Biological evaluation of toxicity caused by combustion of building materials

Abstract

This paper presents results of tests performed on 35 materials, including woods, synthetic and textile materials, which have been submitted to thermal degradation at three different combustion temperatures. In addition, the interpretation and limitations of toxicological test results are discussed more generally. INTRODUCTION -~Although fire fighting techniques have greatly developed and improved over the years and although the way in which buildings are designed as well as the types of materials available to build them have undergone a rapid evolution, the problem of toxicity caused by the burning of building materials, including furniture and decorating elements, remains a very important one.Referring only to a small country like Belgium the list of fire disasters since 1955 is impressive: This leaves out of consideration the family home fires in which one or several people die, as was the case in Deurne in November 1977 where a mother and five children died, or in Herstal in May 1978, costing the lives of five people. The number of such losses every year is serious and although such fires have less impact on the public, they are very important as it has been found that the majority of toxicity victims are to be found in fires in dwellings and that two-thirds of the fatalities are met in the room where the fire started.1 These statistics indicate a rapid incapacitation in which the victims fail to make use of possible excape routes. These facts are relevant to the elaboration of a test method imitating as closely as possible the early stages of fire during which the toxicological hazards play the most important role. The need for a biological assessment of the toxic hazards of fire has become generally acknowledged, and in recent years a great deal of research has been accomplished along these lines in a number of countries including Belgium, Germany, France, Japan, UK, USA etc. It is beyond the scope of the present paper to make reference to the numerous publications which have recently appeared in an increasing number of new journals covering the topic of combustion toxicology.Due to the complexity of the fire situation there are many different approaches possible when trying to establish a procedure for a small-scale test which explains the number of different methods in use at present. They can, in fact be divided into two categories, both systems having advantages and disadvantages as follows :1. In the first category, the animals are placed directly in the degradation chamber2 which may raise problems such as heat stress, oxygen depletion etc. 2. In the second category, degradation of the sample takes place in one apparatus (a moving tube system being used in most of the European c~u n t r i e s~-~) and the effluent products are transferred, with or without dilution, to animal chambers. This raises the problem of the effect of transfer on the composition of the toxic atmosphere.As far as the animal evaluation is concerned, methods Methods of the first type seem preferable in relation to the problem of acu...

Acrylonitrile-butadiene-styrene copolymers (ABS) :

“…However, Herpol did not observe any animal deaths until a temperature of 600°C was reached [37]. This may reflect a difference in material concentration, formulation, or any number of possible variations in the experimental conditions.…”

“…This may reflect a difference in material concentration, formulation, or any number of possible variations in the experimental conditions. Herpol [37] demonstrated an increase in the CO and slight decrease was evident when the temperature was further increased to 800°C (see Table 11). In pure CO experiments, Herpol [37] found that the CO index necessary to cause death during a 30 minute exposure was 120,000 ppm*min (equivalent to a 30 minute exposure to A, 000 ppm).…”

A review of the literature on the gaseous products and toxicity generated from the pyrolysis and combustion of rigid polyurethane foams

“…In one study, samples of a self-extinguishing rigid polyurethane foam (K14), coated with asbestos on both sides, were degraded at three different temperatures, 400,600 and 800 0C. 54 An air flow of 2001 h-' was maintained through the furnace and the combustion products in the exposure chamber were further diluted with an additional air flow of 2001h-'. Rats were exposed in a whole-body mode for 30min and lethality (as measured by the cessation of respiration) was the biological endpoint.…”

“…The T X value for the selfextinguishing rigid polyurethane foam (K14) was 18.00 at 600°C, which places it in the lower 50% of the range of values found for the materials studied. 54 The maximum T X values for the untreated (K5) and self-extinguishing polyurethane foam (K6) were 75.7 (700°C) and 44.4 (500 "C), respectively, which are in the upper 50% of the range of values.56 Foam (K6), however, appeared to be less dangerous than the non-fire retarded polyurethane foam (K5) based on a 'global toxicity index'(an expanded mathematical model of the T X developed by Herpol).…”

Polystyrenes :

“…Herpol and Vandevelde [39,40] also tested polystyrenes according to the procedure outlined above for Herpol [38]. They did not report their raw data.…”