A recent study shows that burning paraffin wax releases harmful chemicals such as toulene, reported to cause harmful effects to humans. Please check the label of the wax tart or candle you're using. Unless it clearly states otherwise, the main ingredient is probably paraffin.
Beyond potential health concerns, you should also be aware that paraffin is a by-product of petroleum refinement. An oil refinery or petroleum refinery is an industrial process plant where crude oil is processed and refined. Oil refineries are typically large, sprawling industrial complexes with extensive piping running throughout, carrying streams of fluids between large chemical processing units. In many ways, oil refineries use much of the technology of, and can be thought of, as types of chemical plants.
Believe it or not, if your are burning or melting paraffin wax in your home, an oil refinery is where your wax tart originated. The feedstock for paraffin is slack wax. Slack wax is a mixture of oil and wax, a byproduct from the refining of lubricating oil.
When U.S. researchers burnt a range of candles in a laboratory for a study published in 2009, the chemicals released in harmful amounts included human carcinogens and chemicals known to cause asthma attacks, such as toluene and benzene. Dr Amid Hamidi of South Carolina University, who led the study, showed that paraffin-based candles produced ‘clear sharp peaks’ for many chemicals, mainly because they do not reach high enough temperatures when being burned to destroy the hazardous molecules they emit. ‘An occasional paraffin candle and its emissions will probably not affect you,’ he said. ‘But lighting many of them every day for years, or lighting them frequently may cause problems.’
A perfectly reasonable alternative to paraffin wax exists. Soy wax causes no known health issues, and is created in a green, renewable manner. Paraffin wax on the other hand, is facing a worldwide decline in production because it is simply not renewable. In fact, demand for paraffin wax is growing fastest as a plasticizer in the production of PVC. Yummy!