EFFECT OF PH ON THE ACUTE TOXICITY OF 2,4,5-TRICHLOROPHENOL TO THE FATHEAD MINNOWS

Acute 96-h flow-through toxicity tests with the compound 2,4,5- trichlorophenol were conducted using 28-d old fathead minnows, Pimephales promelas Rafinesque. Toxicity tests were conducted at six nominal pH levels of 6.2, 6.8, 7.4, 8.0, 8.6 and 9.2 to generate LC50 values at 24, 48, 72 and 96 h of exposure. Tests were conducted in two sets of three toxicity tests using nominal pH's of 6 2, 7.4 and 8.6 as one sample set and nominal pH's of 6.8, 8.0 and 9.2 for the other. Over-lapping of the pH levels within each set of toxicity tests was one method of demonstrating quality control between the two groups of fish used