Excerpts from the EPA report on candles and incense
Analysis And Literature Review, " dated Jan. 2001.
Prepared by National Risk Management, Research Laboratory.
The report summarizes available information on candles and incense as potential sources of indoor air pollution. It
covers (1) market information and (2) a scientific literature review. The market information collected focuses on
production and sales data, typical uses in the US, and data on the sources and quantities of imported products.
The estimated total sales of candles in 1999 varied between $968 million and $2.3 billion, while imports were $486
million. The US
imports and exports of incense in 1999 were $12.4 and 4.6 million, respectively. The scientific literature review gathered
information regarding the emission of various contaminants generated when burning candles and incense, as well as the
potential health effects associated with exposure to these contaminants. Burning candles and incense can be sources of
Burning candles with lead core wicks may result in indoor air concentrations of lead above EPA-recommended thresholds.
Exposure to incense smoke has been linked with several illnesses, and certain brands of incense also contain chemicals
suspected of causing skin
The purpose of this report is to collect economic information regarding the production and sales of candles and incense
in the US, including information about imports. A second objective is to review the scientific literature regarding emission
rates and potential human health effects associated with burning candles and incense. The following is a brief overview
of the findings.
4. POTENTIAL INDOOR AIR QUALITY IMPACTS OF BURNING CANDLES AND INCENSE
When candles are burned, they emit trace amounts of organic chemicals, including acetaldehyde, formaldehyde,
acrolein, and naphthalene (Lau et al., 1997). However, the primary constituent of public health concern in candle
emissions is lead. Metal was originally put in wicks to keep the wick standing straight when the surrounding wax begins
to melt. The metal prevents the wick from falling over and extinguishing itself as soon as the wax fails to support it. The
US candle manufacturing industry voluntarily agreed to cease production of lead-containing candles in 1974, once it was
shown that burning lead-wick candles resulted in increased lead concentrations in indoor air (Sobel et al., 2000b).
Unfortunately, despite the voluntary ban, lead wick candles
can still be found on the market.
According to the National Candle Association (NCA), most US candle manufacturers have abided by the agreement to
cease lead wick production. All of the NCA members have signed pledges not to use lead wicks in candles they
manufacture. In addition, the NCA has sent a letter to all the candle manufacturers registered with the Thomas Register
of American Manufacturers informing them of the potentially adverse health effects associated with wicks that contain
lead and asking them to sign pledges not to use wicks containing lead in their candles. The NCA has also sent letters to
retailer trade associations to inform them of this issue.
The NCA states that only a small number (one or two) of candle manufacturers make their own wicks. The rest purchase
wicks from wick manufacturers. One such manufacturer is Atkins and Pearce, Inc.; they claim to have stopped making
and selling wicks with lead in 1999.
The Candle Product Subcommittee of the American Society of Testing and Materials (ASTM) is working on voluntary
standards for candle content, including labeling standards. It is anticipated that this standard will address the lead issue.
The draft standard was presented at the fall 2000 ASTM meeting.
There have been limited investigations regarding the prevalence and source of candles with lead wicks. ERG did not find
any statistical studies investigating the presence of lead-wick candles in the US marketplace. However, a handful of
studies contain some information about the occurrence of lead-wick candles in the local study areas. The following
discussion and Table 6 present information on lead and other chemicals emitted from candles.
Lead Wick Emissions
In February 2000, the Public Citizen's Health Research Group conducted a study of the lead content of candles in the
Baltimore-Washington area. They purchased 285 candles from 12 stores, excluding candle-only stores, and tested the
wicks for the presence of lead. They found that nine candles, or 3% of the candles they purchased, contained lead. Total
lead content ranged from approximately 24,000 to 118,000 ?g (33 to 85% of the weight of the metal in the candle wick).
An academic study was conducted on the emissions of lead and zinc from candles with metal-core wicks (Nriagu and Kim,
2000). For this study, the researchers purchased and tested candles (found in Michigan stores) that had metal-core
wicks. Fourteen brands of candles manufactured in the US, Mexico, and China were found to contain lead. Emission rates
from candles ranged from 0.52 to 327 ?g-lead/hour, resulting in lead levels in air ranging from 0.02 to 13.1 ?g/m 3 .
These concentrations are below the Occupational Safety and Health Administration (OSHA) Permissible Exposure Limit 4
(PEL- Permissible Exposure Limit: These OSHA standards were designed to provide health protection for industry
employees by regulating exposure to over 300 chemicals. PELs are an 8-hour time weighted average.) of 50 ?g/m 3 ,
but above the EPA outdoor ambient air quality standard (EPA Outdoor Ambient Air Quality Standards: Required by the
Clean Air Act, these standards were set for pollutants thought to harm public health and the environment, including the
health of "sensitive" populations such as asthmatics, children, and the elderly) 5 of 1.5 ?g/m 3 . It is important to note
that, although the EPA standard was not developed for use for indoor air comparisons, it is used throughout this report
as a conservative comparison value. OSHA's PEL values should also be interpreted with some caution for they are
occupational standards not designed for the protection of the general public, children, or sensitive populations.
Another prominent study, van Alphen (1999), examined emissions and inhalation exposure-based risks for candles
having lead wick cores. The mean emission rate was 770 ?g-lead/hour, with a range of 450 to 1,130 ?g-lead/hour. A
candle burned for 3 hours at 1,000 ?g-lead/hour in a 50 m 3 room with poor ventilation is estimated to yield a 24-hour
lead concentration of 9.9 ?g/m 3 , and a peak concentration of 42.1 ?g/m 3 . OSHA's 50 ?g/m 3 PEL is not approached
in this study, but again, EPA's outdoor ambient air standard of 1.5 ?g/m 3 is exceeded.
Sobel et al. (2000a) modeled lead emissions from candles containing lead wicks. After burning multiple candles in a
contained room, 24-hour lead concentrations ranged from 15.2 to 54.0 ?g/m 3 . The candle containing the least amount
of lead produced lead concentrations of 30.6 ?g/m 3 in 3 hours. The maximum concentration of 54 ?g/m 3 is above the
PEL standard of 50 ?g/m 3 and EPA's outdoor ambient air quality standard of 1.5 ?g/m 3 .
After the ban on lead-containing wicks, candle companies began looking for alternatives that provided the desired
characteristics of the lead wick without the harmful emissions. Many companies turned to braided wicks, which consist of
three smaller wicks wound together to provide some stiffness. Zinc cores are also commonly used, since the metal
provides the desired amount of stiffness, burns off readily with the rest of the wick, and does not have the same toxic
effects as lead.
Zinc is an essential element for human health. However, inhaling large amounts of zinc (as zinc dust or fumes from
smelting or welding) over a short period of time (acute exposure) can cause a disease called metal fume fever. Very
little is known about the long-term effects of breathing zinc dust or fumes (Eco-USA.net, 2000).
Nriagu and Kim (2000) found the release of zinc from metal-core wicks to be 1.2 to 124 ?g/hour, which is too low to be
of health concern in indoor air. All nonferrous metals have traces of lead impurities; for zinc, the maximum lead content
is 0.004% (Barker Co., 2000). The lead emissions from zinc wicks are below the detection level of most test methods
(Barker Co., 2000), though one study found emission rates of 0.014 ?g-lead/hour (Ungers and Associates, 2000).
Tin is also commonly used as a stiffener for candle wicks. It is considered to be nontoxic (Chemglobe, 2000). Tin has a
maximum lead content of 0.08%, but, like zinc, lead emissions are below the detection limit when tin wicks are burned
(Barker Co., 2000).
Several organic compounds have been detected in candle emissions. Three articles have focused specifically on this
topic. Lau et al. (1997) measured levels of selected compounds in candle materials and modeled human exposure to a
worst-case scenario of 30 candles burned for 3 hours in a 40 m 3 room with realistic air flow conditions. Schwind and
Hosseinpour (1994) analyzed candle materials and the combustion process, and created a worst-case scenario of 30
candles burned for 4 hours in a 50 m 3 room with approximately 0.7 L/min air flow. Fine et al. (1999) also performed a
series of emission tests on the combustion of paraffin and beeswax candles burned in an air chamber with a volume of
approximately 0.64 m 3 and an air flow rate of 100 L/min. Results of the studies are presented below and in Table 6
(Table 6 currently unavailable at KSL.Com)
Acetaldehyde levels for 30 candles burned in an enclosed room for 3 hours were modeled at 0.834 ?g/m 3 (Lau et al.,
1997); this is above the EPA's 10 -6 excess cancer risk level 6 of 0.5 ?g/m 3 , but below the EPA inhalation reference
concentration (RfC)7 of 9 ?g/m 3 .
Formaldehyde levels were measured at 0.190 ?g/m 3 (Lau et al., 1997) and 17 ?g/m 3 (Schwind and Hosseinpour,
1994). Again, these measurements were above the EPA's 10 -6 excess cancer risk level of 0.08 ?g/m 3 , but below the
OSHA PEL maximum of 921.1 ?g/m 3 . Formaldehyde levels for both studies were far below OSHA's STEL 8 maximum of
2,456.1 ?g/m 3 .
Maximum concentrations of acrolein were measured at 0.073 ?g/m 3 (Lau et al., 1997) and <1 ?g/m 3 (Schwind and
Hosseinpour, 1994). These levels are above the RfC of 0.02 ?g/m 3 and below the PEL of 250 ?g/m 3 . A cigarette
burned in a similar environment produces acrolein levels of 23 ?g/m 3 (Lau et al., 1997).
Levels of PCDD/PCDF were measured at 0.038 pg I-TEQ/m 3 (Schwind and Hosseinpour, 1994). The TEQ is the toxic
equivalency method used to evaluate dioxins. It represents the sum of the concentrations of the multiple dioxin
congeners "adjusted" to account for the toxicity of each congener relative to the most toxic dioxin, 2,3,7,8-TCDD.
Polyaromatic Hydrocarbons (PAHs)
The amount of PAHs measured in candle emissions and soot differs between studies. Fine et al. (1999) found that no
significant levels of PAHs were detected in the emissions from normal burning and smoldering candles. In contrast,
Huynh et al. (1991) found that soot from wax-light church candles contained measurable concentrations of PAHs: the
study measured 882 ?g benzo[ghi]perylene per gram of candle soot and 163 ?g benzo[a]pyrene per gram of candle
However, Huynh et al. did not measure PAH concentrations from candles in air. Wallace (2000) also concluded that a
citronella candle was a source of PAHs in a study of real-time monitoring of PAHs in an occupied townhouse, but did not
quantify the concentration or emission rate.
Concentrations of benzo[a]pyrene in air due to candle emissions can measure 0.002 ?g/m 3 (Lau et al., 1997). This is
below the PEL value of 200 ?g/m 3 . Naphthalene maximum concentration
Black Soot Deposition (BSD) is also referred to as ghosting, carbon tracking, carbon tracing, and dirty house syndrome.
Complaints of BSD have risen significantly since 1992 (Krause, 1999).
Black soot is the product of the incomplete combustion of carbon-containing fuels. Complete combustion would result in
a blue flame, and would produce negligible amounts of soot and carbon monoxide. Until recently, the source for the
black soot in homes was unknown.
Through interviews and recent experiments, it is now believed that frequent candle burning is one of the sources of
black soot. The amount of soot produced can vary greatly from candle to candle. One type of candle can produce as
much as 100 times more soot than another type(Krause, 1999). For example, elemental carbon emission rates varied
from less than 40 to 3,370 ?g/g candle burned in a study of sooting behavior in candles (Fine et al., 1999).The type of
soot may also vary; though primarily composed of elemental carbon, candle soot may include phthalates, lead and
volatiles such as benzene and toluene(Krause1999).
Scented candles are the major source of candle soot deposition. Most candle wax paraffins are saturated hydrocarbons
that are solid at room temperature. Most fragrance oils are unsaturated hydrocarbons and are liquid at room
temperature. The lower the carbon-to-hydrogen ratio, the less soot is produced by the flame. Therefore, waxes that
have more fragrances in them produce more soot. In other words, candles labeled "super scented" and those that are
soft to the touch are more likely to generate soot.
The situation in which a candle is burned can also impact its sooting potential. A small and stable flame has a lower
emission rate than a larger flickering flame with visible black particle emissions (Vigil, 1998). A forced air flow around
the flame can also cause sporadic sooting behavior (Fine et al., 1999). Thus, candles in glass containers produce more
soot because the container causes unsteady airflow and disturbs the flame shape (Stephen et al., 2000). Candles that
are extinguished by oxygen deprivation, or blowing out the candle, produce more soot than those extinguished by
cutting off the tip of the wick. Cutting the wick eliminates the emissions produced by a smoldering candle (Stephen et
When soot builds up in air, it eventually deposits onto surfaces due to one of four factors. First, the particle may
randomly collide with a surface. Second, soot particles can be circulated by passing through home air-conditioning filters.
Third, soot can gain enough mass to become subject to gravity. Homes with BSD often have carpets stained from soot
deposition (Vigil, 1998). Finally, the particles are attracted to electrically charged surfaces such as freezers, vertical
plastic blinds, television sets, and computers (Krause, 1999).
When soot is airborne, it is subject to inhalation. The particles can potentially penetrate the deepest areas of the lungs,
the lower respiratory tract and alveoli (Krause, 1999). ERG did not find research literature on the health effects of
residential exposure to candle soot.
Candles with lead wicks have the potential to generate indoor airborne lead concentrations of health concern. It is also
possible for consumers to unknowingly purchase candles containing lead wick cores and repeatedly exposes themselves
to harmful amounts of lead through regular candle burning.
Lead wicks aside, consumers are also exposed to concentrations of organic chemicals in candle emissions. The
European Candle Association (1997) and Schwind and Hosseinpour (1994) conclude that there is no health hazard
associated with candle burning even when a worst-case scenario of 30 candles burning for 4 hours in a 50 m 3 room is
assumed. However, burning several candles exceeded the EPA's 10 -6 increased risk for cancer for acetaldehyde and
formaldehyde, and exceeded the RfC for acrolein. Once again, the RfC and EPA's 10 -6 increased cancer risk guidelines
are not designed specifically for indoor air quality issues,so these conclusions are subject to interpretation.
Consumers may also not be aware that the regular burning of candles may result in BSD, causing damage to their
homes. Sooting can be reduced by keeping candle wicks short, drafts to a minimum, and burning unscented candles.
Additional research may want to focus on gaps in the literature, such as emissions from scented and multi-colored
candles, and maximum concentrations of organics in air produced by sooting candles.
Reports of PAHs in incense soot have been contradictory. Chang et al. (1997) did not find PAHs in the vapor extract of
incense smoke. However, Koo (1994) determined that PAH levels rose with incense burning in a study of Hong Kong
residences. Incense soot was found to contain measurable concentrations of fluoranthene, pyrene, enzo[b]fluoranthene,
benzo[k]fluoranthene, benzo[a]pyrene, dibenzo[def,p]chrysene, benzo[ghi]perylene, ideno[1,2,3,-cd]pyrene,
anthanthrene, and coronene (Huynh et al., 1991). Though the study established that the maximum dust concentration
corresponded with the burning of incense, maximum concentrations of PAHs from incense burning were not calculated.
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