Carbamic acid, N-[(1R)-2-hydroxy-1-phenylethyl]-, 1,1-dimethylethyl ester

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:

16 June 2016 - 21 July 2016

Reliability:

1 (reliable without restriction)

Data source

Reference

Reference Type:

study report

Title:

Unnamed

Year:

2016

Report date:

2016

Materials and methods

Test guideline

Test guideline 1

Qualifier:

according to guideline

Guideline:

other: HJ/T 153-2004, "The Guidelines for the Testing of Chemicals, Degradation and Accumulation" (2nd edition) (Beijing: China Environmental Press. 2013)

Version / remarks:

2nd edition

Test guideline 2

Qualifier:

equivalent or similar to guideline

Guideline:

OECD Guideline 301 D (Ready Biodegradability: Closed Bottle Test)

GLP compliance:

yes (incl. QA statement)

Test material

Test material information

Constituent 1

Reference substance name:

Carbamic acid, N-[(1R)-2-hydroxy-1-phenylethyl]-, 1,1-dimethylethyl ester

EC Number:

600-273-1

Cas Number:

102089-74-7

Molecular formula:

C13H19NO3

IUPAC Name:

Carbamic acid, N-[(1R)-2-hydroxy-1-phenylethyl]-, 1,1-dimethylethyl ester

Test material form:

solid: particulate/powder

Specific details on test material used for the study:

Purity: 99.99%
Appearance: Powder
Storage conditions: Room temperature & avoid light
Lot number: LS-53-20150815

Study design

Oxygen conditions:

aerobic

Inoculum or test system:

sewage, domestic, non-adapted

Details on inoculum:

Samples of secondary effluent were obtained as the test inoculum from a sewage plant treating predominantly domestic sewage (Nanjing Chengdong Sewage Treatment Plant). Aerobic conditions were maintained in the effluent by aeration from a laboratory supply of oil-free
compressed air. (Batch No.: EW201606161). On the day of the test, the test inoculum was prepared by filtering the sample of sewage effluent through a coarse filter, (discarding the first 200 mL) and collecting the remaining filtrates. This inoculum was maintained under aerobic conditions in the test area until use.

Duration of test (contact time):

ca. 28 d

Initial test substance concentration

Initial conc.:

3 mg/L

Based on:

test mat.

Parameter followed for biodegradation estimation

Parameter followed for biodegradation estimation:

DOC removal

Details on study design:

Test Procedures

Four groups of "inoculum control", "test", "procedure control" and "toxicity control" were
assigned in this test, with 2 replicates each. The test medium was aerated for 20 minutes and
allowed to stand at the test temperature for at least 20 h before use. Dissolved oxygen of the
mineral medium was measured to be 8.62 mg/L.

20 mL of inoculum was added into 20 L BSM, to give a concentration of 1 mL/L.
Firstly, 2.12 mL test substance was added to BOD-bottles (300 mL) of "test" and "toxicity
control". Then, 600 µL of stock solution of sodium benzoate (1002 mg/L) was added to
BOD-bottles of "procedure control" and "toxicity control"; then BSM included inoculum was
added to all BOD-bottles.

a) Inoculum control: containing inoculum only (1 mL/L);
b) Test 1: containing test substance (3.00 mg/L) and inoculum (1 mL/L);
c) Reference control: containing reference substance (2 mg/L) and inoculum (1 mL/L);
d) Toxicity control 1: containing test substance (3.00 mg/L), reference substance (2 mg/L) and
inoculum ( 1 mL/L).

The BOD bottles were fully filled (Total Volume: 300 mL) with the aerated test medium using a
hose which reached down to the bottom of the bottle to achieve adequate mixing. Each bottle was
filled to ensure that no air bubbles were enclosed. Bottle numbers for each treatment groups were
as follows: 4 bottles for toxicity control, 20 bottles for inoculum control, 20 bottles for test group,
and 20 bottles for reference control.

The concentrations of dissolved oxygen in duplicate vessels of each "test", "inoculum control",
"procedure control" and "toxicity control" group were determined after addition of the prepared
solutions to the ROD bottles (0 d) and the remaining bottles were incubated at 20 ± 1°C in
darkness. Subsequent determinations of the concentration of dissolved oxygen (DO) in duplicate
vessels for each group, except toxicity control, were made on 0, 2, 5, 7, 11, 14, 18, 21, 25 and 28
d.

The pH and temperature of the contents of each bottle were measured after the concentration of
dissolved oxygen had been determined. Determinations of DO, pH, and temperature in the "toxicity control" group were made at the start and after 14 days.

Reference substance

Reference substance:

benzoic acid, sodium salt

Results and discussion

% Degradation

Key result

Parameter:

% degradation (DOC removal)

Value:

5.58

Sampling time:

28 d

Remarks on result:

other: Not readily biodegradable based on OECD TG 301 D Closed Bottle Test (pass level of 60% ThOD)

Applicant's summary and conclusion

Validity criteria fulfilled:

yes

Interpretation of results:

not readily biodegradable

Conclusions:

The result indicated that the average biodegradation rate of test substance (N-Boc-D-phenylglycinol) was 5.58 % after 28-days.

As the OECD TG 301 D Closed Bottle Test pass levels for readily biodegradable is 60% ThOD, the substance is considered not readily biodegradable.

Executive summary:

Under valid conditions, the ready biodegradability of N-Boc-D-phenylglycinol was determined in a 28-day dissolved oxygen depletion using secondary effluent from a domestic waste water treatment plant.

During the test, the temperature was kept at 20±1°C. The pH ranges from 7.03-7.43. The oxygen consumption in inoculated blanks was 1.03 mg 02/L after 28 days of incubation, less than 1.5 mg 02/L. The lowest level of dissolved oxygen in test substance group was 7 .14 mg 0 2/L, which did not fall below 0.5 mg 0 2/L and the difference of biodegradation of the test item in the two replicates was less than 20%. Additionally, the biodegradation of the reference substance
achieved 82.8 % within 14 days, achieving 60% within 14 days. Degradation in the toxicity control was 27.9 % after 14 <days, no less than 25% in 14 days. The result indicated that the test substance was not toxic to the inoculum. Thus, all validity criteria listed were met. Therefore the test is considered valid.

Finally the results showed that under the valid conditions, the average biodegradation rate of test substance (N-Boc-D-Phenylglycinol) was 5.58 % after 28-days. As the OECD TG 301 D Closed Bottle Test pass levels for readily biodegradable is 60% ThOD, the substance is considered not readily biodegradable.