INVESTIGATION OF POTENTIAL TOXICITY AND MUTAGENICITY OF DISTILLATES FROM THE DRYING OF 5 SPECIES OF WOOD

The Ames test is frequently used to evaluate the potential for adverse human health effects that may be associated with uncharacterized chem ical compounds or mixtures of compounds. In this research, the Ames te st was used to evaluate condensates distilled from southern yellow pin e, yellow-poplar, red oak, Douglas-fir, and eastern white pine dried a t 250-degrees-F in a closed laboratory extraction system. The purpose of these tests was to mimic ''worst case'' conditions of emissions tha t could be generated during wood drying. Testing of all condensates un der increasing concentrations revealed cytotoxic dose-response relatio nships; but none of the condensates was mutagenic in the absence of me tabolic activation by mammalian liver enzymes. In the presence of rat liver microsomal enzymes, condensates from yellow-poplar, Douglas-fir, white pine, and southern yellow pine produced repeatable mutagenic do se-response relationships. Yellow-poplar condensate resulted in the hi ghest single mutagenic response, yielding 5,340 revertants/ml of conde nsate, but was mutagenic for only 1 of the 4 strains of bacteria used for Ames testing. Douglas-fir and white pine condensates were signific antly mutagenic for three of four Ames strains, and exhibited signific ant cytotoxicity in the presence and absence of rat liver microsomal e xtracts. Southern yellow pine condensate was mutagenic for two of the four Ames strains, but was far less mutagenic and cytotoxic than conde nsates from Douglas-fir or white pine. While these laboratory results show that wood-derived condensates contain only weak mutagens, further testing is being done using condensates from actual kiln-drying opera tions to determine if large volumes of condensate will offset their ap parent weak mutagenicity. Further genotoxicity testing and acute and c hronic toxicity testing with other species and with condensates taken from kiln-drying operations is needed prior to the formulation of any rational regulatory policy governing the disposition of condensate or vapor emissions.