Registration Dossier

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Environmental fate & pathways

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Administrative data

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Additional information

Polysulfides, di-tert-butyl is not readily biodegradable according to OECD 301 guideline criteria. It is expected to strongly sorb to soil and sediment particles based on Koc.

Determination of the hydrolysis rate for polysulfides, di-tert-butyl has been carried out. According to the pre-test performed at 50°C the test item is considered hydrolytically stable at pH 7 and 9. For pH 4 the outcome of the experiments gives no clear indication on the hydrolytic properties of the test item. No consistent decrease was observed. Furthermore a hydrolysis of the sulfide bond is unlikely. Thus the observed decrease in concentration is supposed not to be a consequence of a hydrolysis reaction..

In order to evaluate fish bioaccumulation potential for polysulfides, di-tert-butyl, a fish bioconcentration study according to the revised OECD TG 305 (dietary test) had been proposed in the original registration dossier. Further to the agreement in the final decision sent by ECHA this study has been performed. It shows a BMF = 0.0059 (in parallel, hexachlorobenzene, HCB, as a positive control showed a BMF of 0.7033, in line with expectation). For regulatory purpose, a BCF can be calculated using the linear regression equation issued by Inoue at al. (2011) linking BMF to BCF. The calculated BCF for polysulfides, di-tert-butyl, sets at 188 L/kg, one order of magnitude below the threshold for the "B" criterion. The substance is therefore not considered bioaccumulative in the framework of the PBT assessment.