Aquatic hazard assessment of the toxic fraction from the effluent of a petrochemical plant

Effluent hazard assessment guidelines were applied to determine the environmental safety of discharged chloroether fractions from a chemical plant effluent. The chloroether fraction was identified as a mixture of pentachloroethers (2,5,6-trichlorohexyl 1′,3′-dichloroisopropyl ether [PCE 1,3] and 2,5,6-trichlorohexyl 2′,3′-dichloropropyl ether [PCE 2,3]), tetrachloropropyl ethers (TCPE; a mixture of l,3,1′,3′-tetrachloroisopropyl ether, 1,3-dichloroisopropyl 2′3′-dichloropropyl ether, and 2,3,2′,3′-tetrachloropropyl ether), 1,2,5,6 tetrachlorohexane (TCH), and related components. The fractions were identified in a toxicity identification evaluation (TIE). The chloroether mixture was acutely toxic between 1.5 and 20 mg/L and had no observed effect concentrations (NOEC) for chronic toxicity from 1 to 3.2 mg/L. Individual chloroether components showed acute toxicity (LC50) from 1.5 to 56 mg/L. Acute toxicity predictions from U.S. Environmental Protection Agency (U.S. EPA) structure-activity relationships (SAR) were within a factor of four. Acute to chronic ratios for specific chloroether components were between 3 and 14. Sediment studies showed moderate sorption of TCPE with a log Koc between 2.7 and 2.9. The log Kow was 3.2 for TCPE, and the bioconcentration potential (logBCF) for the mixture was < 2.7. Laboratory and field stream experiments confirmed laboratory predictions for toxicity, with NOEC for trout growth > 0.26 mg/L and effects on Gammarus feeding at 0.44 mg/L of the mixture.