Acute toxicity of the antisapstain chemicals DDAC and IPBC, alone and in combination, to rainbow trout (Oncorhynchus mykiss)

The antisapstain chemicals DDAC and IPBC were tested for acute toxicity with juvenile rainbow trout. The 96-h LC50 estimates were 537 μg DDAC/L and 67 μg IPBC/L. The two chemicals were also tested as a mixture (10:1) and as the commercial formulation NP-1. The 96-h LC50 for NP-1 was 581 μg DDAC+IPBC/L and was 494 μg DDAC+IPBC/L for the 10:1 mixture. The two chemicals exhibited mildly antagonistic behaviour when present in the mixture or formulation. Thus, the data indicate that DDAC and IPBC do not pose any risks of synergistic effects to juvenile rainbow trout when present concurrently in solution.