Pentyl D-glucoside

Toxicity to microorganisms

Link to relevant study record(s)

Reference

Endpoint:

toxicity to microorganisms, other

Remarks:

toxicity control of ready biodegradability test (OECD 301 B)

Type of information:

experimental study

Adequacy of study:

key study

Study period:

23 Apr - 29 May 2014

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

guideline study with acceptable restrictions

Remarks:

Data based on the inhibition control of a ready biodegradability study. This approach is in accordance with the Guidance on information requirements and chemical safety assessment (Chapter R.7b: Endpoint specific guidance, ECHA 2017).

Qualifier:

according to guideline

Guideline:

other: OECD 301 B

Version / remarks:

1992

Deviations:

no

Remarks:

no significant deviations

Qualifier:

according to guideline

Guideline:

other: EU Methood C.4-C

Deviations:

no

Qualifier:

according to guideline

Guideline:

other: EPA OPPTS 835.3100

Deviations:

no

GLP compliance:

yes (incl. QA statement)

Remarks:

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

Vehicle:

no

Test organisms (species):

activated sludge of a predominantly domestic sewage

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.

Test type:

static

Water media type:

freshwater

Limit test:

no

Total exposure duration:

28 d

Test temperature:

19 - 23 °C

pH:

Day 0: 7.5 - 7.6 (post pH-adjustment)
Day 28: 7.5 - 7.6

Nominal and measured concentrations:

Toxicity control: 27.1 mg a.i. test item/L + 17.1 mg sodium benzoate/L equivalent to a total ot 20 mg carbon/L

Details on test conditions:

TEST SYSTEM
- Test vessel: 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.
- No. of vessels per concentration (replicates): 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
- Sludge concentration: 2.9 g/L suspended solids
- Weight of dry solids per volume of reaction mixture: 30 mg/L
- Nutrients provided for bacteria: Mineral medium according to guideline

TEST MEDIUM / WATER PARAMETERS
- Source/preparation of dilution water: Mineral medium according to OECD guidelines purged overnight with CO2-free air for the test.

OTHER TEST CONDITIONS
- Adjustment of pH: es, 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.
- Photoperiod: Continuous darkness during test

EFFECT PARAMETERS MEASURED:
1) Observations: The appearance of the test preparations was recorded on Days 0, 7, 13, 20 and 27.
2) pH measurements: The pH of the test preparations was determined on Day 0 and Day 28 prior to acidification with hydrochloric acid, using a Hach HQ 40d Flexi handheld meter.
3) IC analysis: Samples were taken from the first CO2 absorber vessels on Days 0, 2, 6, 8, 10, 14, 21, 28 and 29. The second absorber vessels were all sampled on Days 0 and 29.
4) IC/TC ratio: Samples were taken on Days 0.

Reference substance (positive control):

yes

Remarks:

Sodium benzoate

Duration:

14 d

Dose descriptor:

NOEC

Effect conc.:

>= 27.1 mg/L

Nominal / measured:

nominal

Conc. based on:

act. ingr.

Basis for effect:

other:

Remarks:

degradation

Remarks on result:

other:

Remarks:

91% biodegradation after 14 d: 27.1 mg a.i. test item/L in 3 L mineral medium

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

 

RESULTS TOXICITY CONTROL

The toxicity control attained 91% biodegradation after 14 d and 107% biodegradation after 28 d thereby confirming that the test item had no toxic effect on activated sludge microorganisms, according to the validity criteria of OECD 301 B on ready biodegradability.

Validity criteria fulfilled:

yes

Remarks:

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

Description of key information

NOEC (14 d) ≥ 27.1 mg a.i./L (nominal, OECD 301 B, activated sludge); read-across

Key value for chemical safety assessment

EC10 or NOEC for microorganisms:

27.1 mg/L

Additional information

The toxicity of D-Glucopyranose, oligomeric, pentyl glycosides (CAS 100231-63-8) to activated sludge microorganisms was inferred from the toxicity control of a standard ready biodegradation test conducted according to OECD 301 B and GLP, as recommended by the Guidance document “Chapter R.7b Endpoint specific Guidance on Information Requirements and Chemical Safety Assessment” (ECHA, 2017) in absence of microbial toxicity tests according to OECD 209.

In the available CO2 evolution test, the toxicity control was prepared by inoculating 27.1 mg a.i. test item/L and 17.1 mg/L reference compound (sodium benzoate) with activated sludge (30 mg/L suspended solids) under aerobic conditions in the dark for 28 d. Degradation was followed by quantification of the produced CO2 trapped by sodium hydroxide, and expressed as percentage of the theoretical CO2 demand.

Degradation of the reference compound in the toxicity control was 91% after 14 d and 107% after 28 d. Thus, the test item did not cause toxic effects on activated sludge microorganisms and a NOEC (14 d) of ≥ 27.1 mg a.i./L was derived, according to the “Guidance on Information Requirements and Chemical Safety Assessment, Chapter R.7b: Endpoint specific Guidance” (ECHA, 2017).