Ethylidynetrimethanol

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

Study period:

2010

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

other: Guideline and GLP-study, validity criteria fulfilled

Reason / purpose for cross-reference:

reference to same study

Reason / purpose for cross-reference:

reference to other study

Qualifier:

according to guideline

Guideline:

EU Method C.11 (Biodegradation: Activated Sludge Respiration Inhibition Test)

Deviations:

yes

Remarks:

3 test substance concentrations instead of 5

GLP compliance:

yes

Specific details on test material used for the study:

Details on properties of test surrogate or analogue material (migrated information):
Not applicable

Analytical monitoring:

not required

Details on sampling:

Not applicable

Vehicle:

no

Details on test solutions:

The test substance was pulverised and dissolved in deionised water by stirring for 18 hours before the start of the test.

Test organisms (species):

activated sludge of a predominantly domestic sewage

Details on inoculum:

- Laboratory culture: yes
- Method of cultivation:
# first, the sludge was settled and the supernatant was decanted
# after centrifuging (15 min at 4500 rpm and 20°C) the supernatant was decanted
# approx. 1 g of the wet sludge was dried to calculate the amount of wet sludge to achieve a concentration of activated sludge of 3 g/L (dry
weight) suspended solids
# the calculated amount of sludge was first dissolved in synthetic medium and than filled up to a defined end volume with deionised water
# aeration of the activated sludge at 20°C ± 2°C, daily fed with synthetic medium
- Preparation of inoculum for exposure: Before use the concentration of suspended solids of the activated sludge was determined again. 10 mL of sludge suspension were dried in order to calculate the amount of sludge suspension to achieve a concentration of activated sludge of 2 g/L (dry weight) suspended solids. The calculated amount of sludge suspension was taken and filled up to a defined end volume with deionised water. The pH was measured and adjusted to pH 6-8.
- Initial biomass concentration: 2 g/L (dry weight) suspended solids were used in order to get a test concentration of 800 mg/L suspended solids

Water media type:

freshwater

Limit test:

no

Total exposure duration:

3 h

Post exposure observation period:

Not indicated

Hardness:

Not indicated

Test temperature:

20°C ± 2°C

pH:

7.8 - 8.0 in the test solutions

Dissolved oxygen:

2.6 - 7.1 mg/L

Salinity:

Not applicable

Nominal and measured concentrations:

Nominal concentrations: 10, 100 and 1000 mg/L

Details on test conditions:

TEST SYSTEM
- Test vessel: 300 mL-Erlenmeyer flasks
- Type (delete if not applicable): open
- fill volume: 250 mL
- Aeration: yes
- No. of vessels per control (replicates): 2
- No. of vessels per physical-chemical oxygen consumption control (medium with test substance and without activated sludge): 1

OTHER TEST CONDITIONS
- Adjustment of pH: yes

EFFECT PARAMETERS MEASURED (with observation intervals if applicable) : Oxygen content


TEST CONCENTRATIONS: 10, 100 and 1000 mg/L

Reference substance (positive control):

yes

Remarks:

3,5 - dichlorophenol

Duration:

3 h

Dose descriptor:

EC50

Effect conc.:

> 1 000 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:

EC10

Effect conc.:

> 1 000 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

inhibition of total respiration

Remarks:

respiration rate

Details on results:

Please refer to the table presented under "Remarks on results including tables and figures"

Results with reference substance (positive control):

EC50 of 3,5 - dichlorophenole is 9.2 mg/L ( 95% C.I. 3 - 24 mg/L)

Reported statistics and error estimates:

EC50 and the confidence interval of the reference substance was determined by probit analysis.

Test substance (nominal)   [mg/L]	Respiration rate   [mg/L x h]	Phys.-chem. O2consumption   [mg/L x h]	Respiratory rate - phys.-chem. O2consumption [mg/L x h]	Inhibition     [%]
10	32.0	0.0	32.0	0.0
100	34.0	0.0	34.0	0.0
1000	32.0	0.0*	32.0	0.0
Control mean	30.8	-
Control 1	30.0	-
Control 2	31.5	-

*The physico-chemical oxygen consumption has been determined at 1000 mg/L test item concentration. As no physico-chemical oxygen consumption was observed at that test item concentration this observation also holds true for the lower test item concentrations.

Validity criteria fulfilled:

yes

Remarks:

respiration rates of the 2 controls differ less than 15 % from each other; the EC50 of the reference compound 3.5-Dichlorophenol is in the range 5 - 30 mg/L

Conclusions:

The EC50 and the EC10 for trimethylolpropane were determined to be > 1000 mg/L.

Executive summary:

The respiration inhibition of activated sludge from predominantly domestic sewage treatment plant by trimethylolpropane was determined according to the EU Guideline C.11 with an incubation time of 3 hours. The concentrations tested were 10, 100 and 1000 mg/L. EC50 of the reference substance 3,5 - dichlorophenole was 9.2 mg/L ( 95% C.I. 3 - 24 mg/L). The respiration rates of the 2 controls differed less than 15% from each other.

The EC50 and the EC10 for trimethylolpropane were determined to be > 1000 mg/L.

The validity criteria of the guideline are fulfilled. The deviation from the guideline used is considered to have no negative impact on the result.

Reference: Neuhahn, 2010

Key value for chemical safety assessment

EC50 for microorganisms:

1 000 mg/L

EC10 or NOEC for microorganisms:

1 000 mg/L

Additional information

Assessment is by read-across to the source substance trimethylolpropane (CAS No: 77-99-6).