Tri-C18-22 (even numbered)-alkyl 2-hydroxypropane-1,2,3-tricarboxylate

Toxicity to microorganisms

Administrative data

Endpoint:

activated sludge respiration inhibition testing

Type of information:

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

Adequacy of study:

key study

Study period:

on day 1998-08-27

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

other: GLP guideline study

Data source

Reference

Reference Type:

study report

Title:

Unnamed

Year:

1998

Report date:

1998

Materials and methods

Test guideline

Qualifier:

according to guideline

Guideline:

OECD Guideline 209 (Activated Sludge, Respiration Inhibition Test

GLP compliance:

yes (incl. QA statement)

Test material

Test material information

Constituent 1

Reference substance name:

Tri (hexyl, octyl, decyl) citrate

IUPAC Name:

Tri (hexyl, octyl, decyl) citrate

Constituent 2

Reference substance name:

-

EC Number:

430-290-8

EC Name:

-

IUPAC Name:

430-290-8

Constituent 3

Reference substance name:

2-Hydroxypropane-1,2,3-tricarboxylic acid, tri (hexyl, octyl, decyl) ester

IUPAC Name:

2-Hydroxypropane-1,2,3-tricarboxylic acid, tri (hexyl, octyl, decyl) ester

Details on test material:

- Name of test material (as cited in study report): Tri (hexyl, octyl, decyl) citrate
- Substance type: pure active substance
- Physical state: liquid
- Stability under test conditions: in water for at least 2 hours
- Storage condition of test material: in original container, at room temperature, in the dark

Specific details on test material used for the study:

Details on properties of test surrogate or analogue material (migrated information):
PHYSICO-CHEMICAL PROPERTIES
- Melting point: -29°C (freezing point: -35.5°C)
- Boiling point: test substance showed decomposition above 260°C
- Vapour pressure: 8.5 x 10E-3 p at 25°C
- Water solubility (under test conditions): < 1 mg/L
- Solubility in organic solvents: soluble
- log Pow: > 6
- pKa: not applicable
- Base or acid catalysis of test material: no data
- UV absorption: no data
- Stability of test material at room temperature: stable
- pH dependance on stability: no data


OTHER PROPERTIES (if relevant for this endpoint)
- Adsorption characteristics: no data

Sampling and analysis

Analytical monitoring:

no

Test solutions

Vehicle:

no

Details on test solutions:

The test substance was directly weighed into the test flasks. Then, the test flasks were filled each with 284 mL tap water.

Test organisms

Test organisms (species):

activated sludge of a predominantly domestic sewage

Details on inoculum:

- Laboratory culture: no
- Method of cultivation: not applicable
- Preparation of inoculum for exposure: The sludge was washed by centrifugation and the supernatant liquid phase was decanted. The solid material was resuspended in tap water and again centrifuged. The latter procedure was repeated twice. An aliquot of the final sludge suspension was weighed, dried and the ratio of wet sludge to its dry weight determined.
- Pretreatment: Calculated aliquots of washed sludge suspension, corresponding to 3 g dry material/L were made up with tap water. To this mixture, 50 mL synthetic sewage feed/L was added daily, starting 3 days prior to use, and the sludge was kept at room temperaure under continuous aeration until use. Just before the start of the test the dry weight was again measured and adjusted to 2 g dry weight/L.

Study design

Test type:

static

Water media type:

freshwater

Limit test:

no

Total exposure duration:

3 h

Post exposure observation period:

none

Test conditions

Hardness:

not mentioned

Test temperature:

19 °C

pH:

7.6 - 8.3

Dissolved oxygen:

5.4 - 9.2 mg/L

Nominal and measured concentrations:

Nominal: 10, 32, 100, 320, 1000 mg/L

Details on test conditions:

TEST SYSTEM
- Test vessel:
- Material, size, headspace, fill volume: 1 L glass flask with a fill volume of 500 mL
- Aeration: compressed air at an air-flow rate of approx. 0.6 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: tap water, synthetic sewage feed according to guideline


OTHER TEST CONDITIONS
- Adjustment of pH: no


EFFECT PARAMETERS MEASURED (with observation intervals if applicable) : Respiration rate of each test medium after 3 hours was measured with an oxygen electrode (ECM-multi, Dr. Lange, Germany), and was recorded for 10 minutes. During measurement, the samples were continuously stirred on a magnetic stirrer. The pH amd the oxygen concentrations were determined before the start of the test and at the end of the incubation period in all test concentrations and controls. The water temperature was measured in one control medium at the start and the end of the incubation period.


TEST CONCENTRATIONS
- Spacing factor for test concentrations: not mentioned
- Range finding study. Not performed

Reference substance (positive control):

yes

Remarks:

3,5-Dichlorophenol (final concentrations in the test: 10, 32 and 100 mg/L)

Results and discussion

Effect concentrations

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

Details on results:

- Any observations (e.g. precipitation) that might cause a difference between measured and nominal values: no
- Effect concentrations exceeding solubility of substance in test medium: yes

Results with reference substance (positive control):

- Results with reference substance valid? yes
- Relevant effect levels: 3-hour EC50 = 15 mg/L

Reported statistics and error estimates:

no statistics performed

Any other information on results incl. tables

Table: Influence of test substance and reference substance on oxygen consumption of activated sludge

Treatment	Concentration [mg/L]	Oxygen consumption[mg O2/L min]	Inhibition[%]
Control	-	0.411 / 0.379*	-
Test substance	10	0.337	14.8
Test substance	32	0.362	8.3
Test substance	100	0.378	4.4
Test substance	320	0.316	20.1
Test substance	1000	0.349	11.7
3,5 -DCP**	10	0.288	27.1
3,5 -DCP**	32	0.036	90.9
3,5 -DCP**	100	0.039	90.1

* repeated test ** reference substance 3,5 -Dichlorophenol

Applicant's summary and conclusion

Validity criteria fulfilled:

yes

Remarks:

The respiration rates of the two control did not differ by more than 15%. The 3-hour EC50 fo the reference substance was in the range of 5 to 30 mg/L. The concentration of dissolved ocygen did not drop below 2.5 mg/L during the incubation period.

Conclusions:

In comparison to the inoculum controls the respiration rate of the activated sludge was inhibited between 4.4 % and 20.1 % up to the highest tested concentration of nominal 1000 mg test substance/L. However, no concentration-effect relationship could be determined. Thus, the respiration rate was not significantly inhibited up to the highest tested concentration. Concentrations exceeding 1000 mg/L nominal were not tested.
From these inhibition rates, the 3-hour EC20 and EC50 could not be quantified. Nevertheless, the 3-hour EC50 was clearly higher than 1000 mg test substance/L under the present test conditions.