ACUTE TOXICITY OF A DIDECYLDIMETHYLAMMONIUM CHLORIDE-BASED WOOD PRESERVATIVE, BARDAC-2280, TO AQUATIC SPECIES

The acute toxicity of the antisapstain wood preservative Bardac 2280 ( principal active ingredient 80% didecyldimethylammonium chloride, DDAC ) was tested with four fish and four aquatic invertebrate species. Whi te sturgeon fry (Acipenser transmontanus) were the most sensitive fish species tested with a 24-h 50% lethal concentration (LC50) value betw een 1 and 10 ppb Bardac 2280. The 96-h LC50 values for the three other fish species ranged from 0.39 ppm for fathead minnows (Pimephales pro melas) to 2.0 ppm for juvenile starry flounder (Platichthys stellatus) . Developmental stage altered the sensitivity of coho salmon to Bardac 2280, with alevins being approximately twice as sensitive as smelts. Altering salinity up to 30 parts per thousand seawater had no signific ant effect on the toxicity of Bardac 2280 to coho smelts. The 48-h LC5 0 values for Daphnia magna, Mysidopsis bahia, Hyalella azteca, and Neo mysis mercedis were 0.037 ppm, 0.039 ppm, 0.106 ppm, and 0.947 ppm, re spectively. Bardac 2280 characteristically produced steep concentratio n-response curves for fish, i.e., a concentration range considerably l ess than 10-fold for a complete range of mortality, and caused no majo r symptoms of sublethal. stress in juvenile starry Bounder following a 24-h exposure.