Candles
Issue
Candles have been used for thousands of years, even dating back to the ancient Egyptians. While candles used to be made out of natural occurring waxes like animal fats (e.g., beef tallow) and beeswax in most of human history; industrialization in the 1850’s brought about a new source for candle wax, coal- and petroleum-based paraffin wax. By the late 1900s the vast majority of candles were made out of paraffin wax, and only in the 1990s new types of waxes started to be developed like soy and palm wax. The concern for paraffin wax is that it contains several impurities and petroleum byproducts, including toluene and benzene, that can be released when burned.
Wicks were made of cotton and rice paper in the past, however, over the years wicks were reinforced with other materials including lead. In 1974 the National Candle Association made a voluntary agreement with it’s members to not use lead in wicks. However, the U.S. Consumer Product Safety Commission (CPSC) found a small percentage of candles sold in the late 1990s and early 2000s still contained lead-cored wicks. The CPSC finalized a ban on manufacturing, importing, or selling lead-core wicks or candles with lead-core wicks in April 2003. This story dives deeper into the details of candle contents, potential hazards, and some solutions.
Solutions
What do you buy?
Purchase natural wax candles with essential oils. Look for labels that indicate the exact content. For example, 100% Soy Wax Candle or 100% Beeswax.
Make candles at home, see our DIY candle instructions below.
Use diffusers instead. For example, reed diffusers in oil and water with essential oils in diffusing machine.
Learn how to make candles at home in 7 easy steps!
How to more safely burn candles
Burn in a well ventilated room, use an air purifier, or crack the windows open.
Cut wicks 1/4 inch from the wax for cleaner burns.
Snuff out flame instead of blowing out. This prevents more particulate matter being released into the air, as shown in this study.
Consider how long, frequent, and the amount of candles you burn.
Get outside in nature! Indoor air quality can be affected by many things, so make you make an effort to get outside.
Bottom Line
After reading or skimming about candles we hope that you feel more informed about the candle industry and what products you purchase at the store. The main takeaways from our research are…
Petroleum-based waxes (e.g., paraffin wax) have a higher risk of releasing certain harmful chemicals like benzene, toluene, and dioxins.
Not all waxes or fragrances are created equal, the quality can vary greatly based on the material’s origin, processing, and additives.
Labels can be misleading for what you are actually buying. Ensure you look at the label and the label guidance above.
If you can, buy candles locally or from a trusted source, which indicates what their candle contains or provides third-party testing results.
Details
Candle Market
According to Futura Market Insights, the U.S. paraffin wax market was estimated to be valued at $9.1 Billion, with 41.9% of that market value used for candles (FMI, 2022). Therefore, in 2021 the U.S. candle market was approximately $3.8 Billion. It is safe to say that paraffin wax dominates the candle market as the most commonly used wax. Several candle sites state that 95% of candles use paraffin wax, which is likely close to the current market share; however, the original source of this figure is uncertain (Malibu Apothecary, 2021; The Beeswax Candle Co, 2023). Most large candle manufacturers use paraffin wax because it is the most economical option.
CandleWax Types
Many different oils can be converted into wax through a process called hydrogenation. While we provide a lot of examples of candle waxes in the current market, there are always new innovative waxes that may emerge in the future. It is also important to keep in mind that all wax is not created equal. The quality of the wax depends on the specific wax manufacturer and source of the oil; for example, lower quality or more heavily processed waxes will introduce more harmful chemicals into the wax.
Paraffin Wax - Derived from petroleum, contains a mixture of chain hydrocarbons, with a small amount of cycloalkanes (hydrocarbons in ring structure) and other impurities. This wax can release potentially harmful chemicals when burned, such as benzene and toluene, which are known carcinogens. Paraffin wax typically contains between <0.5% to 5% oil depending on the level of refinement, and the level oil content can greatly affect amount of hazardous chemicals in the paraffin wax.
Polyethylene Wax - A synthetic plastic wax typically added in small amounts to candle wax to attribute certain properties, like increased hardness and higher melting point.
Gel Wax - A wax made of petroleum-based mineral oil, synthetic polymer resin, and other additives. This wax can be transparent so is used for clear candle or embedding objects in the wax. It also has a gel-like consistency when it is melted making it easier for various creative designs.
Palm Wax - Derived from palm oil, its sustainability is a concern due to deforestation and habitat destruction. Certifications like Roundtable on Sustainable Palm Oil (RSPO) identify that the palm wax is produced sustainably.
Vegetable Wax - A natural wax derived from plant sources, like the carnauba palm or candelilla shrub, which make them more sustainable and a cleaner burn.
Soy Wax - Made from soybean oil, it is generally considered a safer alternative to paraffin wax, but there are negative environmental and socio-economic impacts of industrial scale soy production. Soybean oil is also heavily processed to become wax, including bleaching and deodorizing treatments.
Beeswax - Produced by bees, it is a natural and non-toxic option that burns cleanly.
Coconut Wax - A natural wax derived from coconuts that is generally more sustainable and environmentally friendly than other vegetable waxes.
Rapeseed (or Canola) Wax - A natural wax derived from the hydrogenation of rapeseed oil (or canola oil), which is sourced from rapeseed plants.
Animal Fat Wax - Also known as tallow wax, is derived from the fat of cattle, sheep, or pigs and is less commonly used today due to more sustainable and ethical alternatives.
Candle Wick Types
Lead - Previously used in some candles, lead-core wicks have been banned due to their health risks. Burning candles with lead-core wicks can release toxic lead fumes, which can be harmful when inhaled. Prolonged exposure to lead can cause to neurological and developmental issues, especially in children.
Zinc - While zinc is considered less hazardous than lead, prolonged or excessive exposure to zinc fumes can still cause respiratory irritation. It is generally recommended to avoid candles with zinc-core wicks.
Other Metal Cores (e.g., Tin, Copper, Aluminum, Stainless Steel) - They can still release trace amounts of metal fumes when burned. It is advisable to exercise caution and consider using candles with non-metal core wicks if possible.
Wood - Typically a combination of natural wood and thin, flat piece of wood veneer glued together with a non-toxic adhesive.
Cotton - Cotton fibers are braided and twisted together and sometimes dipped in a solution to make it more rigid.
Paper - Tightly rolled or twisted paper or cardboard that is typically treated to enhance its absorbency and combustion properties.
Hemp - Hemp fibers from the Cannabis sativa plant are spun into threads or yarns then braided or twisted together for form the wick.
Synthetic (e.g., Nylon, Polyester, Rayon, Fiberglass) - These wicks are made from man-made materials and each have many different applications.
Note that many of these wicks are treated to enhance their performance. Some treatment chemicals could be bleaching agents, salts, flame retardants, stabilizers, binders, sizing agents, anti-drip coatings, and colorants. Without knowing the specific chemical and amount it is unclear the safety of these treatments.
Fragrances
Synthetic Fragrances - Typically a mixture of various components including aromatic compounds (natural or man-made), carrier oils (e.g., diethyl phthalate, dipropylene glycol), and other ingredients. Can contain various hazards substances and cause allergic reactions, respiratory irritation, and other adverse health reactions.
Essential Oils - Natural plant oil extracts used in many applications including candles. When using a higher grade (e.g., therapeutic grade) essential oil, these scents can be beneficial even have certain therapeutic benefits.
Chemical Substances Released Burning Candles
Burning anything releases chemicals into the air; however, the candle contents, including the wax, scent, and wick, greatly affect the amount and type of chemicals released. Listed below are some common chemicals and chemical groups released from burning candles. Any of the chemical substances below with HAP is considered a hazardous air pollutant (HAP) by the U.S. Environmental Protection Agency (U.S. EPA, 2022). While HAPs are generally considered hazardous, more information is needed to determine if a certain chemical exposure is hazardous to human health. We must take into account the exposure concentration in the air, duration of the exposure, and potentially other factors to determine the dose-response relationship of the chemical exposure. For example, being exposed to a low air concentration of benzene for a short period of time may not be hazardous; while a chronic (or long-term) exposure to the same air concentration of benzene may be considered high risk or hazardous.
Particulate Matter (e.g., PM2.5, PM10) - Small particles or soot that can be inhaled. Note this is just referring to tiny particles or liquid droplets in the air and not specific chemicals or chemical substances. These small particles can penetrate deep into different parts of the body (e.g., lungs, heart) which may cause respiratory or cardiovascular diseases and systemic inflammation.
Volatile Organic Compounds (VOCs) - Chemicals that vaporize at room temperature and includes fragrance oils in candles. Some VOCs are more harmful to human health than other, the following VOCs are potentially released from candle burning:
Aldehydes - Organic highly-reactive compounds with carbonyl group, which are found in various industrial processes and natural substances.
Acetaldehyde HAP- A colorless liquid or gas at room temperature and considered a carcinogen by the International Agency for Research on Cancer and probable carcinogen by the U.S. EPA. It is a naturally occurring chemical and can be produced in the human body after alcohol consumption and is in food products like coffee, bread, and some ripe fruit.
Acrolein HAP - A toxic chemical which can irritate skin, eye, and lungs and ultimately lead to respiratory tract damage after too much exposure. Acrolein is used in various industrial processes including producing acrylic acid, plastics, and biocide.
Formaldehyde HAP - Recognized as a carcinogen by many different government agencies all over the world. Some candles contain formaldehyde-generating chemicals that produce formaldehyde during the combustion process. For example, candles with limonene, which is a citrus extract used for fragrance, reacts with ozone to form formaldehyde.
BTEX - The following chemicals are grouped together, since they are often released together and of environmental and health concern. These chemicals occur naturally in crude oil and are more common in petroleum-based products, including paraffin wax.
Benzene HAP - A known carcinogen and highly flammable liquid which is used to create plastics and synthetic fibers.
Toluene HAP - A hazardous chemical with potential neurological and respiratory effects which is used in many paints, coatings, adhesives, and gasoline.
Ethylbenzene HAP - A hazardous chemical with potential neurological and respiratory effects which is used to produce plastics, synthetic rubber, and resins.
Xylenes HAP - A mixture of three compounds with potential neurological effects that are used in many different industrial processes.
Semi-Volatile Organic Compounds (SVOCs) - A class of chemicals that can exist as a gas and particle phase (e.g., dust, aerosols) in the air.
Polychlorinated dibenzodioxins (also known as “Dioxins”) - Toxic chemicals that are primarily anthropogenic (from human activity) and are persistent organic pollutants (POPs), or don’t break down easily in the environment or human body. These chemicals can cause cancer, reproductive and developmental problems, immune system damage, and interfere with hormones.
Polychlorinated dibenzofurans (also known as “Dibenzofurans”) - This group of chemicals are similar to dioxins in origin and are also POPs. Dibenzofurans are considered not as toxic as some dioxins (based on EPA’s Toxicity Equivalency Factors), but they cause the same health effects as dioxins including cancer (U.S. EPA, 2010).
Polycyclic Aromatic Hydrocarbons (PAHs) - A group of chemicals that are released into the air during incomplete combustion of organic materials as well as the production and use of coal tar compounds, including coal tar sealant on roads. They occur naturally in coal, crude oil, and gasoline, and therefore, are more prevalent in petroleum products like paraffin wax. PAHs are generally considered hazardous and some are carcinogenic.
Other Chemicals - There are certain chemicals that are mainly produced from the scents incorporated into candles or other candle ingredients.
Phthalates - Synthetic fragrances usually contain phthalates that are released into the air when burning candles. These chemicals are known to increase allergies or asthma and affect hormone levels.
Parabens - These synthetic chemicals are added to synthetic fragrances, waxes, or dyes as a preservative and are also known endocrine-disrupting chemicals, or affect human hormones.
Heavy Metals (e.g., Lead HAP, Zinc) - These metal compounds may be released into the air from burning metal-core wicks.
Evidence of Harmful Chemicals Released from Candles
One study measured the amount of various volatile organic compounds (VOCs) released from candles before and after lighting them. The bar graph shows the amount of formaldehyde released from 6 lit candles with different waxes, scent types, and country of origin.
This graph also compares the amount of formaldehyde measured in this study to the U.S. Department of Labor Occupational Safety and Health Organization (OSHA) Permissible Exposure Limits (PEL) for a 15-minute exposure duration (STEL) and average 8-hour work day exposure duration (TWA) (OSHA, 2023). The American Conference of Governmental Industrial Hygienists (ACGIH) also provide more stringent formaldehyde air exposure limits, called threshold limit values (TLV) (ACGIH, 2023) For a short-term exposure (STEL) of 15 minutes, half of the candles exceeded the ACGIH and/or OSHA exposure guidelines for formaldehyde (Ahn et al., 2014).
A different study analyzed the particulate matter and total polycyclic aromatic hydrocarbons (PAH) air concentrations before and after church service at a Roman Catholic Church in the Netherlands. The study found the PAH concentrations increased by 223% in the church and 882% in the chapel. The particulate matter at 10µm or less (PM10) concentrations increased 304% in the church and 335% in the chapel. Comparing the measured PM10 concentrations against EPA’s Air Quality Index (AQI) Breakpoints in the bar graph shows that after service hazardous levels of PM10 were in the church and chapel (Kok et al., 2004).
Another research study from a Polish University studied the impact of All Saints’ Day Ceremonies on the air concentrations of benzene and toluene. It found the outdoor air concentrations of benzene increased by up to 200% and toluene by up to 366% during All Saints’ Day, where many candles were lit outdoors in two different cemeteries. The bar graph provides a visual of the concentrations before and during All Saints’ Day to show the increase in benzene and toluene air concentrations. This study suggests that benzene and toluene are released from candles, specifically non-refined paraffin wax candles (Olszowski et al., 2013).
BMC health published a study in 2023 that investigated health symptoms amongst university students exposed to scented candles. The study found that exposure to scented candles for more than an hour showed higher occurrences of headache, sneezing, and wheezing (Khathlan et al., 2023).
While these studies show that harmful chemicals are released from candles we want to reiterate that the contents of the candle make a huge difference on which chemicals and how much are released. Therefore, this research is not meant to prove that all candles are hazardous and must be thrown out, but rather to provide you with the knowledge to choose healthier candles at the store.
Labeling
Candle labels do not have any specific regulations and are covered under the Fair Packaging and Labeling Act (16 CFR 500), which mandates all consumer product labels should be accurate and clear. However, this does not always prevent confusing labeling and marketing tactics that misrepresent or leave out certain harmful ingredients. Here are some labels to look out for when choosing a candle:
While the label above may look appealing and non-toxic, the language is broad and potentially misleading. This example candle could contain up to 49% of paraffin wax or other non-soy waxes based on U.S. label regulations. Even though it indicates scented with essential oils, it may contain synthetic fragrances, including endocrine disrupters like parabens and phthalates.
A candle may contain paraffin wax if the label says the following:
Soy Candle - Any candle with 51% or more soy wax can be labeled as a Soy Candle.
Wax Blend, Soy Blend or Similar - May contain a varying amount of different waxes.
Mineral Wax - Can be up to 100% paraffin wax.
“Beeswax” - May contain as little as 1% beeswax and mostly paraffin or other waxes
Other catchy words to look out for include:
Natural or All Natural - This is not regulated and the candle may still contain synthetic ingredients.
Scented with Essential oils - May still contain synthetic fragrances.
Hypoallergenic - Not strictly regulated and still a term used loosely.
Pure - This term in the U.S. means that the product contains only 51% or more of that ingredient.
Biobased - Need a minimum biobased content of at least 88 percent based on the 2012 Department of Agriculture’s Guidelines for Designating Biobased Products for Federal Procurement for Candles and Wax Melts (7 CFR 3201.79).
Progress
There has been quite a bit of progress made in terms of offering more safe and transparent candle options at the store. The following steps have already been made in the right direction:
Some candle manufacturers have to comply with FDA’s 1977 Petroleum Wax regulation (21 CFR 178.371), which requires certain purity indicators for petroleum wax used for products in contact with food sources;
Banning the sale of lead wicks in 2003 (CPSC, 2003);
Implementing fire safety standards (e.g., ASTM F2058);
Public awareness pushing for natural wax alternatives to petroleum-based waxes;
Establishing regulations for clearer labeling and transparency;
Offering third-party testing results for certain candle companies; and
Restricting certain chemicals from being used in candles (e.g., European Chemicals Agency Substances of Very High Concern and REACH).
Questions
Why aren’t there been more candle studies funded when there are known hazardous chemicals in paraffin wax?
Generally, studies for consumer products, especially non-food products, are lagging in scientific research studies which fully characterize the potential human health effects. Also there is some push back between the candle industry and researchers publishing scientific studies. As of October 2023, the National Candle Association’s (trade association representing US candle manufacturers and suppliers) website states that, “To date, no peer-reviewed scientific study has ever collected or analyzed any emissions data on any candle wax, including petroleum-based paraffin, and proven them to be harmful to human health.” This statement is a bit confusing, because there are studies that have shown candles release hazardous chemicals and that the same chemicals released are harmful to human health.
A 2009 Undergraduate Study found that paraffin wax emitted unwanted chemicals, like alkenes and toluene. After being published and reported on several news outlets (including NPR) the scientific article was removed from South Carolina State University website based on National Candle Association claims the research was, “erroneous, unsubstantiated and misleading,” as well as biased because it was funded by the US Department of Agriculture’s (USDA) National Institute of Food and Agriculture (NIFA) agency.
Conversely the lead researcher on this study and South Carolina State University chemistry professor, Dr. Ruhullah Massoudi, stated that “the paraffin candles we tested released unwanted chemicals into the air. For a person who lights a candle every day for years or just uses them frequently, inhalation of these dangerous pollutants drifting in the air could contribute to the development of health risks like cancer, common allergies and even asthma.” (The Sun, 2019). The study was eventually published in the an independent journal in 2017 (Massoudi, 2017). In addition, the NCA had a disagreement with the results of publication used in this story, stating that the measured formaldehyde concentrations were incorrect due to not using a standard room sized air volume (NCA, 2015; Ahn et al., 2014).
Why do many candle studies have conflict of interest concerns?
As stated above, NCA claimed Massoudi’s reasearch was funded by the USDA National Institute of Food and Agriculture (NIFA) agency which support the soy industry. In addition, we found that many different candle studies have been funded by organizations with conflicts of interest. Another study featured on NCA’s website, was funded by the Research Institute for Fragrance Materials Inc. (RIFM), which is a trade association for various companies the manufacture fragrances or consumer products containing fragrances (Petry et al., 2014).
How can we make labels more transparent and less confusing?
While some strides have been made in ensuring clearer labeling for candle products, much more progress can be made in this arena. It is important that buyers are aware of what they are purchasing and the potential hazards.
How many other applications are paraffin wax used for?
In our research on this topic, it is clear that paraffin wax is not only used in candle making, but various other products like skin care, food packaging, agriculture, surf board wax, and pharmaceuticals. Since these uses are very different in terms of types of exposure, they would need to be investigated further to determine if using wax for these applications is hazardous.
References
ACGIH. (2023, October). Formaldehyde. American Conference of Governmental Industrial Hygienists. https://www.acgih.org/formaldehyde-2/
Ahn, J., Jo, H., Seo, Y., & Kim, J. (2014, December). Characterization of hazardous and odorous volatiles emitted from scented candles before lighting and when lit. Journal of Hazardous Materials, 283, 38-47. https://doi.org/10.1016/j.jhazmat.2014.12.040
CFR. (2023, September). Title 21. § 178.3710: Petroleum wax. Code of Federal Regulations. https://www.ecfr.gov/current/title-21/chapter-I/subchapter-B/part-178/subpart-D/section-178.3710
CFR. (2023, October). Title 7. § 3201.79: Candles and wax melts. https://www.ecfr.gov/current/title-7/subtitle-B/chapter-XXXII/part-3201/subpart-B/section-3201.79
CFR. (2023, October). Title 16. § 500: Regulations Under Section 4 of the Fair Packaging and Labeling Act. Code of Federal Regulations. https://www.ecfr.gov/current/title-16/chapter-I/subchapter-E/part-500
FMI. (2022, July). Paraffin Wax Market. Future Market Insights (FMI). https://www.futuremarketinsights.com/reports/paraffin-wax-market
Khathlan, N., Basuwaidan, M., Yami, S., Al-Saif, F., Al-Fareed, S., Ansari, K. (2023, January). Extent of exposure to scented candles and prevalence of respiratory and non-respiratory symptoms amongst young university students. BMC Public Health 23, Article number: 80. https://doi.org/10.1186/s12889-023-15001-6
Malibu Appothecary. (2021, July). Is Paraffin Wax Toxic? https://malibuapothecary.com/blogs/clean-candles/is-paraffin-wax-toxic
Massoudi, R., Hamidi, A. (2017, July). Some Candles Emit Hazardous Materials for Human Health and are Indoor Air Pollutants. International Journal of Tropical Disease and Health. https://doi.org/10.9734/IJTDH/2017/34965
NCA. (2015, July). Comment on “Characterization of hazardous and odorous volatiles emitted from scented candles before lighting and when lit.” National Candle Association. https://doi.org/10.1016/j.jhazmat.2015.07.011
NCA. (2017, April). US Trade Association Calls on South Carolina State University to Stop Promoting Bad Science. National Candle Association. https://candles.org/wp-content/uploads/2019/07/NCA.SCSU-Press-Release-4.11.2017.pdf
NCA. (2023, October). Resources. National Candle Association. https://candles.org/
Petry T., Viale D., Joachim, F., Smith, B., Cruse, L. Mascarenhas, R., Schneider, S., Singal, M. (2014, June). Human health risk evaluation of selected VOC, SVOC, and particulate emission from scented candles. Regulatory Toxicology and Pharmacology, Volume 69, Issue 1, 55-70. https://doi.org/10.1016/j.yrtph.2014.02.010
U.S. CPSC. (2003, April). CPSC Bans Candles With Lead-Cored Wicks. Consumer Product Safety Association. https://www.cpsc.gov/Newsroom/News-Releases/2003/CPSC-Bans-Candles-With-Lead-Cored-Wicks
U.S. EPA. (2010, December). Recommended Toxicity Equivalence Factors (TEFs) for Human Health Risk Assessments of 2,3,7,8- Tetrachlorodibenzo-p-dioxin and Dioxin-Like Compounds. United States Environmental Protection Agency. https://www.epa.gov/sites/default/files/2013-09/documents/tefs-for-dioxin-epa-00-r-10-005-final.pdf
U.S. EPA. (2022, December). Health Effects Notebook for Hazardous Air Pollutants. United States Environmental Protection Agency. https://www.epa.gov/haps/health-effects-notebook-hazardous-air-pollutants
U.S. EPA. (2023, October). AQI Breakpoints. United States Environmental Protection Agency. https://aqs.epa.gov/aqsweb/documents/codetables/aqi_breakpoints.html
Olszowski, T., Andrzej, K. (2013, September). The Impact of Candle Burning During All Saints’ Day Ceremonies on Ambient Alkyl-Substituted Benzene Concentrations. Bulletin of Environmental Contamination and Toxicology, 91, 588-594. https://doi.org/10.1007/s00128-013-1104-6
OSHA (2023, October). 1910.1048 - Formaldehyde. Occupational Safety and Health Association. https://www.osha.gov/laws-regs/regulations/standardnumber/1910/1910.1048
The Beeswax Candle Co. (2023, October). About Us. The Beeswax Candle Co. https://beeswaxcandleco.com/pages/about-us
The Sun. (2019, October). BURN OUT Scented candles ‘give off powerful fumes that could cause asthma and even lung cancer.’ https://www.thesun.co.uk/fabulous/10133513/scented-candles-fumes-asthma-lung-cancer/