Isodecyl pivalate

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:

16 Nov 2011

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

other: Guideline study with acceptable restrictions (no GLP, no analytical purity)

Qualifier:

according to guideline

Guideline:

OECD Guideline 209 (Activated Sludge, Respiration Inhibition Test

Version / remarks:

adopted 1984

Qualifier:

according to guideline

Guideline:

EU Method C.11 (Biodegradation: Activated Sludge Respiration Inhibition Test)

GLP compliance:

no

Remarks:

no GLP statement

Analytical monitoring:

no

Vehicle:

no

Test organisms (species):

activated sludge of a predominantly domestic sewage

Details on inoculum:

- Source of inoculum: Activated sludge was obtained on 14 Nov 2011 from the sewage treatment plant at Maxéville, France, which treats predominantly domestic sewage (98%).
- Treatment of sludge: On the day of collection, the sludge was washed three times with dechlorinated water (centrifugation for 10 min at 1100 x g followed by resuspension).
- Method of cultivation: The sludge was kept under constant aeration and was fed with synthetic sewage every 24 h.
- Initial suspended matter concentration: 4.0 g/L ± 10%
- Concentration of suspended matter in test flasks: 1.6 g/L ± 10%

Test type:

static

Water media type:

freshwater

Limit test:

no

Total exposure duration:

3 h

Test temperature:

20 ± 2 °C

Nominal and measured concentrations:

Nominal: control, 10, 31.6, 100, 316 and 1000 mg/L

Details on test conditions:

TEST SYSTEM
- Test vessel: wide-mouth flasks
- Material, size, fill volume: glass, 1 L flasks for incubation (750 mL of culture), 550 mL flasks for oxygen measurement (550 mL of culture)
- Aeration: yes, aeration rate of 0.5 - 1 L/min
- No. of vessels per concentration (replicates): 1
- No. of vessels per control (replicates): 2

TEST MEDIUM / WATER PARAMETERS
- Source/preparation of dilution water: Dechlorinated tap water was used in the test.

EFFECT PARAMETERS MEASURED:
- After 3 h of incubation, the respiration rate was measured during 10 min.

TEST CONCENTRATIONS
- Spacing factor for test concentrations: 3.16

Reference substance (positive control):

yes

Remarks:

3,5-dichlorophenol

Duration:

3 h

Dose descriptor:

EC10

Effect conc.:

> 1 000 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

inhibition of total respiration

Remarks:

respiration rate

Duration:

3 h

Dose descriptor:

EC50

Effect conc.:

> 1 000 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

inhibition of total respiration

Remarks:

respiration rate

Duration:

3 h

Dose descriptor:

NOEC

Effect conc.:

>= 1 000 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

inhibition of total respiration

Remarks:

respiration rate

Details on results:

- Inhibition of respiration rates: Inhibition was 8, 15, -36, -26 and -12% at 10, 31.6, 100, 316 and 1000 mg/L, respectively (first measurement). Inhibition was -12, -46, -31, -33 and -10% at 10, 31.6, 100, 316 and 1000 mg/L, respectively (second measurement)
- All validity criteria were fulfilled.

Results with reference substance (positive control):

- Results with reference substance valid? yes
- Relevant effect levels: EC50 (3 h) = 15.5 mg/L (accepted range: 5 to 30 mg/L)

Description of key information

NOEC (3 h): ≥ 1000 mg/L (OECD 209)

Additional information

One study investigating the toxicity of isodecyl pivalate (CAS 60209-82-7) to activated sludge microorganisms is available. The study was conducted according to OECD 209 (adopted 1984) under non-GLP conditions. Five concentrations up to 1000 mg/L (nominal) were tested. No inhibition of respiration of activated sludge microorganisms was observed after 3 h, resulting in a NOEC (3 h) ≥ 1000 mg/L and an EC10 (3 h) > 1000 mg/L.