Fate, behavior, and aquatic toxicity of the fungicide DDAC in the Canadianenvironment

National water quality guidelines for protection of aquatic life were devel oped to address concerns regarding toxicity of antisapstains entering surfa ce waters. A review of environmental chemistry, fate, and toxicology of did ecyl dimethyl ammonium chloride (DDAC) was conducted. DDAC is used in Canad a in antisapstain formulations for treatment of freshly sawn lumber, in dis infectant formulations, and as a molluscicide, DDAC is an active ingredient in the most widely used antisapstain formulation (Kop-Coat NP-I), and one of the most widely used pesticides in British Columbia; 454,400 kg of DDAC were used by lumber mills for antisapstain purposes in 1996. DDAC, a cation ic surfactant, is highly water soluble, and binds rapidly to suspended soli ds and sediments. It is not persistent in the water column; movement to sol id phase and microbial degradation are expected to be main routes of dissip ation. DDAC was reported to affect rainbow trout (Oncorhynchus mykiss) at l evels as low as 0.1 mg L-1, and Daphnia magna at levels as low as 0.03 mg L -1. It is not expected to bioaccumulate. An interim water quality guideline of 1.5 mu g L-1 derived according to the Canadian Council of Ministers of the Environment's (CCME) protocol for the derivation of water quality guide lines for protection of aquatic life is recommended. (C) 2000 by John Wiley & Sons, Inc.