5-sulphosalicylic acid

Endpoint summary

Description of key information

The test item is considered to be not ready biodegradable, since the pass level for ready biodegradability that is the removal of 60 % ThODNH4 in a 10-day window was not fulfilled (reference 5.2.1 -1).

The study on adsorption/desorption does not need to be conducted because the substance has a low octanol water partition coefficient and the adsorption potential of this substance is related to this parameter. Based on the physicochemical properties the substance can be expected to have a low potential for adsorption. The substance has a low octanol water partition coefficient  log Pow -2.12@20°C. According to REACH Annex VIII, 9.3.1 Column 2, no test for adsorption/desorption is necessary.

The study on hydrolyses is considered scientifically not nessecary as all functional groups in the substance are listed as resistant against hydrolysis in Lyman's Handbook of chemical property estimation.

Additional information

The ready biodegradation test was conducted according to the test method OECD 301 D (Closed Bottle Test, reference 5.2.1 -1). The test item was exposed to activated sludge from the aeration tank of a domestic waste water treatment plant in completely full and closed bottles in the dark at controlled temperature (22 ± 2 °C) for 28 days. The biodegradation was followed by the oxygen uptake of the microorganisms during exposure. All validity criteria of the study were met. Under the test conditions minimal biodegradation of this test item was noticed. The percentage biodegradation of the test item reached a mean of 12.0 % after 28 days based on its ThODNH4. The pass level for ready biodegradability is the removal of 60 % ThODNH4 in a 10-day window. Minimal biodegradation of the test item occurred in this study; however the value remained far below the pass level; therefore the test item is considered to be not ready biodegradable.

Hydrolysis can be considered as negligible degradation pathway due to the chemical structure and the functional groups present in the substance: The 5-sulfobenzoic acid contains beside the core part "benzene" a "carboxylic acid", an "alcohol" and a "sulfonic acid" as functional group. All of those structure elements are listed as resistant groups against hydrolysis in Lyman's Handbook of chemical property estimation (Lyman, W J, Reehl, W F, and Rosenblatt, D H. Handbook of chemical property estimation methods. United States: N. p., 1990. Web.). This handbook presents simple estimation methods for 26 important properties of organic chemicals that are of environmental concern. This book facilitates the study of problematic chemicals in such applications as chemical fate modelling, environmental assessments, priority ranking of large lists of chemicals, chemical spill modelling, chemical process design, and experimental design. As the substance is expected to be resistant to hydrolysis based on this considerations the study on hydrolysis is scientifically not necessary and this study is waived according to Annex XI, section 1,  to REACH Regulation.