Trisodium bis[3-hydroxy-4-[(2-hydroxy-1-naphthyl)azo]-7-nitronaphthalene-1-sulphonato(3-)]chromate(3-)

Endpoint summary

Description of key information

Stable to hydrolysis; not inherently biodegradable, but with a potentianl to degradate.

No potential for bioaccumulation and adsorption due to the negative logPow.

Additional information

Hydrolysis

Hydrolysis as a function of pH was determined according to OECD guideline 111.

The study was conducted with test item concentrations of 10 mg/l in buffer solutions at pH 4, 7 and 9 at a test temperature of 50 °C (preliminary test).

Samples were taken at test start (0 hours) and test end (120 hours) and analysed via HPLC with UV (DAD) detection on a cyano-propyl column using an external standard. Buffer solutions were analysed at test start and test end and indicated no interference with test item. The analytical method for determination of the test item was validated and tested with satisfactory results in regard to linearity, accuracy, precision and specificity.

Degradation was calculated as the percentage loss of test item over the time. In the preliminary test, the test item was found to be stable at pH 4, 7 and 9, respectively. No further testing was deemed necessary as less than 10 % of the applied test item was transformed after 120 hours (5 days) at a temperature of 50 °C and each of the three pH values as shown in table. Reaction rate constants and half lives could not be calculated because the test item undergoes no significant hydrolysis. A half life of > 1 year could be assumed for environmental typical temperature conditions.

Degradation [%] at 50 °C after 120 Hours

Hydrolysis Time [hours]	Degradation [%]
	pH 4	pH 7	pH 9
120	7.92	8.60	9.80

 

Biodegradation in water: screening tests

Three studies according OECD Guideline 302 B are available. The biodegradation found in these inherent biodegradable studies were 13 % respectively 26.8 % in two static tests. One test was conducted with adapted sludge (adaption 28 days) and showed a biodegradation of 69 % in 20 days. Although the criteria for inherently biodegradability are not fulfilled the results shows that the substance has the potential to biodegrade particularly in an environment with adapted microorganisms which will be found in the STP of the dye factories.

Biodegradation in water and sediment: simulation tests

Waiving according to "column 2" in Annex IX of REACH Regulation (EC 1907/2006): CSA does not indicate need for further investigations; a direct and indirect exposure is unlikely.

Biodegradation in soil

Waiving according to "column 2" in Annex IX of REACH Regulation (EC 1907/2006): CSA does not indicate need for further investigations; a direct and indirect exposure of soil is unlikely.

Bioaccumulation

Waiving according to "column 2" in Annex IX of REACH Regulation (EC 1907/2006): CSA does not indicate need for further investigations; the substaance has a low potential for bioaccumulation. The logKow is negative

Transport and distribution

Waiving according to "column 2" in Annex VIII of REACH Regulation (EC 1907/2006). The study need not to be conducted because based on the physicochemical properties the substance can be expected to have a low potential for adsorption (log Kow negative).