Incense  Smoke

I have read that exposures to incense smoke may cause cancer particularly in children.  We burn incense regularly.  Should we be concerned about our children? Anon

            In a posting on this website on May 24, 2001 it was indicated that little published information was available on either the emissions from burning incense or its potential health effects.  Since that time, however, there has been a significant increase in the number of studies that have focused on incense and its potential health effects and awareness of other published studies.

            Studies on incense have tried to take into account that a variety of substances/materials can be burnt as incense.  Substances used to produce incense includes resins such as frankincense (from the sacred Boswella tree) and myrrh; spices, aromatic wood and bark, seeds, roots, flowers, aromatic oils, and a variety of synthetic materials.  Incense is available as sticks, cones, coils, powders, rope, rocks/charcoal and smudge bundles.

            Incense sticks are made from a slender piece of wood to which incense substances are attached; joss sticks are formed from the incense material itself.  Cones are pointed at the top to facilitate ignition and as they burn down to a larger diameter base produce much more smoke. Coils are designed to burn for a long time and have often contained an insecticide to control insects.  Smudge bundles are bundled herbs and twigs which tend to produce large quantities of smoke.      

            Your question relates to an issue raised in previous postings; that is, the potential for incense combustion by-products to cause cancer in individuals exposed over a period of time.  In a 1982 study, a significant correlation was reported between maternal contact with nitrosamine-containing substances such as incense and brain cancer in children (however, in a 1994 Australian study no relationship was observed between brain cancer and post-natal incense burning).

           Another study showed an increased risk of developing leukemia for children whose parents burnt incense in the home before pregnancy or during the nursing period. A study conducted in Singapore reported that incense burning increased the relative risk of lung cancer . However, four other studies conducted in different countries were not able to show that exposure to incense smoke increased the risk of developing lung cancer.

            Burning incense like many other materials has the potential to produce carcinogens.  The most notable of these are benzene and polycyclic aromatic hydrocarbons (PAHs).  Exposure to benzene has been definitively shown to cause leukemia in industrial workers and there is limited evidence to indicate that emissions of benzene in tobacco smoke is responsible for the increased risk of childhood leukemia in smoking households.  In a 1991 study a benzene production rate of 420-440 µg per gram of benzene burnt was reported.  In large chamber studies conducted in Hong Kong, benzene levels increased by more than 15 fold from pre-incense burning levels.  In Danish studies, an exposure of 1.8 µg/kg body weight per day was estimated as a result of burning one incense stick in an under-ventilated room. 

            PAHs are a class of higher carcinogenic compounds commonly found in the smoke of combusted organic materials.  PAHs, as would be expected, have been found in the smoke from burning incense and in the settled dust of buildings where incense has been burnt.

            Should you be concerned about potential cancer and other health risks to your children because you regularly burn incense?  The answer is of course yes.  Though the science is limited, there is sufficient evidence to practice “prudent avoidance,” that is, don’t subject your children or family to a potential risk like this that can be very easily avoided.

 

November 3, 2006