TOXICITY OF SEDIMENTS CONTAMINATED WITH FRACTIONS OF CREOSOTE

Creosote a mixture of polycyclic aromatic hydrocarbons (PAH), typicall y becomes depleted of low molecular weight compounds once in the envir onment. Previous studies indicated that PAH toxicity increased with in creasing molecular weight up to phenanthrene: heavier compounds were l ess toxic than phenanthrene, possibly due to their limited solubility. A high molecular weight fraction (HMWF) of creosote, with a compositi on similar to environmentally weathered creosote, and a low molecular weight fraction (LMWF) were obtained by distillation. Fish were expose d to suspended sediments contaminated with each fraction for 10 days. Samples of fish were removed on days 2, 4, 7 and 10, observed for gros s pathological abnormalities, weighed, measured, and the livers analyz ed for ethoxyresorufin O-de-ethylase (EROD) activity. Mortality, epide rmal lesions, fin erosion, and temporary induction of EROD activity oc curred in fish exposed to the HMWF. No mortality, fin erosion, or indu ction of EROD activity occurred in fish exposed to the LMWF or unconta minated sediment. Fish exposed to the LMWF did develop lesions, but on ly in the area surrounding the mouth, nares, and opercula. These resul ts suggest that the environmental toxicity of creosote is due to the h igh molecular weight compounds. Copyright (C) 1996 Elsevier Science Lt d.