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Species Invasions in Freshwater Ecosystems
Published in Kezia Barker, Robert A. Francis, Routledge Handbook of Biosecurity and Invasive Species, 2021
Robert A. Francis, Michael A. Chadwick
Chemical control is the application of herbicides and pesticides to kill or reduce competitive or reproductive fitness of organisms. The use of chemicals is a common form of control, and, when utilised correctly, such chemicals can be both cost-effective and have fewer collateral impacts than physical control methods (Hussner et al., 2017). They nevertheless do carry some risk of non-target impact, as in many cases they do not affect individual species alone. For plants, herbicides are usually applied where there are large monocultural stands of non-natives to maximise effectiveness. Common herbicides include 2,4-D, diquat, paraquat, glyphosate, fluridone and triclopyr (Coetzee and Hill, 2009; Hussner et al., 2017), but these have restricted availability in some regions (e.g. some European countries) due to their wider impacts (Hussner et al., 2017). For freshwater animals, common pesticides include various forms of piscicides (esp. rotenone, antimycin and saponins; Ling, 2009), insecticides (often organophosphates, carbamates and pyrethroids) and molluscicides (usually niclosamide/clonitralid).
Life-threatening triclopyr poisoning due to diethylene glycol monoethyl ether solvent
Published in Clinical Toxicology, 2021
K.Z. Isoardi, C.B. Page, M.S. Roberts, G.K. Isbister
Triclopyr (3,5,6-trichloro-2-pyridinyloxyacetic acid) (Figure 1) is a synthetic auxin-like herbicide that is used to control woody and broadleaf weeds. It is formulated with the solvent diethylene glycol monoethyl ether (DEGEE) (Figure 1) or as a triethylamine salt. Triclopyr is classified as a low toxicity herbicide with a rat oral LD50 of 713 mg/kg [1]. There are few published reports of triclopyr poisoning [2–4]. A case series of 17 synthetic auxin-like herbicides including three triclopyr ingestions (70% triclopyr with 2[2-(4-nonylphenoxy)ethoxy]ethanol 4.5%) of 300 mL, 40 mL and 5 mL respectively concluded that poisoning with these compounds is relatively benign [2]. All patients in the series received haemodialysis and haemoperfusion in line with their toxic pesticide protocol. Specific clinical features for the patients ingesting triclopyr are not described. All three patients were discharged day five. Two single case reports describe severe toxicity. The first reports a 57-year-old man who ingested 300 mL of 30% triclopyr triethylamine with 4.5% polyoxyethylene nonylphenol surfactant and developed metabolic acidosis (pH 7.30, HCO3 15 mmol/L), coma and cardiovascular collapse. [3] The other reports a four-year-old child presenting to hospital with status epilepticus following an unknown ingestion, in which triclopyr was subsequently detected in the urine. [4] Both patients fully recovered with supportive care. We report two cases of life-threatening toxicity due to triclopyr co-formulated with DEGEE.