Ethylene glycol, also known as antifreeze, can be fatal if ingested. Breakdown products of antifreeze can be identified as crystals in the victim’s kidney at high magnification.

Ethylene glycol, or antifreeze, is an organic compound commonly used to lower the freezing point of an antifreeze/water mixture. Odorless, colorless, and sweet-tasting, ingested antifreeze is potentially toxic in small quantities. The culprit in antifreeze poisoning is not ethylene glycol itself but instead its metabolites (or breakdown products), glycolic acid and oxalic acid. Ingestion of antifreeze, whether homicidal, suicidal, or accidental, offers a slow and painful death if medical intervention is not sought. The initial symptoms of antifreeze poisoning include central nervous system depression manifested
through slurred speech, incoherence, lack of coordination, and vomiting. After 12 hours, pH abnormalities and cardiovascular dysfunction result. Approximately 36 hours after ingestion normal kidney function ceases.

Ethylene glycol is generally not among the compounds included in a standard toxicology battery and testing must be specially requested. Previous suicide attempts using ethylene glycol, empty containers at the death scene, or indications from a suicide note may raise a pathologist’s suspicions and prompt requests for additional toxicological testing.

Ethylene glycol toxicity can also be reflected in the post-mortem histology of the kidney. Its metabolite, oxalic acid, binds calcium and forms distinctive fan-shaped crystals best seen under polarized light. This photomicrograph is consistent with fatal untreated ethylene glycol ingestion.