Disodium [(9,10-dihydro-9,10-dioxo-1,4-anthrylene)bis[imino(3-methylpropane-1,3-diyl)]]bis(benzenesulphonate)

Biodegradation in water: screening tests

Description of key information

The test material is not readily biodegradable.

Key value for chemical safety assessment

Biodegradation in water:

under test conditions no biodegradation observed

Additional information

The ready biodegradability of the test material was investigated in a Closed Bottle Test conducted in accordance with the standardised guidelines OECD 301 D, EU Method C.4-E and US EPA OPPTS 835.3110 under GLP conditions. The study was assigned a reliability score of 1 in accordance with the criteria for assessing data quality set forth by Klimisch et al. (1997).

The test system was a microbial inoculum of good quality, collected from a sewage plant for domestic sewage. The sludge was washed by centrifugation, filtered through cotton wool and aerated until use (4 g dry material/L).

The sludge was exposed to the test material at a concentration of 3.0 mg/L for a period of 28 days at 22 ± 2 °C in the dark. The biodegradation was followed by the oxygen uptake of the microorganisms during exposure. As reference, sodium benzoate was tested simultaneously under the same conditions and functioned as a procedure control. Blank and toxicity controls were run concurrently.

Under the test conditions the percentage biodegradation of the test material reached a mean of 2.5 % after 28 days based on its ThOD NO₃.

In the toxicity control containing both the test material and the reference material, a mean of 38.9 % biodegradation was noted within 14 days and 43.5 % biodegradation after 28 days of incubation. The test material can therefore be assumed to be not inhibitory at the applied concentration level of 3.0 mg/L on the activated sludge microorganisms because degradation was >25 % within 14 days.

Under the conditions of this study, the test material is considered not readily biodegradable.