Is antifreeze poisonous if boiling

Answer 1

Yes, it is always poisonous.

The main components of antifreezes are:

• Methanol (mainly in windshield antifreeze) - lethal dose is about 6 g/kg body weight. Even before you reach the lethal dose it can kill optic nerves (make you blind) and destroy your liver.
• Propylene Glycol (PG) - main ingredient in "safer" forms of engine antifreeze/ coolants. While it is only about 1/3 as toxic to dogs (who may try to lick up spills because it tastes good to them) the oral LD50 (the dose that will kill 50% of dogs who get that much) of PG in dogs is 22g/k. Consuming PG can result in acidosis, liver damage, and renal insufficiency. Clinical signs of a propylene glycol toxicoses include CNS depression, weakness, ataxia, and seizures. With large ingestion, diuresis and supportive care, such as treatment for acidosis, should be given.
• Ethylene glycol (EG) - the most dangerous form of antifreeze. Most commercial antifreeze products contain between 95-97% ethylene glycol. The minimum lethal dose of undiluted ethylene glycol antifreeze is 4.4-6.6ml/kg in dogs and 1.4ml/kg in cats. The lethal dose in people is about 5 or 6 g/kg. EG can cause metabolic acidosis and acute renal tubular necrosis. In most cases of ethylene glycol poisonings, vomiting is seen within the first few hours and then within 1-6 hours signs of depression, ataxia, weakness, tachypnea, polyuria, and polydipsia occur. By 18-36 hours acute renal failure occurs.