[No public or meaningful name is available]

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:

19 January 2022

Reliability:

1 (reliable without restriction)

Data source

Reference

Reference Type:

study report

Title:

Unnamed

Year:

2022

Materials and methods

Test guideline

Qualifier:

according to guideline

Guideline:

OECD Guideline 301 B (Ready Biodegradability: CO2 Evolution Test)

Deviations:

no

GLP compliance:

yes (incl. QA statement)

Test material

Test material information

Constituent 1

Reference substance name:

Enzymatically produced steviol glycosides

IUPAC Name:

Enzymatically produced steviol glycosides

Test material form:

solid: particulate/powder

Study design

Oxygen conditions:

aerobic

Inoculum or test system:

activated sludge, non-adapted

Remarks:

The inoculum was used as an activated sludge from the aeration tank of a Sewage treatment plant treating predominantly domestic sewage from Sewage (Waste water) Treatment Plant.

Details on inoculum:

A fresh sample of activated sludge was collected from the aeration tank of a Sewage treatment plant treating predominantly domestic sewage from Sewage (Wastewater) Treatment Plant.
Removed the coarse particles and centrifuged for 10 minutes at 3169 rpm (1100 g). The supernatant was discarded.
The sludge was washed in the mineral medium and suspended the concentrated sludge of 18.8864 g in mineral medium to yield a concentration of approximately 3 to 5 g of suspended solids/Litre.
Centrifuged the re-suspended sludge at 3169 rpm (1100 g) for 10 minutes after thorough mixing and discarded the supernatant and again re-suspended the washed sludge in a 1000 mL volume of mineral medium sludge and repeated this procedure once again and the sludge was found to be free from excess substrate and aerobic thereafter until inoculation.

Duration of test (contact time):

28 d

Initial test substance concentration

Initial conc.:

179.6 mg/L

Based on:

TOC

Parameter followed for biodegradation estimation

Parameter followed for biodegradation estimation:

CO2 evolution

Reference substance

Reference substance:

acetic acid, sodium salt

Results and discussion

% Degradation

Parameter:

% degradation (CO2 evolution)

Value:

69.47

Sampling time:

28 d

Details on results:

The results of the CO2 evolution test indicated that the test item has reached a maximum 69.47% biodegradability by day 28. The test item has reached >60% of the ThCO2 (degradation) by day 28. Since, the test item is an UVCB substance containing multi-constituents which accounted for 100% of total composition. Hence, 10-day window criterion should not be considered as a requirement for assuring the desired stringency for multi-component substances.
The test item UVCB substances exceeded the 60% pass level within the standard test duration of 28 days are considered as readily biodegradable substances.
The difference of extremes of replicate values of the removal of the test item at the end of the test is 3.64% which is less than 20%. Therefore, the test was considered valid.
In the toxicity test, which includes both the test substance and the reference substance (sodium acetate) in the same flask, the substances yielded 14.87% biodegradability by day 14 which is less than 25% biodegradation within 14 days. Hence, the test item is regarded as inhibitory to microorganisms in the inoculum.

Applicant's summary and conclusion

Validity criteria fulfilled:

yes

Interpretation of results:

readily biodegradable

Conclusions:

The Assessment of Ready Biodegradability of test item Enzymatically produced steviol glycosides is “Readily Biodegradable” and “Inhibitory to microorganisms in the inoculum” under the conditions of the CO2 Evolution test according to OECD criteria.