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Environmental fate & pathways

Biodegradation in water: screening tests

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Description of key information

The ready biodegradability of the test item was assessed over a 28 day period in a closed bottle test (EU method C 4-E). The test material attained up to 2.9 % biodegradation after 28 days whereas the reference substance (Sodium benzoate) was 60.5 % degraded 28 days. These results indicate that the test item cannot be classified readily biodegradable under conditions of the test.

Key value for chemical safety assessment

Biodegradation in water:
under test conditions no biodegradation observed

Additional information

The purpose of this study was to determine the ready biodegradability of the test item Sika Hardener MH. The test item was exposed to activated sludge from the aeration tank of a domestic waste water treatment plant for 28 days. The biodegradation was followed by the oxygen uptake of the microorganisms during exposure. Under the test conditions the percentage biodegradation of Sika Hardener MH reached a mean of 2.9 % after 28 days based on ThODNO3. (The highest percentage biodegradation value, 8.8 % of Sika Hardener MH was observed on the 21st day based on ThODNO3.) Therefore the test item can be considered to be not ready biodegradable. The reference item Sodium benzoate was sufficiently degraded to a mean of 60.5 % after 14 days (69.2 % degradation was observed already on the 7th day of the test), and to a mean of 76.3 % after 28 days of incubation, based on ThODNH4, thus confirming the suitability of the used activated sludge inoculum. In the toxicity control containing both, the test item and the reference item, a mean of 31.0 % biodegradation was noted within 14 days and 36.2 % biodegradation after 28 days of incubation. Thus, the test item can be assumed to not inhibit the activated sludge microorganisms (higher than 25 % degradation occurred within 14 days).