Experimental toxicology of pyrolysis and combustion hazards.

Abstract

Data are presented on the acute toxicity (mortality only) of the thermal degradation products of polymers obtained by two methods of degradation. One system utilized a slowly increasing temperature (5 degrees C/min) and gradual degradation of the polymer with the rats being exposed to degradation products as they were evolved. In this system the more toxic polymers included wool, polypropylene, poly(vinyl chloride), and urethane foam. The second system utilized conditions of rapid combustion and exposure of rats to the total products of combustion for a period of 4 hr. In this system the more toxic materials included red oak, cotton, acrylonitrile-butadiene-styrene (ABS), and styrene-acrylonitrile. It is of interest to note that the natural product wool is among the least toxic under these rapid combustion conditions and among the most toxic under slow pyrolysis conditions. Other materials also vary in the comparative toxicity of their thermal degradation products, depending upon the conditions of degradation and animal exposure. The two experimental techniques presented here may well represent the two extreme conditions of rapid combustion versus slow pyrolysis. Intermediate types of fire situations might be expected to result in relative acute toxicities somewhere between these two extremes. This report deals with acute toxicity on the basis of mortality data only and does not include other parameters of toxicity such as organ weights and histopathology.

The Combustion Toxicology of Polyvinylchloride Revisited

“…He &dquo;normalised&dquo; the results by estimating the LC50's and multiplying them by the exposure duration to give the exposure intensity. The values he derived were clustered around 1000 mg/l.mins with a range of 350 to 2000 mg/l.mins except for one report (Cornish et al, 1975) which used a long exposure time of 4 hours in a static chamber during which time most of the HCI had come out of the atmosphere. The minimal effect of the varied experimental conditions is aptly illustrated.…”

Update on smoke toxicity of vinyl compounds

“…These methods differ in a variety of respects: in particular in the relative rankings they generate for the various materials they test. A case in point was made in a study of the toxic potency of 14 materials by two methods (5). It showed (Table 1 ) that the material deemed most toxic by one of the protocols appeared to be the least toxic by the other method.…”