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Environmental fate & pathways

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Information on aerobic and anaerobic degradation of acetophenone are available. In the study conducted according to OECD Guideline 301C, acetophenone proved to be readily biodegradable and fulfilling the 14 d window criterion (64.7% biodegradation after 14 d). A number of supportive studies confirm this result obtained at the well-known stringent conditions of the MITI Test (very high ratio substance/inoculum). Under anaerobic conditions, acetophenone was biodegraded neither in the standard test nor in the low concentration test in appreciable amounts (general: 30% biodegradation after 28 d; in the low concentration test: 15% degradation after 28 d, value taken from a figure). Two simulation test on biodegradation in surface waters are available: In a study conducted according to the standard BOD technique (APHA (1980) and using three different inoculum sources (ground water, river water, and harbour water), acetophenone biodegradation and the corresponding half-lives were in the range between ca. 40 and 82% and 4 (harbor water), 8 d in river water, and 32 d (ground water), respectively. The authors assumed, that the observed high biodegradation rate of acetophenone using harbour water as inoculum may be due to the fertility and/or the presence of microorganisms that were pre-exposed to the test chemical or similar chemicals. In another study, the biodegradation of acetophenone was investigated using Ohio River water as inoculum. The biodegradability was followed by determination of carbon dioxide production. After 10 d samples were redosed to check possible acclimation. Initially, a lag phase of about three days was observed. Thereafter acetophenone was biodegraded relative quickly: ca. 50% degradation after 6 days based on CO2 production due to oxidation of test item and ThCO2 production. Redosing after 10 days resulted in rapid degradation: ca. 50% were degraded after 3 days.