Fatty acids, C10-12, esters with polylactic acid, sodium salts

Toxicity to microorganisms

Link to relevant study record(s)

Reference

Endpoint:

toxicity to microorganisms, other

Type of information:

experimental study

Adequacy of study:

key study

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

other: 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 2012).

Reason / purpose for cross-reference:

reference to same study

Qualifier:

according to guideline

Guideline:

other: OECD Guideline 301 B (Ready Biodegradability: CO2 Evolution Test)

GLP compliance:

yes (incl. QA statement)

Analytical monitoring:

no

Vehicle:

no

Test organisms (species):

activated sludge

Details on inoculum:

- Source of inoculum/activated sludge:
The sludge was taken from a biologic sewage treatment plant which is treating mostly domestic sewage. Sludge was taken on Sep 7th, 2012, from the activation basin of ESN (Stadtentsorgung Neustadt) sewage treatment plant, located in Altenschemel, NW-Lachen - Speyerdorf in Germany.
- Pretreatment: The sludge was filtrated, washed with tap water twice, then washed with resuspended test medium. Then aerated for ≥ 12 hours.
- Concentration of sludge: 25,0 mg dry matter/L, determined by 4120 mg suspended sludge/L.

Test type:

static

Water media type:

freshwater

Limit test:

yes

Total exposure duration:

14 d

Details on test conditions:

TEST CONDITIONS
- Composition of medium: according to guideline
- Test temperature: 20.5 - 23.0 °C
- pH: 6.94 - 7.62
- pH adjusted: no
- Inoculum concentration: 25 mg/L
- Continuous darkness: yes

TEST SYSTEM
- Culturing apparatus: 2000 mL glass flasks
- Number of culture flasks/concentration: 2
- Method used to create aerobic conditions: The test vessels were aerated with purified (by activated charcoal), CO2-scrubbed, moistened air. The scrubbing of carbon dioxide was achieved by bubbling the purified air through a flask containing 1.5 m-NaOH. To control the absence of CO2, the air was then led through a flask containing a solution of Ba(OH)2 before reaching the test vessels.
- Details of trap for CO2 and volatile organics if used: flask containing a solution of Ba(OH)2

SAMPLING
- Sampling frequency: Sampling was done on days 0, 2, 4, 7, 9, 11, 14, 18, 22 and 29
- Sampling method: 10 samples of 1 mL each were taken from each front scrubber flask. On day 29, samples from both flasks were taken.

Reference substance (positive control):

yes

Remarks:

Aniline

Duration:

14 d

Dose descriptor:

NOEC

Effect conc.:

34.9 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

other: Result of toxicity control from ready biodegradability test

Results with reference substance (positive control):

Aniline was chosen as positive control.
Activated sludge was used as inoculum (concentration in the test 25.0 mg dry matter/L). The test was left running for 28 days.
All validity criteria were met. Degradation of the positive control was 63 % after fourteen days.

The toxicity control attained 73.7% degradation after 14 days of incubation. Thus, the test item is not toxic to the inoculum. An inhibtion of of the activated sludge microorganisms is not expected.

The test item concentration in the toxicity control of 34.9 mg/L can be used as NOEC value for the toxicity to aquatic microorganisms.

Description of key information

NOEC (14 d): 34.9 mg/L (nominal, OECD 301B)

Key value for chemical safety assessment

EC10 or NOEC for microorganisms:

34.9 mg/L

Additional information

Studies investigating the toxicity to aquatic microorganisms are not available. The assessment is therefore based on the data reported in the available ready biodegradability tests on the substance. A substance can be assumed to be not inhibitory to aquatic microorganisms, if in the toxicity control of a ready biodegradation test, more than 25% degradation based on O2 consumption or CO2 evolution occurred within 14 days (OECD guideline 301). This was clearly the case in all three available ready biodegradability test. Thus, the inhibition control of the available screening test following OECD 301 B was used to derive a NOEC for the toxicity to aquatic microorganisms.

The inhibition control included the available ready biodegradability test according to OECD 301B attained 73.7% degradation after 14 days. The test item concentration in the toxicity control was 34.9 mg/L, the concentration of the reference substance Aniline was 25.2 mg/L. The test item concentration of 34.9 mg/L can be used as NOEC.