Toxicity of Particles Emitted from Combustion of Waste Crankcase Oil: In Vitro and in Vivo Studies

Abstract

Toxicity of Panicles Emitted from Combustion of Waste Crankcase Oil: In Vitro and in Vivo Studies. MUMFORD, J.L., HATCH, G.E., HALL, R.E., JACKSON, M.A., MERRILL, R.G., JR., AND LEWTAS, J. (1986). Fundam. Appl. Toxicol. 7, 49-57. The ever-rising cost of energy provides incentives for the utilization of low-cost waste crankcase oil (WCO) for space heating. Although WCO is known to contain toxic heavy metals, the potential health hazards of emissions and waste products resulting from the combustion of WCO are unknown. Thus, the toxicity of the emission particles and waste products from two different types of burners, a Dravo atomizing oil burner (AOB) and a Kroll vaporizing oil burner (VOB), is evaluated using automotive WCO. Samples are characterized by performing elemental analysis and scanning electron microscopy. Both burners emitted fine (≥3 /im), respirable particles. The AOB emission particles contained high concentrations of toxic heavy metals, especially Pb, which showed concentrations as high as 7.5%. The VOB retained a significant amount of heavy metals in the burner residue and emitted a much smaller quantity into the air. The toxicity of AOB emission particles, VOB emission particles, and VOB waste residue is evaluated in three bioassay systems, including a rabbit alveolar mac-rophage (RAM) cytotoxicity in vitro assay, an intratracheal injection infectivity assay, and a peritoneal irritancy test in mice. The emission particles from both burners and leachate from VOB residue produce a dose-related reduction in viability and cellular adenosine triphosphate (ATP) in alveolar macrophages following 20-hr exposure. Acidity of the RAM medium due to the presence of VOB emission particles and waste leachate contributes to its toxicity. Mortality due to infection with aerosolized Streptococcus sp is not significantly elevated by intratracheal injection of AOB emission particles at 100 μg/mouse, whereas a similar dose of VOB ash produced significant elevations in mortality (61.1/). Emission particles from both burners cause a dose-related sensory irritant response when injected ip in mice. The WCO emission particles from both burners are comparable in overall potency to the most toxic combustion particles tested previously, with the exception of AOB particles in the infectivity assay.