4''-Ethyl-2'-fluor-4-propyl-1,1':4',1''-terphenyl

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:

Dec 12, 2006 - Feb 27, 2007

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 (Carbon and Ammonium Oxidation))

Version / remarks:

July, 2010

Deviations:

no

GLP compliance:

yes (incl. QA statement)

Specific details on test material used for the study:

Purity: 99.9 %

Analytical monitoring:

no

Vehicle:

no

Details on test solutions:

The test substance was insufficiently soluble to permit addition via aqueous solution. Individually weighed quantities of test substance were added directly to the appropriate test vessels.

Test organisms (species):

activated sludge of a predominantly domestic sewage

Details on inoculum:

Activated sludge, micro organisms from a domestic waste water treatment plant was supplied by the sewage plant Darmstadt, Germany.

Preparation and Maintenance
The activated sludge was washed by centrifugation and the supernatant liquid phase was decanted. The solid material was re-suspended in tap water and again centrifuged. The latter procedure was repeated twice. The washed sludge was re-suspended in tap water and sewage feed ( 50 mL per L) was added. The sludge was kept at room temperature under continuous aeration until use for one day.
Immediately before use, the dry weight of the activated sludge was detennined, and diluted to 3.5 g/L with tap water. Tue pH of the activated sludge was 7.9 and therefore no adjustment
was necessary.

Test type:

static

Water media type:

freshwater

Limit test:

yes

Total exposure duration:

3 h

Test temperature:

20 ± 2°C

pH:

7.01 - 7.25

Dissolved oxygen:

saturated

Nominal and measured concentrations:

10, 32, 100, 320 and 1000 mg/L

Details on test conditions:

TEST SYSTEM
- Test vessel: ca 250 mL glass conical flask
- Type (delete if not applicable): open
- Aeration:compressed air supply
- No. of vessels per control (replicates): 1
- Sludge concentration (weight of dry solids per volume): 3 g/L
- Nutrients provided for bacteria: no
- Biomass loading rate:

TEST MEDIUM / WATER PARAMETERS
- Source/preparation of dilution water: dechlorinated tap water
- Particulate matter:
OTHER TEST CONDITIONS
- Adjustment of pH: yes

EFFECT PARAMETERS MEASURED (with observation intervals if applicable) :
TEST CONCENTRATIONS
- Spacing factor for test concentrations: 3.2
- Justification for using fewer concentrations than requested by guideline: n.a.
- Range finding study no
- Test concentrations: 10, 32, 100, 320, 1000 mg/L

Reference substance (positive control):

yes

Key result

Duration:

3 h

Dose descriptor:

NOEC

Effect conc.:

1 000 mg/L

Nominal / measured:

meas. (initial)

Conc. based on:

test mat.

Basis for effect:

inhibition of total respiration

Results with reference substance (positive control):

3,5-DCP:
Total Respiration: 8.2 mg/L

Validity criteria fulfilled:

yes

Conclusions:

Based on the measured inhibition of respiration rates, neither EC20 nor EC50 could be calculated. Since the inhibition of respiration rates was clearly below 20% up
to and including the concentration of 1000 mg/L, the EC20 and EC50 can be assumed to be higher than 1000 mg/L. A NOEC can be established at 1000 mg/L since the respiration inhibition was clearly lower than 20% at this concentration.

Executive summary:

Purpose

The influence of the test item on the activity of activated sludge was evaluated by measuring the respiration rate under defined conditions. 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 of the test item after an incubation period of 3 hours.

 

Study Design

The information for this endpoint study record was obtained from an experimental study. The OECD GLP criteria were met and the methods applied are fully compliant with OECD TG 209.

Test concentrations of 10, 32, 100, 320 and 1000 mg /L have been applied. 3,5 -Dichlorophenol served as positive control substance at concetrations of 3.2, 10 and 32 mg/L. Two inoculum controls have been used.

 

Results

 

Toxicity of the test item

The test item is sparingly soluble in water. Therefore, the test item was directly weight into the test vessels and stirred for about 24 hours before using in the experiment. The maximum inhibition of respiration activity was fond to be about 11 %, the inhibition rates were in a range of 5% to 11 %. Concentrations exceeding 1000 mg/L nominal were not tested.

 

3-hour effect concentrations of the test item

Based on the measured inhibition of respiration rates, neither EC20 nor EC50 could be calculated. Since the inhibition of respiration rates was clearly below 20% up

to and including the concentration of 1000 mg/L, the EC20 and EC50 can be assumed to be higher than 1000 mg/L. A NOEC can be established at 1000 mg/L since the respiration inhibition was clearly lower than 20% at this concentration.

 

Toxicity of 3,5-Dichlorophenol

The 3-hour EC50 for the positive control 3,5-Dichlorophenol, which was tested in the same way as the test item, was found to be 8.2 mg/L and is within the range of 5 - 30 mg/L recommended by the test guidelines; thus, confirming suitability of the activated sludge.

Description of key information

OECD 209 study (Reliability 1): NOEC = 1000 mg/L

Key value for chemical safety assessment

EC50 for microorganisms:

1 000 mg/L

EC10 or NOEC for microorganisms:

1 000 mg/L