What you may have heard
Burning scented candles emits cancer-causing chemicals.
What science tells us
Burning scented candles could lead to cancer-causing exposures through wax and wicks. Some aromatherapy candles are made of paraffin, which is a petroleum byproduct that releases carcinogenic soot when burned (Green America). At high exposure levels, this soot can also cause or aggravate respiratory problems and damage the inside of your house (for example computers, electrical appliances, ductwork). Harmful concentrations of other pollutants that may be found in scented candles (for example, formaldehyde, carbon dioxide, carbon monoxide, particulate matter, and volatile organic compounds [VOCs]) are also found in homes that burn scented candles regularly (Adamowicz et al.).
In addition, candles made before 2003 may have lead-core wicks. A candle with a lead-core wick releases five times the amount of lead considered hazardous for children and exceeds EPA pollution standards for outdoor air (Green America). No amount of lead is safe for humans and high lead exposure has been linked to hormone disruption, behavioral problems, learning disabilities, and many other health problems (CDC), including cancer.
There is limited epidemiological evidence about exposure to scented candles and cancer risk.
Laboratory Evidence/ Supportive Evidence
Laboratory evidence has shown that candles themselves are not a concern. A 2007 study found that the chemicals that make up candles are well below the threshold value of causing health problems (AECM). However, burning of candles releases volatile organic compounds (VOCs) into the air, which can be harmful. A 2014 laboratory study showed that the amount of VOCs released from burning candles is very low, and not large enough to be harmful to human health (Petry et al.).
IARC Carcinogen Classification: Not classified
How to reduce your risk
There are plenty of non-toxic candle alternatives: 100% beeswax candles with cotton wicks are free of toxic chemicals, as are candles made from 100% vegetable-based or soy waxes (Green America). To reduce soot, regardless of the type of candle, trim wicks to ⅛ of an inch. Candle-free aromatherapy is another way to release pleasant scents without any harmful byproducts. Essential oils are non-toxic and can be released through a diffuser, a ring burner, or added to a warm bath.
Occasional use of scented candles is unlikely to have carcinogenic effects, but frequent burning of some non-vegetable or non-soy-based scented candles may increase cancer risk. Pick non-toxic alternatives when buying scented candles.
Learn More From These Trusted Sources
Green America: Toxic candles
Adamowicz et al. Scented Candles as an Unrecognized Factor that Increases the Risk of Bladder Cancer; Is There Enough Evidence to Raise a Red Flag?
Snopes: Scented candles and cancer
Centers for Disease Control and Prevention (CDC): Lead
Published: June 29, 2021
Verified/updated: August 22, 2022