Decanoic acid, mixed esters with heptanoic acid, isovaleric acid, octanoic acid and pentaerythritol

Toxicity to microorganisms

Link to relevant study record(s)

Reference

Endpoint:

activated sludge respiration inhibition testing

Type of information:

experimental study

Adequacy of study:

key study

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

The substance, CAS 68130-51-8; EC  268-594-6, is analogous to the substances to be read across to, in terms of basic form, and the degree of substitution of functional groups is not considered to effect the proposed read across for the endpoint of toxicity to microorganisms. The substance is not considered to be toxic to microorganisms on the basis of read across.

Key value for chemical safety assessment

EC50 for microorganisms:

10 000 mg/L

Additional information

A 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)

Therefore, by read-across CAS 68130-51-8; EC  268-594-6,is not considered to be toxic to aquatic microorganisms.

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