Decanoic acid, mixed esters with heptanoic acid, octanoic acid and trimethylolpropane

Toxicity to microorganisms

Link to relevant study record(s)

Reference

Reference 1

Endpoint:

toxicity to microorganisms

Type of information:

migrated information: read-across based on grouping of substances (category approach)

Adequacy of study:

weight of evidence

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:

no

Test organisms (species):

activated sludge, domestic

Details on inoculum:

- Source of inoculum/activated sludge: Activated sludge from the aeration basin of the domestic sewage treatment plant in Lachen-Speyerdorf, Germany (2008-05-08)
- Preparation of inoculum for exposure: The sludge was aerated continually, washed with and re-suspended in mineral medium.
- Initial biomass concentration: 25 mg suspended solids/L

Test type:

static

Water media type:

freshwater

Limit test:

yes

Total exposure duration:

14 d

Test temperature:

22 ± 1°C

Nominal and measured concentrations:

Nominal test substance concentration:
30 ± 2 mg/L

Details on test conditions:

TEST SYSTEM
- Test vessel: 2000 mL-SCHOTT-flasks
- Fill volume: 1500 mL
- Aeration: with purified, CO2-scribbed, moistened air

TEST MEDIUM / WATER PARAMETERS
- Source/preparation of dilution water: Mineral medium according to OECD guideline

EFFECT PARAMETERS MEASURED:
CO2 evolution on day 0, 2, 4, 7, 9, 11 and 14

Reference substance (positive control):

yes

Remarks:

Anilin

Key result

Duration:

14 d

Dose descriptor:

NOEC

Effect conc.:

30.4 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):

The reference material (Anilin) was degraded by 3.5% after 7 days, 60% pass level was reached.

Degradation (%) the toxicity control in ready biodegradability study following OECD Guideline 301 B (Ready Biodegradability: CO2 Evolution Test)

Day	Toxicity control
2	1.3
4	41.8
7	65.9
9	70.4
11	74.4
14	80.4
17	77.2
23	84.3
29	87.9

Reference 2

Endpoint:

activated sludge respiration inhibition testing

Type of information:

migrated information: read-across based on grouping of substances (category approach)

Adequacy of study:

weight of evidence

Study period:

14 May 1998

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

other: GLP Guideline study with acceptable restrictions: No analytical purity is given. , no analytical monitoring)

Qualifier:

according to guideline

Guideline:

OECD Guideline 209 (Activated Sludge, Respiration Inhibition Test

Deviations:

no

GLP compliance:

yes

Analytical monitoring:

no

Vehicle:

no

Details on test solutions:

PREPARATION AND APPLICATION OF TEST SOLUTION
- Method: Test substanz was emulsified using Ultra-Turrax.

Test organisms (species):

activated sludge, domestic

Details on inoculum:

- Laboratory culture: Activated sludge from sewage plant Bempflingen, Germany
- Preparation of inoculum for exposure: Activated sludge was washed with tap water twice, afterwards centrifuged and the dry residue was determined. The amount of the sludge was weighed per liter, which was corresponded to 4 g dry mass.

Test type:

static

Water media type:

freshwater

Limit test:

yes

Total exposure duration:

3 h

Hardness:

not stated

Test temperature:

20 ± 2 °C

pH:

not stated

Dissolved oxygen:

> 6.5 mg/L

Nominal and measured concentrations:

Nominal: 10000 mg/L

Details on test conditions:

TEST SYSTEM
- Test vessel: beaker
- Material: glass; Size: 1 L; Fill volume: 500 mL
- Aeration: continously to reach an oxygen content > 6.5 mg/L
- No. of vessels per concentration: 1
- No. of vessels per control: 2

TEST MEDIUM / WATER PARAMETERS
- Source/preparation of dilution water: dechlorinated tap water

EFFECT PARAMETERS MEASURED: Respiration inhibition by decrease of oxygen content was measured in 15-minutes-pulses over a test period of 3 h using an OXI-meter.

Reference substance (positive control):

yes

Remarks:

3,5 dichlorphenol

Key result

Duration:

3 h

Dose descriptor:

EC50

Effect conc.:

> 10 000 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

inhibition of total respiration

Remarks:

respiration rate

Key result

Duration:

3 h

Dose descriptor:

EC10

Effect conc.:

> 10 000 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

inhibition of total respiration

Remarks:

respiration rate

Results with reference substance (positive control):

- Results with reference substance valid? Yes, result is in the range of 5 to 30 mg/L
- Relevant effect levels: EC50 = 5 mg/L

An increase about 43% of respiration rate could be observed at the nominal tested concentration of 10000 mg/L in comparison to the control.

Table 1: Respiration rate of control, reference and test substance and inhibition of the respiration rate of test and reference substance (*A negative sign means an increase of the respiration)

	Replicates	Concentration [mg/L]	Respiration rate [mg O2/L x h]	Inhibition [%]
Control	1		24.0 25.0	-
Referenz	1 2 3	2.5 10 30	22.0 11.0 5.0	10.2 55.1 79.6
Test substance	1	10000	35.0	-43.0*

 *: negative value indicate an increase of respiration

Description of key information

No relevant studies are available for decanoic acid, mixed esters with heptanoic acid, octanoic acid and trimethylolpropane. Two studies that evaluated the toxicity to aquatic microorganisms are available for closely related structural analogues (CAS 11138-60-6 and CAS 78-16-0).

Key value for chemical safety assessment

EC50 for microorganisms:

10 000 mg/L

Additional information

Two studies that evaluated the toxicity to aquatic microorganisms are available for closely related structural analogues:

The first study was conducted with CAS 11138-60-6 using activated sludge (domestic) according to OECD 209. It showed an increase about 43% of respiration rate at the nominal tested concentration of 10000 mg/L in comparison to the control. No inhibition of respiration rate was observed. Therefore the EC50 and EC10 (3h) can be stated as > 10000 mg/L (nominal).

The second study with CAS 78-16-0 was based on the inhibition control of a ready biodegradability study. Since more than 80.4% degradation occurred in the toxicity control, the substance is with a high probablity not toxic to aquatic microorganisms. The test item concentration in the toxicity control of 30.4 mg/L can be used as NOEC value for the toxicity to aquatic microorganisms.

Therefore, by read-across, decanoic acid, mixed esters with heptanoic acid, octanoic acid and trimethylolpropane is not considered to be toxic to aquatic microorganisms.

A report justifying the read-across approach is included in IUCLID Chapter 13.