Sodium 4-(2-hydroxyethyl)piperazin-1-ylethanesulphonate

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:

key study

Justification for type of information:

Please refer to the attached read-across justification in section 13.

Reason / purpose for cross-reference:

read-across source

Key result

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:

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

Reference 2

Endpoint:

activated sludge respiration inhibition testing

Type of information:

experimental study

Adequacy of study:

key study

Study period:

2002-10-22 to 2002-12-13

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

guideline study

Qualifier:

according to guideline

Guideline:

OECD Guideline 209 (Activated Sludge, Respiration Inhibition Test

Version / remarks:

1984

Deviations:

no

GLP compliance:

yes (incl. QA statement)

Analytical monitoring:

no

Details on sampling:

No concentrations of the test substance were measured.

Vehicle:

no

Details on test solutions:

PREPARATION AND APPLICATION OF TEST SOLUTION
- Method: 1000 mg test item were filled up to 200 mL with deionised water and completely dissolved. Thus, a concentration of 5.0 g/L was obtained.
- Controls:
Blank control performed with the test solution without test substance
Positive control performed with the reference substance 3,5-Dichlorophenol
- Evidence of undissolved material: no

Test organisms (species):

activated sludge, domestic

Details on inoculum:

- Name and location of sewage treatment plant where inoculum was collected: Sewage plant Gross-Zimmern, Germany
- 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 washed sludge suspension was made up with tap water. To this mixture, 50 mL synthetic sewage feed per litre was added daily, starting three days prior to use, and the sludge was kept at room temperature under continuous aeration until use. Immediately before use, an aliquot of the final sludge suspension was weighed, dried and the ratio of wet sludge (g) to its dry weight (g) determined.
- Initial biomass concentration: 3 g dry material per litre

Test type:

static

Water media type:

freshwater

Limit test:

no

Total exposure duration:

3 h

Post exposure observation period:

none

Hardness:

not specified

Test temperature:

19 - 21 °C

pH:

7 - 8.6

Dissolved oxygen:

7 - 8 mg/L

Salinity:

not applicable

Conductivity:

not specified

Nominal and measured concentrations:

Nominal concentration: 0, 32, 100, 320, 1000 mg/L nominal; measured concentrations not available

Details on test conditions:

TEST SYSTEM
- Test vessel: Glass flasks of approximately 1 litre volume and Karlsruher flasks of 250 mL volume
- Type: open
- Aeration: yes, with compressed air (approximately 0.6 litre per minute)
- No. of vessels per concentration: 1
- No. of vessels per control: 1
- No. of vessels per positive control: 1
- No. of vessels per toxicity control: 1
- No. of vessels per abiotic control: 1
- Sludge concentration (weight of dry solids per volume): 3 g dry material/L

TEST MEDIUM / WATER PARAMETERS
- Source/preparation of dilution water: According to guideline OECD 209 (1984)

OTHER TEST CONDITIONS
- Adjustment of pH: no
- Photoperiod: darkness

EFFECT PARAMETERS MEASURED: Determination of the inhibitory effects on the respiration rate (oxygen consumption after 180 minutes).

TEST CONCENTRATIONS
- Spacing factor for test concentrations: 3.2
- Range finding study: not performed

Reference substance (positive control):

yes

Remarks:

3,5-dichlorophenol (DCP)

Key result

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:

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:

- Inoculum control: The respiration rates of the two controls did not differ by more than 15 %.
- Reference Item: The 3-hour EC50 of the reference item 3,5-dichlorophenol was determined to be 5.0 mg/L and is thus in the range of 5 to 30 mg/L for the used activated sludge batch.
- Dissolved Oxygen: The concentration of dissolved oxygen did not drop below 2.5 mg O2/L during the incubation period, and just before the measurements of the respiration rates the oxygen concentrations were at least 6.9 mg O2/L.
- Determination of the Inhibitory Effects: The 3-hour EC50 of the reference item was calculated by Probit analysis. The 3-hour EC20 and EC50 of the test item could not be calculated due to the low toxicity of the test item to microorganisms under the tested conditions.
- Any observations that might cause a difference between measured and nominal values: no
- Effect concentrations exceeding solubility of substance in test medium: no
- Adsorption: no
- After 3 hours the EC50 was determined to be >1000 mg/L.

Results with reference substance (positive control):

The 3-hour EC50 of the reference item 3,5-dichlorophenol was determined to be 5.0 mg/L and is thus in the range of 5 to 30 mg/L for the used activated sludge batch.

Reported statistics and error estimates:

The 3-hour EC50 of the reference item was calculated by Probit analysis.

Validity criteria fulfilled:

yes

Conclusions:

The toxic effects of the test substance on the oxygen consumption rate of aerobic micro-organisms (activated sludge) was determined according to the OECD 209 (1984). After 3 hours the EC50 was determined to be >1000 mg/L.

Executive summary:

The toxic effects of the test substance on the oxygen consumption rate of aerobic microorganisms (activated sludge) was determined according to the OECD 209 (1984) under GLP conditions. The study was performed to evaluate the influence of the test item on the activity of activated sludge by measuring the respiration rate under defined conditions. The sewage treatment plant where inoculum was collected was the sewage plant Gross-Zimmern, Germany. 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 washed sludge suspension was made up with tap water. To this mixture, 50 mL synthetic sewage feed per litre was added daily, starting three days prior to use, and the sludge was kept at room temperature under continuous aeration until use. Immediately before use, an aliquot of the final sludge suspension was weighed, dried and the ratio of wet sludge (g) to its dry weight (g) determined 3 g dry material per litre. The respiration rate (oxygen consumption) of an aerobic activated sludge fed with a standard amount of synthetic sewage was measured in the presence of various concentrations (10, 32, 100, 320 and 1000 mg/L) of the test item after an incubation period of 3 hours. In comparison to the inoculum controls, the respiration rate of the activated sludge was not inhibited by -5.4 % and -1.6 % at the two lowest nominal concentrations of 10 and 32 mg/L, respectively. At the three highest nominal concentrations of 100, 320 and 1000 mg/L, the respiration rates were inhibited by 2.8 %, 0.4 % and 4.4 %, respectively. Test item concentrations exceeding 1000 mg/L were not tested. Based on measured inhibition rates, the 3-hour EC20 and EC50 could not be quantified because up to the highest nominal test concentration of 1000 mg/L less than 20 % inhibition was noted after three hours incubation. After 3-hour EC20 and EC50 are clearly higher than 1000 mg/L under the present test conditions.

Description of key information

The toxic effects of the read-across source substance on the oxygen consumption rate of aerobic micro-organisms (activated sludge) was determined according to the OECD 209 (1984) (reference 6.1.7-1). After 3 hours the EC50 was determined to be >1000 mg/L.

Additional information

No experimental data on the toxicity of the registration substance to microorganisms is available, but information of a GLP-compliant guideline study with the read-across source substance HEPES (CAS no. 7365-45-9) is available.

The toxic effects of the source substance on the oxygen consumption rate of aerobic micro-organisms (activated sludge) was determined according to the OECD 209 (1984) under GLP conditions. The study was performed to evaluate the influence of the test item on the activity of activated sludge by measuring the respiration rate under defined conditions. The sewage treatment plant where inoculum was collected was the sewage plant Gross-Zimmern, Germany. 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 washed sludge suspension was made up with tap water. To this mixture, 50 mL synthetic sewage feed per litre was added daily, starting three days prior to use, and the sludge was kept at room temperature under continuous aeration until use. Immediately before use, an aliquot of the final sludge suspension was weighed, dried and the ratio of wet sludge (g) to its dry weight (g) determined 3 g dry material per litre. The respiration rate (oxygen consumption) of an aerobic activated sludge fed with a standard amount of synthetic sewage was measured in the presence of various concentrations (10, 32, 100, 320 and 1000 mg/L) of the test item after an incubation period of 3 hours. In comparison to the inoculum controls, the respiration rate of the activated sludge was not inhibited by -5.4 % and -1.6 % at the two lowest nominal concentrations of 10 and 32 mg/L, respectively. At the three highest nominal concentrations of 100, 320 and 1000 mg/L, the respiration rates were inhibited by 2.8 %, 0.4 % and 4.4 %, respectively. Test item concentrations exceeding 1000 mg/L were not tested. Based on measured inhibition rates, the 3-hour EC20 and EC50 could not be quantified because up to the highest nominal test concentration of 1000 mg/L less than 20 % inhibition was noted after three hours incubation. After 3-hour EC20 and EC50 are clearly higher than 1000 mg/L under the present test conditions.

 

Conclusion

Based on reliable data for the read-across source substance the 3 hours EC50 of the target substance is considered to be >1000 mg/L.