A mixture of: 2-ethylhexyl mono-D-glucopyranoside; 2-ethylhexyl di-D-glucopyranoside

Toxicity to microorganisms

Link to relevant study record(s)

Reference

Endpoint:

activated sludge respiration inhibition testing

Type of information:

experimental study

Adequacy of study:

key study

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

other: Study according to international guideline, not GLP and with reference substance which meets validity criteria.

Qualifier:

according to guideline

Guideline:

OECD Guideline 209 (Activated Sludge, Respiration Inhibition Test

Deviations:

yes

Remarks:

see principles of method other than guideline

Principles of method if other than guideline:

No actual measurements of concentrations and instead of three concentrations of reference substance only one concentration was used.
3 controls instead of 2.

GLP compliance:

no

Specific details on test material used for the study:

Test substance name Reaction mass of 2-ethylhexyl mono-D-glucopyranoside 2-ethylhexyl di-D-glucopyranoside
Group: Alkyl glycosides
Product name: Berol AG 6202
CAS no 161074-93-7
EC no 414-420-0
Water solubility: >790 g/L
Sample received on April 19 1994
contains 65 ± 2 % surfactant
Samples were stored at 5 °C until use.

Analytical monitoring:

no

Remarks:

It is not required to quantify the exposure concentrations

Details on sampling:

The oxygen consumption was measured after 30 minutes and 3 hours

Vehicle:

no

Details on test solutions:

Standard test medium:
Synthetic sewage was made by adding 12 mL of the following stock solution to a total test volume of 400 mL in Erlenmeyer bottles.
16 g peptone
11 g meat extract
3 g urea
0.7 g NaCI
0.4 g CaCI2 · 2H20
0.2 g MgS04 · 7H20
2.8 g K2HP04
in 1 litre of Millipore water.

The volume in the test vessels was made up to 400 mL with demineralised water. Apart from sludge, test substance and reference substance, also a physico-chemical control was made without addition of activated sludge as a control for abiotic oxygen consumption.

Test organisms (species):

activated sludge of a predominantly domestic sewage

Details on inoculum:

Activated sludge from Usserod Treatment plant, which mainly receives household waste water was used in the tests. The sludge was collected on 27 April 1994 and was used for testing the same day.
Synthetic sewage was made and activated sludge was added to achieve the chosen concentrations

Test type:

static

Water media type:

freshwater

Limit test:

no

Total exposure duration:

3 h

Remarks on exposure duration:

The test was also performed with a 30 minutes exposure duration

Post exposure observation period:

None

Hardness:

Standard test medium was used.

Test temperature:

20 +/- 1 °C

pH:

7.5 - 8.1

Dissolved oxygen:

Oxygen consumption is parameter under investigation.

Salinity:

Standard test medium was used

Conductivity:

Standard test medium was used

Nominal and measured concentrations:

Nominal test concentrations:
10 - 20 - 50 - 100 - 200 mg/L

Details on test conditions:

The test was performed at 20+/- 1 °C with magnetic stirring.

Reference substance (positive control):

yes

Remarks:

3,5-dichlorophenol

Key result

Duration:

3 h

Dose descriptor:

EC50

Effect conc.:

> 130 mg/L

Nominal / measured:

nominal

Conc. based on:

act. ingr.

Basis for effect:

inhibition of total respiration

Key result

Duration:

3 h

Dose descriptor:

EC50

Effect conc.:

> 200 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

inhibition of total respiration

Remarks:

respiration rate

Duration:

3 h

Dose descriptor:

other: EC20

Effect conc.:

> 200 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

inhibition of total respiration

Remarks:

respiration rate

Details on results:

No significant inhibition of the respiration rate was measured after 3 hours of exposure to any of the test substance concentrations.
The abiotic controls showed no oxygen consumption.
The reference substance showed the validity of the test system as well as the respiration rate of the control being within 15% of the control replicates.

Results with reference substance (positive control):

The 3h results were in line with the requirements in the guideline.
The concentration used (10 mg/L) gave sufficient respiration rate inhibition in all tests performed (59-69% inhibition)

Reported statistics and error estimates:

The respiration rate was calculated on the basis of a linear regression analysis of oxygen concentration versus time. The respiration rate was related to the content of activated sludge measured as suspended solids (SS). The inhibition was calculated as the reduction of the respiration rate compared to an unexposed control divided by the respiration rate in the unexposed control. The concentrations that inhibited the respiration by 20 and 50% (EC20 & EC50) were estimated by linear regression of the exposure concentration (in mg/L) versus the natural logarithm of the inhibition (in % of control). Only the range of exposure concentrations that caused a significant effect was used for the calculations.

Validity criteria fulfilled:

yes

Conclusions:

The test had a satisfactory sensitivity. The test substance did not have a significant inhibitory effect on the respiration of activated sludge within the tested concentration range (0-200 mg/L).

Executive summary:

The inhibition of the respiration of activated sludge by Berol AG 6202 was tested according to OECD guideline 209. The substance was tested in five concentrations (10, 20, 50, 100 and 200 mg test item/L). No significant inhibition of the respiration rate was found within the tested concentration range, while the test showed satisfactory sensitivity (variation in controls < 15% and reference substance inhibition in acceptable range). The EC50 and EC20 were therefore > 200 mg/L test substance based on a nominal test concentration.

Description of key information

The inhibition of the respiration of activated sludge by Berol AG 6202 was tested according to OECD guideline 209. The substance was tested in five concentrations (10, 20, 50, 100 and 200 mg test item/L). The test item contained 65 ± 2% surfactant. No significant inhibition of the respiration rate was observed within the tested concentration range, while the test showed satisfactory sensitivity (variation in controls < 15% and reference substance inhibition in acceptable range). The EC50 and EC20 were therefore > 200 mg/L test substance based on a nominal test concentration (or > 130 mg a.i./L)

Key value for chemical safety assessment

EC50 for microorganisms:

130 mg/L