1,6-Bis(methoxybenzoyloxy)hexane

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:

8 January 2004

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

other: see 'Remark'

Remarks:

The study includes data generated according to generally valid and internationally accepted testing guidelines and performed according to GLP. The study was based on: -OECD Guidelines for Testing of Chemicals, Section 2: Effects on biotic systems, Guideline no. 209, "Activated Sludge, Respiration Inhibition Test", adopted April 4, 1984. - EEC Directive 67/548 amended November 18, 1987 (87/302), Part C: Methods for the determination of ecotoxicity, Publication No. L 133, "Biodegradation: Activated sludge respiration inhibition test", adopted May 30, 1988.

Qualifier:

according to guideline

Guideline:

OECD Guideline 209 (Activated Sludge, Respiration Inhibition Test

Deviations:

no

Qualifier:

according to guideline

Guideline:

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

Deviations:

no

GLP compliance:

yes

Remarks:

GLP Statement date: 27/01/2004

Analytical monitoring:

not required

Vehicle:

yes

Details on test solutions:

TEST SUBSTANCE - PREPARATION AND TEST CONDITIONS

Since Setafix X 11342 was poorly soluble in water, the test substance was quantitatively added to the test vessels. A nominal concentration of 100 mg/I was tested in duplicate. The concentration was approved by the study director in the study files. Due to the test set-up (continuous aeration and stirriing) optimal contact between the test substance and test medium was ensured.

Test organisms (species):

other: Micro-organisms in activated sludge

Details on inoculum:

-Source:
Municipal sewage treatment plant: 'Waterschap de Maaskant', 's-Hertogenbosch, the Netherlands, receiving predominantly domestic sewage.

- Number of micro-organisms:
Number of micro-organisms was determined as the amount of Mixed Liquor Suspended Solids (MLSS) per litre test medium.

- Preparation of the sludge:
The sludge was coarsely sieved and washed with tapwater. A small amount of the sludge was weighed and dried at ca. 105°C to determine the amount of suspended solids (3.6 g/I of sludge, as used for the test). The pH was 7.5. The batch of sludge was used on the subsequent day, therefore 50 ml of synthetic sewage feed was added to each litre of activated sludge at the end of the day. The sludge was kept aerated at test temperature until use.

- Rationale:
Recognized by international guidelines as the recommended test system.

Test type:

other: Continuous aeration and stirring

Water media type:

freshwater

Limit test:

yes

Total exposure duration:

30 min

Remarks on exposure duration:

During which aeration and stirring took place.

Post exposure observation period:

30 minutes

Hardness:

Not specified

Test temperature:

19.4 - 19.6 °C

pH:

7.3

Dissolved oxygen:

7.7 - 8.0

Salinity:

Not specified

Nominal and measured concentrations:

Nominal Concentration: 100 mg/L

Details on test conditions:

TEST SYSTEM
- Test vessel: All glass, 300 ml oxygen bottles and 1 L test bottles.
- Aeration: Clean, oil-free air
- No. of vessels per concentration (replicates): 2
- No. of vessels per control (replicates): 2

TEST MEDIUM / WATER PARAMETERS
- Source/preparation of dilution water:
Milli-RO I Milli-Q water: Tap-water purified by reverse osmosis {Milli-RO) and subsequently passed over activated carbon and ionexchange cartridges {Milli-Q) {Millipore Corp., · Bedford, Mass., USA).

- Synthetic sewage feed:
16 g peptone, 11 g meat extract, 3 g urea, 0.7g NaCl, 0.4 g CaCl2.2H20, 0.2 g MgS04.?H20, 2.8 g K2HP04, Dissolved in Milli-Q water, made up to 1 I and filtered, The pH was 7.0.

- Oxygen meter
WTW inolab Oxi Level 2 supplied with a WTW CellOx 325 oxygen electrode, electrolyte type ELY/G.

PERFORMANCE OF THE TEST
The synthetic sewage feed (16 ml) and an adequate amount of the test substance were mixed and made up to 300 ml with Milli-RO water. Activated sludge (200 ml) was added to provide a final volume of 500 ml. The mixture was then aerated in a 1 L bottle during the contact time, using a pipette as an aeration device.
Then a well mixed sample of the contents was poured into a 300 ml oxygen bottle, and the flask was sealed with an oxygen electrode connected to a recorder, forcing the air out of the vessel. Oxygen consumption was measured and recorded for approximately 10 minutes. During measurement, the sample was not aerated but continuously stirred on a magnetic stirrer.
The pH was determined in the remaining part of the reaction mixture. Temperature was determined in the remaining part of the reaction mixture of the first control and first test substance vessel.
This procedure was repeated for the duplicate concentration. In each test series two controls without test substance were tested, one at the start and one at the end.

Reference substance (positive control):

yes

Remarks:

3,5-dichlorophenol

Duration:

30 min

Dose descriptor:

other: No inhibition of respiration rate of the sludge was recorded at 100 mg Setafix X 11342 per litre

Effect conc.:

100 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

inhibition of total respiration

Remarks:

respiration rate

Details on results:

No inhibition of respiration rato of the sludge was recorded at 100 mg Setafix X 11342 per litre. The duplicate measurement confirmed the result of the first measurement. Therefore no further testing was needed.

Results with reference substance (positive control):

The EC50 of 3,5-dichlorophenol was in the accepted range of 5-30 mg/I (10 mg/I, regression line: Y = 70.95 X-21.53, Y = % inhibition and X =log concentration (mg/I).

Validity criteria fulfilled:

yes

Remarks:

All criteria for acceptability of the test were met

Conclusions:

In conclusion, under the conditions of this present test, Setafix X 11342 was not toxic to waste water (activated sludge) bacteria at a concentration of 100 mg/L.

Executive summary:

The principal objective of this study was the assessment of the effect of a test substance on micro-organisms by measuring the respiration rate under defined conditions in the presence of different concentrations of test substance Setafix X 11342. The test method is a rapid scrnening method whereby test substances which may adversely affect aerobic microbial treatment plants can be identified. The study procedure was based on OECD Guideline No. 209, adopted April 4, 1984 and EEC Directive 67/548 amended November 18, 1987 (87/302), Part C, Publication No. L 133, adopted May 30, 1988.

The influence of Setafix X 11342 on the respiration rate of activated sludge was investigated after a contact time of 30 minutes. Setafix X 11342 was a light yeillowish solid. Since Setafix X 11342 was poorly soluble in water, the test substance was quantitatively added to the test vessels. A nominal concentration of 100 mg/L was tested in duplicate. Due to the test set-up (continuous aeration and stirring) optimal contact between the test substance and test medium was ensured.

No inhibition of respiration rate of the sludge was recorded at 100 mg Setafix X 11342 per litre. The duplicate measurement confirmed the result of the first measurement. Therefore no further testing was needed.

Since all criteria for acceptability of the test were met, this study was considered to be valid.

In conclusion, under the conditions of this present test, Setafix X 11342 was not toxic to waste water (activated sludge) bacteria at a concentration of 100 mg/L.

Description of key information

No inhibition of respiration rate of the sludge was recorded at 100 mg Setafix X 11342 per litre. The duplicate measurement confirmed the result of the first measurement. Therefore no further testing was needed.
In conclusion, under the conditions of this present test, Setafix X 11342 was not toxic to waste water (activated sludge) bacteria at a concentration of 100 mg/L.

Additional information

The principal objective of this study was the assessment of the effect of a test substance on micro-organisms by measuring the respiration rate under defined conditions in the presence of different concentrations of test substance Setafix X 11342. The test method is a rapid screening method whereby test substances which may adversely affect aerobic microbial treatment plants can be identified. The study procedure was based on OECD Guideline No. 209, adopted April 4, 1984 and EEC Directive 67/548 amended November 18, 1987 (87/302), Part C, Publication No. L 133, adopted May 30, 1988.

The influence of Setafix X 11342 on the respiration rate of activated sludge was investigated after a contact time of 30 minutes. Setafix X 11342 was a light yellowish solid. Since Setafix X 11342 was poorly soluble in water, the test substance was quantitatively added to the test vessels. A nominal concentration of 100 mg/L was tested in duplicate. Due to the test set-up (continuous aeration and stirring) optimal contact between the test substance and test medium was ensured.

No inhibition of respiration rate of the sludge was recorded at 100 mg Setafix X 11342 per litre. The duplicate measurement confirmed the result of the first measurement. Therefore no further testing was needed.

Since all criteria for acceptability of the test were met, this study was considered to be valid.

In conclusion, under the conditions of this present test, Setafix X 11342 was not toxic to waste water (activated sludge) bacteria at a concentration of 100 mg/L.