ethyl N,S-bis(4-oxo-4-(2,6,6-trimethylcyclohex-3-en-1-yl)butan-2-yl)cysteinate

Biodegradation in water: screening tests

Administrative data

Endpoint:

biodegradation in water: ready biodegradability

Type of information:

experimental study

Adequacy of study:

key study

Study period:

April – June, 2018

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

guideline study with acceptable restrictions

Remarks:

conducted under GLP conditions

Data source

Reference

Reference Type:

study report

Title:

Unnamed

Year:

2018

Report date:

2018

Materials and methods

Test guideline

Test guideline 1

Qualifier:

according to guideline

Guideline:

OECD Guideline 301 F (Ready Biodegradability: Manometric Respirometry Test)

Version / remarks:

1992

Deviations:

yes

Remarks:

An optional toxicity control as suggested by guideline 301F and the measurement of Nitrite/Nitrate content of the test flask was as foreseen in the respective Standard operating procedure was not performed. The study validity is not adversely affected.

Test guideline 2

Qualifier:

according to guideline

Guideline:

EU Method C.4-D (Determination of the "Ready" Biodegradability - Manometric Respirometry Test)

Deviations:

yes

Remarks:

An optional toxicity control as suggested by guideline 301F and the measurement of Nitrite/Nitrate content of the test flask was as foreseen in the respective Standard operating procedure was not performed. The study validity is not adversely affected.

Test guideline 3

Qualifier:

according to guideline

Guideline:

EPA OPPTS 835.3110 (Ready Biodegradability)

Deviations:

yes

Remarks:

An optional toxicity control as suggested by guideline 301F and the measurement of Nitrite/Nitrate content of the test flask was as foreseen in the respective Standard operating procedure was not performed. The study validity is not adversely affected.

GLP compliance:

yes (incl. QA statement)

Test material

Test material information

Constituent 1

Reference substance name:

ethyl N,S-bis(4-oxo-4-(2,6,6-trimethylcyclohex-3-en-1-yl)butan-2-yl)cysteinate

EC Number:

866-600-7

Cas Number:

2173997-41-4

Molecular formula:

C31H51NO4S

IUPAC Name:

ethyl N,S-bis(4-oxo-4-(2,6,6-trimethylcyclohex-3-en-1-yl)butan-2-yl)cysteinate

Test material form:

liquid

Study design

Oxygen conditions:

aerobic

Inoculum or test system:

activated sludge, domestic, non-adapted

Details on inoculum:

Fresh activated sludge from a biological waste water treatment plant treating predominantly domestic sewage (Bois-de-Bay, Satigny, Switzerland) was used.

The sludge was collected in the morning, washed three times in the mineral medium (by centrifuging at 1000 g for 10 minutes, discarding the supernatant and resuspending in mineral medium) and kept aerobic until being used on the same day.

Inoculum concentration = 30 mg/L (dry weight)

Duration of test (contact time):

40 d

Initial test substance concentration

Initial conc.:

30 mg/L

Based on:

test mat.

Parameter followed for biodegradation estimation

Parameter followed for biodegradation estimation:

O2 consumption

Details on study design:

Test substance samples (7.65 mg, corresponding to 30.0 mg/l in 255 ml of test medium) are weighed in small aluminium boats and added directly to the test flasks of the Oxitop. For reference substance samples 12.75 mg (corresponding to 50.0 mg/l in 255 ml of test medium) are weighed in small aluminium boats and added directly to the test flasks of the Oxitop.

Flasks are filled with 250 ml of mineral medium. Samples of test or reference substance are added. Then 5.00 ml of suspended sludge diluted to a concentration of 1.53 g/l dry matter is added. Except when the test substance has an acid or alkaline character, the pH of each flask is not measured but assumed to be the same as the mineral medium (see 3.5.), in order not to remove any floating undissolved test substance from the test medium by dipping a glass electrode in it. Neutral test substances, even sodium benzoate, were shown not to affect the pH of the medium by more than 0.1 pH unit. Two sodium hydroxide pellets are placed in the quivers on top of the bottle, and the flasks are closed tightly with the measuring heads. The flasks are allowed to equilibrate to the test temperature. The measurement is started by programming the measuring unit of the Oxitop test flasks, and the test flasks are placed in the temperature controlled cupboard of the Oxitop system. After temperature equilibration, the controller of the instrument starts the data acquisition (time zero of the experiment).

Everyday the oxygen consumption of each flask is recorded and correct temperature and stirring are checked.

At the end of the test period (normally 28 days), the pH of each flask is measured again.

An optional toxicity control as suggested by OECD guideline 301 F was not performed. The validity of the study is not adversely affected.

The measurement of Nitrite/Nitrate content of the test flask was as foreseen in the respective Standard operating procedure was not performed. The percentages of biodegradation were calculated using the formulas excluding nitrification.

Reference substance

Reference substance:

benzoic acid, sodium salt

Remarks:

Sodium benzoate (Fluka, Buchs, Switzerland, Art. No. 71300), purity : min. 99.0%.

Results and discussion

Test performance:

Everyday the oxygen consumption of each flask is recorded and correct temperature and stirring are checked.

At the end of the test period, the pH of each flask is measured again.

The respirometer used during this study is an Oxitop Control System, made by Wissenschaftlich-Technische Werkstätten (WTW), Weilheim, Germany.

% Degradation

% Degradation 1

Key result

Parameter:

% degradation (O2 consumption)

Value:

6

Sampling time:

28 d

% Degradation 2

Parameter:

% degradation (O2 consumption)

Value:

12

Sampling time:

40 d

Details on results:

GR-87-0307 did not inhibit the intrinsic respiration of the inoculum at the test concentration and was therefore considered to be non-toxic to the inoculum at the test concentration.

Thus, GR-87-0307 should be regarded as not readily biodegradable according to this test.

BOD5 / COD results

Results with reference substance:

Degradation of sodium benzoate exceeded 40% after 7 days and 65% after 14 days: the activity of the inoculum was thus verified (validity criterion).
The repeatability validity criterion (not more than 20% difference between replicates) is fulfilled. Therefore, the test is considered valid.

Applicant's summary and conclusion

Validity criteria fulfilled:

yes

Interpretation of results:

not readily biodegradable

Conclusions:

GR-87-0307 undergoes 6% biodegradation after 28 days (12% biodegradation after 40 day) in the test conditions.

GR-87-0307 did not inhibit the intrinsic respiration of the inoculum at the test concentration and was therefore considered to be non-toxic to the inoculum at the test concentration.

Thus, GR-87-0307 should be regarded as not readily biodegradable according to this test.

Executive summary:

The Ready Biodegradability of GR-87-0307 was determined by the Manometric Respirometry Test according to the OECD Guidelines for Testing of Chemicals, Method No. 301 F.

 

GR-87-0307 undergoes 6% biodegradation after 28 days (12% biodegradation after 40 day) in the test conditions.

 

GR-87-0307 did not inhibit the intrinsic respiration of the inoculum at the test concentration and was therefore considered to be non-toxic to the inoculum at the test concentration.

 

Thus, GR-87-0307 should be regarded as not readily biodegradable according to this test.