The clinical toxicity of imidacloprid self-poisoning following the introduction of newer formulations.

BACKGROUND: Self-poisoning with imidacloprid has been previously shown to have low toxicity in humans. Since 2007 newer formulations of Imidacloprid with unknown solvents have been introduced and the potential clinical consequences of these products have not been described. METHODS: Clinical and demographic data were prospectively collected from admissions following oral ingestion of imidacloprid from seven hospitals in Sri Lanka. Data was collected from 2002 to 2007 in an already published study. We compared this data on poisonings collected from 2010 to 2016 following the introduction of new formulations of imidacloprid. RESULTS: From 2002-2007, there were 56 patients with ingestion to imidacloprid compared to 67 patients post 2010 The median time to presentation prior to 2007 was 4 h (IQR 2.3-6.0 hrs) and post 2010 was only 2.0 hr (IQR 1.5 to 3.1 hrs). The median amount ingested was 15 ml (IQR 10.0-50.0mls) prior to 2007 and 27.5mls (IQR 5.0-71.8mls) post 2010. In both studies most patients developed non-specific symptoms including nausea, vomiting, epigastric pain and headache. However, prior to 2007 only 1.9% of the cohort required mechanical ventilation due to respiratory failure and there were no reported deaths. In contrast, post 2010; deaths occurred in 3.0% of the cohort and 6.0% required mechanical ventilation for respiratory failure. The cause of mortality was due to one case of cardiorespiratory failure and the other due to a prolonged admission complicated with lobar pneumonia leading to decompensated liver failure on the background of undiagnosed liver cirrhosis. CONCLUSION: Although acute exposure to imidacloprid is usually associated with mild non-specific symptoms, since the introduction of new formulations of imidacloprid, the toxic profile has changed with reported cases of death as well as an increase in cases requiring mechanical ventilation. The change in toxicity could be due to the solvents used in the newer formulations but also due to higher dose of imidacloprid described in our latter cohort. Further research into these solvents needs to be done and continued toxicovigilance is required.

Imidacloprid poisoning case series: potential for liver injury.

Introduction: Imidacloprid is a commonly used neonicotinoid insecticide in Thailand. Limited reports suggest it may be associated with liver injury.Case series: A retrospective poison center case series identified 128 cases of imidacloprid ingestion from 2010-2016, of which four developed liver injury.Results: Three patients ingested soluble liquid concentrates and one ingested water-dispersible granules of imidacloprid. The estimated doses of ingestion ranged from 2-35 g. One patient developed cholestatic liver injury, two developed hepatocellular liver injury, and the remaining patient, who ingested the highest dose, developed a mixed pattern of liver injury. Median onset of liver injury was 5.5 days.Discussion: In prior case reports and animal studies, these cases suggest imidacloprid toxicity is associated with liver injury that may be delayed. This is consistent with our finding. The cases also demonstrated a possible dose-response relationship of imidacloprid ingestion with severity and type of liver injury. All findings suggested that imidacloprid might contribute to liver injury.Conclusion: We report four cases of liver injury, which are possibly related to ingestion of imidacloprid. In management, consideration should be given to repeating liver tests as an outpatient if initial tests are normal, with counseling on the possibility of delayed liver injury.

Imidacloprid Poisoning of Songbirds Following a Drench Application of Trees in a Residential Neighborhood in California, USA.

In March 2017, 26 American goldfinches (Spinus tristis) were found dead following a drench application of imidacloprid in California (USA). Identical seed fragments were present in the digestive tracts. Imidacloprid was detected in 4 separate pooled samples from 18 birds, in crop/gizzard contents (4.8 ± 1.3 ppm; range 2.2-8.5 ppm) and liver tissues (3.9 ± 0.6 ppm; range 2.1-4.8 ppm). We suspect that fallen elm (Ulmus sp.) seeds were contaminated with imidacloprid during the drench application and subsequently ingested, resulting in acute toxicity and death. Environ Toxicol Chem 2019;38:1724-1727. © 2019 The Authors. Environmental Toxicology and Chemistry published by Wiley Periodicals, Inc. on behalf of SETAC.

Qualitative identification of imidacloprid in postmortem animal tissue by gas chromatography-tandem mass spectrometry.

During an avian mass mortality event investigation at the National Fish and Wildlife Forensic Laboratory in Ashland, OR, imidacloprid became an insecticide of concern. A qualitative analytical toxicology screen of seeds, plucks (tongue, esophagus, and trachea), and ventricular contents was requested. A method for the extraction and qualitative analysis of the insecticide in animal tissues was therefore developed. The procedure relies on a combined Food Emergency Response Network (FERN) and QuEChERS (Quick, Easy, Cheap, Effective, Rugged, and Safe) approach to sample extraction followed by qualitative analysis by gas chromatography-tandem mass spectrometry. Since imidacloprid is not amenable to the conditions of gas chromatography, a trimethylsilyl derivative was created and characterized. Proposed mechanisms for the creation of this derivative and its mass spectrum are described. The imidacloprid-trimethylsilyl (TMS) derivative was detected in all samples submitted.

Analytical confirmation of imidacloprid poisoning in granivorous Cape spurfowl (Pternistis capensis).

Reports were received that Cape spurfowl (Pternistis capensis) fell during flight and scrambled uncoordinatedly for cover and some died. Three carcases were submitted for necropsy examination, which revealed mainly congestion of the carcases and haemorrhages. Common causes of acute mortalities in birds were first excluded, but there was a history of possible exposure to imidacloprid-treated barley seeds. Imidacloprid, a neonicotinoid insecticide, is used to protect various crops against invertebrate pests. The combined crop contents and pooled liver samples collected from the Cape spurfowl during necropsy were submitted for liquid chromatography-high-resolution mass spectrometry (LC-HRMS) for imidacloprid analysis. Imidacloprid and several of its metabolites were detected in the samples. Farmers should cover sown seeds with a layer of soil and remove any spilled seeds, as granivorous birds are susceptible to imidacloprid intoxication. Regulatory authorities should re-evaluate the risk posed by imidacloprid-treated seeds for pollinators and granivorous birds.