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Environmental fate & pathways

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The hydrolysis study of Diphenyl sulphone was conducted according to the standard OECD guideline 111. The preliminary test for hydrolysis of Diphenyl sulphone was conducted at 50 ± 0.5°C in the dark at pH 4, 7 and 9 buffer solutions for a period of 5 days. Based on the preliminary test data generated in this study, Diphenyl sulphone was found hydrolytically stable, with less than 10% degradation at each pH, which would indicate a DT50 of >1 year at 25°C. So according to the instructions of the test guideline, an additional test was not conducted.

The biodegradation of diphenyl sulphone in a standard OECD 301C (MITI) test was estimated by BIOWIN version 4.10. included in the EpiSuite programs of US-EPA. The conclusion of BIOWIN is that diphenyl sulphone is not readily biodegradable in a standard OECD 301C (MITI) test. The mineralisation is estimated to take weeks and the primary degradation occurs within a timeframe of days.

The aerobic biodegradation of diphenyl sulphone was estimated by the models Biowin 1 (Linear Biodeg Probability) and Biowin 2 (Non-Linear Biodeg Probability), included in BIOWIN, which are intended to convey a general indication of biodegradability under aerobic conditions, and not for any particular medium.  The models show that Diphenyl sulphone biodegrades fast.

Half lives in surface water and sediment were estimated with the PBT profiler (US-EPA) which calculates half life values from ultimate biodegradation estimations in the Biowin 3 model included in BIOWIN. The calculated half life values for Diphenyl sulphone are 15 days for surface water and 140 days for sediment. To account for the slower biodegradation under anaerobic conditions in the deeper layers of the sediment, the overall half life in sediment is estimated to be about 9 times higher than the half life in water.

 

According to the standard information requirements in Annex IX point 9.3.2 column 2, a bioaccumulation study does not need to be conducted if the substance has a low potential for bioaccumulation i.e. if the log Pow <3. The log Pow of diphenyl sulphone is 2.60. The bioaccumulation potential of diphenyl sulphone is low and a bioaccumulation study does not has to be conducted.

According to the standard information requirements in Annex VIII point 9.3.1 column 2, an adsorption/desorption study can be waived if the substance has a low potential for bioaccumulation i.e. if the log Kow <3. The log Kow of diphenylsulfone is 2.60. The bioaccumulation potential of diphenyl sulphone is low and an adsorption/desorption study does not have to be conducted.