Antifreeze / engine coolant (ethylene glycol-based) — household safety profile

What is this product?

Engine coolant containing 90-95% ethylene glycol (EG) with corrosion inhibitors, dyes, and anti-foaming agents. Ethylene glycol has a sweet taste that attracts children and animals. Ingestion of as little as 100 mL can be fatal to an adult (LD50 ~1.4 mL/kg). EG is metabolized to glycolic acid and oxalic acid, causing metabolic acidosis, renal tubular necrosis, and death. Leading cause of poisoning death from automotive products. Approximately 6,000 US poison exposures annually, with ~90 deaths.

What's in it

Click any compound name for its full safety profile, regulatory consensus, and exposure data.

How to use it more safely

• Use only in closed cooling systems
• Clean up all spills immediately and thoroughly
• Store in locked cabinet away from children and pets
• Use products with bittering agent (denatonium benzoate)

Red flags — when to walk away

• Open container of brightly colored fluid — Sweet-tasting lethal poison accessible to children/pets

Green flags — what to look for

• 'Bittered' or denatonium benzoate on label — Bittering agent reduces (but does not eliminate) accidental ingestion risk

Safer alternatives

• Propylene glycol-based antifreeze — Much lower toxicity (LD50 ~20 mL/kg vs. ~1.4 mL/kg for EG); still not safe to drink but significantly less hazardous
• Pre-diluted (50/50) coolant — Half the ethylene glycol concentration of concentrate; reduces but does not eliminate poisoning risk

Frequently asked questions