- Author
- Sanders, D. C. | Endecott, B. R. | Chaturvedi, A. K.
- Title
- Inhalation Toxicology. Part 12. Comparison of Toxicity Rankings of Six Polymers by Lethality and by Incapacitation in Rats.
- Coporate
- Federal Aviation Administration, Oklahoma City, OK
- Sponsor
- Federal Aviation Administration, Washington, DC
- Report
- DOT/FAA/AM-91/17; Task AM-B-90-TOX-58, December 1991, 11 p.
- Distribution
- Available from National Technical Information Service
- Keywords
- inhalation toxicity | combustion toxicity | combustion products | aircraft compartments | rats | pyrolysis products | toxic gases | LC 50
- Identifiers
- time-to-incapacitation; time-to-death; effective inhalation dose
- Abstract
- Polymeric aircraft cabin materials have the potential to produce toxic gases in fires. Lethality (LC50) in animal models is a standard index to rank polymers on the basis of their combustion product toxicity. However, the use of times-to-incapacitation (tis) may be more realistic for predicting relative escape times from a fire environment. Therefore, LC50s and tis for six pure polymers of different chemical classes were determined and compared. The polymers were polyamide (I), polystyrene (II), Nylon 6/6 (III), polysulfone (IV), polyethylene (V) and chlorinated polyethylene (VI). In the study, male Sprague-Dawley rats (150-250 g), 12 animals per fuel loading, were exposed to the pyrolysis products from selected weights of each polymer for 30 min in a 265-L combustion/exposure system, and LC50s were determined following a 14-day observation period. For each polymer, tis were also measured at 16 g, that is 60 mg/L, and at their respective LC50s using the inability of rats (n ≥ 12) to walk in rotating cages as a criterion for incapacitation. The LC50s (mg/L) of the polymers had the order of I (45.7) < II (56.6) = III (58.1) < IV (63.2) < V (75.5) < VI (87.5), while their tis (min) at 16 g (60 mg/L) had the order of III (6.6) = I (7.3) < V (11.7) = II (12.0) < VI (18.4) < IV (21.1). Based on the tis (min) at LC50s, the polymers were grouped into III and V (10.5, 11.0); I, II and VI (14.1-15.0); and IV (19.5). The two toxicological end points, LC50 and ti, did not exhibit the same relative toxic hazard rankings for these polymers. Also, tis were not equal at the LC50 concentrations, a condition of equal lethality. These findings demonstrate the possible involvement of different mechanisms of action for the combustion products of these polymers at the selected end points.