I have always had an obsession with scented candles: however, after moving into a wooden and carpeted house in Shanghai, my parents forbid me to use these candles because of the risks involved. I was upset, and I decided to do a little research on the benefits of using scented candles in order to convince them otherwise. When I found more negative than positive effects, I was shocked.
Candles contain Parrafin wax, which is derived from petroleum (alternatively, and more expensive, are candles made from plant oils such as palm, soybean, and beeswax). According to Ruhullah Massoudi, PhD professor of chemistry at South Carolina State University, Parrafin when burned has been proven to release small amounts of cancer causing agents benzene and styrene, as well as toluene and hydrocarbon chemicals such as alkanes and alkenes. (Main)
Benzene (C6H6) is a colorless liquid with a pleasant odor, and a trace amount of this chemical is usually released whenever carbon-rich materials undergo an incomplete combustion. It is produced in forests fires and volcanoes, and is also a component of cigarette smoke. Benzene can irritate the nose and the throat, and may cause upset stomach/ vomiting. Benzene is also used as an inhalant: when inhaled, it can make you feel dizzy/ lightheaded, and can in extreme cases lead to convulsion and then death. These harmful effects can also be experienced without inhaling the chemical, as it has the ability to pass through the skin. . (Wikipedia) Prolonged exposure to benzene can cause interference with the production of bone marrow in the human body, thus resulting in aplastic anemia or certain types of leukemia. This is because pure benzene oxidizes in the body to produce benzene oxide, which is not readily excreted. Benzene oxide can interact with DNA to produce harmful mutations. The US Department of Health and Human Services (DHHS) classifies benzene as a hazardous substance and a human carcinogen. (Benzene Toxicology)
Styrene (C6H5CH=CH2) is a colorless oily liquid with a sweet smell. It is also known as vinyl benzene and phenyl ethane. Like benzene, styrene is usually oxidized in humans by cytochrome P450 (a group of enzymes) to form styrene oxide, which is considered to be mutagenic, and possibly carcinogenic. According to the U.S Environmental Protection Agency, styrene is “a suspected toxin to the gastrointestinal tract, kidney, and respiratory system, among others.” Chronic exposure to styrene leads to tiredness and lethargy, headaches, memory deficits, and vertigo. (Wikipedia)
Synthetic fragrances are also present in scented candles: these, like Parrafin wax, are derived from petroleum and contain phthalate esters. These are added to the candle to help the smell linger: however, they are not much healthier than the contaminants released by car exhausts. According to the Environmental Protection Agency, can interfere with a body’s hormone system, making the person more susceptible to diabetes, certain cancers, obesity, and thyroid disease. Phthalates can also build up as household dust and linger for long periods of time. They can be ingested by inhaling or through the skin. (Tierny 2011)
Lastly, the most harmful and abundant emission from scented candles is soot. Soot is the product of an incomplete combustion of organic fuels, usually petrochemical based. This is also what makes the flame of a candle glow. As Parrafin wax burns, the surrounding air is constantly filled with particulate matter (soot) with the potential to cause sever damage to the lungs: “Their size, less than 1 µm, allows deep penetration of the respiratory system and alveolar deposition. The insoluble, carbonaceous core structure with high surface area allows adsorption of extractable volatile, and semi-volatile organic compounds.” (Krause 1999) “Soot can also accumulate on furniture, carpeting and walls, and linger for long periods of time. (Main)
When studies suggest that the negative effects of candle soot may be equivalent to those of factory emissions, are we right to complain about the air pollution outside our homes when the quality of air inside our homes is within our control, and yet we still manage to contaminate it? (Main)
While the negative information I found on the topic overwhelmed me, I also researched possible solutions to overcoming indoor pollution. The most common suggestion I found was to stop using scented candles altogether, and instead set out some baking soda or a bowl of white vinegar in a room to get rid of an odd smell. Good quality essential oils can also be used (as long as they are not burned).
If one wishes to occasionally use a scented candle, beeswax candles are recommended. In a Paraffin candle, the flame does not get hot enough to completely burn oil and thus results in an incomplete combustion and release of toxic chemicals. Beeswax candles however, burn at a lower temperature and therefore do not have that problem. They smell sweet without chemical fragrances, and beeswax is believed to contain negative ions that improve indoor air quality. (Main)
Side note: Candles made from palm oil (vegetable wax) should be avoided as the palm oil comes from pal tree plantations, for which rainforests are sacrificed. Wicks should be checked as many candlewicks contain lead: when burned, inhaling the fumes has been proven to be harmful to human health. According to Jerome O. Nriagu, Ph.D., a professor of environmental chemistry at the University of Michigan in Ann Arbor, candle-makers use metal-core wicks because “cotton wicks are often limp and fall over into the wax, extinguishing the flame.” (Downey)
From what I gathered by reading between the lines of various articles on the issue, it is not likely that occasional exposure to fumes from scented candles will severely harm us, but prolonged/ daily exposure should be avoided.
Main, E. (n.d.). Study: Candle chemicals pollute indoor air. Retrieved from http://www.rodale.com/candles-and-indoor-air-quality?page=0,0
Wikipedia. In Benzene. Retrieved from http://en.wikipedia.org/wiki/Benzene
Styrene. In Styrene. Wikipedia. Retrieved from http://en.wikipedia.org/wiki/Styrene
–> (Krause 1999)
Krause, D. (1999). Us scented candles study. Retrieved from http://www.lead.org.au/lanv7n4/L74-9.html
Downey, C. (n.d.). Toxins in burning candles, candle wicks, and incense. Retrieved from http://www.anapsid.org/cnd/mcs/candles.html
–> (Benzene Toxicology)
Benzene: Toxicology. (n.d.). Retrieved from http://www.crios.be/benzene/toxicology.htm
–> (Tierney 2011)
Tierney, J. (2011, March 15). Scented candles can cause ‘indoor air pollution’. Retrieved from http://www.katu.com/news/medicalalert/118018784.html