INVESTIGATION OF ACUTE TOXICITY OF DISTILLATES FROM 5 SPECIES OF WOODFOR FATHEAD MINNOWS

Condensates prepared from Douglas-fir, red oak, eastern white pine, so uthern yellow pine, and yellow-poplar by drying at 250 degrees F in a closed laboratory extraction system were tested for acute toxicity usi ng the fathead minnow (Pimephales promelas) in a U.S. EPA-recommended test system. The purpose of testing was to expose minnows to ''worst c ase'' emissions that could be generated during wood drying, and to det ermine if such condensates posed a toxicity threat to fish. Condensate s were mixed in two-fold concentrations (0.8% to 13% vol./vol.) with w ell water routinely used for the rearing of rainbow trout and Atlantic salmon. Testing of condensates from all five wood species over a 24-h our period revealed significant toxicity with positive dose-response r elationships. In the case of Douglas-fir and southern yellow pine cond ensates, the concentration resulting in 50 percent mortality (LC(50)) was 9.2 percent. The LC(50) for red oak condensate was 4.6 percent; fo r eastern white pine condensate, 2 percent; and for yellow-poplar cond ensate, 2.5 percent. For Douglas-fir and red oak condensates, a signif icant drop in the pH of the test solution to below 5.5 was likely resp onsible for mortalities observed. In the cases of eastern white pine, southern yellow pine, and yellow-poplar condensates, however, mortalit ies were observed at pH values between 5.5 and 7.2. These results sugg est that condensates distilled from eastern white pine, southern yello w pine, and yellow-poplar contain components that are acutely toxic fo r fish at moderately acidic pH. In contrast, toxicity associated with Douglas-fir and red oak condensates was most likely a result of the ac idity of the condensates themselves, rather than simply being an effec t of one or more specific toxic components.