Comparison of toxicity rankings of six aircraft cabin polymers by lethality and by incapacitation in rats.
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 toxicity. However, the use of times-to-incapacitation (ti) may be more realistic for predicting relative escape times from a fire. Therefore, LC50 and ti for polymers, polyamide (I), polystyrene (II), Nylon 6/6 (III), polysulfone (IV), polyethylene (V) and chlorinated polyethylene (VI), of different chemical classes were determined and compared. Male rats, 12/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 LC50 values were determined following a 14-d observation period. For each polymer, ti was measured at 16 g and at its respective LC50 using the inability of rats (n greater than or equal to 12) to walk in rotating cages as a criterion for incapacitation. LC50 (45.7-87.5 mg/L) of the polymers had the order of I less than II approximately III less than IV less than V less than VI, while their ti (6.6-21.1 min) at 16 g (60 mg/L) had the order of III approximately I less than V approximately II less than VI less than IV. Based on ti at LC50, polymers were grouped into III & V; I, II & VI; and IV. LC50 and ti did not exhibit the same relative toxic hazard rankings for these polymers; ti were also not equal at the LC50 concentrations. These findings demonstrate the possible involvement of different mechanisms of action for the combustion products of these polymers at the selected end points.
Sanders
D C
DC
Biochemistry Research Section, FAA Civil Aeromedical Institute, Oklahoma City, OK 73125-5066.
Endecott
B R
BR
Chaturvedi
A K
AK
D000401:Aircraft; D000818:Animals; D003252:Construction Materials / Q000633:toxicity*; D005390:Fires; D005739:Gas Poisoning / Q000209:etiology; D008297:Male; D009757:Nylons / Q000633:toxicity; D011095:Polyethylenes / Q000633:toxicity; D011108:Polymers / Q000633:toxicity*; D011137:Polystyrenes / Q000633:toxicity; D051381:Rats; D017207:Rats, Sprague-Dawley; D013450:Sulfones / Q000633:toxicity
D009757:Nylons; D011095:Polyethylenes; D011108:Polymers; D011137:Polystyrenes; D013450:Sulfones; C017662:polysulfone P 1700