Pentyl D-glucoside

Biodegradation in water: screening tests

Link to relevant study record(s)

Reference

Endpoint:

biodegradation in water: ready biodegradability

Type of information:

experimental study

Adequacy of study:

key study

Study period:

23 Apr - 29 May 2014

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

guideline study

Qualifier:

according to guideline

Guideline:

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

Version / remarks:

1992

Deviations:

no

Remarks:

no significant deviations

Qualifier:

according to guideline

Guideline:

EU Method C.4-C (Determination of the "Ready" Biodegradability - Carbon Dioxide Evolution Test)

Deviations:

no

Qualifier:

according to guideline

Guideline:

EPA OPPTS 835.3100 (Aerobic Aquatic Biodegradation)

Version / remarks:

Paragraph (m)

Deviations:

no

GLP compliance:

yes (incl. QA statement)

Remarks:

The Department of Health of the Government of the United Kingdom (12 - 14 Mar 2014)

Oxygen conditions:

aerobic

Inoculum or test system:

activated sludge, domestic, non-adapted

Details on inoculum:

- Source of inoculum/activated sludge: Aeration stage of the Severn Water Plc sewage treatment plant, Loughborough, Leicestershire, UK (28 Apr 2014)
- Storage conditions: Continuous aeration at 21 °C
- Storage length: The activated sludge was used on the day of collection.
- Preparation of inoculum for exposure: The activated sewage sludge sample was washed twice by settlement and resuspension in mineral medium to remove any excessive amounts of dissolved organic carbon (DOC) that may have been present. The washed sample was then maintained in the laboratory and used on the day of collection.
- Concentration of sludge: 2.9 g/L suspended solids
- Initial cell/biomass concentration at test start: 30 mg suspended solids (ss)/L
- Water filtered: Yes, the suspended solids level of the activated sewage sludge was carried out by filtration of 100 mL washed activated sludge by suction through pre-weighed filter paper using a Buchner funnel.
- Type and size of filter used for activated sludge: GF/A filter paper was used for the filtration of washed, activated sewage sludge.

Duration of test (contact time):

28 d

Initial conc.:

27.1 mg/L

Based on:

test mat.

Remarks:

active ingredient

Initial conc.:

10 mg/L

Based on:

DOC

Parameter followed for biodegradation estimation:

CO2 evolution

Details on study design:

TEST CONDITIONS
- Composition of medium: Mineral medium according to OECD guidelines, purged overnight with CO2-free air for the test
- Test temperature: 19 - 23 °C
- pH: Day 0: 7.5 - 7.6 (post pH-adjustment); Day 28: 7.5 - 7.6
- pH adjusted: Yes, the pH was adjusted to pH 7.4 ± 0.2 before adjusting the test solutions to 3 L using diluted hydrochloric acid or sodium hydroxide on Day 0, after the addition of the test and reference items to the test vessels containing 2400 mL mineral medium, which were previously aerated overnight.
- Suspended solids concentration in test vessel: 30 mg/L
- Continuous darkness: Yes
- The test vessels were sealed and CO2-free air bubbled through the solution at a rate of 30 to 100 mL/min per vessel and stirred continuously by magnetic stirrer.

TEST SYSTEM
- Culturing apparatus: 5 L test culture vessels filled with 3 L test solution. The test vessels were sealed and CO2-free air bubbled through the solution at a rate of 30 to 100 mL/min per vessel and stirred continuously by magnetic stirrer.
- Number of culture flasks/concentration: 2
- No. of vessels per inoculum control (replicates): 2
- No. of vessels per procedure control (replicates): 2
- No. of vessels per toxicity control (replicates): 1
- Method used to create aerobic conditions: Aeration overnight
- Measuring equipment: DOC (Shimadzu TOC-Vcph TOC analyzer); IC and TC Analysis (Tekmar-Dohrmann Apollo 9000 TOC analyzer and Shimadzu TOC-VCSH TOC analyzer)
- Details of trap for CO2: The CO2 produced by degradation was collected in two 500 mL Dreschel bottles containing 350 mL of 0.05 M NaOH. The CO2-absorbing solutions were prepared using purified de-gassed water.
- Other: The CO2-free air was produced by passing compressed air through a glass column containing self-indicating soda lime (Carbosorb®) granules.

SAMPLING
- Sampling frequency (IC analysis): 2 mL samples were taken from the first CO2 absorber vessel on Days 0, 2, 6, 8, 10, 14, 21, 28 and 29. The second absorber vessels were all sampled on Days 0 and 29. On Day 28, 1 mL of concentrated hydrochloric acid was added to each vessel to drive off any inorganic carbonates formed. The vessels were resealed, aerated overnight and the final samples taken from both absorber vessels on Day 29.
- Sampling frequence (DOC analysis/ IC:TC ratio): 30 mL samples were removed from the inoculum control and test item vessels on Day 0 and analyzed for IC and TC.
- Sampling method: The 30 mL samples for DOC analysis were first filtered through 0.45 µm Gelman AcroCap filters (first approximate 5 mL discarded in order to pre-condition the filter) prior analysis.
- Sample storage before analysis: All samples were analyzed for IC immediately.

CONTROL AND BLANK SYSTEM
- Inoculum blank: In duplicate (inoculated mineral medium)
- Toxicity control: 1 replicate with a final concentration of 20 mg carbon/L (27.1 mg a.i./L test item + 17.1 mg/L reference item)
- Procedure control: In duplicate with a final concentration of 10 mg carbon/L (17.1 mg/L reference item sodium benzoate)

Reference substance:

benzoic acid, sodium salt

Parameter:

% degradation (CO2 evolution)

Value:

70

Sampling time:

28 d

Remarks on result:

other:

Remarks:

10-d window was satisfied

PRELIMINARY INVESTIGATIONAL WORK

The results obtained from the samples taken for DOC analysis in the preliminary work indicated that the test item did not adsorb to filter matrices or to activated sewage sludge.

VALIDITY CRITERIA

The study fulfilled the validity criteria defined by the guideline (Table 1).

Table 1: Validity criteria for OECD 301B.

Criterion from the guideline	Outcome	Validity criterion fulfilled
Difference of extremes of replicate values of the removal of the test chemical at the plateau, at the end of the test or at the end of the 10-d window, as appropriate, is less than 20%.	The difference between the values for CO2 production at the end of the test for the replicate vessels was < 20%.	yes
Percentage degradation of the reference compound has reached the pass levels by day 14.	Sodium benzoate attained 99% biodegradation after 14 d and 103% after 28 d.	Yes, the inoculum was therefore suitable
The toxicity control should degrade to at least 35% (based on DOC) or at least 25% (based on ThOD or ThCO2) within 14 d.	The toxicity control attained 91% biodegradation after 14 d and 107% after 28 d.	Yes, the test item did not inhibit activated sludge microorganisms
The IC content of the test substance suspension in the mineral medium at the beginning of the test must be less than 5% of the TC.	The IC content of the test item suspension in the mineral medium at the start of the test was < 5%.	yes
The total CO2 evolution in the inoculum blank at the end of the test should not normally exceed 40 mg/L medium.	The total CO2 evolution in the inoculum control vessels on Day 28 was 26.27 mg/L.	yes

 

 

BIODEGRADATION

The test item attained 70% biodegradation after 28 d and satisfied the 10-d window validation criterion, whereby 60% biodegradation must be attained within 10 d of the biodegradation exceeding 10% (Table 2). The test item can therefore be considered to be readily biodegradable under the strict terms and conditions of OECD guideline 301 B.

Table 2. Percentage Biodegradation Values

Day	% biodegradation
	procedure control	test item	toxicity control
0	0	0	0
2	33	25	45
6	80	47	68
8	87	51	87
10	81	61	75
14	99	70	91
21	92	64	88
28	98	73	102
29*	103	70	107

 * Day 29 values corrected to include any carry-over of CO2 detected in the second absorber vessel.

Validity criteria fulfilled:

yes

Remarks:

For further details please refer to “Any other information on results incl. tables”.

Interpretation of results:

readily biodegradable

Description of key information

Readily biodegradable (70% in 28 d, 10-d window fulfilled, OECD 301 B, act. sludge, 28 d)

Key value for chemical safety assessment

Biodegradation in water:

readily biodegradable

Type of water:

freshwater

Additional information

There is one GLP study available, in which the ready biodegradability of D-Glucopyranose, oligomeric, pentyl glycosides (CAS 100231-63-8) was assessed according to OECD guideline 301 B.

The test item at a concentration of 10 mg carbon/L was inoculated with 30 mg/L (suspended solids) of activated sludge microorganisms from a local sewage treatment plant treating predominantly domestic sewage for 28 d in the dark under aerobic conditions. An inoculum blank, toxicity and procedure control were run in parallel for validation. Biodegradation was assessed by the determination of the carbon dioxide produced during the test by IC analysis.

After 28 d, the test item attained 70% biodegradation and satisfied the 10-d window validation criterion, whereby 60% biodegradation must be attained within 10 d of the degradation phase beginning at 10%. The toxicity control attained 91% biodegradation after 14 d and 107% after 28 d thereby confirming that the test item was not inhibitory to microorganisms of activated sludge. The procedure control attained 99% after 14 d and 103% after 28 d, confirming the suitability of the inoculum and the test conditions.

Therefore, it is concluded that the test item is readily biodegradable according to OECD guideline criteria.