Fate, behavior, and aquatic toxicity of the fungicide DDAC in the Canadian environment

Abstract

National water quality guidelines for protection of aquatic life were developed to address concerns regarding toxicity of antisapstains entering surface waters. A review of environmental chemistry, fate, and toxicology of didecyl dimethyl ammonium chloride (DDAC) was conducted. DDAC is used in Canada in antisapstain formulations for treatment of freshly sawn lumber, in disinfectant formulations, and as a molluscicide. DDAC is an active ingredient in the most widely used antisapstain formulation (Kop-Coat NP-1), 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 cationic surfactant, is highly water soluble, and binds rapidly to suspended solids and sediments. It is not persistent in the water column; movement to solid phase and microbial degradation are expected to be main routes of dissipation. DDAC was reported to affect rainbow trout (Oncorhynchus mykiss) at levels 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 μg L−derived according to the Canadian Council of Ministers of the Environment's (CCME) protocol for the derivation of water quality guidelines for protection of aquatic life is recommended. © 2000 John Wiley & Sons, Inc. Environ Toxicol 15: 174–200, 2000