Biphenyl-2-ol

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: Non-GLP guideline study

Qualifier:

according to guideline

Guideline:

OECD Guideline 209 (Activated Sludge, Respiration Inhibition Test

GLP compliance:

no

Analytical monitoring:

no

Vehicle:

no

Details on test solutions:

Stock solutions of 0.5 to 5.0 g/L were prepared in deionized water

Test organisms (species):

activated sludge of a predominantly domestic sewage

Details on inoculum:

- Laboratory culture: activated sludge were obtained form a local municipal wastewater treatment plant on the day prior the first day of test start
- Method of cultivation:
- Preparation of inoculum for exposure: Solid were allowed to settle and the waste liquor was discarded. The solids were diluted to ca. 8.5 L deionized water. The system was initially mixed by aerating. The sludge was washed three times with appropiate volumes of water. After washing, the system was then aerated continuously and incubated at a temperature of 21 °C

Test type:

static

Water media type:

freshwater

Limit test:

no

Total exposure duration:

3 h

pH:

7.4 - 8.0

Details on test conditions:

The reaction mixtures were prepared by adding 16 ml of synthetic sewage stock solution and the desired ammount of the test chemical to a 500 ml graduated cylinder. The mixture was diluted to a volume of 300 ml with deionized water. Activated sludge inoculum (200 ml) containing approx. 800 mg of suspended solids dw was then added and the final volume of 500 ml were transferred to a 1 L bottle.

Reference substance (positive control):

yes

Remarks:

3,5-dichlorophenol

Duration:

3 h

Dose descriptor:

EC50

Effect conc.:

56 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:

supporting 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

Description of key information

EC50 (3 h) = 56 mg/L (nominal, OECD 209) 

Key value for chemical safety assessment

EC50 for microorganisms:

56 mg/L

Additional information

To investigate the effects of OPP (CAS-No. 90-43-7) on aquatic microorganisms two studies are available. In a non-GLP test, which was carried out according to OECD 209 using predominantly domestic sludge, an EC50 (3h) of 56 mg/L was determined (Klecka et al., 1983). The second test was performed according to ISO 8192 with industrial sludge. This test shows similar results as the test conducted with predominantly domestic sludge. The EC50 (3h) was 62.5 mg/L and the EC10 (3 h) was 31 mg/L (Mueller, 1990 and Weyers, 2006).