[No public or meaningful name is available]

Biodegradation in water: screening tests

Link to relevant study record(s)

Reference

Endpoint:

biodegradation in water: ready biodegradability

Type of information:

read-across from supporting substance (structural analogue or surrogate)

Adequacy of study:

weight of evidence

Justification for type of information:

Please refer to read-across justification attached in IUCLID Section 13.

Reason / purpose for cross-reference:

read-across source

Reason / purpose for cross-reference:

read-across source

Key result

Parameter:

% degradation (DOC removal)

Value:

55.4

Sampling time:

28 d

Remarks on result:

other: Reference: RCC, 1986

Key result

Parameter:

% degradation (O2 consumption)

Value:

26

Sampling time:

28 d

Remarks on result:

other: Reference: Toxicoop, 2019

Description of key information

The biodegradability potential of the source test item was determined in an OECD 301E and OECD 301D studies, where the source item reached 55.4 % and 26 % biodegradation in 28 days, respectively. Thus, the source item is considered to be primarily inherently biodegradable.

Key value for chemical safety assessment

Biodegradation in water:

inherently biodegradable, fulfilling specific criteria

Type of water:

freshwater

Additional information

No data on the substance itself is available. Therefore, read-across was applied to the source substance Phosphoric acid, 2-ethylhexyl ester, sodium salt (CAS 68186-64-1). This approach is considered appropriate since both substances are multi-constituent substances consisting of a mono-, bis- and tris- substituted phosphate with C-chains (4 - 6 C), only the cation is different. In the target substance the cation is ammonium, while the source substance has sodium.

OECD 301D

The ready biodegradability of the test item was determined with a non-adapted domestic activated sludge over a test period of 28 days in the Closed bottle test according to OECD 301D, Regulation (EC) No. 440/2008 Method C.4 -E and EPA OPPTS 835.3110 under GLP. The test item was tested at a concentration of 3 mg/L, corresponding to a chemical oxygen demand (COD) of 1.78 mg O2/L. The oxygen concentration was measured with an O2 electrode [working based on LDO (Luminescent Dissolved Oxygen) method]. The total oxidised nitrogen (nitrite and nitrate) was measured in all vessels using Nitrite and Nitrate Cell Tests (MERCK®). The change of the measured dissolved oxygen concentrations in the test item bottles did not correspond to the consumed oxygen of ammonium oxidation processes. Because of the relationship between oxygen uptake resulting from a possible ammonium oxidation and oxygen uptake of applied microbial population was equivocal, any correction of the measured dissolved oxygen concentrations was considered as not possible. The biodegradation of the reference item was not inhibited by the test item in the toxicity control. The biodegradation of the test item came to 26.0 % after 28 days. In conclusion, the test item is not readily biodegradable as the pass level of 60 % degradation was not reached in a 10-d-window within the 28 days period of the study but a pass level of 20 % was reached and the test item is considered to be primarily inherently biodegradable.

OECD 301E

The biodegradation of the test item was determined in a test according to OECD 301E. The test substance is suspended in mineral medium, inoculated with a mixed population of aquatic microorganisms and incubated for 28 days in the dark at 20 - 25 °C. During this period, the biodegradation of the test substance is determined on the basis of the reduction of DOC. Within the test period of 28 days, a degradation of 55.4 % was determined. The degradation of the toxicity control was 95 % after 14 days.

Based on the results from the two studies, it was concluded that the source item is primarily inherently biodegradable. Due to the structural similarities between the source and the target substance, the target substance is also considered to be primarily inherently biodegradable.