Fatty acids, C16-18 tridecyl esters

Toxicity to microorganisms

Administrative data

Endpoint:

activated sludge respiration inhibition testing

Type of information:

experimental study

Adequacy of study:

key study

Study period:

2012

Reliability:

2 (reliable with restrictions)

Data source

Reference

Reference Type:

publication

Title:

Unnamed

Year:

2012

Report date:

2012

Materials and methods

Test guideline

Qualifier:

according to guideline

Guideline:

OECD Guideline 209 (Activated Sludge, Respiration Inhibition Test (Carbon and Ammonium Oxidation))

Deviations:

no

GLP compliance:

yes (incl. QA statement)

Test material

Test material information

Constituent 1

Reference substance name:

Dodecyl oleate

EC Number:

252-862-4

EC Name:

Dodecyl oleate

Cas Number:

36078-10-1

Molecular formula:

C30H58O2

IUPAC Name:

9-Octadecenoic acid (9Z)-, dodecyl ester

Test material form:

liquid

Specific details on test material used for the study:

SOURCE OF TEST MATERIAL
Name of test material (as cited in study report): Dodecyl-Oleat
- Analytical purity: 100%
- Lot/batch No.: K120424B
- Storage condition of test material: ambient temperature

Sampling and analysis

Analytical monitoring:

no

Test solutions

Vehicle:

no

Details on test solutions:

- Method: 586 µl of the test item were added into the test vessels to obtain final concentrations of 1000 mg/L. Three parallel vessels of the test item were prepared.
- Eluate: no
- Differential loading: yes
- Controls: yes, blank control

Test organisms

Test organisms (species):

activated sludge of a predominantly domestic sewage

Details on inoculum:

- Source: Activated sludge from the municipal wastewater treatment plant Staufener Bucht (Germany) was used as test system. The treatment plant clarifies predominantly domestic wastewater of the region of Staufen and has a capacity of 140 000 inhabitant equivalents. Sampling date of activated sludge was 16 Oct 2012.
- Laboratory culture: no
- Preparation of inoculum for exposure: The activated sludge was kept aerated and fed with synthetic sewage (50 mL per litre and day) until use. Dry solids of the activated sludge was determined as 5.3 g/L by weight measurements before and after 3 h drying at 105°C (mean of triplicate measurements). The activated sludge was washed twice by settling the sludge, decanting the supernatant, and re-suspending the sludge in aerated tap water. Before using, the activated sludge was diluted to 3 g/L dry solids with tap water, in order to obtain a final concentration of 1.5 g/L dry solids in the test.
- Initial biomass concentration: 1.5 g/L (dry solids)

Study design

Test type:

static

Water media type:

freshwater

Limit test:

yes

Total exposure duration:

3 h

Test conditions

Test temperature:

18 - 20°C

pH:

7.7

Nominal and measured concentrations:

nominal: blank, 1000 mg/L

Details on test conditions:

TEST SYSTEM
- Test vessel: BOD bottles
- Fill volume: 500 mL
- Aeration: All vessels were stirred and aerated throughout the contact time with room air at a rate of 0.5 - 1 L/min using a membrane pump.
- No. of vessels per concentration (replicates): 3
- No. of vessels per control (replicates): 6

TEST MEDIUM / WATER PARAMETERS
- Source/preparation of dilution water: according to guideline (demineralised water)

EFFECT PARAMETERS MEASURED: respiration rate was measured every 15 min to allow a contact time of 3 h

Reference substance (positive control):

yes

Remarks:

3,5-dichlorophenol

Results and discussion

Effect concentrations

Effect concentrations 1

Key result

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 on result:

other: Respiration rate

Effect concentrations 2

Key result

Duration:

3 h

Dose descriptor:

NOEC

Effect conc.:

>= 1 000 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

inhibition of total respiration

Remarks on result:

other: Respiration rate

Results with reference substance (positive control):

- Results with reference substance valid? yes
- Relevant effect levels: EC50 (3 h): 22.48 mg/L. The EC50 was calculated with ToxRat version 2.09 (ToxRat Solutions GmbH, Alsdorf, Germany) by probit analysis using linear max. likelihood regression.

Applicant's summary and conclusion

Validity criteria fulfilled:

no

Conclusions:

The results of a first test with a concentration of 1000 mg/L showed high negative inhibitions (until -53%) and a relative low start value of oxygen at the beginning of the measurement. Therefore, the aeration of the test was optimized and the test was repeated. The data of the first test are not shown in detail in the report. In the repetition the values of oxygen at the start of measurement were considerably higher and the evaluation showed conclusive results.