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Environmental fate & pathways

Biodegradation in water and sediment: simulation tests

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Description of key information

This endpoint is completed by read across from polysulfides di-tert-dodecyl. For further information please see the read across justification attached in the IUCLID robust study summary.

The study shows rapid migration of the test item from the water to sediment phase (half-life DT50 6.4 days in “SL” system and 6.6 days in “SW”). In sediment, DT50 values of 180 days in “SL” and 158 days in “SW” sediment were calculated.

Key value for chemical safety assessment

Additional information

This endpoint is completed by read across from polysulfides di-tert-dodecyl. For further information please see the read across justification attached in the IUCLID robust study summary.

A study following OECD guideline 308 is available to assess the biodegradation potential of the source substance in freshwater sediments (Brands 2015, Baltussen 2015), using two sediment systems, “SL” (organic carbon poor) and “SW” (organic carbon rich). The test substance was spiked at an initial concentration of 0.1 mg/L in a tetrahydrofuran solution into the overlying water. The incubation period was 98 days, at 20°C in the dark. Analysis of the different phases was conducted using UPLC-MS/MS. The results show rapid migration of the test item from the water to sediment phase (half-life DT50 6.4 days in “SL” system and 6.6 days in “SW”). In sediment, after an initial concentration increase from 28 days onwards the concentrations decreased in both systems, with DT50 values of 180 days in “SL” and 158 days in “SW” sediment calculated. Tert-dodecyl mercaptan (TDM), the expected degradation product was assessed, but the analysis was not conclusive. Some TDM was detected at the start of the study, suggesting interference. It was determined that certain congeners of the test material undergo a side reaction with the derivatising agent (dansyl chloride) when the samples are prepared before analysis, which leads to TDM-dansyl being present. The study met all of the validity criteria and is therefore considered to be reliable without restrictions.