The recent increased popularity of scented candles has prompted concerns by consumers and public health officials about their emission products. According to the National Candle Association, candle sales are approaching 2 billion dollars annually. The combustion of scented candles in residences, which typically have low ventilation rates, may raise indoor concentrations of combustion products. A recently described phenomenon of residential black soot deposition, sometimes associated with scented candle usage, prompted concerns that occupant exposures to soot and other candle emissions may constitute a health risk. The lack of data on candle emissions prompted this research into the volatile, semi-volatile and particulate emissions from scented candles and their potential health risks.
This study characterized the products of emission by individually burning 91 candles inside a stainless-steel combustion chamber and determining specific emission rates of soot, benzene and lead. Candle soot was typically less than 1 μm, contained up to 66% elemental carbon and carried numerous adsorbed organic compounds including dibutyl phthalate, diethyl phthalate, toluene and styrene. Volatile organic compound emissions included benzene, styrene, toluene, ethyl benzene, naphthalene, acetylaldehyde, benzaldehyde, benzeneethanol, and 2-butanone. Analysis for lead revealed some candles emitted significant quantities of aerosolized lead during combustion. A risk assessment of occupant exposures to soot, benzene and lead resulted in the highest attributable risk being from soot, ranging from 9.7 x 10-5 to 4.7 x 10-2. Benzene exposures were estimated using an indoor exposure model resulting in an increased cancer risk of less than 10-5. Lead exposures were modeled for children and suggest the potential to raise blood lead levels of children above 10 μg/dl when typical background exposures are also present. The possible impacts on public health from consumer use of scented candles may include increased risk of cancer, neurological and behavioral deficits and acute aggravation of existing respiratory diseases such as asthma.
Masters Thesis: University of South Florida
Written by J. David Krause
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