Anticoagulant Rodenticides in Red-Tailed Hawks (Buteo jamaicensis) from New York City, New York, USA, 2012-18.

Anticoagulant rodenticides (AR), principally difethialone, brodifacoum, and bromadiolone, were detected in the livers of 89% of 72 Red-tailed Hawks (Buteo jamaicensis) from New York City, New York, US examined for cause of death over a 7-yr period (January 2012-December 2018). Fatal hemorrhage likely attributable to AR exposure was diagnosed in 41% (30/74) of cases, and 46% (18/39) of the cases analyzed with no gross evidence of AR-mediated hemorrhage had liver concentrations of AR that overlapped those with an AR-poisoning diagnosis. Although urban areas like New York City can support surprisingly dense populations of Red-tailed Hawks, the threat posed by extensive use of AR can be large.

Chiral liquid chromatography-tandem mass spectrometry analysis of superwarfarin rodenticide stereoisomers - Bromadiolone, difenacoum and brodifacoum - In human plasma.

Superwarfarins are second-generation long-acting anticoagulant rodenticides that can cause unintended human and wildlife toxicity due, in part, to their prolonged half-lives. Commercially available superwarfarin rodenticides are synthesized as racemates with two asymmetric carbons, producing four stereoisomers. To support studies of human plasma half-lives of individual superwarfarin stereoisomers, a method was developed based on LC-MS/MS to separate and quantify stereoisomers of the commercially important superwarfarins bromadiolone, difenacoum and brodifacoum. Human plasma samples were prepared using protein precipitation and centrifugation. Chiral-phase HPLC separation was carried out on-line with tandem mass spectrometric quantitative analysis of the eluting stereoisomers using selected-reaction monitoring with positive ion electrospray on a triple quadrupole mass spectrometer. All four stereoisomers of each superwarfarin were resolved within 12.5 min with calibration curves spanning 2-3 orders of magnitude and lower limits of quantitation between 0.87 and 2.55 ng/mL. This method was used to determine the half-lives of superwarfarin stereoisomers in plasma from patients who had inhaled synthetic cannabinoid products contaminated with superwarfarins. These data may be used to guide the development of safer next generation anticoagulant rodenticides stereoisomers.

Sudden nasal bleeding and brodifacoum: A case of accidental exposure or attempted homicide?

A 50-year-old man was admitted to the emergency department with abrupt massive epistaxis. An accurate anamnesis and physical evaluation could not reveal any other anomalies, while coagulation tests showed potentially life threatening prolonged prothrombin time, with activated partial thromboplastin and thrombin time, with fibrinogen and antithrombin III within limits. Despite the prompt pharmacological and compressive local treatment, bleeding continued and the patient was therefore hospitalized. Highly specific coagulation and toxicological testing-among others high-performance liquid chromatography assessment on plasma-were performed, leading to the unexpected identification of brodifacoum. Police and criminal justice authorities revealed the source of exposure to brodifacoum after several months of investigation, residing in his everyday life. Brodifacoum is a long-lasting anticoagulant, acting as a vitamin K antagonist, and belongs to the family of superwarfarins. Brodifacoum use is authorized as rodenticide in many countries worldwide, but has been reported as cause of severe coagulopathies in humans, both intentional or involuntary, even consumed as a contaminant of herbal drugs, such as cannabis. The original contribution of this case to the knowledges of human brodifacoum intoxication resides in the multidisciplinary approach and the collaborative interplay of clinical and toxicology experts as well as judicial authorities.

Determination of anticoagulant rodenticides in faeces of exposed dogs and in a healthy dog population.

BACKGROUND: Exposure to anticoagulant rodenticides (ARs) in dogs is among the most common causes of poisoning in small animal practice, but information about toxicokinetic of these rodenticides in dogs is lacking. We analysed blood and faeces from five accidentally exposed dogs and 110 healthy dogs by reversed phase ultra-high performance liquid chromatography-tandem mass spectrometry. The aim of the study was to estimate elimination of brodifacoum, bromadiolone and difenacoum after acute exposure, calculate the half-lives of these rodenticides in dogs, estimate faecal elimination in a litter of puppies born, and further to identify the extent of AR exposure in a healthy dog population. RESULTS: Three dogs were included after single ingestions of brodifacoum; two dogs ingested bromadiolone and one dog ingested difenacoum. Maximum concentrations in faeces were found after day 2-3 for all ARs. The distribution half-lives were 1-10 days for brodifacoum, 1-2 days for bromadiolone and 10 days for difenacoum. Brodifacoum and difenacoum had estimated terminal half-lives of 200-330 days and 190 days, respectively. In contrast, bromadiolone had an estimated terminal half-life of 30 days. No clinical signs of poisoning or coagulopathy were observed in terminal elimination period. In blood, the terminal half-life of brodifacoum was estimated to 8 days. Faeces from a litter of puppies born from one of the poisoned dogs were examined, and measurable concentrations of brodifacoum were detected in all samples for at least 28 days after parturition. A cross-sectional study of 110 healthy domestic dogs was performed to estimate ARs exposure in a dog population. Difenacoum was detected in faeces of one dog. Blood and faecal samples from the remaining dogs were negative for all ARs. CONCLUSIONS: Based on the limited pharmacokinetic data from these dogs, our results suggest that ARs have a biphasic elimination in faeces using a two-compartment elimination kinetics model. We have shown that faecal analysis is suitable and reliable for the assessment of ARs exposure in dogs and a tool for estimating the AR half-lives. Half-lives of ARs could be a valuable indicator in the exposed dogs and provides important information for veterinarians monitoring AR exposure and assessment of treatment length in dogs.

Plasma fluoroacetic acid concentrations: Symptoms, hematological, and biochemical characteristics in patients with fluoroacetic acid poisoning in the emergency department.

Fluoroacetic acid (FAcOH) was once a highly toxic rodenticide widely used in the world. In the past, studies on the toxicity of FAcOH have focused on animal experiments. The toxicity of FAcOH to humans and the changes of FAcOH in plasma have not been studied. Therefore, the present study aimed to describe the changes of plasma FAcOH concentrations, hematological, and biochemical characteristics in patients with FAcOH intoxication. According to clinical symptoms, 68 patients from the emergency department were divided into different groups: convulsion group, unconsciousness group, death group, and control groups. Plasma FAcOH concentrations, hematological, and biochemical parameters were investigated. Results demonstrated that patients in the convulsion group and the unconsciousness group had a significant increase (p < 0.01) in the level of neuron-specific enolase (NSE), creatine kinase MB (CKMB), glucose (GLU), and white blood cell count (WBC) and a significant decrease (p < 0.01) in serum potassium compared with the control group, respectively. Moreover, patients in the death group had a significant increase (p < 0.01) in the level of NSE, CKMB, N-terminal pro-brain natriuretic peptide, GLU, and WBC and a significant decrease (p < 0.01) in serum potassium and total calcium compared with the survival group. The concentrations of FAcOH in plasma in the convulsion group, the unconsciousness group, and the death group were 72.31 ± 42.29, 118.33 ± 55.41, and 163.78 ± 43.32 µg/mL, respectively. These changes and the plasma FAcOH concentrations may increase our understanding of the toxicity of FAcOH to humans and may help doctors to judge the clinical prognosis of patients with FAcOH intoxication.

Continued Anticoagulant Rodenticide Exposure of Red-tailed Hawks (Buteo jamaicensis) in the Northeastern United States with an Evaluation of Serum for Biomonitoring.

Prior studies (2006-2016) in birds of prey admitted to a wildlife clinic in Massachusetts, USA, revealed widespread exposure to second-generation anticoagulant rodenticides (SGARs) among red-tailed hawks (Buteo jamaicensis, RTHAs). Continued monitoring of species for which historic data are available can reveal trends in exposure that aid in evaluating the effectiveness of risk-mitigation measures. While the majority of exposure-monitoring studies utilize liver tissue collected postmortem, antemortem modalities, such as serum analysis, may be desirable for risk assessments in certain populations. However, the sensitivity of serum for detecting anticoagulant rodenticides (ARs) is not well studied. Paired liver and serum samples from 43 RTHAs were evaluated from 2017 to 2019. In liver tissue, 100% of birds were positive for ARs, with the SGARs brodifacoum, bromadiolone, and difethialone identified most frequently; 91% of birds had liver residues of 2 to 4 ARs. These findings represent the highest exposure both to ARs overall and to multiple ARs in RTHAs compared to previous studies. All birds diagnosed with AR toxicosis (n = 14) were positive for ARs in serum; however, all subclinically exposed birds (n = 29) were negative in serum. These data show that exposure to SGARs remains widespread in RTHAs in this geographic area. In addition, although serum analysis is not sensitive for detecting sublethal exposures in RTHAs, it can potentially support a diagnosis of AR toxicosis in conjunction with other consistent signs. Environ Toxicol Chem 2020;39:2325-2335. © 2020 SETAC.

Production of a specific monoclonal antibody and a sensitive immunoassay for the detection of diphacinone in biological samples.

Diphacinone (DPN) is an extensively used anticoagulant rodenticide that is also considered a hazardous chemical, which poses a threat to nontarget species. DPN poisoning cases in humans or other species frequently occur, while rapid and sensitive detection methods are rarely reported. Thus, it is meaningful to develop an immunoassay for DPN detection with high sensitivity and specificity. In this study, a hapten was synthesized and then conjugated with carrier proteins to prepare the immunogens with different conjugation ratios for the preparation of antibody. After evaluation of the antisera using an indirect competitive enzyme-linked immunosorbent assay (icELISA) and statistical analysis, we found that the immunogen prepared using the N,N-dicyclohexylcarbodiimide (DCC) method with a conjugation ratio of 28.5 could elicit mice to generate antibodies with high performance. Using hybridoma technology, we obtained the specific monoclonal antibody (mAb) 4G5 with a half maximal inhibitory concentration (IC50) of 0.82 ng/mL in buffer solution. We initially explored the recognition mechanism of DPN/CLDPN and mAb from both conformational and electronic aspects. Then, mAb 4G5 was applied to develop icELISA for biological samples. The limits of detection (LODs) of icELISA were 0.28 µg/L, 0.32 µg/L, and 0.55 µg/kg for swine plasma, urine, and liver samples, respectively, and the recoveries ranged from 72.3 to 103.3% with a coefficient of variation (CV) of less than 12.3% in spiked samples. In summary, we developed a sensitive, specific, and accurate icELISA for the detection of DPN in biological samples, which showed potential in food safety analysis and clinical diagnosis. Graphical abstract.

Widespread anticoagulant poison exposure in predators in a rapidly growing South African city.

Anticoagulant rodenticides (ARs) are used worldwide to control rodent populations. ARs bioaccumulate across trophic levels and threaten non-target wildlife. We investigated the prevalence of AR exposure in seven predator species in the rapidly developing Greater Cape Town region of South Africa - a mosaic of natural, urban, and agricultural areas within a global biodiversity hotspot. We focused sampling on caracals (Caracal caracal, n = 28) as part of a larger caracal ecology study, but also opportunistically sampled Cape Clawless otters (Aonyx capensis, n = 9), large-spotted genets (Genetta tigrina, n = 4), honey badger (Mellivora capensis, n = 1), water mongoose (Atilax paludinosus, n = 1), small gray mongoose (Galerella pulverulenta, n = 1), and Cape Eagle owl (Bubo capensis, n = 1). We tested livers from all species, and blood from ten caracals, for eight AR compounds to assess prevalence and amount of exposure for each compound. We used generalized linear models to test spatial, demographic, and seasonal risk factors for ten measures of AR exposure in caracals. We detected at least one of the four most toxic AR compounds in six species. Exposure was high for caracals (92%) and all species combined (81%). For caracals, proximity to vineyards was the most important AR exposure risk factor. Vineyards in Cape Town do not use ARs to protect their vines but do host commercial hospitality structures where ARs are used. Vineyards may thus link caracals that forage within vineyards to the rat poisons used in and around their commercial structures. Residue levels were unexpected in large-spotted genets and Cape Clawless otters, suggesting invertebrate vectors. ARs may present a cryptic threat to populations already vulnerable to increasing habitat loss, vehicle collisions, poachers and fire. Targeted mitigation should include a mix of environmentally responsible policies that reduce AR use, particularly in areas near wildlife habitat.

Changes in Detected Anticoagulant Rodenticide Exposure in Barn Owls ( Tyto alba) in Kentucky, USA, in 2012-16.

Anticoagulant rodenticides (ARs) are widely used across North America to control rodent infestations but may cause direct mortality or nonlethal effects when secondarily consumed by raptors. Barn Owls ( Tyto alba) are at high risk for secondary consumption because they specialize in rodent prey and often live in human-made structures. We investigated the exposure of Barn Owls in Kentucky, US, to ARs and to dicoumarol, an anticoagulant compound naturally found in certain moldy forages. We tested the liver tissue of 48 Barn Owl carcasses collected during 2012-16. We confirmed exposure to one or more ARs in 33% of the birds examined and detected dicoumarol in 13% of the samples. Rodenticides detected included brodifacoum, coumachlor, and bromadiolone. The prevalence of detected exposure to brodifacoum for after-hatch-year birds (65%) was significantly ( P=0.012) higher than hatch-year birds (22%). Brodifacoum was the most commonly detected AR, found in 88% of AR-positive birds. The pesticide registration for this chemical in the US was canceled in 2015 for general consumer products, which likely resulted in a decreasing rate of detected exposure to brodifacoum during our study. We present these results as an example of secondary exposure rates during a period when a pesticide has been restricted and then removed from the consumer market.

Urbanization and cattle density are determinants in the exposure to anticoagulant rodenticides of non-target wildlife.

The persistence and toxicity of second generation anticoagulant rodenticides (SGARs) in animal tissues make these compounds dangerous by biomagnification in predatory species. Here we studied the levels of SGARs in non-target species of wildlife and the environmental factors that influence such exposure. Liver samples of terrestrial vertebrates (n = 244) found dead between 2007 and 2016 in the region of Aragón (NE Spain) were analysed. The presence of SGARs was statistically analysed with binary or ordinal logistic models to study the effect of habitat characteristics including human population density, percentage of urban surface, livestock densities and surface of different types of crops. SGARs residues were detected in 83 (34%) of the animals and levels >200 ng/g were found in common raven (67%), red fox (50%), red kite (38%), Eurasian eagle-owl (25%), stone marten (23%), Eurasian buzzard (17%), northern marsh harrier (17%), and Eurasian badger (14%). The spatial analysis revealed that the presence of SGARs residues in wildlife was more associated with the use of these products as biocides in urban areas and cattle farms rather than as plant protection products in agricultural fields. This information permits to identify potential habitats where SGARs may pose a risk for predatory birds and mammals.

Sensitive determination of nine anticoagulant rodenticides in blood by high resolution mass spectrometry with supported liquid extraction pretreatment.

Anticoagulant rodenticides (ARs) have been widely used for controlling rodents in agriculture and households. It often occurs that non-target animals are poisoned by ARs. Also, the abuse of ARs has been often encountered in poisoning and suicide cases. Herein we report the determination of nine commonly used ARs by high resolution mass spectrometry (HRMS) with supported liquid extraction (SLE) pretreatment. The factors affecting SLE (elution solvents and pH values) were systematically tested and optimized. The application of parallel reaction monitoring (PRM) mode led to the highest sensitivity obtained for these compounds, with LODs ranging for 0.006-0.02ng/mL. Reasonable extraction recoveries for all the analytes were obtained ranging in 73.9%-110.7%. Good precision was achieved for the spiked blood samples, with intra-day RSD ranging in 5.0%-9.2% and inter-day RSD ranging in 6.3%-10.5%. The values of ME ranged in 82.9%-103.2% for QC sample, which are reasonable. The application of HRMS in PRM mode also resulted in high selectivity. The method was applied to the detection and quantification of ARs in blood samples from real forensic cases. This methodology possesses high potential for determination of rodenticides in clinical and forensic cases.

[Simultaneous determination of 12 rodenticides in whole blood and urine samples by high performance liquid chromatography-tandemmass spectrometry].

Objective: To develop a method for Simultaneous and rapid determination of 12 rodenticides including pindone, vacor, coumatetralyl, warfarin, diphacinone, coumachlor, chlorphacinon, difenacoum, brodifacoum, bromadiolone, difethialone and flocoumafen in whole blood and urine samples by high performance liquid chromatography-tandem mass (LC-MS-MS) . Methods: The whole blood samples were precipitated with acetonitrile, purified by OstroTM 96-well plate, The urine samples were extracted by acetonitrile, and then separated on a ODS column, analyzed with high-performance liquid chromatography-tandem mass spectrometry (LC-MS/MS) . The external standard calibration were tested. Results: A good linearity was observed in their respective concentration ranges of 12 rodenticides. The related coefficients were 0.993 0~0.999 8. The limit of detections were 0.05 µg/L~1.4 µg/L. The rates of recovery were 92.5%~118.0%. The relative standard deviations were between 0.8%~17.3%. Conclusion: The method was simple, rapid, sensitive, accurate and suitable for simultaneous detection of the 12 rodenticides in whole blood and urine samples of intoxicated patients.

Analysis of monofluoroacetic acid in human plasma by UFLC-MS/MS and its application in patients with sodium monofluoroacetate or monofluoroacetamide poisoning.

Monofluoroacetic acid (FAcOH), was once widely used in baits as a rodenticide in agriculture. For intentional and unintentional misuses, the incidence of FAcOH poisoning has increased in recent years. Organic fluorine rodenticides such as sodium monofluoroacetate and monofluoroacetamide, the analogs of FAcOH, can easily be converted to FAcOH in vivo and cause injury. It is urgent to establish a simple and sensitive analytical method of FAcOH in human plasma and applied to clinical poison analysis. In this paper, an ultra-fast liquid chromatography-tandem mass spectrometry (UFLC-MS/MS) method was developed for determination of FAcOH in patient plasma. We used isotopic labelled FAcOH-13C2, D2 as the internal standard (IS). Plasma samples were simply precipitated with acetonitrile and the supernatant was injected directly for analysis. The chromatographic column was Phenomenex Luna® Silica column (100 × 2 mm, 3 µm), FAcOH was eluted by isocratic elution with a mobile phase of acetonitrile-water contains 5 mM ammonium formate with 0.2% formic acid. The retention time of FAcOH was 2.31 min A good linear response was from 0.25 to 200 µg/mL, with a correlation coefficient of r = 0.9980. The limit of detection was 0.05 µg/mL. The recoveries at three spiking levers were 89.51-93.03% with relative standard deviations ranged between 2.55-3.61%. This new method has been successfully applied to monitor 31 cases of patients suspected with sodium monofluoroacetate or monofluoroacetamide poisoning.

Simultaneous Determination of 13 Anticoagulant Rodenticidesin Human Blood by Liquid Chromatography-Tandem Mass Spectrometry and its Application in Three Poisoning Cases.

Anticoagulant rodenticides are widely used for rodent control around the world. A rapid and sensitive method was developed and validated for the simultaneous determination of 13 anticoagulant rodenticides (coumafuryl, pindone, valone, warfarin, coumatetralyl, coumachlor, diphacinone, dicumarol, chlorophacinone, bromadiolone, difenacoum, flocoumafen, and brodifacoum) in human blood by liquid chromatography-tandem mass spectrometry. After liquid-liquid extraction, the anticoagulant rodenticides were separated on an Eclipse Plus C18 column. Linearities were observed for each analyte in blood ranging from 0.5 to 50 ng/mL, with correlation coefficients over 0.99. The limits of detection ranged from 0.01 to 0.2 ng/mL, and the limits of quantification were 0.5 ng/mL for all analytes. The intraday and interday precisions were <15%, and accuracies ranged from 80.3% to 111.0%. This validated method with high sensitivity has been applied in three anticoagulant rodenticide poisoning cases and has been used successfully in monitoring blood concentrations for months.

Sensitive and simultaneous determination of nine anticoagulant rodenticides in human blood by UPLC-MS-MS with phospholipid removal pretreatment.

A sensitive and rapid method for the simultaneous determination of nine anticoagulant rodenticides (ARs) in human blood is reported herein. The method involves phospholipid removal pretreatment for reduced matrix effect (ME) and detection with ultra-performance liquid chromatography coupled with tandem mass spectrometry. Satisfactory recoveries were achieved ranging from 80.6% to 113.1% for the nine analytes, with the intra-day relative standard deviations (RSDs) in the range of 3.4-7.9% and inter-day RSDs in the range of 4.1-8.3%, indicating good precision. Linear relationships with correlation coefficients above 0.998 (n = 6) were found in the range of 1-2,000 ng/mL. High sensitivity was achieved with limits of detection ranging from 0.02 to 0.3. The application of phospholipid removal step significantly optimized the ME, and the reduction of ME ranged from 6.1% to 15.5%. This method was successfully applied to the determination of ARs for blood samples from real forensic cases. These results prove that this method is reliable for rapid forensic and clinical diagnosis. The removal capabilities for five representative phospholipids that are abundant in blood were evaluated individually with Phree™ phospholipid removal plates. While significant capabilities for phospholipid removal were confirmed, the results showed that the removal capability for certain phospholipid could be improved.

Quantitative method for analysis of six anticoagulant rodenticides in faeces, applied in a case with repeated samples from a dog.

BACKGROUND: Accidental poisoning with anticoagulant rodenticides is not uncommon in dogs, but few reports of the elimination kinetics and half-lives in this species have been published. Our objectives were to develop and validate a new method for the quantification of anticoagulant rodenticides in canine blood and faeces using reversed phase ultra-high performance liquid chromatography-tandem mass spectrometry (UHPLC-MS/MS) and apply the method on a case of anticoagulant rodenticide intoxication. RESULTS: Sample preparation was liquid-liquid extraction. Six anticoagulant rodenticides were separated using a UPLC® BEH C18-column with a mobile phase consisting of 5 mM ammonium formate buffer pH 10.2 and methanol. MS/MS detection was performed with positive electrospray ionization and two multiple reaction monitoring transitions. The limits of quantification were set at the levels of the lowest calibrator (1.5-2.7 ng/mL or ng/g). The method was successfully applied to a case from a dog accidentally poisoned with anticoagulant rodenticide. Coumatetralyl and brodifacoum concentrations were determined from serial blood and faecal samples. A terminal half-life of at least 81 days for coumatetralyl in blood was estimated, which is longer than previous reported in other species. A slow elimination of brodifacoum from the faeces was found, with traces still detectable in the faeces at day 513. CONCLUSIONS: This study offers a new method of detection and quantification of six frequently used anticoagulant rodenticides in canine faeces. Such drugs might cause serious health effects and it is important to be able to detect these drugs, to initiate proper treatment. The very long elimination half-lives detected in our study is important to be aware of in assessment of anticoagulant rodenticide burden to the environment.

The rapid determination of bromadiolone in liver and blood plasma by in-injector pyrolysis gas chromatography - Ion trap tandem mass spectrometry.

The unintentional poisoning of off-target animals by bromadiolone, a second generation anticoagulant rodenticide, is an undesirable outcome requiring sensitive analytical methods. In this study, a rapid and sensitive method for the determination of bromadiolone in liver and blood plasma by means of gas chromatography coupled with tandem mass spectrometry without need for derivatization was developed. The method is based on the in-injector pyrolysis of bromadiolone and subsequent gas chromatography coupled with ion trap tandem mass spectrometry with electron ionization. Sample preparation includes extraction with methanol, evaporation under nitrogen stream, and dissolution in toluene. The pyrolysis of bromadiolone was carried out in an injector at 390°C. Chromatographic separation of the pyrolytical fragment of bromadiolone was achieved using a VF-5ms column with helium as the mobile phase. Tandem in-time mass spectrometry of the separated pyrolytical fragment of bromadiolone was carried out using an ion trap mass spectrometer after electron ionization. Recovery ranged from 94 to 98%. The method showed good linearity up to 1000µgkg-1 for liver and 1000µgL-1 for plasma. The limit of detection was 0.38µgkg-1 for liver and 0.26µgL-1 for plasma. The developed method was used successfully in several animal poisoning cases.

A negative association between bromadiolone exposure and nestling body condition in common kestrels: management implications for vole outbreaks.

BACKGROUND: Vole outbreaks have been extensively described, along with their impacts on humans, particularly in agricultural areas. The use of rodenticides is a common legal practice to minimise crop damage induced by high vole density for biocidal use. However, rodenticides can have negative direct and indirect impacts on non-target species that feed on voles. We studied whether the use of a second-generation anticoagulant rodenticide (SGAR), bromadiolone, can be detected in the blood of fledglings of wild common kestrels Falco tinnunculus in two areas of central Spain, exploring its possible indirect effects. RESULTS: We found that 16.9% of fledglings had a detectable concentration of bromadiolone in their blood, with an average concentration of 0.248 ± 0.023 ng mL-1 . Fledglings with bromadiolone in their blood, regardless of the concentration, had 6.7% lower body mass than those without detectable bromadiolone. CONCLUSION: The use of bromadiolone was detectable in the blood of alive non-target species. Detected bromadiolone in blood may reduce the body condition of nestlings, potentially reducing their fitness. The source of bromadiolone found in nestlings needs to be determined in future studies to derive accurate management advice. However, we urge the discontinuation of official SGAR distribution to farmers and their use in agrarian lands to minimise damage of voles on crops, particularly where common kestrels breed, and encourage the use of alternative effective practices. © 2016 Society of Chemical Industry.

Novel revelation of warfarin resistant mechanism in roof rats (Rattus rattus) using pharmacokinetic/pharmacodynamic analysis.

Roof rats (Rattus rattus) live mainly in human habitats. Heavy use of rodenticides, such as warfarin, has led to the development of drug resistance, making pest control difficult. There have been many reports regarding mutations of vitamin K epoxide reductase (VKOR), the target enzyme of warfarin, in resistant rats. However, it has been suggested there are other mechanisms of warfarin resistance. To confirm these possibilities, closed colonies of warfarin-susceptible roof rats (S) and resistant rats from Tokyo (R) were established, and the pharmacokinetics/pharmacodynamics of warfarin in rats from both colonies was investigated. R rats had low levels of warfarin in serum and high clearance activity. These rats can rapidly metabolize warfarin by hydroxylation. The levels of accumulation in the organs were lower than those of S rats. R rats administered warfarin showed high expression levels of CYP2B, 2C, and 3A, which play roles in warfarin hydroxylation, and may explain the high clearance ability of R rats. The mechanism of warfarin resistance in roof rats from Tokyo involved not only mutation of VKOR but also high clearance ability due to high levels of CYP2B, 2C and 3A expression possibly induced by warfarin.

Plasma metabolic profiling analysis of toxicity induced by brodifacoum using metabonomics coupled with multivariate data analysis.

Brodifacoum is one of the most widely used rodenticides for rodent control and eradication; however, human and animal poisoning due to primary and secondary exposure has been reported since its development. Although numerous studies have described brodifacoum induced toxicity, the precise mechanism still needs to be explored. Gas chromatography mass spectrometry (GC-MS) coupled with an ultra performance liquid chromatography tandem mass spectrometry (UPLC-MS/MS) was applied to characterize the metabolic profile of brodifacoum induced toxicity and discover potential biomarkers in rat plasma. The toxicity of brodifacoum was dose-dependent, and the high-dose group obviously manifested toxicity with subcutaneous hemorrhage. The blood brodifacoum concentration showed a positive relation to the ingestion dose in toxicological analysis. Significant changes of twenty-four metabolites were identified and considered as potential toxicity biomarkers, primarily involving glucose metabolism, lipid metabolism and amino acid metabolism associated with anticoagulant activity, nephrotoxicity and hepatic damage. MS-based metabonomics analysis in plasma samples is helpful to search for potential poisoning biomarkers and to understand the underlying mechanisms of brodifacoum induced toxicity.