An initial study by CREPIM France, for pinfa (see Editorial above) has collated and assessed available scientific literature on how PIN flame retardants affect fire smoke toxicity.
The literature survey covers both fire gases and smoke particles (soot). This initial assessment did not consider PIN chemicals expressly used as smoke suppressants. 135 relevant publications were identified, over the last 30 years, of which 22 were found to contain useable information and data (of these, 6 deal with real fires rather than lab fire tests). These studies are analysed in detail in the 140 page report. The report notes that smoke emissions and toxicity in real fires are controlled by how the fire develops (ventilation, temperature) and by the quantity and type of materials which burn. For most materials, both natural and synthetic, yields of toxicants are much higher in under-ventilated fire conditions, and smoke toxicity of nearly all materials is nearly identical (within the margin of error of measurement). Modern plastics generally produce the same types and levels of both acute toxicants (carbon monoxide, hydrogen cyanide) and of carcinogenic VOCs (volatile organic carbons) as does wood. The overall estimated toxicity of fire effluents (FED, fractional effective dose) varies by a factor of around 100 depending on fire scenario, and by a factor of around 10 depending on materials burning. This makes it very difficult to extrapolate the results of lab fire tests to real fires. The CREPIM report concludes that materials in which no flame retardant is present emit high quantities of toxicant in real fires. It also concludes that there is no evidence in any of the publications identified that PIN FRs or synergists increase smoke toxicity. No data was found for inorganic FRs and CREPIM notes that e.g. ATH or MDH have no known toxicity problems, which probably explains the absence of publications. CREPIM note that PIN FRs acting in the solid phase (generation of a protective char layer) can trap and so reduce fire gas and soot emissions. They also note that although some phosphorus PIN FRs act in the gas phase (flame inhibition) there is no evidence of increased smoke toxicity. CREPIM finally underline that “What really matters is that the proper use of PIN FRs and synergists can reduce both the flammability and the heat release rate. This helps fires to remain small for a longer time by delaying the occurrence of the flashover, thus increasing the required safe escape time (RSET) for people and decreasing the fire fatalities.” pinfa understands that the main conclusion of this initial literature study is the lack of directly applicable scientific publications, and therefore intends to pursue this question with further data collection, stakeholder consultation and/or testing.
“Study 1901/01/166 – How PIN FRs affect gas and soot toxicity of smoke in case of fire? Review of the literature”, 140 pages, C.R.E.P.I.M (Centre de Recherche et d’Etudes sur les Procédés d’Ignifugation des Matériaux), 28th April 2017. The study will be presented by CREPIM at the AMI Fire Resistance in Plastics, 5-7 December, Köln https://www.ami.international/events/event?Code=C847