Sodium 4-morpholin-1-ylethylsulphonate

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:

key study

Justification for type of information:

ANALOGUE APPROACH JUSTIFICATION
Please refer to the attached read across justification in section 13

Reason / purpose for cross-reference:

read-across source

Key result

Parameter:

% degradation (CO2 evolution)

Value:

1

Sampling time:

29 d

Remarks on result:

not determinable

Description of key information

In a study according to OECD TG 301 B under GLP, the source substance was found to be not readily biodegradable. Therefore, the target substance is considered to be not readily biodegradable (reference 5.2.1-1).

Key value for chemical safety assessment

Biodegradation in water:

under test conditions no biodegradation observed

Type of water:

freshwater

Additional information

No experimental data on biodegradation with the test item was available. Read-across to a structural analogous substance was done instead.

The ready biodegradability of the read-across source substance was investigated in a study according to OECD TG 301 B and under GLP conditions using a test item concentration of nominal 20 mg organic carbon/L (corresponding to 51.5 mg test item/L). The biodegradation was measured by determination of the CO₂-evolution. As a reference item aniline was tested simultaneously under the same conditions as the test item, and functioned as a procedure control. Activated sludge was used as inoculum (concentration in the test 24.9 mg dry matter/L). The test item in a mineral medium was inoculated and incubated under aerobic conditions in the dark and the test was left running for 28 days. The amount of DOC in the test solution due to the inoculum was kept as low as possible compared with the amount of organic carbon due to the test item. Allowance was made for the endogenous activity of the inoculum by running parallel blanks with inoculum but without test item. Measurements were taken at sufficiently frequent intervals to allow the identification of the beginning and end of biodegradation. All validity criteria were met. The reference item aniline was sufficiently degraded to a mean of 68.1 % after 14 days, and 76.9 % after 28 days of incubation, thus, confirming the suitability of the used activated sludge inoculum. In the toxicity control containing both, the test item and the reference item, a biodegradation of 35 % was observed after 28 days of incubation. Thus, the test item can be assumed to be not inhibitory on the activated sludge microorganisms. No degradation was detected within the 10 day window. The test item emitted almost no CO₂, so that the biodegradation after 29 days was determined as 1 %. Ready degradability is defined in the guidelines as degradation surpassing 60 % within 10 days after reaching a level of 10 %. Therefore, the test item cannot be considered as “readily biodegradable”. Degradation of the test item missed 60 % within 28 days, too. Therefore, the test item is not considered as “biodegradable within 28 days”, either.

Based on the data from the read-across source substance, the target substance is determined to be not readily biodegradable.