|Fig. 1: A common candle. (Source: Wikimedia Commons)|
A recent study presented at the American Chemical Society's national meeting in fall of 2009, in Washington D.C. generated international media coverage. Dr. Ruhuallah asserted that cancerous toxins were given off by paraffin-based candles (see Fig. 1), threatening the lives of candlelit bubble bath enthusiasts world wide. 
Paraffin is a waxy ingredient derived from petroleum. Candles made from the substance are suspected to give off toxic chemicals, like toluene and benzene.  Toluene and benzene are known to be carcinogens (cancer causing agents). Toluene specifically induces DNA strand break downs which affect the central nervous system.
Research on cancerous effects of candles are being funded by the Department of Agriculture. A body which would benefit greatly from a rise in soybean candle production. If paraffin-based candles were to be replaced by soybean it would require 60 million pounds of soybeans anually, which would directly benefit soybean farmers.
Scientists from candlestick companies claim that there's no difference between parafin and vegetable-based candles, with both emitting soot when burned as a natural byproduct of incomplete combustion. With little conclusive evidence on candle emissions let's turn to the general topic of the cancer-causing effects of soot.
Soot is a type of particle matter. Particle matter (PM) is the general term for the mixture of solid particles and water droplets in the air. Particle matter can be large and visible, in the form of soot, smoke, or dust. Particle matter can also be microscopic and invisible to the naked eye. PM2.5 describes fine particle matter with particles less than 2.5 micrometers. 
Polycyclic aromatic hydrocarbons (PAHs) found in fine particle matter were found to be carcinogens.  PAH exposure has been tied to elevated levels of DNA adducts, mutations, and reproductive defects. PAHs come from biomass burning, coal and petroleum combustion, coke and metal production, and car emissions (with diesel-engine and two-wheelers giving off the greatest amount of PAHs).  All of which are common in urban areas. Thus, they tend to have the highest concentrations of PAHs. However, wildfire and open straw burning are among the world's largest PAH contributors. 
According to a study sampling 500,000 Americans in 116 different cities, prolonged exposure to soot particle matter increases the risk of dying from lung cancer or other heart and lung diseases. 
© Mariah Lee. The author grants permission to copy, distribute and display this work in unaltered form, with attribution to the author, for noncommercial purposes only. All other rights, including commercial rights, are reserved to the author.
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 A. C. Revkin, "Soot Particles Strongly Tied to Lung Cancer, Study Finds," New York Times, 6 Mar 02.