Registration Dossier

Environmental fate & pathways

Endpoint summary

Administrative data

Description of key information

The primary source of possible substance environmental release is represented by industrial waste waters; the substance is not expected to be directly released to soil and air compartment can be considered as not relevant.

Direct Black 168 is hydrolytically stable and it is not readily biodegradable.

The substance is likely to possess a low affinity for soil / sediment. In addition, it is expected to be characterized by a low potential for bioaccumulation and/or a low potential to cross biological membranes.

Additional information

The test substance is a solid powder under environmental conditions. Based on the thermal behaviour, the substance does not melt, either boil up to high temperature. Evaporation is not a relevant characteristic of Direct Black 168, thus the possibility to be dispersed in air, the amount and the persistence in this compartment are related to the granulometry, which confirms the non-relevance of this compartment.

Direct Black 168 is highly water soluble and, based on the chemical characteristics, it is expected to be stable under typical environmental pH conditions.

The primary source of possible substance environmental release is represented by industrial waste waters, thus the fate and pathways of the substance in surface water is of primary concern.

Considering the intended use in aqueous-based treatments, Direct Black 168 is not expected to be directly released to air, either soil. As abovementioned, the physicochemical properties of the item confirm that the air compartment can be considered as not relevant and that the soil compartment in expected to be non concerning Direct Black 168.

Based on the preliminary test results, Direct Black 168 is hydrolytically stable: hydrolysis rate was found to be lower than 10 % at pH 7 and 50 °C, after 5 days; thus, a half-life of about one year at 25 °C and pH 7 was estimated.

Although it was not investigated, phototransformation in air/water/soil is not expected to be an important mechanisms for transformation/removal of Direct Black 168.

Direct Black 168 is not readily biodegradable. The substance did not show any potential of microorganisms impact neither in the specific test, either in the biodegradation experiments. Thus, it is deemed to not negatively impact the STP systems.

The substance is likely to possess a low affinity for soil / sediment. The adsorption potential of the Direct Black 168 on soil and on sewage sludge was evaluated on the basis of the available information on the analogous Similar Substance 01 and the study outcomes confirmed the mentioned expectation.

There is no empirical bioaccumulation data available for the substance under investigation, nevertheless on the basis of the negative log Pow, it is expected to be characterized by a low potential for bioaccumulation and/or a low potential to cross biological membranes. Due to the molecular mass greater than 700 and due to the steric hindrance, the possible passage of gill membranes or cell membranes of respiratory organs is expected to be negligible