Propylene Glycol vs Brominated Flame Retardants: which is worse?

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 Brominated Flame Retardants?

Brominated flame retardants (BFRs) are a class of synthetic chemicals added to consumer products and materials to reduce flammability. They include polybrominated diphenyl ethers (PBDEs), hexabromocyclododecane (HBCD), and others. While not direct food additives, they contaminate the food supply through environmental pathways and food packaging.

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.

Brominated Flame Retardants: PBDEs and other BFRs are endocrine disruptors, neurodevelopmental toxicants, and probable carcinogens. They accumulate in human adipose tissue, breast milk, and blood. PBDEs were found in 100% of samples in multiple US population biomonitoring studies. US women have PBDE body burdens 10-100 times higher than European women, reflecting the US's historically heavy PBDE use before bans. Neurodevelopmental effects: multiple studies have associated prenatal PBDE exposure with lower IQ, attention deficits, and behavioral problems in children. A 2012 Environmental Health Perspectives study found inverse associations between PBDE cord blood levels and child IQ and behavioral outcomes. Thyroid disruption: BFRs structurally mimic thyroid hormones and compete with thyroid hormone binding proteins, disrupting the thyroid axis — critical for fetal brain development. Carcinogenicity: some PBDEs are associated with thyroid cancer risk in human studies. PBDEs enter the food supply primarily through fatty fish (salmon, tuna), meat, dairy, and some contaminated produce from biosolid-amended soils.