Registration Dossier

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Environmental fate & pathways

Endpoint summary

Administrative data

Description of key information

Diazopyrazolon pigments are highly insoluble in water and no functional groups are present in the molecule that could hydrolize, except a cyclic amide structure. For these groups a calculation with EPIWIN shows that hydrolytical cleavage is unlikely. Therefore the pigment is regarded as hydrolytically stable. In addition, due to the very low solubility in water, testing is technically not feasable.


One inherent biodegradability study is available for the diazopyrazolone pigments pointing out low biodegradability. Due to this a more stringent study on ready biodegradability is scientificaly not necessary. The three substances of the Diazopyrazolone group are to be regarded as not readily and not inherently biodegradable.


The registration substance is highly insoluble in water and indirect or direct exposure of soil and sediment is not expected. The CSA does not indicate the need for further investigations.


The P-criterion of the PBT assessment is accepted. Therefore no further testing is warranted as no further relevant information could be expected from additional testing.


Due to an n-octanol/water partitioning coefficient below the trigger value of 4.5, a low biodegradation potential can be expected. As an insoluble solid the potential to cross biological membranes is negligible.


This is supported by a 6 weeks bioconcentration test in Carp (Cyprinus carpio) performed with Pigment Orange 13 according to OECD 305C.


Because of the low log Pow-value (<< 3) no testing of absorption-desorption behaviour of the substance is required. An absorption/desorption screening test according to OECD 121 (HPLC estimation method) could not be expected to yield any reasonable information. In addition, due to the very low solubility in water and in n-octanol, testing is technically not feasable.

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