With little hard information to base this opinion on, I contacted Brian Sause, Director of Testing, Certification, & Standards at the HPVA Lab, who said:
The makeup of a fiberboard panel is dependent on the desired properties of the final product. There is a high degree of variability in the products with regard to wood fiber content and alignment, adhesive or resin type used, and other additives to adjust the performance of the panels. I would agree that, as a general precaution, you should consider any composite material unsafe to burn in a household environment due to the unknown makeup. While there are concerns over high emitting products containing formaldehyde in an indoor air environment, toxicity of any combustible materials when ignited is a much greater concern.
HPVA's certification of engineered wood products ensures that they do not contribute to elevated levels of formaldehyde in the home. Formaldehyde naturally occurs in raw wood and even in the human body. A certification does not mean that the products do contain additional formaldehyde, but maintains that they are safe and controlled under anticipated conditions of normal use. For those who are concerned, there are many products available to consumers on the market today that are certified as No-Added Formaldehyde (NAF) and Ultra-Low Emitting Formaldehyde (ULEF) products.
