Fatty acids, C16-18, 2-butyloctyl esters

Toxicity to microorganisms

Link to relevant study record(s)

Reference

Endpoint:

toxicity to microorganisms

Type of information:

experimental study

Adequacy of study:

key study

Study period:

2005-01-13 - 2005-02-11

Reliability:

1 (reliable without restriction)

Qualifier:

according to guideline

Guideline:

other: OECD 301 B

GLP compliance:

yes

Specific details on test material used for the study:

Details on properties of test surrogate or analogue material (migrated information):
The CO2-free air production system consisted of an air compressor, two 1000 ml gas wash bottles filled with dry soda lime, followed by one bottle filled with 0.1 M NaOH (sodium hydroxide) and one gas wash bottle filled with demineralised water. The CO2-free air was passed on to an air distributewith two input and 22 output channels and through PE-tubes. Gas wash bottles (2000 ml volume) with lateral connecting pieces for butyl rubber septums were used as reactors. The liquid volume was fixed as 1.500 ml each. Mixing was performed by a magnetic stirrer with 2 cm stir bars. 43.4 µl of the test item were added into the three test vessels and the vessel for toxicity control, corresponding to a TOC concentration of 20 mg/l TOC. From the reference compound 5.15 ml of a stock solution of 10 g/l were added to the reference vessels and the vessels for toxicity control. The CO2 produced in the reactors was absorbed in two 250 ml gas wash bottles in series, each filled with 200 ml 0.2 M NaOH. Sampling was performed through the lateral connecting pieces through the butyl rubber septum using 5 ml PE syringes. The amount of CO2 released from the reactors is calculated through IC-measurements in the CO2-absorber while considering the amount of CO2 removed for IC-measurement.

Test organisms (species):

activated sludge, domestic

Details on inoculum:

Activated sludge from the municipal wastewater treatment plant Breisgauer Bucht was used as inoculum with a concentration corresponding to 30 mg dry solids per litre. The treatment plant clarifies predominantly domestic wastewater of the region of Freiburg and has a capacity of 600.000 inhabitant equivalents. Sampling date of activated sludge was January 11th, 2005. Dry solids of the activated sludge was determined as 5.4 g/l by weight measurements after 2 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.

Test type:

static

Water media type:

freshwater

Total exposure duration:

28 d

Key result

Duration:

28 d

Dose descriptor:

NOEC

Effect conc.:

> 24.86 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Remarks:

20 mg/L organic carbon, Organic carbon in the test substance 80.45 %

Duration:

28 d

Dose descriptor:

NOEC

Effect conc.:

> 20 mg/L

Nominal / measured:

nominal

Conc. based on:

other: organic carbon

Validity criteria fulfilled:

yes

Conclusions:

The degradation in the toxicity control was 75.8% within 14 days and 93.8% within 28 days (after acidification), so there was no inhibition of the inoculum caused by the test item.

Executive summary:

The degradation in the toxicity control was 75.8% within 14 days and 93.8% within 28 days (after acidification), so there was no inhibition of the inoculum caused by the test item.

In the Toxicity control 5.15 ml of a stock solution of 10 g/l reference substance and 43.4 µl of the stock solution of the test item were added into the vessel. This correspondens to 40 mg/L organic carbon.

43.4 µl stock solution correspondens to 20 mg/L organic carbon. The test substance contains 80.45 % Organic Carbon. That means that 24.86 mg/L test substance does not have effects on activated sludge. Activated sludge was used as inoculum with a concentration corresponding to 30 mg dry solids per litre.

Description of key information

In the biodegradation test no inhibition of the inoculum caused by the target substance Fatty acids, C16-18, 2-butyloctyl esters was found. 
in that study 24.86 mg/L test substance does not have effects on activated sludge.

Key value for chemical safety assessment

EC10 or NOEC for microorganisms:

24.86 mg/L

Additional information

The degradation in the toxicity control of an OECD 301B test performed with the test substance, Fatty acids, C16-18, 2-butyloctyl esters achieved 75.8% within 14 days and 93.8% within 28 days (after acidification), so there was no inhibition of the inoculum caused by the test item. In the Toxicity control 5.15 ml of a stock solution of 10 g/l reference substance and 43.4 µl of the stock solution of the test item were added into the vessel. This corresponds 40 mg/L organic carbon. 43.4 µl stock solution corresponds to 20 mg/L organic carbon. The test substance contains 80.45 % Organic Carbon. That means that 24.86 mg/L test substance does not have effects on activated sludge. Activated sludge was used as inoculum with a concentration corresponding to 30 mg dry solids per litre.