Nonlethal method for forensic evaluation of aldicarb exposure in wildlife

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.

Parameters for Carbamate Pesticide QSAR and PBPK/PD Models for Human Risk Assessment

Our interest in providing parameters for the development of quantitative structure physiologically based pharmacokinetic/pharmacodynamic (QSPBPK/PD) models for assessing health risks to carbamates (USEPA 2005) comes from earlier work with organophosphorus (OP) insecticides (Knaak et al. 2004). Parameters specific to each carbamate are needed in the construction of PBPK/PD models along with their metabolic pathways. Parameters may be obtained by (1) development of QSAR models, (2) collecting pharmacokinetic data, and (3) determining pharmacokinetic parameters by fitting to experimental data. The biological parameters are given in Table 1 (Blancato et al. 2000). Table 1 Biological Parameters Required for Carbamate Pesticide Physiologically Based Pharmacokinetic/Pharmacodynamic (PBPK/PD) Models.(a).

Age dependent acute oral toxicity of hexahydro-1,3,5-trinitro-1,3,5-triazine (RDX) and two anaerobic N-nitroso metabolites in deer mice (Peromyscus maniculatus)

Hexahydro-1,3,5-trinitro-1,3,5-triazine (RDX) transforms anaerobically into N-nitroso compounds: hexahydro-1-nitroso-3,5-dinitro-1,3,5-triazine (MNX), hexahydro-1,3-dinitroso-5-nitro-1,3,5-triazine (DNX), and hexahydro-1,3,5-trinitroso-1,3,5-triazine (TNX). Exposure to these N-nitroso metabolites may occur in areas contaminated with explosives, as anaerobic degradation occurs via some bacteria and is one remediation strategy used for RDX. Few papers report acute oral toxicity and none have evaluated age dependent toxicity of RDX or its N-nitroso metabolites. Median lethal dose (LD50) was determined in deer mice (Peromyscus maniculatus) of three age classifications 21 d, 50 d, and 200 d for RDX, MNX, and TNX using the US EPA up-and-down procedure (UDP). Hexahydro-1,3,5-trinitro-1,3,5-triazine and N-nitroso metabolites caused similar overt signs of toxicity. Median lethal dose for 21 d deer mice were 136, 181, and 338 mg/kg for RDX, MNX, and TNX, respectively. Median lethal dose for 50 d deer mice were 319, 575, and 338 mg/kg for RDX, MNX, and TNX, respectively. Median lethal dose for 200 d deer mice were 158, 542, and 999 mg/kg for RDX, MNX, and TNX, respectively. These data suggest that RDX is the most potent compound tested, and age dependent toxicity may exist for all compounds and could play a role in RDX and RDX N-nitroso metabolite ecological risk evaluation of terrestrial wildlife at RDX contaminated sites.

Differential toxic effects of Carbofuran and Diazinon on time of flight in pigeons (Columba livia): potential for pesticide effects on migration

Cholinesterase inhibiting compounds such as carbamates and organophosphate insecticides have been widely used in agriculture since the ban on organochlorines in the 1970s. Carbofuran, a carbamate, and diazinon, an organophosphate, are among the most commonly implicated cholinesterase inhibitors in episodes of accidental avian toxicity and mortality. Despite the apparent effects of these compounds, little work has been done to study effects of low-level, environmentally relevant doses at the population level in migratory bird species. In this study, homing pigeons were used as surrogate species to assess the differences in the effect of incrementally low doses (0.0, 0.25, 0.5, and 1.0 mg/kg) of carbofuran and diazinon on time of flight and determine whether there was a threshold dose of either or both xenobiotics when orally administered at these levels. The results indicate that there is a significant dose-dependent increase in flight time in pigeons dosed with carbofuran while diazinon exposed pigeons showed little effect. More profound effects were noted with carbofuran with pigeons falling off the pace of the flock and a dose for highly significant increase in flight time elucidated between 0.5 and 1.0 mg/kg. The results of the studies validate the homing pigeon as a good subject for comparative studies of cholinesterase inhibitors in birds and the need for further research on repeated low-level exposures on populations of avian species.