Incense sticks (or agarbattis as called in India and adjoining nations) are one of omnipresent essential entity of all religious rituals in East, both for living as well for dead. If the advertisements are to be believed, incense provides a soothing pleasant aroma that helps in concentration, meditation and even has aphrodisiac ability.
Intelligent people don’t believe in advertisement and neither did the researchers from South China University of Technology and the China Tobacco Guangdong Industrial Company in China. This group of researchers for the first time proved that incense smoke is as harmful as cigarette smoke.
Indoor air pollution affects the health of the household because of two apparent reasons:
a: Activities like cooking, smoking, and burning incense happen on daily basis. Moreover, these activities are repeated day over, so the harmful residues from these activities get concentrated over time.
b: People spend most of their indoors. Thus, they breathe air which is highly concentrated with the residues of the flame-dependent activities.
Just like cigarette smoke, epidemiological investigations have demonstrated that the combustion of incense is correlated with lung cancer, childhood leukemia and brain tumors. Incense burning being a part of tradition (and religion) prevented in-depth analysis of its harmful effects. The raw materials used to make incenses are diverse, but two of the most common ingredients are agarwood and sandalwood tree resin. The researchers short-listed two incense types with these two components for their study. The smoke from a cigarette (3R4F reference cigarette, University of Kentucky) was measured on a smoking machine, according to ISO 3308:2000. The total particulate matter and major chemical components of two types of incense smoke were characterized using an electrical low pressure impactor and gas chromatography coupled with mass spectrometry. Their genotoxicity and cytotoxicity were compared with mainstream tobacco smoke using in vitro assays.
Four different incense sticks (sourced from Australia, Indonesia, Malaysia and southwest China) were experimentally involved in 45 min of incense burning. The observations/analysis of these experiments are reported as:
Particle size distribution: The aerodynamic diameters of particulates emitted by these four samples were all below 5 uM. Particles smaller than 0.1 uM are labeled ultrafine particles, and those between 0.1 and 2.5 uM are termed fine particles. The data obtained from this study clearly showed that the particulate number and mass measured in incense smoke were dominated by ultrafine and fine particles (99%) which is likely to cause adverse health effects such as bronchitis etc.
Chemical composition: The highly volatile compounds common to all four samples were mostly irritants and hypotoxic. A number of compounds occurred in all four samples, including monoterpenes, methoxylated phenolics, two hexose dehydration compounds, as well as other highly volatile compounds. There also were some hypertoxic compounds detected in one or two samples, for example ethyl cyanoacetate and 2-butenal.
In vitro mutagenicity: The total particulate matter from four incense smoke samples was shown to be mutagenic in Ames tests. Incense smoke contains chemical properties that could potentially change genetic material such as DNA, and therefore cause mutations.
In vitro cytotoxicity: Genotoxicity to different strains of certain incense samples was higher than for the reference cigarette sample with the same dose. The half maximal inhibitory concentration of this cigarette was much higher than for the four incense samples, indicating that incense smoke was more cytotoxic against Chinese hamster ovary cells.
Incense smoke was also more cytotoxic and genotoxic than the cigarette smoke used in the study. This means that incense smoke is potentially more toxic to a cell, and especially to its genetic contents. Mutagenics, genotoxins and cytotoxins have all been linked to the development of cancers.
The authors conclude as “Clearly, there needs to be greater awareness and management of the health risks associated with burning incense in indoor environments but one should not simply conclude that incense smoke is more toxic than cigarette smoke. The small sample size, the huge variety of incense sticks on the market and differences in how it is used compared to cigarettes must be taken into account.”
The burning of incense might need to come with a health warning.
Article Citation: Zhou, R.; et. al. Higher cytotoxicity and genotoxicity of burning incense than cigarette. Environmental Chemistry Letters. 2015. DOI:10.1007/s10311-015-0521-7.