Farnesol

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

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

guideline study with acceptable restrictions

Remarks:

Minor limitations in experimental design and reporting (no blank control, four concentrations tested only, experimental design and replication not reported, no statistical analysis of data).

Qualifier:

according to guideline

Guideline:

OECD Guideline 209 (Activated Sludge, Respiration Inhibition Test

Version / remarks:

1993

Deviations:

no

Qualifier:

according to guideline

Guideline:

ISO 8192 (Water quality - Test for inhibition of oxygen consumption by activated sludge for carbonaceous and ammonium oxidation)

Version / remarks:

1986 (E), Method B

Deviations:

no

Qualifier:

according to guideline

Guideline:

ISO 8192 (Water quality - Test for inhibition of oxygen consumption by activated sludge for carbonaceous and ammonium oxidation)

Version / remarks:

1994

Deviations:

no

GLP compliance:

yes

Analytical monitoring:

no

Vehicle:

no

Test organisms (species):

activated sludge of a predominantly domestic sewage

Details on inoculum:

- Preparation of inoculum for exposure: washed, then aerated for 24 h
- Initial biomass concentration: 1 g/L dry matter

Test type:

static

Water media type:

freshwater

Limit test:

no

Total exposure duration:

180 min

Test temperature:

20 +/- 2 deg C

pH:

7.7 (highest test concentration)

Dissolved oxygen:

During aeration: > 2.5 mg/L
At sampling time: > 6.5 mg/L

Nominal and measured concentrations:

20, 100, 500, 1000 mg/L

Details on test conditions:

Test medium: 8 mL of 100-fold dilution of OECD medium

Reference substance (positive control):

yes

Remarks:

3,5-dichlorphenol

Duration:

30 min

Dose descriptor:

other: EC20

Effect conc.:

75 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

inhibition of total respiration

Remarks:

respiration rate

Key result

Duration:

180 min

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

Results with reference substance (positive control):

- Results with reference substance valid? Yes
- Relevant effect levels: EC50 is between 5 - 30 mg/L

Reported statistics and error estimates:

Not reported.

Validity criteria fulfilled:

yes

Conclusions:

The 30-min EC20 was determined to be 75 mg/L and 180-min EC50 was > 1000 mg/L.

Executive summary:

Based on nominal concentrations, the 30 -minute EC20 was determined to be 75 mg/L and the EC50 was not reached after 180 -minute at the highest test concentration of 1000 mg/L. This study is considered reliable with restrictions (Klimisch 2) as it was conducted according to a guideline method and GLP, however there are minor limitations in experimental design and reporting.

Description of key information

The 30-min EC20 was determined to be 75 mg/L and 180-min EC50 was > 1000 mg/L.

Key value for chemical safety assessment

EC50 for microorganisms:

1 000 mg/L

Additional information

In a respiration inhibition test with activated sludge, the 30-min EC20 was determined to be 75 mg/L and the EC50 was not reached after 180 minutes at the highest nominal test concentration of 1000 mg/L (1998). This study was conducted according to GLP and followed OECD guideline 209, however there are minor limitations in experimental design and reporting (no blank control, four concentrations tested only, experimental design and replication not reported, no statistical analysis of data). This study is considered to be reliable with restriction (Klimisch 2).