Pinoxaden has a low acute toxicity potential by oral, dermal and inhalation routes (LD50was greater than 5000 mg/kg bw, Toxicity category III or IV). Formulation is irritating to the to skin and eye. pinoxaden is also a respiratory tract irritant (Toxicity category I) (United States Environmental Protection, 2005;EFSA, 2013).
Based on the low incidence of malformations of the diaphragm, the majority of the experts considered that classification for developmental effects should be proposed:“Possible risk of harm to the unborn child (EFSA, 2013).
Pinoxaden inibits acetyl CoA carboxylase in plants thereby blocking fatty acid synthesis (United States Environmental Protection, 2005).
Kinetic studies reported that pinoxaden is rapidly and extensively absorbed after oral administration (time to peak within 1 hour). Pinoxaden was eliminated rapidly, with 90% of the dose eliminated within 72 hours predominantly via urine (60–70% of the dose), followed by faeces (24–29%) and bile (9–12%) (JMPR, 2005;EFSA, 2013).
Pinoxaden was completely metabolized, with no unchanged parent present in urine, bile or faeces via hydrolysis, hydroxylation, dealkylation, ring cleavage and ring formation reactions, followed by conjugation with glucuronide and other sugars and sulfate The major metabolite was the hydrolysis product 8-(2,6-diethyl-4-methyl-phenyl)-tetrahydro-pyrazolo[1,2-d][1,4,5]oxa-diazepine-7,9-dione. At high dose levels enterohepatic recirculation is suggested (JMPR, 2005).
In the short term studies in rats and mice, the liver and kidney were target organs (JMPR, 2005).
EFSA, European Food Safety Authority (2013). Conclusion on the peer review of the pesticide risk assessment of the active substance pinoxaden. EFSA Journal 11(8):3269, 112 pp. doi:10.2903/j.efsa.2013.3269.
United States Environmental Protection (2005). Office of Prevention, Pesticides and Toxic Substances Agency (7501C). Pesticide Fact Sheet. Pinoxaden
JMPR (2005). Pinoxaden (293). Toxicology. https://www.fao.org/fileadmin/templates/agphome/documents/Pests_Pesticides/JMPR/Report2016/PINOXADEN.pdf