Farnesol

Biodegradation in water: screening tests

Link to relevant study record(s)

Reference

Reference 1

Endpoint:

biodegradation in water: ready biodegradability

Type of information:

experimental study

Adequacy of study:

weight of evidence

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

guideline study

Qualifier:

according to guideline

Guideline:

other: BOD test for insoluble substances (BODIS), preliminary guideline of the Bundesumweltamt Berlin

Version / remarks:

1990

Deviations:

no

GLP compliance:

no

Oxygen conditions:

aerobic

Inoculum or test system:

activated sludge, industrial, adapted

Details on inoculum:

- Source of inoculum/activated sludge (e.g. location, sampling depth, contamination history, procedure): Activated sludge from the aeration tank of the municipal sewage treatment plant of Pforzheim, Germany, washed twice by centrifugation with mineral solution. Activated sludge was collected one week prior to the test.
- Preparation of inoculum for exposure: Activated sludge mixed with mineral solution was pre-incubated for one week with inoculum at test conditions. The bottles were closed with glass stoppers and shaken witout test substance the dark at 20 °C and 100 rpm.
- Pretreatment: The vessels were aerated for 15 minutes prior to the test.
- Concentration of sludge: 3 g/L

Duration of test (contact time):

28 d

Initial conc.:

0.007 other: g

Initial conc.:

0.007 other: g

Initial conc.:

0.007 other: g

Parameter followed for biodegradation estimation:

O2 consumption

Details on study design:

TEST CONDITIONS
- Composition of medium: KH2PO4 - 85 mg/L, K2HPO4 - 217.5 mg/L, Na2HPO4 * 2H2O - 334 mg/L, NH4Cl - 5 mg/L, CaCl2 * 2H2O - 36.42 mg/L, MgSO4 * 7 H2O - 22.5 mg/L, FeCl3 8 6 H2O - 0.25 mg/L
- Test temperature: 20°C
- pH: 7.00 - 7.59
- Aeration of dilution water: Yes, aerated for 15 minutes prior to the test and at 7, 14, 21 and 28 days after the measurements of the remaining O2 concentration in the test vessels by a membrane air pump with hoses and Pasteur pipettes.
- Continuous darkness: Yes

TEST SYSTEM
- Culturing apparatus: The test vessels were incubated in a 20°C test chamber in the dark on a rotary shaker at 100 rpm
- Number of culture flasks/concentration: 3 flasks for blank control, for test substance and for reference substance
- Measuring equipment: oximetr (WTW Oxi 191)
- Test performed in closed vessels: Yes, test vessels closed with glass stoppers

SAMPLING
- Sampling frequency: Weekly
- Sampling method: The O2 concentration measured in the test vessels with an oximeter

CONTROL AND BLANK SYSTEM
- Inoculum blank: Yes
- Abiotic sterile control: No
- Toxicity control: Yes, sodium benzoate used as reference substance

Reference substance:

benzoic acid, sodium salt

Key result

Parameter:

% degradation (O2 consumption)

Value:

51.7

Sampling time:

28 d

Results with reference substance:

The degradation rate of sodium benzoate was 72.2%.

Validity criteria fulfilled:

yes

Interpretation of results:

not readily biodegradable

Conclusions:

51.7% degradation was demonstrated after 28 days.

Executive summary:

The biodegradability of the test item was determined with the BOD test for insoluble substances (BODIS). The degradation was followed by weekly measurements of the oxygen consumption in closed vessels for 28 days. Sodium benzoate was used as a reference substance. The degradation rate of the test item was 51.7% after 28 days, while the degradation rate of sodium benzoate was 72.2%. This study is reliable with restrictions (Klimisch 2) as it was conducted according to guideline, however GLP status is unknown.

Reference 2

Endpoint:

biodegradation in water: ready biodegradability

Type of information:

experimental study

Adequacy of study:

weight of evidence

Study period:

21 October 1997 - 20 November 1997

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

guideline study

Remarks:

Mineral media composition and test temperature are not reported .

Qualifier:

according to guideline

Guideline:

OECD Guideline 301 F (Ready Biodegradability: Manometric Respirometry Test)

Version / remarks:

1993

Deviations:

no

Qualifier:

according to guideline

Guideline:

EU Method C.4-D (Determination of the "Ready" Biodegradability - Manometric Respirometry Test)

Version / remarks:

1992

Deviations:

no

Qualifier:

according to guideline

Guideline:

ISO DIS 9408 (Ultimate Aerobic Biodegradability - Method by Determining the Oxygen Demand in a Closed Respirometer)

Version / remarks:

1991

Deviations:

no

GLP compliance:

yes

Oxygen conditions:

aerobic

Inoculum or test system:

activated sludge, domestic (adaptation not specified)

Details on inoculum:

- Initial cell/biomass concentration: 30 mg/L total solids
- Preparation of inoculum for exposure: washed and aerated for 24 h

Duration of test (contact time):

30 d

Initial conc.:

810 other: mg/g

Based on:

other: ThOC

Initial conc.:

97.6 - 102.4 mg/L

Based on:

test mat.

Initial conc.:

3 001 other: mg/g

Based on:

other: ThOD

Parameter followed for biodegradation estimation:

O2 consumption

Details on study design:

TEST CONDITIONS
- pH: 7.5 - 7.6 (initial), 7.5 - 9.3 (end)

Reference substance:

aniline

Preliminary study:

30-m EC20 = 75 mg/L

Key result

Parameter:

% degradation (O2 consumption)

Value:

70 - 80

Sampling time:

28 d

Details on results:

3 day adaptation window, 26 day degradation window

Validity criteria fulfilled:

yes

Interpretation of results:

readily biodegradable

Conclusions:

70 - 80% degradation was demonstrated within 28 days.

Executive summary:

The ready biodegradability of the test item was tested by manometric respirometry according to OECD guideline 301F. The test item is readily biodegradable. Although the 10-day window criterion was not met,

as the substance is a mixture of E and Z isomers, the 10-day window criterion does not apply (EFEO/IFRA Guidelines on the Environmental Assessment of Natural Complex Substances (NCS), 2016). 70 - 80 % biodegradation was observed after 28 days, at measured test concentrations of 97.6 - 102.4 mg test item/L. This study has a reliability rating of 1 as it conforms to GLP and fulfils test validity criteria of the test guidelines OECD 301F, EU C.4 -D and ISO 9408.

Reference 3

Endpoint:

biodegradation in water: ready biodegradability

Type of information:

experimental study

Adequacy of study:

weight of evidence

Study period:

24 February 2011 - 05 May 2011

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

guideline study

Qualifier:

according to guideline

Guideline:

OECD Guideline 301 F (Ready Biodegradability: Manometric Respirometry Test)

Version / remarks:

1992

Deviations:

yes

Remarks:

The optional toxicity control was not performed.

Qualifier:

according to guideline

Guideline:

EU Method C.4-D (Determination of the "Ready" Biodegradability - Manometric Respirometry Test)

Version / remarks:

2008

Deviations:

no

Qualifier:

according to guideline

Guideline:

EPA OPPTS 835.3110 (Ready Biodegradability)

Deviations:

no

GLP compliance:

yes (incl. QA statement)

Oxygen conditions:

aerobic

Inoculum or test system:

activated sludge, domestic, non-adapted

Details on inoculum:

- Source of inoculum/activated sludge: biological WWTP treating predominantly domestic sewage, Bois-de-Bay, Satigny, Switzerland
- Preparation of inoculum for exposure: Sludge collected in the morning, washed 3 times in mineral medium (centrifuging at 1000 g for 10 min, supernatant discarded and sludge resuspended in mineral medium) and kept aerobic until use (same day)

Duration of test (contact time):

50 d

Initial conc.:

30 mg/L

Based on:

test mat.

Parameter followed for biodegradation estimation:

O2 consumption

Details on study design:

TEST CONDITIONS
- Composition of medium: mineral medium, pH 7.4 +/- 0.2
- Solubilising agent (type and concentration if used): Deionised water, < 10 mg/L DOC
- Test temperature: 22.1 - 22.8 deg C
- pH: 7.46 - 7.97

TEST SYSTEM
- Measuring equipment: Oxitop Control System

SAMPLING
- Sampling frequency: daily

CONTROL AND BLANK SYSTEM
- Toxicity control: None

Reference substance:

other: Sodium benzoate

Key result

Parameter:

% degradation (O2 consumption)

Value:

70

Sampling time:

28 d

Details on results:

24, 59 and 77 % biodegradation of Farnesol after 3, 13 and 50 days, respectively.
40 and 65 % biodegradation of reference substance after 7 and 14 days, respectively.
Farnesol considered to be non-toxic to the inoculm at the test concentration.

Validity criteria fulfilled:

yes

Interpretation of results:

readily biodegradable

Conclusions:

70% biodegradation was demonstrated after 28 days.

Executive summary:

The biodegradability of the test item was tested by manometric respirometry according to OECD guideline 301F. At a nominal test concentration of 30 mg test item/L, 70% biodegradation was observed after 28 days. The test item is considered to be readily biodegradable. Although the 10-day window criterion was not met, as the substance is a mixture of E and Z isomers, the 10-day window criterion does not apply (EFEO/IFRA Guidelines on the Environmental Assessment of Natural Complex Substances (NCS), 2016)

This study is reliable without restriction (Klimisch 1) as it conforms to GLP and fulfils test validity criteria of the test guidelines OECD 301F, EU C.4 -D and EPA OPPTS 835.3110.

Description of key information

The test item is readily biodegradable based on the weight of evidence. Over 70% biodegradation has been reported after 28 days in two studies, and a third study demonstrated 51.7% degradation after 28 days. As the substance is a mixture of E and Z isomers, the 10 -day window criterion does not apply (EFEO/IFRA Guidelines on the Environmental Assessment of Natural Complex Substances (NCS), 2016).

Key value for chemical safety assessment

Biodegradation in water:

readily biodegradable

Additional information

The biodegradability of the test item was determined in three studies. Two GLP studies conducted according to OECD guideline 301F (manometric respiration) reported 70% and 70 - 80% biodegradation over 28 days, respectively (2011, 1997). Both studies are reliable without restriction (Klimisch 1). The test item was also analysed in a closed-vessel BOD test for insoluble substances (BODIS), as outlined in the Guidance of German Environmental Agency (1990). The test item degradation in this test was 51.7% after 28 days (1996). According to EFEO/IFRA Guidelines on the Environmental Assessment of Natural Complex Substances (NCS) (2016), "the 10 day window may be waived for a complex multi-constituent substance with structurally similar constituents and only the pass level of 60% at 28 days applied for a readily biodegradability classification". The test item is a mixture of E and Z isomers, therefore the 10 -day window criterion does not apply.

Ready biodegradation tests are stringent and therefore a negative result for ready biodegradation does not necessarily mean the test item will not degrade in the environment. Based on weight of evidence, the test item can be considered readily biodegradable.