© 1994 Oxford University Press
research-article |
Correlation of Systemic and Developmental Toxicities with Chemical Component Classes of Refinery Streams
Mobil Environmental and Health Sciences Laboratory P.O. Box 1029, Princeton, New Jersey 08543-1029
Received February 10, 1993; accepted October 25, 1993
Refinery streams are complex mixtures, but of a relatively few homologous series of hydrocarbons (paraffins, olefins, naph-thenics, and aromatics). Studies were performed to determine if systemic and developmental toxicity were related to the presence and levels of certain classes of refinery stream components. We have performed systemic toxicology studies in the rat on 13 refinery streams: Clarified Slurry Oil, Coker Light Gas Oil, Distillate Aromatic Extract, Heavy Atmospheric Gas Oil, Heavy Coker Gas Oil (from three refineries), Heavy Vacuum Gas Oil, Light Catalytically Cracked Naphtha, Light Cycle Oil, Syn-tower Bottoms, Vacuum Tower Overhead, and Visbreaker Gas Oil. Rats were exposed via repeated dermal administration (daily) at several dose levels. Developmental toxicology studies were performed on these same streams with the following exceptions: only two Heavy Coker Gas Oils were tested and Vis-breaker Gas Oil was not tested. End points for systemic toxicity (13-week) studies included skin irritation, body and organ weights, hematology, and serum chemistry; for developmental toxicity studies some of these same end points (excluding hematology) were considered, but they also included resorption and fetal body weight. In general, toxicity was correlated with concentrations of polycyclic aromatic compounds (PAQ composed of 3, 4, 5, 6, and/or 7 rings (decreased thymus weight, increased liver weight, aberrant hematology and serum chemistry, increased incidence of resorption, decreased fetal body weight), PAC containing nonbasic nitrogen heteroatoms (increased mortality, decreased body weight, decreased thymus weight, increased liver weight, decreased hemoglobin content and hemato-crit level, decreased fetal body weight), and/or PAC containing sulfur heteroatoms (decreased red blood cell and platelet counts, increased sorbitol dehydrogenase.) A relationship between 2-ring PAC and skin irritation was demonstrated. Severity of effect was ranked against concentration of component class and statistical significance determined by the rank-order correlation of Spearman. For the 13 streams tested, the presence and severity of systemic and developmental toxicity were dependent upon the levels of PAC and nonbasic nitrogen PAC. These classes of compounds are also believed to be major contributors to the dermal carcinogenic activity of crude oils, certain refinery streams, and poorly refined lube oils.