Sodium 2-biphenylate

Toxicity to microorganisms

Link to relevant study record(s)

Reference

Reference 1

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: GLP guideline study with some missing details

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:

yes (incl. QA statement)

Analytical monitoring:

no

Details on test solutions:

PREPARATION AND APPLICATION OF TEST SOLUTION (especially for difficult test substances)
- Method: direct weighing, the test substance was added to abput 130 ml deionzed water and stirred before testing for 2 hours.

Test organisms (species):

activated sludge of a predominantly industrial sewage

Details on inoculum:

- Preparation of inoculum for exposure: The sludge is settled and supernatant is decanted. After centrifuging (20 min at 4000 rpm and 20°C) the supernatant is decanted again. 1 g of wet sludge is dried in order to calculate the amount of wet sludge to achieve a concentration of activated sludge of 6 g/L (dry wet) suspended solids. The calculated amount of sludge is first dissolved in synthetic medium and then filled up to a defined end volume with deionised water.
- Initial biomass concentration: 6 g/L dw suspended solids

Test type:

static

Water media type:

freshwater

Limit test:

no

Total exposure duration:

3 h

Test temperature:

20°C ± 2 °C

pH:

7.1 - 8.0

Nominal and measured concentrations:

Nominal test concentrations: control, 10, 18, 56, 100 mg a.i./L

Details on test conditions:

TEST SYSTEM
- Biomass loading rate: 6 g/L dw suspended solids

EFFECT PARAMETERS MEASURED (with observation intervals if applicable) : respiration inhibition after 3 hours

TEST CONCENTRATIONS
- Range finding study: yes
- Test concentrations:
- First range-finding test:100, 1000, 10000 mg/L
- Second range-finding test: 1, 10 and 100 mg/L
- Results used to determine the conditions for the definitive study: Since the first range-finding test showed an inhibition greater than 50% at 100 mg/L, a second range-finding test with lower test substance concentrations was conducted. The second test revealed inhibition rates of 0 % and 1.5 % for test substances concentrations of 1 and 10 mg/L, respectively

Reference substance (positive control):

yes

Remarks:

3,5-dichlorophenol

Duration:

3 h

Dose descriptor:

other: EC05

Effect conc.:

26 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:

EC10

Effect conc.:

31 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.:

62.2 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):

EC50 = 9.2 mg/L

Table 1: Respiratory rates, oxygen-consumption and respiration inhibition of the treated activated sludge

Nominal test concentration [mg a.i./L]	Respiratory rate [mg/L x h]	Phys.-chem. O2consumption [mg/L x h]	Respiratory rateminusphys.-chem. O2consumption [mg/L x h]	Inhibition [%]
10 18 32 56 100	20 18 19 9.4 3.0	0.0* 0.0* 0.0* 0.0* 0.0*	20 18 19 9.4 3.0	0 0 0 47.6 83.3
Control 1 Control 2 Control, mean	18 18 18

Reference 2

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 analogue justification provided in IUCLID section 13

Reason / purpose for cross-reference:

read-across source

Duration:

3 h

Dose descriptor:

other: EC05

Effect conc.:

26 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:

EC10

Effect conc.:

31 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.:

62.2 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

inhibition of total respiration

Remarks:

respiration rate

Description of key information

EC10 (3 h): 31 mg/L (read across)

Key value for chemical safety assessment

EC50 for microorganisms:

62.2 mg/L

EC10 or NOEC for microorganisms:

31 mg/L

Additional information

Reliable data on the toxicity of sodium 2-biphenylate (CAS 132-27-4) to microorganisms are not available. The assessment was therefore based on a study conducted with the analogue substance 2-phenylphenol (CAS 90-43-7) as part of a read across approach, which is in accordance with Regulation (EC) No 1907/2006, Annex XI, 1.5. Further justification is given within the overall summary chapter 6.1 and within the analogue justification in IUCLID section 13.

The effect of 2-phenylphenol (CAS 90-43-7) on aquatic micro-organism was investigated according to ISO guideline 8192 comparable with OECD 209 (Mueller, 1990). The study was re-evaluated according to recent regulatory requirements by Weyers (2006). At nominal test concentrations of 10 - 100 mg/L, inhibition of respiration in activated sludge was observed between 0% and 83.3% and a dose - response relationship was demonstrated. An inhibition of microbial activity by 50% was determined at EC₅₀(3 h) = 62.2 mg/L. The EC10(3 h) of 31 mg/L was used for further assessment.

Additional information is available from a study investigating the toxicity of sodium 2-biphenylate toPseudomonas fluorescensandEscherichia coli(Hamburger, 1974). The study followed the modified German Uniform Procedure L8 and determined no adverse effects onE. coliup to 10 g/L and toxic effects onP. fluorescensat concentrations ≥ 1 g/L.