Use of the Daphnia magna Test to Estimate the Toxicity of the Ozonation By-products of Phenols and Chlorophenols

The toxicities of the ozonation products of 18 phenols were assayed with the Daphnia magna 24-hour toxicity test. The toxicities of the ozonation products of eight individual chlorophenols, and a mixture of them, are significantly lower than the toxicities of untreated solutions of chlorophenols. For some other phenols, including ordinary phenol (oxybenzene), toxicity increased during ozonation, and the formation of very toxic products was observed.