Diisononyl adipate

Toxicity to microorganisms

Link to relevant study record(s)

Reference

Reference 1

Endpoint:

activated sludge respiration inhibition testing

Type of information:

read-across from supporting substance (structural analogue or surrogate)

Adequacy of study:

supporting study

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

other: Guideline study

Qualifier:

according to guideline

Guideline:

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

Version / remarks:

Cited as Directive 87/302/EEC, part C, p. 118 (Biodegradation: Activated sludge respiration inhibition test)

GLP compliance:

yes

Analytical monitoring:

no

Vehicle:

no

Details on test solutions:

PREPARATION AND APPLICATION OF TEST SOLUTION
- Method: The test substance were added directly into the test vessels.

Test organisms (species):

activated sludge

Details on inoculum:

- Laboratory culture: obtained from municipal wastewater treatment plant of Marl-Ost (Germany), which predominantely treats domestic sewage.
- Preparation of inoculum for exposure: The activated sludge were centrifuged four times for 5 min at 2000 rpm and cleaned afterwards with 600 mL tap water.
- Initial biomass concentration: 3.7 g suspended solids/L

Test type:

static

Water media type:

freshwater

Limit test:

no

Total exposure duration:

3 h

Test temperature:

18 - 20.6 °C

pH:

7.8 - 8.4

Nominal and measured concentrations:

Nominal: 100.8, 127.4, 190.8, 269.6 and 352.4 mg/L

Details on test conditions:

TEST SYSTEM
- Aeration: continuously
- No. of vessels per concentration (replicates): 1
- No. of vessels per control (replicates): 2

TEST MEDIUM / WATER PARAMETERS
- Source/preparation of dilution water: tap water
- Intervals of water quality measurement: at the end of the incubation phase (after 3h)

EFFECT PARAMETERS MEASURED: O2 consumption was measured for 8 minutes after an incubation time of 3h.

Reference substance (positive control):

yes

Remarks:

3,5-Dichlorophenol

Duration:

3 h

Dose descriptor:

NOEC

Effect conc.:

> 350 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.:

> 350 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
- Relevant effect levels: EC50 (3h) = 5.5 mg/L

Table 1: Respiration inhibition of control, test and reference substance

Treatment	Nominal concentration [mg/L]	Measuring time	Inhibition [%]
Test item	352.4	5	-6.6
Test item	269.6	6	-8.0
Test item	190.8	6	-6.6
Test item	127.4	6.5	-7.7
Test item	100.8	5	-9.7
Reference	5	6.5	45.9
Reference	15	7.5	77.9
Reference	30	8	86.1
Control		6.5
Control		7

Validity criteria fulfilled:

yes

Conclusions:

A 3h respiration inhibition test with domestic activated sludge revealed that DEHA is not inhibitory to aquatic microorganisms up to the saturation limit in water.

Executive summary:

A 3h activated sludge respiration inhibition test was performed according to EU method C.11 under GLP conditions. Different test concentrations up to ~ 350 mg/L were tested. No respiration inhibition but stimulation was observed in all treatments compared to the control. Thus, the 3h-EC50 value is determined to be above the highest concentration tested : >350 mg/L.

Reference 2

Endpoint:

activated sludge respiration inhibition testing

Type of information:

experimental study

Adequacy of study:

key study

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

other: guideline study, non-GLP, no analytical monitoring

Qualifier:

according to guideline

Guideline:

ISO 8192 (Water quality - Test for inhibition of oxygen consumption by activated sludge for carbonaceous and ammonium oxidation)

GLP compliance:

no

Analytical monitoring:

no

Vehicle:

no

Details on test solutions:

PREPARATION AND APPLICATION OF TEST SOLUTION
- Method: The test substance was directly added to the test vessels.

Test organisms (species):

activated sludge, domestic

Details on inoculum:

- inoculum: 50 mL = 1g/L dry substance per test vessel

Test type:

static

Water media type:

freshwater

Limit test:

no

Test temperature:

20-25 °C

Nominal and measured concentrations:

Nominal: 198.8, 498.4 and 1001.2 mg/L

Details on test conditions:

- 250 ml test volume

Reference substance (positive control):

no

Key result

Duration:

30 min

Dose descriptor:

other: EC20

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:

No effect on the bacteria were measured up to the highest test concentration (1000 mg/L).

Description of key information

EC20(0.5h) > 1000 mg/L (nominal) for oxygen consumption of activated sludge (ISO 8192)

Additional information

One study investigating the toxicity of Diisononyl adipate (DINA) to aquatic microorganisms is available. The study was performed according to ISO guideline 8192 using non-adapted municipal activated sludge ass inoculum (BASF 1985). Concentrations between 198 and 1000 mg/L were tested without removing undissolved test material from the test system. The 0.5h-EC20 is determined to be > 1000 mg/L based.

Further, in the available ready biodegradability test according to a guideline equivalent to OECD TG 301F with diisononyl adipate, no inhibition of the inoculum was observed in the inhibition control at a concentration of 100 mg/L diisononyl adipate, indicating no toxicity to microorganisms.

Additionally, a supporting study for the structurally analogue substance bis(2-ethylhexyl) adipate is available. The study was conducted according to GLP and EU Method C.11 (87/302/ECC, part C, p.118). No effects were observed up to the maximum nominal test concentration of 352.4 mg/L. Consequently a NOEC >= 350 mg/L was determined.

In conclusion, diisononyl adipate is not toxic to microorganisms.