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Last updated January 1, 2014

Toxins in Burning Candles, Candle Wicks, and Incense

Compiled by Melissa Kaplan

Sweet Smelling Danger
Some Candles Emit Dangerous Levels of Lead
Links to Related Articles/Sites on Candle & Wick Toxicity
Incense and Other Sources of Indoor Pollution


Sweet Smelling Danger?
Charles Downey
WebMD Medical News

When Cathy Flanders, 41, of Plano, Texas, started burning candles for their pleasant smell in the spring of 1997, it never occurred to her she could be poisoning her family.

Three years, a serious illness, and a lawsuit later, Flanders has a lesson to share with anyone buying scented candles: Watch out for metal wicks. Lead emitted by this type of candle is a serious health hazard.

"Candles are fast becoming one of the most common unrecognized causes of poor indoor air quality," says Diane Walsh Astry, Executive Director of the Health House Project, an American Lung Association education project in St. Paul, Minnesota.

The Flanders' woes started when Cathy was shopping at a clothing store and spotted some candles whose labels promised to fill her house with the pleasant fragrances of "winter" and "spring." Within six months of burning the candles, she noticed soot damage around her house. But Cathy didn't pinpoint the source of the problem until after Ron Bailey of Bailey Engineering in Palm Beach Gardens, Florida, analyzed the Flanders' candles and discovered lead emissions.

Around that time, 11-year-old Andrew Flanders' grades dropped precipitously. His teacher wondered if he had attention deficit disorder. When blood tests revealed an elevated level of lead, the Flanders promptly sent him to live with his aunt.

"The lead deposits in our home are such that we could not sell the house if we wanted to," says Flanders. As for the candles, the doctor ordered a total ban. Testing revealed the lead level in the Flanders' home to be 40 milligrams per square foot -- 27 times the limit allowed in Housing and Urban Development homes.

The Flanders aren't the only ones falling victim to pleasant-smelling candles with toxic wicks. Candle sales in general have skyrocketed in recent years, according to the National Candle Association in Washington D.C., from $500 million in 1995 to $2.3 billion in 1999. Part of the candle craze may be due to new interest in aromatherapy, a type of alternative medicine in which odors are used for relaxation or to treat illness.

Ironically, the very candles sometimes used for aromatherapy can cause serious health problems. The chief culprits are candles with wicks made with metal cores.

"Some candle makers use metal-core wicks because cotton wicks are often limp and fall over into the wax, extinguishing the flame," explains Jerome O. Nriagu, Ph.D., a professor of environmental chemistry at the University of Michigan in Ann Arbor who has studied scented candles.

Lead poisoning can lead to behavior changes and damage internal organs, especially the kidneys. Cathy's husband, Kip, had his gall bladder removed because of an illness he blames on the candles.

Metal Wicks
Nriagu measured the lead released from 14 brands of candles. He found that burning four metal-wick candles for two hours can result in airborne lead concentrations that pose a threat to human health. People with weak immune systems, including children and the elderly, are particularly at risk.

"Besides breathing lead fumes, children can be exposed to even more lead that is deposited on the floor, furniture, and walls because they often put their hands in their mouths," says Nriagu. After similar research in Australia, lead wicks in candles were banned there in September 1999. But despite the urging of experts like Nriagu, the candles are still legal in the United States.

Not all candles -- or even all scented candles -- cause hazardous pollution. But since labels won't tell which ones are safe, Astry and other candle experts offer this advice:

Watch out for shiny metal wire inside the wicks of candles. Opt for pure paper or cotton instead.

Keep wicks trimmed to one-quarter inch for more complete combustion, and keep candles out of drafts. Windiness blows more toxins into the air and causes inefficient burning.

Watch out for slow-burning candles with additives. (These candles often feel greasy to the touch.) Instead, look for pure beeswax candles, which emit less pollution.

For aromatherapy, put a few drops of scented oil in a defuser -- a tray made to fit on a lightbulb. Or you can put the drops into some boiling water.

Don't use candles in jars when the candle leaves a soot ring on the jar's lip. The soot may be an indication of lead dust.

Andrew Flanders, now 14, has moved back home. And the family is still hopeful their lawsuit will win compensation from the store that sold them the candles. But no matter what the result of the suit, Cathy only wishes she'd had some whiff of the danger when she first spotted those innocent-looking candles among the racks of shirts and pants.


Some Candles Emit Dangerous Levels Of Lead
Daily University Science News

A University of Michigan School of Public Health study of candles purchased from stores in southeast Michigan shows that some candles on the market today are made with wicks that have either lead or lead cores that emit potentially dangerous levels of lead into the air.

The study is by Jerome Nriagu, a professor of environmental health sciences, who examined lead emissions from 15 different brands of candles made in the United States, Mexico and China. He also examined the concentration levels of lead that lingered in the air in an enclosed space, such as a room measuring 12 feet by 12 feet and 10 feet high, after one hour and then again for five hours.

Nriagu's study showed that lead emission rates for the candles ranged between 0.5 and 327 micrograms per hour. After burning the candle for one hour, the lead levels in the air of an enclosed space were estimated to range from 0.04 to 13.1 micrograms per cubic meter, which compares to the U.S. Environmental Protection Agency recommendation of 1.5 micrograms per cubic meter for ambient air. After one hour, five of the candles Nriagu tested emitted unsafe levels of lead into the air that measured greater than 1.5 micrograms per cubic meter.

After five hours, the lead levels in an enclosed space ranged from an estimated 0.21 to 65.3 micrograms per cubic meter. Candles produced in China and the United States released the highest levels of lead into the air.

Regular exposure to lead in this manner in confined spaces could pose health risks to people with weak immune systems, especially children and the elderly, Nriagu said.

"Lead poisoning remains one of the most serious environmental health diseases in this country and other parts of the world. It affects many organ systems and biochemical processes with the most serious sequelae often occurring in the central nervous, cardiovascular and blood systems," Nriagu said.

Nriagu's findings are consistent with an Australian study due to be published in the journal Science of the Total Environment. In that study, Mike van Alphen of Lead Sense, an independent consultancy in Australia involved in environmental lead testing, lead exposure investigations and consumer product testing, examined a single brand of candle sold in Australia. The candle he examined released up to 1,130 micrograms of lead per hour.

Studies have shown that the central nervous system of children is particularly sensitive to lead. Some of the most damaging neuropsychological effects of lead poisoning of young children include learning disabilities, reduced psychometric intelligence and behavioral disorders. These effects have been associated with chronic low-level exposure to lead and are believed to be irreversible.

Nriagu's study measured the rate of lead emission in a laboratory setting using a flux chamber. The lead released as candle fume was collected in nitric acid and analyzed by means of an atomic absorption spectrometer. In addition to measuring emission rates, he calculated concentration levels of lead in the air in an enclosed space after one hour and then again, for five hours.

"The half-life of lead in air obviously would make a difference in terms of it being inhaled. A recent study has shown that particles emitted by candles during a normal burn are sub-micron in size and should remain suspended in the atmosphere for some time. Even if a particle is deposited after only a short trajectory through the atmosphere, it adds to the lead burden in the house dust. Airborne lead represents a hazard in more ways than one," Nriagu said.

House dust is widely recognized as a primary route of childhood lead exposure through hand-to-mouth activities.

"Assuming that only 50 percent of the lead released is deposited in an area measuring 12 feet by 15 feet (such as a living room), we estimate that the loading of the lead to house dust will exceed the U.S. EPA guideline of 100 micrograms per square meter by burning one of the Chinese candles for a few hours. Our data thus shows that burning leaded candles can result in extensive contamination of the air and house dust with lead," Nriagu said.

In general, Nriagu found that metal cores in Chinese candles were made of either pure lead or lead alloy while those made in the United States or Mexico consisted of zinc or lead-containing alloys. Lead was detected in small quantities in emissions from zinc-based wicks, suggesting that the lead may be a common contaminant in the zinc, wick or wax. The levels of lead were small, but still may represent a health risk over a long period of time.

Not all candles are made with wicks that have metallic cores. The practice is primarily used with candles that are needed to burn longer, such as scented or ceremonial candles. A metal core is used to provide rigidity to the wick which provides an even and slower burn rate, and to reduce the mushrooming at the tip. Since lead and its alloys melt at relatively low temperature, a large fraction of the wick core material is volatilized as the candle is burned.

"Because it is costly and difficult to control lead once it is released to the environment and medical treatment does not fully reverse the health effects, the optimal strategy for minimizing the risk involves the reduction or elimination of exposure in various forms. This study shows that there are still other important domestic sources of lead exposure that have escaped public scrutiny and legislative control. Leaded candles were recently banned in Australia, and we recommend a similar action in this country," Nriagu said.

Incense and Other Sources of Indoor Pollution
Along with candle wicks and certain types of candle wax, and aromatics used in fragranced household and aromatherapy products, there are other point-sources of pollution in the home that may cause health problems in those who are already suffering from neurocognitive, respiratory, cardiovascular and immune disorders, as well as put young children, the elderly, and pets at risk for health disorders.

Some abstracts of interest from PubMed:

Real-time monitoring of particles, PAH, and CO in an occupied townhouse.
Appl Occup Environ Hyg 2000 Jan;15(1):39-47

Investigations of the proximity effect for pollutants in the indoor environment.
Expo Anal Environ Epidemiol 1999 Nov-Dec;9(6):602-21

Effects of indoor environmental factors on respiratory health of children in a subtropical climate.
Environ Res 1997 Oct;75(1):49-55. Of possible concern to those with pets kept in humid rooms (or enclosures in rooms) in which incense is burned regularly.

Physical characterization of incense aerosols.
Sci Total Environ 1996 Dec 20;193(2):149-58

Indoor sources of mutagenic aerosol particulate matter: smoking, cooking and incense burning.
Mutat Res 1991 Sep;261(1):21-8


From Other National Institutes Of Health Sites
Toxicology and Carcinogenesis Studies of Isobutyl Nitrite (CAS No. 542-56-3) in F344 Rats and B6C3F1 Mice (Inhalation Studies)


Related Articles and Sites
Are your candles killing you?
Aromatic Products May Pollute Indoor Air
Black Soot Deposition
Combustible Pollutants In Your Home
Candles – A Burning Air Quality Issue
The Core of the Candle Problem
Lead & Other Toxic Emissions & Exposures from Candles
CDC Childhood Lead Poisoning Prevention Program
List of Fragrance Chemicals

Breathing Room: Students learn to calculate indoor air volume and importance of air quality. Part of the Air Quality curriculum, one of several available at the EPA's Teacher's Resource Center website. (Requires Adobe's Acrobat reader software. If you don't already have one, you can download one for free.)




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