Bittering agents: their potential application in reducing ingestions of engine coolants and windshield wash

Ethylene glycol automobile engine coolants and methanol-based windshield washer liquids are toxic. Despite international attempts to improve the safety of these products through better labelling and packaging, accidental and intentional ingestions continue a source of poisonings worldwide. The rejection of bitter tasting substances forms part of the human defense against ingestion of harmful substances. Denatonium benzoate (DB) is currently recognised as a means to prevent ingestion of ethyl alcohol intended for industrial use. This study investigated the use of this bitter substance also as a deterrent against ingesting ethylene glycol and methanol. The palatability of ethylene glycol and methanol with and without the addition of DB was assessed using a human taste panel; 30 ppm DB rendered each product intolerable to the panel. The addition of DB to ethylene glycol engine coolants and methanol-based windshield washer liquids at low concentrations could afford protection against accidental ingestions.