Yucca schidigera, ext.

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:

2018-11-12 - 2019-01-30 (experimental phase: 2018-11-22 - 2018-12-20)

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

guideline study

Remarks:

GLP

Data source

Reference

Reference Type:

study report

Title:

Unnamed

Year:

2019

Report date:

2019

Materials and methods

Test guideline

Test guideline 1

Qualifier:

according to guideline

Guideline:

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

Version / remarks:

OECD Guidelines for the Testing of Chemicals Part 301 F, adopted 17. Jul. 1992
„Manometric Respirometry Test“

Deviations:

no

Test guideline 2

Qualifier:

according to guideline

Guideline:

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

Version / remarks:

Commission Regulation (EC) No. 440/2008, Guideline C.4-D, adopted 30. May 2008 “Manometric Respirometry Test”

Deviations:

no

GLP compliance:

yes (incl. QA statement)

Remarks:

Landesamt für Umwelt, Kaiser-Friedrich-Straße 7, 55116 Mainz, Germany

Test material

Test material information

Constituent 1

Reference substance name:

Yucca schidigera, ext.

EC Number:

607-033-5

Cas Number:

223749-05-1

IUPAC Name:

Yucca schidigera, ext.

Test material form:

solid: particulate/powder

Remarks:

fine beige

Details on test material:

Storage: Room Temperature (20 ± 5 °C)
Homogeneity: homogeneous

Specific details on test material used for the study:

The test item was stored in the test facility in a tightly closed vessel at room temperature (20 ± 5 °C).

Study design

Oxygen conditions:

aerobic

Inoculum or test system:

activated sludge, domestic (adaptation not specified)

Details on inoculum:

- Source of inoculum/activated sludge (e.g. location, sampling depth, contamination history, procedure): The sludge was taken from the activation basin of the ESN (Stadtentsorgung Neustadt) sewage treatment plant, Im Altenschemel, NW-Lachen-Speyerdorf.
Date of collection: 22. Nov. 2018, batch no:20181122.
- Preparation of inoculum for exposure / Pretreatment: The sludge was filtrated, washed with medium 2x, and re-suspended in test medium. It was then aerated.
- Concentration of sludge: The dry matter was determined as 4700 mg suspended solids/L.

Duration of test (contact time):

28 d

Initial test substance concentration

Initial test substance concentration 1

Initial conc.:

77 mg/L

Based on:

test mat.

Initial test substance concentration 2

Initial conc.:

99.62 mg/L

Based on:

ThOD

Parameter followed for biodegradation estimation

Parameter followed for biodegradation estimation:

O2 consumption

Details on study design:

TEST CONDITIONS
- Composition of medium:
All chemicals used in the test were “analytical grade” or otherwise proved suitable.
Note: The weights depend on the final volume which was needed in the test. Actual values are stated in the raw data.
Stock Solutions
Solution a
Potassium dihydrogen phosphate (KH2PO4) 8.5 g
Dipotassium hydrogen phosphate (K2HPO4) 21.75 g
Disodium hydrogenphosphate dihydrate (Na2HPO4*2H2O) 33.4 g
Ammonium chloride (NH4Cl) 0.5 g
H2O demin. ad 1000 mL
The pH was 7.4.
Solution b
Calcium chloride (CaCl2) 27.5 g
H2O demin. ad 1000 mL
Solution c
Magnesium sulphate heptahydrate (MgSO4*7H2O) 22.5 g
H2O demin. ad 1000 mL
Solution d
Iron(III) chloride hexahydrate (FeCl3*6H2O) 0.25 g
Disodium ethylene-diaminetetraacetate dihydrate (Na2EDTA*2H2O) 0.4 g
H2O demin. ad 1000 mL
Test Medium
The medium was freshly prepared. 10 mL of solution a were mixed with 800 mL water, then 1 mL of solutions b, c and d were added and filled up to 1 L with H2O demin (volumes were adapted to final volume needed in the test).
Composition:
Solution a 10 mL
Solution b 1 mL
Solution c 1 mL
Solution d 1 mL
H2O demin ad 1000 mL

Mercury Chloride
HgCl2 (10 g/L), used for poisoning of abiotic flasks
Soda lime
CO2 adsorbent
Hydrochloric acid, 1 M for pH-adjustment.

- Test temperature: 20.8 – 22.0°C
- pH: pH was adjusted to 7.3 – 7.6
- pH adjusted: yes
- Suspended solids concentration: 25.0 mg/L

TEST SYSTEM
- Culturing apparatus: 500 mL-flasks were used as test vessels.
All glassware was cleaned with the laboratory cleaning agent and then rinsed with tap water (3x), diluted HCl (1x), tap water (3x) and deionised water (3x).
- Number of culture flasks/concentration:
Number of control flasks: 3 (medium and inoculum)
Number of positive control flasks: 3 (sodium- benzoate, medium and inoculum)
Number of test vessels: 3 (test item, medium and inoculum)
Abiotic control: 1 (test item and 10 mL 1% HgCl2 solution/L)
Toxicity control: 1 (200 mg/L ThOD, 100 mg/L ThOD each of test item and positive control nominal)
- Measuring equipment: OxiTop® measuring heads
- Other:
Volume of test vessels: 500 mL (590 mL total volume including measuring head)
Volume test solution: 250 mL (toxicity flask 125 mL)

CONTROL AND BLANK SYSTEM
- Inoculum blank: 3 (medium and inoculum)
- Abiotic sterile control: 1 (test item and 10 mL 1% HgCl2 solution/L)
- Toxicity control: 1 (200 mg/L ThOD, 100 mg/L ThOD each of test item and positive control nominal)

STATISTICAL METHODS:

Reference substance

Reference substance:

benzoic acid, sodium salt

Remarks:

60 mg /L sodium benzoate (corresponding to 99.83 mg/L ThOD)

Results and discussion

Preliminary study:

not performed

Test performance:

All validity criteria were met.
Oxygen consumption in the blank controls and in the positive controls was normal, indicating that the test system has worked properly.

% Degradation

% Degradation 1

Key result

Parameter:

% degradation (O2 consumption)

Value:

74

Sampling time:

28 d

% Degradation 2

Parameter:

% degradation (O2 consumption)

Value:

60

Sampling time:

12 d

Remarks on result:

other: 10d window

Remarks:

starting on day 2

Details on results:

Assessment
The degree of biodegradation reached 74 % after 28 days.
The 10-day-window began on day 2 (this is stated as lag phase), at its end (day 12), 60 % were reached, obtaining the pass level of 60 % given in the OECD guideline.
The degradation phase is defined as interval between the end of the lag phase and the reaching of 90 %. This was reached on day 17.
The degradation phase was from day 2 – 17 (67%).
Therefore, when applying the 10-day-window, the test item Yucca schidigera, ext. is readily biodegradable following OECD 301F/EU C.4-D.
Because the test item is a mixture the 10-day-window does not have to be taken into ac-count. As degradation surpassed 60% in the course of the test, Yucca schidigera, ext. is considered as readily biodegradable, within 28 days.

BOD5 / COD results

Results with reference substance:

The positive control reached the pass level of 60% on day 3 (criterion: <= 14). Individual flasks reached 88.6%, 88.6% and 84.9% biological degradation after 28 days.

Applicant's summary and conclusion

Validity criteria fulfilled:

yes

Interpretation of results:

readily biodegradable

Conclusions:

The study was performed according to OECD TG 301F and EU Method C.4-D (GLP) with no deviation and is therefore considered to be of the highest quality (reliability Klimisch 1).
The ThOD of the test item was calculated based on a theoretical formula of the test item, calculated as C3.49H6.41N0.03O2.74. The formula was based on elemental analysis. The sum of analysed elements (41.94 % C, 6.46 % H, 0.47 % N, 43.9 % O, weight percent) was 92.77 %. The presence of unknown elements which do not consume oxygen would result in a lower ThOD and therefore in a higher degradation.
Since qualitative analysis of nitrate and nitrite gave negative results, no nitrification had taken place and thus, ThOD with nitrification was not assessed.
The 10-day-window began on day 2 (this is stated as lag phase), at its end (day 12), 59.6 % were reached, staying below the pass level of 60 % given in the OECD guideline. For the 3 test replicates, the mean value was 59.6 %. (57.2 %, 65.3 % and 56.3 %).
Because the test item is a mixture the 10-day-window does not have to be taken into ac-count. As degradation surpassed 60% in the course of the test, Yucca schidigera, ext. is considered as readily biodegradable, within 28 days.

Executive summary:

The biodegradability of the test substance was investigated according to EU method C.4 -D and OECD guideline 301 F (GLP) under GLP.

The test item Yucca schidigera, ext. was tested using a concentration of nominal 77 mg test item/L (equivalent to a theoretical oxygen demand of 99.62 mg O2/L). Activated sludge was used as inoculum. The test was left running for 28 days.

All validity criteria were met. The positive control reached the pass level of 60% on day 3 (criterion:≤14).

The following data could be determined for the test item Yucca schidigera, ext.:

10-day-window: day 2 – 12

Degradation phase day 2 - 17

Degradation at the end of 10-day-window 60 %

Degradation at the end of the test 74 %

Because the test item is a mixture the 10-day-window does not have to be taken into account. As degradation surpassed 60% in the course of the test, Yucca schidigera, ext. is considered as readily biodegradable, within 28 days.