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Please be aware that this old REACH registration data factsheet is no longer maintained; it remains frozen as of 19th May 2023.

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The Stilbene Fluorescent Whitening Agents (SFWA), also sometimes referred to as stilbene optical or fluorescent brighteners, are treated as members of a category, comprising the following substances: OB 1-MSA, OB 1-DSA, OB 2-A, OB 2-MSA, OB 2-DSA, OB 3a-A(free acid), OB 3a-A(Na), OB 3a-A(NaK), OB 3a-DSA, OB 3a-MSA, OB 3b-A, OB 3c-MSA, OB 4 -MSA and OB 5 -A.

For these fourteen registered substances tests were conducted according to the data requirements of the associated tonnage band. According to the general rules for grouping of substances and read-across approach laid down in Annex XI, Item 1.5, of Regulation (EC) No 1907/2006, substances may be considered as a category provided that their physicochemical, toxicological and ecotoxicological properties are likely to be similar or follow a regular pattern as a result of structural similarity. The substances within the category are based on these principles are considered to apply to these general rules. In addition some of the proposed members where firstly assessed within the chemical category of Stilbene Fluorescent Whitening Agents recognized under the framework of the US HPV Chemical Challenge Program. In each case of read-across, the best suited read-across was chosen where possible, or a weight of evidence approach in accordance with Annex XI, Item 1.2, of Regulation (EC) No 1907/2006. Nevertheless, as it can be seen in the data matrix of the category justification in IUCLID Section 13, all reliable data in the category support the hazard assessment of each category member by showing a consistent pattern of results.

For a detailed reference list please refer to the CSR or IUCLID section 13.

The test substance is a solid with very low vapour pressure, very high solubility and low Kow. It was estimated as hydrolytically stable at pH 4, 7 and 9 at 50 °C and it has an estimated half-life period longer than one year at 25 °C at pH 4, 7 and 9. The substance has not hydrolysable chemical groups in the chemical structure.

Based on calculations according to AOPWIN v1.92, the substance is indirectly photodegraded by reaction with hydroxyl radicals in the atmosphere with half-lives of about 30 min taking into account a 12 -h day and a mean OH radical concentration of 1.5 E6 molecules/cm³ (Degradation rate constant:264E-12 cm³/molecules*s (trans-isomer)).

The substance is a member of the Stilbene Fluorescent Whitening Agents category and based on the data on analogous substances in the category it is estimated to undergo direct photodegradation in surface waters, with half-lives ranging from about to 4 to 5 hours in the photic zone of lakes and rivers. Field measurements combined with mathematical modelling of sedimentation and photolysis show that direct photolysis is the only pathway of degradation and effective throughout the aquatic zone due to the dynamics of rivers and layers in lakes. There is no indication of biodegradability.

Adsorption will partially bring the substance onto the surface of suspended particles and will also contribute to the adsorption of the substance into sediments, where an anaerobic degradation process can be effective. Nevertheless this is unlikely to occur in the usual conditions of use, where the substance is adsorbed to the sludge in the STP, therefore significant release into surface waters is not expected and exposure of sediment is thereby unlikely.

The substance has been estimated as not bioaccumulative based on the log Kow and the testing results on similar substances in the category.