Comparative study of the toxicity of combustion products from flame retardant and untreated materials

Abstract

Fire retardants improve reaction to fire characteristics such as ignitability and flame propagation. This paper presents the toxicological results of tests performed on eleven pairs of untreated and treated materials, including woods, synthetic materials and textiles (both natural and synthetic). It is shown that the effects of fire retardants on toxicity results can be variable. In addition, the problem of the use of toxicity results is discussed more generally. INTRODUCTIONToxic effects are to be considered as a part of the general reaction to fire behaviour of a material including other characteristics such as ignitability, flamc propagation, rate of heat release, smoke opacity and corrosivity. All those properties of a material interact to determine the growth of a fire and the resulting damage to life and property.Fire retardant treatments make it possible to improve such characteristics as the ignitability and flame propagation of materials. From the safety point of view the effect of such treatments on the toxicity of the effluent thermal degradation products is also important. In a previous paper' comparison of four pairs of fire retardant and untreated woods and synthetic polymers led to the conclusion that all treated materials were more dangerous than the untreated ones, the difference being of varying degrees of importance. This raises a real problem: is it preferable that a product should flare and spread flames without producing too great amounts of toxic gases, or that the same product having been treated, should smoulder while producing more lethal gases?Since the testing of four pairs of materials does not provide sufficient evidence on which to base more general conclusions the present paper presents results on eleven pairs of materials tested in three different temperature conditions. Previous results at approximately 400", 600" and 800°C' have shown that for a majority of the thirty-five materials tested the temperature of approximately 600 "C was the most critical condition as far as toxicity is concerned. It was therefore decided to reduce the temperature interval and to perform this series of tests at approximately 500", 600" and 700 "C. METHODSThe biological testing method, using Wistar rats, has been described in previous paper^.^-^ It is a so-called MATERIALSThe tested materials are listed below with a reference indication for further presentation and discussion of the results. They include wood products (B), plastics (synthetic) (K) and textiles (both natural and synthetic) (T). Where possible, thickness of the sample in mm (d) and the density of the material in kgm-3 ( D ) are given. All samples had a length of 300mm and their weight is given in Table 1 and diammonium-hydrophosphate (NH4)2HP04, approximately 310 g mP2. T7 = Curtain fabric: 58% cotton; 42% fibranne, approximately 250 g m-2. T8 = T7, treated to become fire retardant with ammonium-salts and sodium-tetraborate or Borax (Na2B407.10H20), approximately 250 g mp2.(10.0 g wood; 1.1 to 1.4 g varnish).33). Table 2 gives an ide...

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