Scented candles—especially paraffin-based—don’t just smell cozy. Multiple studies show they release toxic chemicals like benzene, formaldehyde, toluene, carbon monoxide, and polycyclic aromatic hydrocarbons (PAHs)—many of which are carcinogenic, hormone-disrupting, or linked to respiratory disease.

A 2025 study by UC Davis analyzed 201 toddlers (ages 2–4) from four U.S. states and found 96 different chemicals in their urine—48 found in over half of the kids, 34 in more than 90%—many not even tracked by national surveys.