theirs health hazard for burning incense sticks in your home!?

Question

is this true and if so what

Answer 1

Evaluation basis
Incense sticks are manufactured from incense mass of dried pulverised herbs and wood kept together with a binding agent. The incense sticks contain or is added different forms of aromatic (perfumed) or stimulating compounds that often are herbs or extracts from plants, wood, etc.

The burning of incense sticks causes the emission of a strong smoke and fragrance. Because the burning in general takes place in confined environments (e.g. closed rooms) the influence may be heavy.

Since incense sticks are not labelled, which substances they are manufactured from the smoke and the added stimulating substances may pose a health problem.

Incense sticks can be purchased in specialised shops or on the Internet. The labelling usually concerns the country of origin (China, Indonesia, India, etc.), which fragrance is dominant or which effect the fragrances are stated to have or affect (headaches, stress, or similar).

After the qualitative analyses are performed, the results are evaluated. Data on the individual substances such as threshold limit values, effect levels, no observed adverse effect level (NOAEL) or lowest observed adverse effect level (LOAEL), or other relevant data are used, as they are available. If data are unavailable, alternatively information from analogous substances or data based on structure analyses on the chemical substance (QSAR: quantitative structure analysis relationship) may be used. A comparison with the EU classification criteria is performed.

The exposure of the consumer is evaluated on basis of consumer scenarios. The principles for the evaluation will be based on the EU revised Technical Guidance Document (EC 2003) for risk assessments. The exposed consumers will in consideration of realistic worst case be adults with a body weight of 70 kg and children with a body weight of 10 kg.

The primary exposure route for incense is considered to be via inhalation (i.e. inhalation of vapours and aerosols).

The exposure will depend on contact parameters such as frequency and duration of the use of the product, the amount of product used at each event and the concentration of the contained chemical substances. Because most often one incense stick is used at a time, the consumer scenario will be based on 1 incense stick burned in a room of limited volume of 20 m3 with an air change (ventilation) of 0.5 times per hour. The burning duration of the individual incense sticks varies between 25 to 50 minutes (cf. table 3.6).

Therefore, to be able to compare the incenses, an exposure during the burning of one incense stick in a 20 m3 room is calculated as µg substance per incense stick (µg/incense stick) and the exposure per hour by continuous burning for one hour (µg/hour).

For the evaluation of the level of exposure, different scenarios based on the measured emission are calculated in a box model (standard room of 20 m3 with an air change of 0.5 times/hour). This will be discussed in a separate section.

Method
Of the chemical substances found in the emissions from the incense it was evaluated which substances appeared to be the most problematic. The selection was made in agreement with the Danish Environmental Protection Agency. Data on the individual substances were then procured from available sources with the purpose of a health hazard evaluation based on known information from previous Danish and foreign monographs, reviews, etc. The data on toxicity found were then compared with the concentrations estimated in the used scenarios.

The methodology used is approximately the same as recommended in connection with risk assessment in the European Union (EU) i.e. Technical Guidance Document (TGD 2003). In the TGD the potential risk to the consumer is estimated as the ratio between the predicted exposure concentration (PEC) and the predicted no-effect concentration (no-adverse-effect level (NOAEL). NOAEL is usually based on mammalian data other than humans: typically rats, mice and rabbits. Therefore, safety factors are introduced to cover differences extrapolating from other animals to humans. This is expressed either by attaching a fixed safety factor (SF) or by expressing the margin of safety (MOS), which represents the distance of the estimated concentration to the NOAEL. Typically MOS is preferred to be above 100.

The safety factor is interpreted as being a margin of safety applied to a NOAEL to produce a value below which exposures are presumed to be without significant health risk (i.e. safe). The safety factor is traditionally composed of a factor 10 for extrapolation between species (animal to human, intraspecies variation), a factor 10 to protect the most sensitive individuals of the population (e.g. children: interspecies variation). A third factor is applied depending on the data and may vary. For instance it is 10 if LOAEL (lowest observed adverse effect level) is used instead of NOAEL. The total safety factor is a result from multiplication of the three factors.

The effect level divided by the safety factors or the assessment factor is used to evaluate whether there is reason of concern (concern level) or a further refinement of methodology or data is necessary. Thus the evaluation may be expressed on basis of concentration divided by the safety factor or MOS (humans).

The classification authorised in Denmark (Miljøministeriet 2002), which is an implementation of the EU classification (28th amendment to EU directive 67/548/EEC), is used in the evaluation. For the evaluation of each compound is used the threshold limit values obligatory for the working environment in Denmark (Arbejdstilsynet 2002) applied with a safety factor of 100. The safety factor is derived by recalculating threshold limit value from the working environment based on 8 hours per day for 5 days a week to indoor values at 24 hours a day for 7 days a week (24/8´ 7/5 = 4.2), applying an extra safety factor of 10 for sensitive individuals and an extra factor of 2: a total of 100. This means that a safety margin of 100 is used.

The threshold limit value for the working environment (Arbejdstilsynet 2002) is only valid where the chemical substances are used in the production. The threshold limit values are based on 8-hour time weighted average (a working day). It is important to note that the threshold limit value does not include consumers at home.

Other parameters included for the health evaluation were:

ADI:
Acceptable Daily Intake. A value calculated from NOAEL by an official authority as an acceptable daily intake (mg/kg body weight/day. ADI is usually based on chemical substances in food.

C-value:
Contribution value: The C-value is defined in Miljøstyrelsen (2002) as the total maximal allowed contribution to the air pollution from an enterprise to the environment outside the production site.

RfC
Reference concentration. RfC is an inhalation reference concentration based on the assumption that a threshold limit value for certain toxic effects exists. The value is based on NOAEC from inhalation studies of subchronic or chronic character and includes safety factors. The value is given in mg/m3.

RfD
Reference dosis. RfD is an oral reference dosis based on the assumption that a threshold limit for certain toxic effects exists. The value is based on NOAEL from subchronic or chronic studies using oral administration and includes safety factors. The value is given in mg/kg body weight/day.

TDI:
Tolerable Daily Intake. Almost identical to ADI but usually based on chemical pollutants.


Evaluation methodology
Effect level
The effect level for each incense is based on evaluation of individual substances. The established Danish threshold limit values are used when they exist. When no Danish threshold limit values exist, foreign threshold limit values are used including description of their background, if available.

The used threshold limit values for the measured substances are presented in Appendix B with the classification.

The indoor air quality depends of several factors (ventilation, temperature, etc.) and other sources. In this report only the contribution from incense is considered but it should be noted that other sources to the same chemical compound may exist in the consumer´s residence (e.g. by smoking, cooking, volatiles from paint, lacquers, carpets, etc.).

The exposure of the consumer in the home is besides the concentration in the indoor air also dependent on the exposure duration. Because the exposure duration may vary considerably, a maximal exposure of 1 hour is assumed. However, the ventilation is included using an assumed air change in the indoor scenarios of 0.5 times per hour, i.e. 50% of the air is exchanged every hour.

Inhalation
Exposure to the substance via inhalation may occur from inhalation of vapours and aerosols. The vapours are sampled on XAD2, DNPH and charcoal filters. The aerosols are sampled on Whatman Glass fibre filters, which also sample particles like smoke, soot, etc.

The exposure period may theoretically extend from the acquisition or purchase of the incense until it is used. The substances, to which consumer is exposed during the holding period, may approximately be assumed to be the substances observed in the "head-space" analyses.

The exposure via inhalation is expressed as the concentration of the chemical substance in the air in the breathing zone and expressed as an average concentration over a reference period, e.g. 8 hours for the working environment. For the consumers of incense the exposure period may be from the time, which 1 incense stick takes to burn to considerably longer time if more incense is burned and the duration for all emission products to be ventilated out of the room/home.

For estimation of the exposure via inhalation, the inhalation rate must be known, the size of the room and the emission rate of the substance to the room or the concentration in the room.

The inhalation rate for an average adult is set to 20 m3/day corresponding to 0.83 m3/hour (standard in TGD 2003) and for a child to 3 m3/day corresponding to 0.125 m3/hour.

The concentration in closed rooms is assumed to be higher than in ventilated rooms. For the calculation of the concentration in the room it is assumed that the substance is emitted instantly to the entire room and is homogeneously dispersed. The size of the standard room is set to 8 m2 and the height 2.5 meter, i.e. the volume of the room is 20 m3.

The concentration in inhaled air can then be calculated according to the equation:



Cinh
Concentration in inhaled air
mg/m3

Qprod
Quantity of incense (product) used in the room
g

Qair
Quantity substance emitted from the incense to the room
mg/g

Vroom
Volume of the room
m3
Used: 20 m3


Amount of inhaled substance is then (TGD 2003):



Iinh
Amount inhaled substance
mg/kg bw/d

Fresp
Inhalable or respirable fraction of the substance
set to 1 (i.e. 100%)

Cinh
Concentration in the air
mg/m3

Qinh
Inhalation rate for adult
m3/hour
(adult: 0.83 m3/hour)

Tcontact
Duration of exposure
hours

Nevent
Number of events
(usually per day)

BW
Body weight
kg
(Used:
Adult: 70 kg
Child: 10 kg


As a starting point as previously mentioned a scenario of a room with the volume 20 m3 is used. The size of the room is deliberately assumed small considering the realistic "worst case" but including an air change of 0.5 times per hour.

In return it could be argued that the incense does not distribute itself evenly throughout the room or instantly. A scenario using an air volume of 2 m3 around the exposed person may be more realistic. However, such a high concentration would probably be of short duration and present large variations in the exposure. Therefore it was chosen to maintain a distribution in 20 m3 as a reasonably high "average" of what would be expected as normal during use of 1 incense unit (incense stick or cone) which may take 25 to 50 minutes.

Product evaluation
A comparison of each product was not the purpose of this study. The survey was to focus on which substances could be found in a representative selection of incense types and if they could be expected to cause any problems to the consumer of incense.

An attempt of comparison has been performed anyway considering only the range observed in the study. For comparison a common unit is needed and the effects from the emitted substances are widely different. Therefore, a comparison based on the emission of volatile organic compounds and the emission of aerosols is used. The aerosol emission expresses the amount of particle material emitted during burning of incense. Refer to chapter 5 for further details.

Answer 2

Depends on if you're asthmatic. Incense gives of a perfumed scent and the smoke from it contains soot. Hold a white 5x7 card above the burning stick or cone and see what accumulates on the card, high enough not to burn the card.

Answer 3

Burning incense can be if you happen to be sensitive to strong fragrances. If the weather allows open the windows when you burn it so that the fragrance is diluted. Plus, of course, you should burn it on a surface that won't catch fire and keep an eye on it.

Answer 4

People with respiratory problems must be careful. There have been some allergic reactions documented too. Make sure you get good quality sticks that won't fill your room with smoke, and keep a window open.

Answer 5

no if there were they would have to advertise that or you would of heard about it more publicaly