Registration Dossier

Environmental fate & pathways

Endpoint summary

Administrative data

Description of key information

Biodegradation in water

The percentage biodegradation of the test item reached a mean of 8.8 % after 28 days based on its theoretical oxygen demand (ThODNH4).

Under the conditions of study, the test item is considered to be not readily biodegradable, since the pass level for ready biodegradability is removal of 60 % theoretical oxygen demand (ThODNH4) in a 10-day window.

Additional information

The ready biodegradability of the test material was investigated in a Closed Bottle Test conducted in accordance with OECD TG 301D and EU method C.4 under GLP conditions. For this purpose the test item was exposed to activated sludge from the aeration tank of a domestic waste water treatment plant in completely full and closed bottles in the dark at controlled temperature (22 ± 2 °C) for 28 days. The biodegradation was followed by the oxygen uptake of the microorganisms during exposure.

The test item was investigated at the concentration of 3.0 mg/L. The test item concentration was chosen based on the theoretical oxygen demand of the test item (ThODNH4 calculated according to equation given in the guidelines, assuming that no nitrification occurs) of 2.02 mg O2/mg. 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 applied test conditions, no ready biodegradation of this test item was noticed. The percentage biodegradation of the test item reached a mean of 8.8 % after 28 days based on its theoretical oxygen demand (ThODNH4). (The highest biodegradation value of 8.9 % was obtained on the 7th day of the test.).

The concurrently conducted analytical determination of possible nitrite and nitrate development showed slight changes in nitrite concentrations in both parallels of the end (28-day) toxicity control samples; however, the measured dissolved oxygen concentrations did not correspond to the consumed oxygen of ammonium oxidation processes; the relationship between oxygen uptake resulting from a possible ammonium oxidation and oxygen uptake of applied microbial population was equivocal; therefore any correction of the measured dissolved oxygen concentrations was considered as not possible. Most likely technical effects (turbidity and/or discoloration) influenced the nitrite concentration determinations. The biodegradability value of the test item was calculated based on its ThODNH4; any correction, based on the measured nitrite nitrate content was not performed

The reference item, sodium benzoate, was sufficiently degraded to a mean of 75.3 % after 14 days, and to a mean of 77.5 % after 28 days of incubation, based on ThODNH4. (The biodegradation reached its plateau on about the 7th day and from this day onwards the observed slight changes were considered as being within the biological variability range of the applied test system). In the toxicity control containing both, the test item and the reference item, a mean of 35.5 % biodegradation was noted within 14 days and after 28 days of incubation (from about the 5th - 7th days of the test onwards the obtained slight changes in the biodegradability values were considered as being within the biological variability range of the applied test system).

The test item is considered to be not readily biodegradable, since the pass level for ready biodegradability is removal of 60 % theoretical oxygen demand (ThODNH4) in a 10-day window. The percentage biodegradation of the reference item confirms the suitability of the used activated sludge inoculum. According to the test guidelines the test item can be assumed as not inhibitory at the applied concentration level on the activated sludge microorganisms because the degradation in the toxicity control group was higher than 25 % within 14 days.