(47cv) Possible Two Physical Hazard Scenarios for Polystyrene Foams, Based on Life Cycle Stages

Polystyrene foams are good thermal insulators and therefore widely used in building insulation materials, such as roofs, and/or walls, down to foundation. However these foams have significant physical hazards (fire, etc.), because flammable blowing agent has come to be used, and foamed polystyrene itself is combustible. And so, HBCD (Hexabromocyclododecane) is generally used as flame retardant in polystyrene insulation foams, while currently a global ban on HBCD is being considered under the framework of Stockholm Convention on Persistent Organic Pollutants (POPs), due to persistence, toxicity and eco-toxicity.

Under these circumstances, attempts to find environmental-compatible flame retardants are being performed by, such as ENFIRO, a European Commission-funded project of offering a prototypical case study on substitution options for specific brominated flame retardants for plastics, based on flammability, environmental and toxicological risks.

On the other hand, the incident scenarios for chemical process are generally related to the immediate impact of unplanned releases of material and energy, where the effects of fire, explosion or acute toxicity are targeted. It is indeed possible to cause a fire, in case of flammable blowing gas release from polystyrene foam to the atmosphere, such as in a warehouse of low air exchange rate, because static electricity can be accidentally the ignition source. Regarding the toxic potency in fire hazard, a model, based on the calculation of a Fractional effective Exposure Dose (FED) of mixture of smoke gases, had been previously developed by Building and Fire Research Laboratory, NIST, where some most toxic chemicals in LC50, caused by plastic burning, played important role in mixture gas toxicity.

This paper describes the possible two physical scenarios for polystyrene foams, based on life cycle stages; 1)Production/import, 2)Storage/transport, 3)Industrial usage/private usage, 4)Waste disposal. One is acute toxicity gas release scenario by incomplete combustion case (nearly 400C), and the other is flammable blowing gas release scenario directly from the foam itself (nearly 100C).

The acute toxicity gas releases between two flame retardants (HBCD and phosphorous based chemical) in EPS fabricated products, were compared at 400C, heated by electric furnace, and analyzed by gas chromatography. The detected CO gas concentration was higher at EPS foams with HBCD than foams of tested phosphorous retardant.

The flammable gas releases between two foams (EPS, XPS) were analyzed by FTAI (Fauske & Associates), while XPS(Company A, B) was higher in concentration than EPS (company C), which was the same inclination with gas chromatography analysis.