The heating of sugars over 200 oC can lead to the progressive dehydration of the sugar molecules to produce volatile and nonvolatile products. Pyrolysis temperatures, the presence or absence of oxygen and the duration of process can all influence the number and types of byproducts. Products formed can run the gamut from H2O, CO, CO2, aldehydes, ketones and carboxylic acids to more complex structures such as polyaromatic hydrocarbon (PAHs) and phenols. Decarbonylation and decarboxylation reactions can also progress to charring and the generation of elemental carbon.
It is very likely that one or more of these byproducts will possess carcinogenic / mutagenic properties.