2-[[4-[ethyl(2-hydroxyethyl)amino]phenyl]azo]-6-methoxy-3-methylbenzothiazolium methyl sulphate

Endpoint summary

Description of key information

The test item has a low volatility (1.6E-5 hPa at 20 °C) and should therefore not be released into air. The test item is a surface-active substance which is soluble in water (ca. 46 g/L, 20°C) and has a low log Kow (-1.6, 20.0 °C). Based on the QSAR prediction by means of the BCFBAF program v3.01, the substance is considered to have a very low potential for bioaccumulation.

In pre-tests according to OECD 121 the log Koc values of 2.6 (peak 1) / 3.1 (peak 2) and 2.5 (peak 1) / 3.1 (peak 2) at pH 4 in soil and sewage sludge, respectively, were determined at pH 4. Although determination of the Koc by the HPLC method at pH 7 and 9 was not possible, the corresponding value the test substance can be expected to be significantly higher than the estimates for pH 4. In view of the HPLC retention times at pH 7 and 9 of 16.361 and 22.097 minutes, respectively, log Koc values clearly above 6.0 can be anticipated.

Based on these results – and taking into account the charged moieties within the compound – it can be concluded that the test item has a high adsorption potential in soil and sewage sludge. Therefore, a log Koc of 6 will be used as basis for exposure estimation by means of Chesar/EUSES.

The test item is not considered to be readily biodegradable as the BOD5/COD-ratio of the test substance is 0.003. The chemical oxygen demand (COD) of the test substance was investigated in a test according to method EU C.9 and the biological oxygen demand after 5 days (BOD5) of the test substance was conducted according to ISO 5815, second edition 1989-08-01 (E). According to known substance data, the substance is stable at high temperatures and acidic and neutral pH. Consequently, the substance is considered to be persistent in the environment.