Exhumation of Wistar rats experimentally exposed to the carbamate pesticides aldicarb and carbofuran: A pathological and toxicological study

Precision of in Vivo Pesticide Toxicology Research Can Be Promoted by Mass Spectrometry Imaging Technology

Pesticides are crucial for agricultural production, but their excessive use has become a significant pollution source, leading to increased pesticide residues in the environment and food and posing a threat to human health. In vivo pesticide toxicology research aims to protect humans with detection technology playing a key role. Spatial information plays a crucial role in in vivo pesticide toxicity research. However, current technologies cannot simultaneously analyze the content and spatial information on pesticides in vivo. Mass spectrometry imaging (MSI) technology can address this limitation by simultaneously analyzing the content and spatial distribution of chemicals in vivo with high sensitivity and efficiency, aiding in the discovery of toxic biomarkers and mechanisms. Nevertheless, the limited application of MSI in vivo pesticide toxicology research hinders the accuracy of such research. Therefore, MSI should be promoted to enhance the accuracy of in vivo pesticide toxicology research.

Case studies and technical aspects of the forensic necropsy of exhumed companion animals

Veterinary forensics is becoming increasingly important in the acquisition of evidence in cases of animal cruelty, unlawful killing, violation of wildlife law and medical malpractice. However, although forensic veterinary necropsy is one of the main techniques for gathering information about actions that have resulted in the unlawful killing of an animal, forensic necropsy of exhumed remains is rarely performed. We hypothesized that necropsy of exhumed animals can provide valuable information for the elucidation of cause of death. Hence, the present study aimed to describe the pathological changes observed in the necropsies of eight exhumed companion animals and to determine the frequencies of causes of death and diagnoses. This retrospective and prospective study was performed during the period 2008-2019. The causes of death of six of the eight disinterred animals were attributed to neurogenic shock (37.5 %), respiratory failure (25 %) and hypovolemic shock (12.5 %), with 50 % of necropsies providing conclusive diagnoses of physical/mechanical lesions and 25 % of infectious disease. The deaths of two animals could not be elucidated because of the advanced state of putrefaction. Ancillary testing comprised computed tomography (50 %), radiography (25 %), immunohistochemistry together with polymerase chain reaction/sequencing (12.5 %) and toxicology (12.5 %). The results support our original hypothesis since it was possible to observe macroscopic alterations that disclosed new information about the events connected with the demise of 100 % of the animals and to achieve irrefutable conclusions about the circumstances of death in 75 % of the studied cases.

Simultaneous determination of carbofuran and 3-hydroxycarbofuran in duck liver by an UPLC-MS/MS

Carbofuran is a carbamate pesticide, a broad-spectrum, high-efficiency, low-residue, and highly toxic insecticide, acaricide, and nematicide, widely used in agriculture. Carbofuran is most harmful to birds, and birds or insects killed by furan poisoning can be killed by secondary poisoning after being foraged by raptors, small mammals, or reptiles. In this paper, an UPLC-MS/MS method was developed for the determination of carbofuran and its metabolite, 3-hydroxycarbofuran, in duck liver. Liver tissue was first ground into a homogenate and then passed through ethyl acetate liquid-liquid extraction processing samples. Multiple reaction monitoring (MRM) mode was used for quantitative analysis, m/z 222.1 → 165.1 for carbofuran, m/z 238.1 → 180.9 for 3-hydroxycarbofuran and m/z 290.2 → 198.2 for an internal standard. The standard curves of carbofuran and 3-hydroxycarbofuran in duck liver were within a range of 2–2000 ng/g, where the linearity was good, the lower limit of quantification was 2 ng/g. The intra-day precision of carbofuran and 3-hydroxycarbofuran was <14%, and the inter-day precision was <13%, the accuracy range was between 91.8 and 108.9%, the average extraction efficiency was higher than 75.1% with a matrix effect between 93.4 and 107.7%. The developed method was applied to a situation of suspected duck poisoning at a local farm.

Effect of Terbufos (Organophosphate) on the Cadaveric Colonization Process: Implications for Postmortem Interval Calculation

The determination of necrophagous fly specie's development time is considered an accurate method for estimating postmortem interval (PMI). However, pesticides and other chemicals can alter the flies' life cycle, inducing errors in PMI estimation. Thus, this work aimed to evaluate the effect of different doses of Terbufos (Organophosphates) on the temporal dispersion pattern and development of immature dipterans associated with decaying rat carcasses. For this, 150 g female Wistar rats received, via gavage, 200 µl of Terbufos (5 or 10 mg/kg) or distilled water (control) and, after 30 min of administration, the animals were euthanized and distributed in suspended traps to decompose under environmental conditions. The dispersing immatures were collected daily, and their development time was monitored until the emergence of adult flies. After data analysis, it was observed that Terbufos altered 1) the temporal pattern of larval dispersion; 2) the composition and structure of the colonizing assemblage (emerged adults); 3) species' development time, accelerating or delaying their cycle, depending on the dose used; and 4) the califorids and sarcophagids emergence rate, increasing the mortality of pupae from intoxicated carcasses. Thus, this work demonstrates experimentally that Terbufos directly influences the development of flies with forensic potential and discusses the implications for PMI estimation, which can assist in future investigative processes with suspected poisoning by this organophosphate.

Carrion decomposition and assemblage of necrophagous dipterans associated with Terbufos (Organophosphate) intoxicated rat carcasses

Organophosphate use represents one of the main causes of intentional and accidental poisoning in Brazil. Because they induce alteration in carcass decomposition and succession of necrophagous Diptera, they are important investigative tool in forensic entomology for determining the postmortem interval (PMI) and cause of death. Thus, this work aimed to evaluate the influence of Terbufos, the most commonly used organophosphate for suicides in Rio Grande do Norte, Brazil, in the decomposition process and necrophagous fly assemblies in intoxicated rat carcasses. For this, 150g female Wistar rats received, by gavage, 200µL of Terbufos (5mg/kg or 10mg/kg) or distilled water (control). Approximately 30 minutes after administration, animals were euthanized and distributed in suspended traps to decompose under environmental conditions. Decomposition was monitored daily, with photographic record and collection of the visiting dipterofauna until the dry phase. Data show that the higher dose of Terbufos i) accelerates carcass decomposition in 24h; ii) decreases the species richness and abundance of scavengers flies when compared to the control; iii) changes the succession pattern, delaying the arrival of important species for the PMI estimate and iv) causes 8% mortality of the visiting dipterofauna. This work provides relevant information about dipteran assemblages and changes in the cadaver decomposition process associated with Terbufos intoxication, which may assist in future investigative processes with suspected organophosphate poisoning.