In response to chemical testing recommendations made by the TSCA Interagency Testing Committee (ITC), the U.S. Environmental Protection Agency (EPA) had to develop or modify many test methods (guidelines) before the manufacturers of the recommended chemicals could conduct tests recommended by the ITC. Test guidelines had to be developed to conduct certain health effects, chemical fate and ecological effects tests. This paper focuses on two ecological effects test guidelines that had to be developed to implement the ITC's testing recommendations.
A test guideline for tadpoles was developed to measure the toxicity of branched 4-nonylphenol added to sediment. The 30-day tadpole LC50 (260 mg/Kg sediment or 0.1 to 0.4 mg/L interstitial water) was comparable to the 2-day Daphnia magna EC50 (0.44 mg/L surface water) and the 4-day fathead minnow LC50 (0.3 mg/L surface water) and could have been attributed to sediment or water concentrations of branched 4-nonylphenol. To assess the utility of this test guideline to measure the toxicity of chemicals added to sediments the following should be addressed: 1) other chemicals and sediments should be evaluated; 2) aqueous phase tests should be conducted to measure the influence of sediment on toxicity; and 3) relationships between bioconcentration and toxicity should be determined.
A test guideline for midge larve was also developed to measure the toxicity and bioconcentration of anthraquinone, tetrabromobisphenol A and octamethylcyclotetrasiloxane added to sediments. In aqueous phase tests, tetrabromobisphenol A was more toxic than anthraquinone or octamethylcyclotetrasiloxane. In sediment phase tests, octamethylcyclotetrasiloxane was more toxic than anthraquinone tetrabromobisphenol A; tetrabromobisphenol A had the highest bioconcentration factor. To improve the reliability of the data that are developed from using this test guideline, only test chemicals for which an exact aquatic LC50 or EC50 value can be estimated should be used and midge survival in control and solvent control sediments needs to be increased so that at least 80% of the control midges survive for the duration of the test.