Fatty acids, coco, esters with 1,3-butanediol

Toxicity to microorganisms

Link to relevant study record(s)

Reference

Endpoint:

toxicity to microorganisms, other

Remarks:

Toxicity control of ready biodegradability test according to OECD 301F

Type of information:

experimental study

Adequacy of study:

key study

Study period:

25 Oct - 12 Dec 2017

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 2017).

Reason / purpose for cross-reference:

reference to same study

Qualifier:

according to guideline

Guideline:

other: Toxicity control of OECD Guideline 301 F (Ready Biodegradability: Manometric Respirometry Test)

Version / remarks:

1992

GLP compliance:

yes

Analytical monitoring:

no

Details on sampling:

SAMPLING
- Sampling frequency: on days 0, 1, 2, 3, 4, 6, 9, 13, 20, 28
- Sampling method: Oxygen consumption was measured by decreasing of the pressure in the bottles. The Biological Oxygen Demand values were extracted from the measurement heads.

Vehicle:

no

Test organisms (species):

activated sludge, domestic

Details on inoculum:

- Source of inoculum/activated sludge: Valence’s Waste treatment Plant (collected on 26th October 2017)
- Pretreatment: The sludge was settled and the liquid supernatant discarded. The concentrated sludge was then suspended in the mineral solution. These two steps were repeated twice.
- Concentration of sludge: The concentration of suspended solids was determined after rinsing the sludge. An activated sludge volume was filtered on a 1.2 μm filter with a vacuum pump. Then, the filter
was dried in drying oven at 105 °C. Solid matter was 4.52 g/L.

Test type:

static

Water media type:

freshwater

Limit test:

yes

Total exposure duration:

14 d

Test temperature:

20.5 ° C ± 1

pH:

7.5 - 7.8 (at Day 0 and 28)

Nominal and measured concentrations:

Nominal: 23.1 mg test item/L

Details on test conditions:

TEST CONDITIONS
- Composition of medium: according to the OECD 301F guideline
- Additional substrate: no
- Solubilising agent (type and concentration if used): no
- Continuous darkness: yes
- Other: The flasks were closed with the measuring heads and stirred with a magnetic stirrer.

TEST SYSTEM
- Culturing apparatus: 650 mLwhite glass bottles
- Number of culture flasks/concentration: 1
- Measuring equipment: heads and oxitop® controller
- Details of trap for CO2: The CO2 released was trapped by soda pellets.

CONTROL AND BLANK SYSTEM
- Inoculum blank: 2 replicates (250 mL tes media + 1.7 mL inoculum)
- Reference control: 2 replicates (250 mL test media + 26.3 mL reference item + 1.7 mL inoculum)
- Abiotic control: 1 replica (23.2 mL test item + 250 mL media)

Reference substance (positive control):

yes

Remarks:

benzoic acid, sodium salt

Duration:

14 d

Dose descriptor:

NOEC

Effect conc.:

>= 23.1 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

other: O2 consumption

Remarks on result:

other: Result of toxicity control from ready biodegradability test

Details on results:

70.4 % biodegradation took place in the toxicity control within 13 d and therefore the test item was not toxic to micro-organisms.
The degradation of test item was not abiotic as the abiotic control revealed.

Results with reference substance (positive control):

> 60% biodegradation of the reference substance took place within 13 d (84.9 and 83.8%).

BIOLOGICAL RESULTS:

Table 1: % Biodegradation of reference control, toxicity control and abiotic control

Time (Days)	Reference control A	Reference control B	Test item solution A	Test item solution B	Toxicity control	Abiotic control
0	0	0	0	0	0	0
0.5	0	0	0.7	1.5	0.5	5.3
1	10.5	9.8	7.4	8.5	7.6	4.5
2	36.4	38	14.1	14.7	12.9	3.8
3	48.1	47.8	18	19.5	16.4	4.5
4	61.8	60.9	22.6	23.6	21.3	4.1
6	76.2	73.5	27.5	29.4	45.4	4.5
9	81.4	80.8	34.5	35.9	52.6	4.5
13	84.9	83.8	41.1	42.1	57.7	4.1
20	89	91.7	52.5	54	72.4	3.7
28	90.2	92.9	59.2	60.9	82.5	4.1

Validity criteria fulfilled:

not applicable

Description of key information

NOEC (14 d) >= 23.1 mg/L (nominal, toxicity control, OECD 301F, activated sludge)

Additional information

Since no studies on the toxicity to aquatic microorganisms are available the results of a ready biodegradability study are used to draw conclusion on the toxicity of the substance to aquatic microorganisms. If a compound biodegrades readily in a biodegradability test or does not inhibit at a certain concentration the degradation of a reference substance in the positive control the substance is not considered toxic to microorganisms and the concentration applied in the toxicity control can be set as the NOEC value. This approach is in accordance with the Guidance on information requirements and chemical safety assessment (Chapter R.7b: Endpoint specific guidance, ECHA 2017). 

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 ThOD occurred within 14 days (OECD guideline 301).

For the test item fatty acids, coco, esters with 1,3-butanediol (CAS 73138-39-3) a biodegradation test according to OECD guideline 301F is available. The test includes a toxicity control, which contains 23.1 mg/L of the test item and 24.4 mg/L benzoic acid. The toxicity control attained 57.7% degradation after 13 days of incubation. Hence, the substance is considered not toxic to aquatic microorganisms and the test item concentration of 23.1 mg/L can be used as NOEC.