Propylene Glycol vs Formaldehyde (free): which is worse?
Quick answer: Formaldehyde (free) carries the heavier risk profile. Propylene Glycol is — in the EU and — in the US; Formaldehyde (free) is banned in the EU and allowed in the US.
| Property | Propylene Glycol | Formaldehyde (free) |
|---|---|---|
| EU status | — | Banned |
| US status | — | Allowed |
| Risk level | — | high |
| Banned in | — | European Union |
| Restricted in | European Union (not permitted as a direct food additive in most food applications; only permitted as a carrier solvent for specific additives at low levels) | — |
| Category | additive | cmr |
| Where it hides | — | nail hardener, keratin treatment, eyelash glue |
What is Propylene Glycol?
Propylene glycol is a synthetic organic compound used as a humectant, solvent, and emulsifier in food, pharmaceuticals, cosmetics, and industrial applications. It is produced from propylene oxide (derived from petroleum). Its chemical formula is C3H8O2.
What is Formaldehyde (free)?
Formaldehyde (free) is free formaldehyde used directly as a preservative and in salon hair treatments.
Documented risks
Propylene Glycol: Propylene glycol is generally considered safe by the FDA and is metabolized by the liver to lactic acid and pyruvate (normal metabolites). However, at high doses — particularly from intravenous pharmaceutical formulations — propylene glycol can accumulate and cause lactic acidosis, kidney toxicity, and CNS effects. These effects are seen in critically ill patients receiving high-dose PG-containing intravenous medications, not from food consumption. In children and people with impaired liver or kidney function, PG accumulation may occur at lower doses than in healthy adults. Animal studies have found reproductive and developmental effects at high doses. EFSA's 2018 re-evaluation found no concerns at typical food use levels but noted the EU limits PG use as a direct food additive, using it only as a carrier solvent for permitted additives.
Formaldehyde (free): A known human carcinogen (IARC Group 1). Banned from direct use in EU cosmetics; allowed in US products with limited oversight.
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