Paraffin is a petroleum product - a byproduct of oil refining. Most fragrance oils used for candle making are petroleum-based synthetics. The soot from these materials can contain carcinogens, neurotoxins, and reproductive toxins. Testing and air chamber analysis by the Environmental Protection Agency (EPA) has found the following compounds, in significant quantity, in a random group of over 30 candles tested: acetone, benzene, trichloroflouromethane, carbon disulfide, butanone, trichloroethane, carbon tetrachloride butanone, trichloroethane, carbon tetrachloride, carbon black (soot) particulate matter, trichloroethene, tetrachloroethene, tolulene, chlorobenzene, ethylbenzene, styrene, xylene, phenol, cresol, cyclopentene, and lead. Obviously, you would have to be a chemist to truly know what most of these chemicals are, but according to the EPA, they pose a health hazard with continued exposure over time.