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Environmental fate & pathways

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Biodegradation in water: screening tests

The inherent biodegradation of tributyl acetyl citrate was investigated in a study conducted corresponding to OECD Guideline 302C: "Inherent Biodegradabilty: Modified MITI Test (II)"over a period of 28 days and using activated sludge as inoculum. The biodegradation rate was determined by measurement of oxygen consumption. Inoculum blank and procedural/functional control with the reference substance aniline were performed.The test item proved to be inherently biodegradable under the test conditions employed (82% biodegradation after 28 d). The functional control reached the pass level >60% after 14 d.

The ready biodegradation of tributyl acetyl citrate was investigated in a study conducted according to EU Method C.4-E (Determination of the "Ready" Biodegradability - Closed Bottle Test; 2008) and OECD Guideline 301 D (Ready Biodegradability: Closed Bottle Test; 1992) over a period of 28 days and using a mixed inoculum composed of sewage from a sewage treatment plant working predominantly on domestic sewage and soil. The biodegradation rate was determined by measurement of oxygen consumption. Inoculum blank, procedural/functional control with the reference substance sodium benzoate, and toxicity control using 1.642 mg/L test substance and 3.033 mg/L reference compound were performed.The test item proved to benot readily biodegradable under the test conditions employed (16% biodegradation after 28 d).The functional control reached the pass level >60% after 14 d. In the toxicity control containing both test and reference item 47%biodegradation based on ThOD occurred within 14 d thus indicating that the test item was not inhibitory at the concentration tested.

Biodegradation in soil:

From several test results on mineralization in soil and compost, acetyl tributy citrate can be classified as readily biodegradable in these substrates. The reduced degradation in one test with compost could be attributed to deficiencies in the applied method.