles with nest-boxes as perches.In conclusion, under the conditions of our study area, nest-box provisioning seemed to be an effective technique to reduce vole abundance, but also had some undesired side-effects on non-target species. However, these side-effects affected mainly to common bird species and can thus be considered less relevant than those caused by SGARs, often affecting to endangered rodent predators and that could thus have negative effects over any potential future natural control of vole abundance, potentially increasing future needs of SGAR use in a vicious circle.

Toxic time bombs: Frequent detection of anticoagulant rodenticides in urban reptiles at multiple trophic levels

Anticoagulant rodenticides (ARs) are regularly used around the world to control pest mammals. Second-generation anticoagulant rodenticides (SGARs) are highly persistent in biological tissue and have a high potential for bioaccumulation and biomagnification. Consequently, exposure and poisoning of non-target organisms has been frequently documented, especially in countries with unregulated AR sales and usage. Most of this research has focussed on rodent-predators, usually raptors and predatory mammals, although exposure has also been documented in invertebrates and insectivorous fauna. Few studies have explored non-target exposure in reptiles, despite species sharing similar trophic positions and dietary preferences to other exposed fauna. We tested three abundant urban reptile species in Perth, Western Australia that differ in diet and trophic tiers for multiple AR exposure, the dugite Pseudonaja affinis (rodent-predator), the bobtail Tiliqua rugosa (omnivore) and the tiger snake Notechis scutatus occidentalis (frog-predator). We found frequent exposure in all three species (91% in dugites, 60% in bobtails and 45% in tiger snakes). Mean combined liver concentrations of ARs of exposed individuals were 0.178 mg/kg in dugites, 0.040 mg/kg in bobtails and 0.009 mg/kg in tiger snakes. High exposure frequency and liver concentration was expected for the dugite. Exposure in the other species is more surprising and implies widespread AR contamination of the food web. We discuss the likelihood of global AR exposure of urban reptiles, highlight the potential for reptiles to be important vectors of ARs in the food web and highlight implications for humans consuming wild reptiles.

Separation and Quantification of Superwarfarin Rodenticide Diastereomers-Bromadiolone, Difenacoum, Flocoumafen, Brodifacoum, and Difethialone-in Human Plasma.

Superwarfarins, second-generation long-acting anticoagulant rodenticides, are 4-hydroxycoumarin analogues of warfarin that contain a large hydrophobic side chain. These compounds contain two chiral centers and are synthesized for commercial use as two pairs of diastereomer. To support studies of superwarfarin pharmacokinetics and other efforts to improve clinical care for poisoning victims, a quantitative assay was developed for the measurement of diastereomer of bromadiolone, difenacoum, flocoumafen, brodifacoum, and difethialone in human plasma. Based on ultrahigh-pressure liquid chromatography-tandem mass-spectrometry (UHPLC-MS/MS), this method was validated according to U.S. Food and Drug Administration (FDA) guidelines. Sample preparation involved simple protein precipitation followed by reversed phase UHPLC, which resolved all five pairs of cis/trans diastereomer in less than 10 min. Superwarfarins were measured using negative ion electrospray followed by selected-reaction monitoring on a triple quadrupole mass spectrometer. Calibration curves covered 3-4 orders of magnitude with linear regression coefficients of >0.999. The lower limits of quantitation were from 0.013 to 2.41 ng/mL, and intra-day and inter-day accuracy and precision coefficients of variation were <12%. A 10-min UHPLC-MS/MS assay was developed and validated for the separation and quantitative analysis of the pairs of diastereomer of five superwarfarins in human plasma. This method was used to identify and measure superwarfarins and their cis/trans diastereomers in plasma obtained from patients treated for coagulopathy following consumption of contaminated synthetic cannabinoid products.

Intravenous vitamin K1 normalises prothrombin time in 1 hour in dogs with anticoagulant rodenticide toxicosis.

Four dogs with anticoagulant rodenticide toxicosis were treated with intravenous vitamin K1 in lieu of plasma transfusion due to client cost constraints. Two dogs experienced a suspected anaphylactoid reaction, necessitating cessation of the treatment in one dog. Prothrombin time was rechecked 1 h after treatment in the remaining three dogs and all results were within the normal reference range. All four dogs were discharged from hospital within 48 h of presentation. Intravenous vitamin K1 rapidly reverses the coagulopathic state in dogs with anticoagulant rodenticide toxicosis. It is a viable alternative therapy to plasma transfusion if circumstances preclude its use; however, patients must be monitored for anaphylactoid reactions.

Trophic transfer of pesticides: The fine line between predator–prey regulation and pesticide–pest regulation

Abstract Understanding pesticide impacts on populations of target/non‐target species and communities is a challenge to applied ecology. When predators that otherwise regulate pest densities ingest prey contaminated with pesticides, this can suppress predator populations by secondary poisoning. It is, however, unknown how species relationships and protocols of treatments (e.g. anticoagulant rodenticide [AR]) interact to affect pest regulation. To tackle this issue, we modelled a heuristic non‐spatialized system including montane water voles, specialist vole predators (stoats, weasels) and a generalist predator (red fox) which consumes voles, mustelids and other prey. By carrying out a broad‐range sensitivity analysis on poorly known toxicological parameters, we explored the impact of five farmer functional responses (defined by both AR quantity and threshold vole density above which AR spreading is prohibited) on predator–prey interactions, AR transfer across the trophic chain and population effects. Spreading AR to maintain low vole densities suppressed mustelid and fox populations, leading to vole population dynamics being entirely regulated by AR use. Such vole‐suppression treatment regimes inhibited predation ecosystem services and promoted pesticide dependence. Keeping vole density below acceptable bounds by spreading AR while maintaining sufficient voles as prey resources led to less AR being applied and extended periods without AR in the environment, benefiting predators while avoiding episodes with high vole density. This may meet farm production interests while minimizing the impact on mustelid and fox populations and associated ecosystem processes. These alternating phases of mustelids and farmer regulation highlight the consequence of intraguild relationship where mustelids may rescue foxes from poisoning. Both global and wide‐range sensitivity analysis illustrate the tightrope between predator–prey regulation and pesticide–pest regulation. Synthesis and applications. Different pesticide protocols lead to a rich variety of predator–prey dynamics in agro‐ecosystems. Our model reveals the need to maintain refuges with sufficient non‐poisoned voles for sustaining specialist mustelids, to conserve the predator community given the potential of secondary poisoning with rodenticides. We suggest that long periods without pesticide treatment are essential to maintain predator populations, and that practices of pesticides use that attempt to permanently suppress a pest over a large scale are counterproductive.

Sub-lethal exposure to a mammalian pesticide bait alters behaviour in an orthopteran

Pesticides are a crucial tool to control introduced pest species, facilitating restoration of native ecosystems and reducing mortality risk in endemic species. However, non-target species, including many invertebrates, consume pesticides. Although lethal effects on these non-target species are often documented, sub-lethal effects are poorly understood. New Zealand presents a unique case study in this field, with a range of introduced mammalian pest species that threaten a large proportion of endemic fauna. Current research suggests that vertebrate pesticide baits do not cause mortality in invertebrate consumers, but few studies investigate sub-lethal behavioural effects. In this study, we tested whether consumption of a widely dispersed anticoagulant rodenticide, brodifacoum, influenced the expression and repeatability of behaviour in a known consumer of the bait, Wellington tree weta (Hemideina crassidens) over a 40-day treatment period. We compared refuge emergence, activity, refuge-seeking tendencies and defensive responses of brodifacoum-exposed and untreated control weta. Bait-exposed individuals showed increased emergence but decreased activity, boldness and aggression compared to untreated controls. These results show that brodifacoum, although not directly causing mortality, may alter behaviours directly related to foraging, mating, competitive interactions and anti-predator responses, which could be detrimental to fitness and survival. More research should be undertaken to investigate the capacity for H. crassidens to tolerate exposure, and to determine any age- or duration-related responses. These results should also be a catalyst for further research on non-target behavioural effects in other pesticide-exposed insect species.

Diets of European polecat Mustela putorius in Great Britain during fifty\xa0years of population recovery

Following nineteenth-century declines, polecats Mustela putorius are recolonising Great Britain. Polecat diet relates to two potential risks to recovery. First, rabbits Oryctolagus cuniculus, which are important prey for polecats, have experienced extreme population fluctuations, with near extirpation due to myxomatosis in the 1950s, recovery in 1960s–1990s and declines in 1990s–2010s. Second, polecats are secondarily exposed to anticoagulant rodenticides by eating contaminated rodents, and the frequency of polecat exposure to rodenticides is increasing. We analysed stomach contents from 99 polecats collected in 2012–2016 and compared results with earlier studies. Lagomorphs were the most abundant prey (66% frequency of occurrence, 95% confidence interval 53–74%), followed by other mammals (12%, 4–18%), amphibians (10%, 3–16%) and birds (7%, 1–13%). Diet varied seasonally; lagomorph occurrence was highest in spring and summer and lowest in autumn. Dietary niche breadth was greater in the 1960s, when rabbits were scarce, than in other decades, but did not differ between the 1990s and 2010s, indicating that diets have not diversified with recent rabbit declines. This may be because rabbit abundance is not yet low enough to cause dietary diversification or because polecats were collected in areas where rabbits were still abundant. Rodents did not increase in diet between the 1990s and 2010s and still occur with < 10% frequency, indicating that rodents need not contribute much to diet to expose polecats to rodenticides. This potentially limits the effectiveness of management actions designed to minimise polecat exposure to contaminated rodent prey.

Comparative biological properties of the four stereoisomers of difethialone, a second-generation anticoagulant rodenticide, in rats: development of a model allowing to choose the appropriate stereoisomeric ratio.

The current management of rodent pest populations is based on second-generation anticoagulant rodenticides (SGAR). These molecules, of which difethialone is part, are much more efficient than the first generation. Nevertheless, this efficiency comes with a major drawback, SGARs are tissue persistent that increases the exposure of rodent predators to them. According to its chemical structure, difethialone has four stereoisomers, whose specific inhibition potency and pharmacokinetic have never been described and might be useful to design new eco-friendly rodenticides. The study aimed to investigate the ability to inhibit anticoagulant target enzyme (VKORC1) and the pharmacokinetics in rats of the four difethialone stereoisomers in rats. We show that stereoisomers are all highly efficient to inhibit VKORC1 activity, but they have distinct initial half-life with 6.0h, 25.4h, 69.3h, and 82.3h for, respectively, E4-trans, E2-cis, E1-trans, and E3-cis stereoisomer. These results open the way of the development of eco-friendly and efficient rodenticide by mixing some of these stereoisomers. Preferential incorporation of the E4-trans stereoisomer (high inhibitory VKORC1 potency, relatively shorter liver half-life) into difethialone rodenticides baits might result in a more eco-friendly product than current commercially available difethialone formulations. In addition, we put forward modelling to help design bait according to the circumstance of use (presence of non-target species, food competition, etc.) by modulating the theorical AUC and and the theorical concentration of the product at the death of the rodent pest. Thus, this modeling might allow to diminish the use of laboratory animal in assay.

Vitamin K antagonist rodenticides display different teratogenic activity

Vitamin K antagonists (VKA) are not recommended during pregnancy because warfarin (a first-generation VKA) is associated with a malformation syndrome “the fetal warfarin syndrome” (FWS). VKA are also used for rodent management worldwide. Recently, the Committee for Risk Assessment responsible for the European chemical legislation for advances on the safe use of chemicals had classed 8 anticoagulant used as rodenticides in the reprotoxic category 1A or 1B. This classification emerges from a read-across prediction of toxicity considering the warfarin malformation syndrome. Herein, our study explores the teratogenicity of warfarin at the human therapeutic dose and that of bromadiolone, a second-generation anticoagulant rodenticide. Using a rat model, our study demonstrates that warfarin used at the therapeutic dose is able to induce teratogenicity, while in the same conditions bromadiolone does not induce any teratogenic effect, challenging the classification of all VKA as reprotoxic molecules.

Acute toxicity and clotting times of anticoagulant rodenticides to red-toothed (Odonus niger) and black (Melichthys niger) triggerfish, fathead minnow (Pimephales promelas), and largemouth bass (Micropterus salmoides).

Anticoagulant rodenticides (ARs) are used in rat eradication efforts on island wildlife refuges. AR bait pellets can get into coral reef areas during broadcasting and lead to exposure of non-target organisms, such as marine fishes. The objective of this study was to determine the sensitivity of representative saltwater fishes, Red-toothed triggerfish (Odonus niger) and Black triggerfish (Melichthys niger), and common freshwater fishes, fathead minnow (Pimephales promelas), and largemouth bass (Micropterus salmoides) to first generation ARs, diphacinone (DPN) and chlorophacinone (CPN), as well as a second-generation AR, brodifacoum (BROD). Acute toxicity of ARs was evaluated by single dose, intraperitoneal injections. The median lethal dose (LD50) ranges were 137−175 μg DPN/g, 155−182 μg CPN/g, and 36−48 μg BROD/g for Red-toothed triggerfish and 90−122 μg DPN/g, 125−164 μg CPN/g, and 50−75 μg BROD/g for black triggerfish. Laboratory surrogate test fish species fathead minnow and largemouth bass were of similar sensitivity toward AR-induced toxicity compared to triggerfish based on LD50 values. Sublethal effects on elevated clotting time occurred in dose-dependent fashion in all fish tested. Fish appear to have low sensitivity to AR chemicals as compared to other taxa, in particular mammals and birds, based on across-taxa comparisons of species sensitivity distributions of whole body, single dose acute lethality (LD50 values). The sensitivity of fish to waterborne exposures of ARs has yet to be fully evaluated and indeed may prove more hazardous to fish.

Brodifacoum Toxicity in American Kestrels (Falco sparverius) with Evidence of Increased Hazard on Subsequent Anticoagulant Rodenticide Exposure.

A seminal question in ecotoxicology is the extent to which contaminant exposure evokes prolonged effects on physiological function and fitness. A series of studies were undertaken with American kestrels ingesting environmentally realistic concentrations of the second-generation anticoagulant rodenticide (SGAR) brodifacoum. Kestrels fed brodifacoum at 0.3, 1.0, or 3.0 µg/g diet wet weight for 7 d exhibited dose-dependent hemorrhage, histopathological lesions, and coagulopathy (prolonged prothrombin and Russell's viper venom times). Following termination of a 7-d exposure to 0.5 µg brodifacoum/g diet, prolonged blood clotting time returned to baseline values within 1 wk, but brodifacoum residues in liver and kidney persisted during the 28-d recovery period (terminal half-life estimates >50 d). To examine the hazard of sequential anticoagulant rodenticide (AR) exposure, kestrels were exposed to either the first-generation AR chlorophacinone (1.5 µg/g diet) or the SGAR brodifacoum (0.5 µg/g diet) for 7 d and, following a recovery period, challenged with a low dose of chlorophacinone (0.75 µg/g diet) for 7 d. In brodifacoum-exposed kestrels, the challenge exposure clearly prolonged prothrombin time compared to naive controls and kestrels previously exposed to chlorophacinone. These data provide evidence that the SGAR brodifacoum may have prolonged effects that increase the toxicity of subsequent AR exposure. Because free-ranging predatory and scavenging wildlife are often repeatedly exposed to ARs, such protracted toxicological effects need to be considered in hazard and risk assessments. Environ Toxicol Chem 2020;39:468-481. © 2020 SETAC.

Interaction of Pindone and its Tautomers with Calcium Dication – A DFT Study

Calcium dication has an important role at various stages of blood coagulation mechanism. On the other hand, pindone is an important anticoagulant rodenticide which undergoes 1,3-type proton tautomerism to yield two enolic isomers of pindone. Although, the anticoagulant mode of action of pindone is attributed to blocking of a liver enzyme responsible for the recycling of vitamin K, nothing is known about whether the interaction of it with calcium dication has some role as well. In the present study, the interactions of pindone and its tautomers with Ca++ have been investigated within the restrictions of density functional theory at the level of B3LYP/6-311++G(d,p). It has been found that Ca++ highly affects pindone and its tautomers in many respects at the molecular level, hence their anticoagulation effect should vary.

Effects of brodifacoum and diphacinone exposure on four species of reptiles: tissue residue levels and survivorship.

Anticoagulant rodenticides are used worldwide to control pest rodent species. However, the risks posed to non-target reptiles have not been well characterized. In this study, 46 giant ameivas (Ameiva ameiva), 39 boa constrictors (Boa constrictor), 33 wood turtles (Rhinoclemmys pulcherrima), and 47 green iguanas (Iguana iguana) were orally dosed with one of two levels of either diphacinone or brodifacoum anticoagulant in propylene glycol solutions. Dosages were derived using daily food intake (DFI) equations, converting DFI to an equivalent anticoagulant bait amount and gavaging the solution volume needed to deliver the quantity of anticoagulant in that amount of bait. Animals were dosed on days 0 and 7 and monitored for a further 7 days for signs of anticoagulant intoxication and differences in behaviors and postures. At necropsy on day 14, animals were examined for thoracic and abdominal bleeding, and both tissue and organ samples were taken for histology. Liver and whole-body anticoagulant residues were assessed. No turtles or boas died due to anticoagulant exposure. However, anticoagulant intoxication was suspected in one iguana dosed with brodifacoum. A few treated ameivas died but exhibited no hemorrhaging. Liver residue levels were higher than whole-body remainder residue levels for all species. Unlike the other species, turtles had higher diphacinone residue levels than brodifacoum. Turtles and boas exhibited a relative insensitivity to diphacinone and brodifacoum, while the lizards appeared to be somewhat more sensitive to these compounds. This study provides data for future assessments of the risks to these species associated with anticoagulant use. Published 2019. This article is a U.S. Government work and is in the public domain in the USA.

Enantiomeric fraction evaluation of the four stereoisomers of difethialone in biological matrices of rat by two enantioselective liquid chromatography tandem mass spectrometry methods: Chiral stationary phase or derivatization

The need for the control of rodent populations with anticoagulant rodenticides remains actual, and enantioselective analytical methods are mandatory to understand ecotoxicity issues of those chiral pesticides. This study presents two enantioselective methods to achieve the residue levels and differentiated persistence of the four stereoisomers of difethialone (called in this work E1-trans, E2-cis, E3-cis and E4-trans), which is one of the most toxic second generation anticoagulant rodenticide. Their enantiomeric fraction evaluation in biological matrices of rats was determined by two LC-MS/MS methods. The first one (chiral-LC-MS/MS) combined a chiral column employed in reversed-phase mode (with acetonitrile-water mobile phase) to be compatible with mass spectrometry detection. The second one was also a LC-MS/MS method but with a reversed phase column after a derivatization step with (1S)-(−)-camphanic chloride. Extraction process combined Solid-Liquid extraction and sorbent cartridges. The methods were fully validated. The chiral column was chosen as a reference method for our laboratory because it was quicker and cheaper, and enantioresolution and sensitivity were better. This chiral-LC-MS/MS method was used to measure the enantiomeric fraction of the four stereoisomers of difethialone in rodent biological matrices (liver, plasma, blood and feces) of female rats treated with 3.5 mg/kg of difethialone. The results showed that metabolism is not the same for all the stereoisomers: cis-E3-difethialone was the most persistent, and E4-trans-difethialone was the most quickly eliminated.This chiral-LC-MS/MS method will be used to study the pharmacokinetics of the four stereoisomers of difethialone, and for ecotoxicological surveillance to evaluate the specific persistence of each stereoisomer of difethialone in case of secondary exposure of wildlife non-target species.

Investigation of the distribution of anticoagulant rodenticide residues in red fox (Vulpes vulpes) livers to ensure optimum sampling protocol

Abstract The lobular distribution of 9 different anticoagulant rodenticide (AR) residues in the liver of a sentinel predator/scavenger i.e. the red fox (Vulpes vulpes) was determined following multi-residue analysis using Ultra (High) Performance Liquid Chromatography tandem Mass Spectrometry (UHPLC-MS/MS). The aim of the study was to address concerns that if distribution of AR residues in the liver was significantly heterogeneous, analysis of random sub-samples or finite remnants of liver could result in false negatives or lead to incorrect toxicological diagnoses. Intact livers excised from animals shot as part of routine legal pest control activities in Scotland during 2018 and 2019 were sub-sectioned and the lobular concentration of AR residues was investigated. Analysis of individual lobes from 10 different fox livers revealed that AR residues initially detected in a randomly selected small portion of liver tissue were present throughout the liver. Also, in cases where AR residues were not found in the initial randomly selected portion, they were not found in the subsequent more detailed examination. The limit of quantitation was 3 μg kg‐1 and AR residue concentrations ranged from 3 to 885 μg kg−1. Statistical analysis of variance (ANOVA) was performed on the eight and six out of ten livers that tested positive for bromadiolone and brodifacoum, respectively. No statistical evidence was found of differences in mean residue levels of bromadiolone throughout the liver i.e. within and between liver lobes. However, brodifacoum showed a statistically significant difference (p

Types of pesticides involved in domestic and wild animal poisoning in Italy

Data obtained from samples of poisoned domestic and wild animals sent for toxicological evaluation during the period between 2005 and 2014 have been analyzed. Among the 4606 tested samples, the majority of which were collected in the northern regions of Italy, 2006 (43.55%) were found positive for pesticides. Analytical detections were performed via solvent extraction followed by separation and chromatographic characterization and all the methods applied for the toxicological investigations were developed by IZSLER.Insecticides, mainly represented by acetylcholinesterase inhibitors (carbamates 17.55%, n = 352; organophosphates 15.15%, n = 304) and organochlorines (29.21%, n = 586), were found to be the first category of pesticides involved in intoxications, in both domestic and in wild animals, followed by rodenticides (anticoagulant rodenticides 21.09%, n = 423; zinc phosphide 2.59%, n = 52; chloralose 0.95%, n = 19 and thallium 0.15%, n = 3) and molluscicides (metaldehyde 6.63%, n = 133). Second and third generation anticoagulants (bromadiolone and brodifacoum) were the most represented (10.52%, n = 211) but also first generation compounds (i.e. coumatetralyl and warfarin) were still found responsible of intoxications. Even if some pesticides are frequently involved in domestic animal poisoning (i.e. metaldehyde and strychnine), they did not show the same diffusion in wild animals. In particular, unlike domestic species, cyanide and pyrethroids have not been found responsible of intoxications in wild animals.Interestingly, a great number of positive samples involved banned pesticides like α- (14.41%, n = 289) and β- (14.16%, n = 284) endosulfan, carbofuran (5.73%, n = 115), methamidophos (9.47%, n = 190), strychnine (6.23%, n = 125) but, on the other hand, many positives were due to the exposure to commercially available products (i.e. metaldehyde and anticoagulant rodenticides). Thus, together with measures aimed to reduce illegal uses, educational campaigns and a wider range of compounds to detect would be beneficial in order to address the issue of animal poisoning, which besides has also repercussions on environmental and public health.

An outbreak of severe coagulopathy from synthetic cannabinoids tainted with Long-Acting anticoagulant rodenticides

Objective: To describe a large regional poison center’s experience managing an outbreak of long-acting anticoagulant rodenticide (LAAR) poisoning associated with synthetic cannabinoid (SC) use.Methods: This is a retrospective review of exposures reported to the Illinois Poison Center between March 10 and August 1, 2018. All cases coded as exposure to Δ9-tetrahydrocannabinol homologs were identified. Patients with suspected SC use, positive LAAR testing, and coagulopathy (signs or symptoms of bleeding or international normalized ratio [INR] > 2) were included. If confirmatory LAAR testing was performed and resulted as negative, the patient was excluded from this analysis. In the absence of LAAR testing, patients with suspected SC use, an INR >2, and no alternative explanation of coagulopathy were included. Suspected SC use was defined as use suspected by a member of the treating team or reported by the patient. Presenting signs and symptoms, laboratory findings, management, healthcare utilization, outcomes, and disposition of patients affected by this outbreak were reported.Results: One hundred seventy-eight cases met inclusion criteria. Most patients were male (73%) and young to middle-aged (median age 32, IQR 25–40). Most presented to hospitals in Peoria (35%) and Cook (31%) counties. Median hospitalization was three days (IQR 2–4). Eighty-eight percent of patients presented with an INR >10. Eighteen cases had qualitative anticoagulant testing, all of which were positive for brodifacoum. Other identified LAARs included difenacoum (10/18) and bromadiolone (1/18). Sixty-three percent of patients had back, flank or abdominal pain; 70% of patients presented with hematuria. One hundred six cases received IV vitamin K1; no adverse or anaphylactoid reactions were reported. Forty-one (22%) patients left AMA. Thirty-eight patients (21%) were re-hospitalized during the study period. Patients leaving AMA were 1.6 times more likely to be re-hospitalized than patients with other dispositions. Intracranial hemorrhage, present in 3% of total cases, was present in 4 of 5 fatalities.Conclusions: We describe an outbreak of multiple LAARs contaminating SCs. Patients presented with bleeding from varied sites, often required blood products, factor replacement, and high dose vitamin K1 for stabilization.

Effects of vitamin K1 treatment on plasma concentrations of long-acting anticoagulant rodenticide enantiomers following inhalation of contaminated synthetic cannabinoids

Background: An outbreak of synthetic cannabinoid (SC)-associated coagulopathy and bleeding in Illinois, USA was determined to be due to inhalation of SC contaminated with brodifacoum (BDF), difenacoum (DiF), and bromadiolone (BDL), highly potent long-acting anticoagulant rodenticides (LAARs). Treatment with high-dose vitamin K1 (VK1) prevented mortality; however, plasma LAAR levels were not measured risking recurrence of coagulopathy and bleeding due to premature discontinuation. The goal of this study was to determine if plasma LAAR levels were reduced following standard of care treatment to normalize coagulopathy.Methods: Blood samples were collected from a cohort of 32 patients, and ultra-high performance liquid chromatography-tandem mass spectrometry (UHPLC-MS/MS) analysis used to quantify plasma LAAR levels including enantiomers.Results: BDF was detected in 31 samples; 30 also contained DiF and 18 contained BDL. Initial plasma levels were 581 ± 87, 11.0 ± 1.9, and 14.9 ± 5.9 ng/mL for BDF, DiF, and BDL, respectively (mean ± SE). At discharge plasma, BDF levels remained elevated at 453 ± 68 ng/mL. Plasma half-lives for BDF, DiF, and BDL were 7.5 ± 1.3, 7.2 ± 1.9, and 1.8 ± 0.3 days, respectively. The half-life for trans-BDF enantiomers (5.7 ± 0.8 days) was shorter than for cis-enantiomers (7.6 ± 1.9 days). BDF half-lives were shorter, and coagulopathy normalized faster in patients receiving intravenous VK1 as compared to oral VK1. Patients prescribed VK1 at discharge had fewer re-admittances.Conclusions: These results demonstrate that plasma LAAR levels at discharge were elevated in poisoned patients despite normal coagulation, and that the route of VK1 administration affected LAAR pharmacokinetics and INR normalization. We propose plasma LAAR levels and coagulation be monitored concomitantly during follow-up of patients with LAAR poisoning.KEY POINTSIn patients treated with high-dose vitamin K1 for LAAR poisoning, plasma levels remained 40-fold above safe levels upon discharge from hospital.LAAR half-lives, normalization of coagulopathy, and readmittances were reduced by treatment with intravenous vitamin K1.

Examining Sublethal Effects of Anticoagulant Rodenticides on Haemosporidian Parasitemia and Body Condition in Migratory Red-Tailed Hawks

Anticoagulant rodenticides (ARs) are a source of mortality to nontarget wildlife, including raptors. Raptors that consume a large quantity of rodents, such as Red-tailed Hawks (Buteo jamaicensis), are especially at risk of secondary exposure due to bioaccumulation and biomagnification of ARs. However, few studies have focused on the sublethal effects of ARs and how they can lead to potentially lethal outcomes. We investigated the effects of ARs on both parasitemia and body condition in juvenile Red-tailed Hawks from the Marin Headlands—the site of a migratory bottleneck for raptors on the west coast of the United States—north of San Francisco, California. We investigated the presence of several ARs in the plasma of 116 Red-tailed Hawks. We used the ratio of heterophils to lymphocytes (H/L ratio), levels of haemosporidian parasitemia, and polychromatic erythrocytes in blood smears as indices of body condition. Based on studies of other carnivores, we predicted higher levels of parasitemia and increased H/L ratios in raptors with ARs in their blood serum, but we found no significant difference in parasitemia or H/L ratio between raptors with and raptors without ARs in their blood. In contrast, individuals exposed to ARs had increased levels of polychromasia, or immature red blood cells, possibly as a result of AR exposure, though levels of polychromasia were within the typical range. Because ARs in blood have a short half-life, we do not know each individual's exposure history, which may play a role in subsequent parasitemia. Future studies should focus on individuals with known exposure history or obtain a longer temporal resolution using liver samples.

Anticoagulant Rodenticides, Islands and Animal Welfare Accountancy.

Simple SummaryAnticoagulant rodenticides are a mainstay of rodent management in many domestic, municipal, agricultural, and conservation settings. Anticoagulant poisoning has poor welfare outcomes for mammals and birds and, worldwide, this means potentially very large numbers of animals are poisoned annually consequent (intended or not) to rodenticide use. Critical differences in use patterns of anticoagulants applied for ongoing rodent control, versus application for rodent eradication especially on islands, have clear implications for animal welfare costs measured as cumulative number of animals affected over time. Here we outline these differences and discuss how animal welfare considerations can be weighed in decisions to use anticoagulant rodenticides for island eradication attempts.Anticoagulant rodenticides are used to manage rodents in domestic, municipal, agricultural, and conservation settings. In mammals and birds, anticoagulant poisoning causes extensive hemorrhagic disruption, with the primary cause of death being severe internal bleeding occurring over days. The combined severity and duration of these effects represent poor welfare outcomes for poisoned animals. Noting a lack of formal estimates of numbers of rodents and nontarget animals killed by anticoagulant poisoning, the ready availability and worldwide use of anticoagulants suggest that very large numbers of animals are affected globally. Scrutiny of this rodent control method from scientific, public, and regulatory perspectives is being driven largely by mounting evidence of environmental transfer of residual anticoagulants resulting in harmful exposure in wild or domestic animals, but there is also nascent concern for the welfare of targeted rodents. Rodent control incurs a cumulative ledger of animal welfare costs over time as target populations reduced by poisoning eventually recover to an extent requiring another reduction. This ‘rolling toll’ presents a critical contrast to the animal welfare accountancy ledger for eradication scenarios, where rodent populations can be completely removed by methods including anticoagulant use and then kept from coming back (e.g., on islands). Successful eradications remove any future need to control rodents and to incur the associated animal welfare costs.