Airway reactivity response to aged carbon–graphite/epoxy composite material smoke

Abstract

Exposure of naïve guinea pigs for a total of 30 min to aged smoke from pyrolysis of 5, 10 and 100 g of carbon-graphite/epoxy-advanced composite material (cgeCM) elicited changes in the ventilation and breathing pattern reminiscent of an acute, asthmatic episode. The severity of these responses was dose related. Although breathing pattern changes were not definitive of stimulation by a single type of respiratory irritant, non-dimensional indices derived from breath structure appeared to be characteristic of bronchoconstriction possibly complicated by CO(2)-stimulated ventilation. The highest exposure concentration also elicited convulsions in the animals, which may or may not be related to the airway reactivity (AR) response. Upon treatment with fresh air, breathing returned to normal. However, this recovery was transient with some respiratory parameters returning to abnormal levels, possibly indicating a rebound or delayed component of the response. Filtration of particulate material from the smoke moderated but did not eliminate the AR response. Animals exposed to diluted smoke from the pyrolysis of 2 g of cgeCM showed no remarkable changes in breathing or ventilation, suggesting that there may be a threshold for aged cgeCM smoke-elicited AR response.

Carbon Dioxide Accumulation during Small Animal, Whole Body Plethysmography: Effects on Ventilation, Indices of Airway Function, and Aerosol Deposition

“…Under conditions where aerosol generation is not continuous throughout the exposure/response evaluation period, the bias flow leads to dilution of the test aerosol, thereby complicating experimental protocol. 18 This problem can be overcome by eliminating the bias flow; however, expired CO 2 will accumulate in the WBP with time. Elevation of ventilation is a well-known effect of CO 2 inhalation 29 ; in fact, Chapin's 1 original application of barometric plethysmography was to investigate aspects of this effect.…”

“…WBP requires little or no physical or chemical restraint of animals and is often used to evaluate airway responsiveness (AR) during or after exposure to therapeutic aerosol 11 or respiratory tract irritants and environmental pollutants. [12][13][14][15][16][17][18] In addition, this type of plethysmography also has been used extensively to characterize immediate and delayed AR to challenge with bronchoconstricting aerosols such as histamine or acetylcholine in studies of respiratory allergens. [19][20][21][22][23][24][25][26][27][28] Because animals may be completely contained within the confines of the WBP, these devices are routinely operated with a bias flow to replenish the air supply, which is particularly necessary when examining delayed responses to inhaled allergens or respiratory irritants.…”

Review of Smoke Toxicity of Fiber-Polymer Composites Used in Aircraft

“…Kimmel et al [82] used guinea pigs to evaluate the toxic potency of smoke released by a graphite-epoxy composite. The gases in the smoke were mostly CO 2 and CO, with small amounts of NO 2 and SO 2 .…”

Health Hazards of Composites in Fire

“…At this time, the toxicity and health problems caused by the inhalation of most types of compounds released by thermally decomposing polymers and polymer composites are not known [24][25][26]. Understanding the health effects of the smoke is complicated by the fact that the types and amounts of gases released by composites depend on many factors.…”

“…Kimmel et al [25] used guinea pigs to determine the toxic potency of smoke released by a smouldering carbon/epoxy composite. The smoke consisted mostly of CO 2 and CO, with small amounts of NO 2 and SO 2 .…”