Registration Dossier

Environmental fate & pathways

Endpoint summary

Administrative data

Description of key information

Biodegradation in water:

The test item is considered to be ready biodegradable not fulfilling the 10-day criterion, since the pass level for ready biodegradability is removal of 60 % ThODNH4 in a 10-day window.

Additional information

Biodegradation in water: screening test:

The purpose of this study was to determine the ready biodegradability of the test item. 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. As a reference item sodium benzoate was tested simultaneously under the same conditions as the test item and functioned as a procedure control. This study is recognised by the test guidelines and provides a rational basis to assess the ready biodegradation properties of the test item when incubated with activated sludge.

The test item was investigated at the concentration of 3.0 mg/L. The concentration was chosen based on the preliminary test results and based on the theoretical oxygen demand of 1.89 mg O2/ mg test item (ThODNH4, calculated according to equation given in the guidelines, assuming that no nitrification occurs). In parallel (under the same conditions as the test item), positive reference item, sodium benzoate at the concentration of 3.0 mg/L (as procedure control), inoculum control and toxicity control were investigated. All validity criteria of the study were met.

Under the test conditions significant level of test item biodegradation was noticed. The percentage biodegradation of the test item reached a mean of 61.1 % after 28 days based on its ThODNH4. While the threshold for ready biodegradability (60 % biodegradation based on the ThODNH4) was reached on about the 21st day of the test, the additionally needed 10-day window criterion was not fulfilled; therefore the test item can be considered as ready biodegradable not fulfilling the 10-day window criterion.

The reference item sodium benzoate was sufficiently degraded to a mean of 72.4 % after 14 days, and to a mean of 83.8 % after 28 days of incubation, based on ThODNH4.

In the toxicity control containing both, the test item and the reference item, a mean of 52.5 % biodegradation was noted within 14 days and 61.3 % biodegradation after 28 days of incubation.