Fluoren-9-one

Toxicity to microorganisms

Administrative data

Endpoint:

toxicity to microorganisms, other

Remarks:

Microtox assay

Type of information:

experimental study

Adequacy of study:

supporting study

Study period:

March 2019

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

guideline study without detailed documentation

Data source

Reference

Reference Type:

study report

Title:

Unnamed

Year:

2019

Report date:

2019

Materials and methods

Test guideline

Qualifier:

according to guideline

Guideline:

other: ISO-11348 Water quality — Determination of the inhibitory effect of water samples on the light emission of Vibrio fischeri (Luminescent bacteria test) — Part 3: Method using freeze-dried bacteria

Version / remarks:

2008

Deviations:

not specified

Principles of method if other than guideline:

Based on the available data, it cannot be determined whether deviations from the guideline occurred.

GLP compliance:

not specified

Test material

Test material information

Constituent 1

Reference substance name:

Fluoren-9-one

EC Number:

207-630-7

EC Name:

Fluoren-9-one

Cas Number:

486-25-9

Molecular formula:

C13H8O

IUPAC Name:

9H-fluoren-9-one

Test material form:

not specified

Details on test material:

Tested samples were water samples containing several contaminants. No further details on the test substance were reported for this sample.

Sampling and analysis

Analytical monitoring:

yes

Details on sampling:

- Concentrations: the initial concentration of test substance in the samples was not specified
- Sampling method: not specified, homogenized aqeous samples were used. In total, three samples were anlysed: one analysed directly, while the other two samples had been subject to 14 days degradation.
- Sample storage conditions before analysis: not specified

Test solutions

Vehicle:

yes

Remarks:

Acetone

Details on test solutions:

PREPARATION AND APPLICATION OF TEST SOLUTION:
The sample was decanted prior to testing and only the liquid phase was used. Because the test organism works optimally at a salinity of roughly 2% and within the pH-interval 6.8 -7.2, the salinity and pH of the samples were adjusted. NaOH was used to adjust the pH of the vehicle sample and original 'Spikad' sample; water samples '532-1 T1-1', '532-2 TI-2' and '532-2 T3-2' were adjusted as well but with unspecified acid.
- Chemical name of vehicle: acetone
- Water samples '532-1 T1-1', '532-2 TI-2' and '532-2 T3-2' were tested at 6.25, 12.5, 25, 50 and 100%; dilution water not specified.

Test organisms

Test organisms (species):

Vibrio fisheri

Details on inoculum:

- Test organisms: freeze-dried Vibrio fischeri bacteria, Lot No. 17K4276 (Modern Water)
- Pretreatment: the bacteria were reconstituted in Reconstitution Solution, Lot No. 16D4031 (Modern Water).
- Validity of the batch: qualification of the bacteria from this batch, performed on 16 November 2018, gave an EC50 of 17.6 mg/L phenol which is within the acceptance range (13.0 -26.0 mg/L), indicating that the bacteria batch is suitable for usage in testing.

Study design

Test type:

static

Water media type:

saltwater

Remarks:

Roughly 2% salinity

Limit test:

no

Total exposure duration:

30 min

Remarks on exposure duration:

Test organisms were exposed for 5, 15 and 30 minutes

Test conditions

Test temperature:

not specified

pH:

6.8-7.2

Salinity:

2%

Nominal and measured concentrations:

Nominal concentrations:
The original sample was spiked with 9-fluorenone (0.06 mg/L) and 9-fluorenol (0.42 mg/L), concentrations below are % (v/v) of the samples in test water.
Original samples (spiked and not spiked): 0.02, 0.04, 0.09, 0.18, 0.35, 0.7 and 1.4 (% v/v).
Samples after degradation (1 non-spiked sample, 2 spiked samples): 6.25, 12.5, 25, 50 and 100 (% v/v).
These sample concentrations were not analysed for measured concentrations. Details from the analysis showed a good recovery of the original samples while the test substance was below reporting limits (< 1 μg/L) for the degraded samples.

Details on test conditions:

TEST SYSTEM
- Details on the test system were not available.
- No. of vessels per concentration (replicates): 1 for acetone, spiked original sample, non-spiked sample from degradation test Day 14. 2 for spiked sample from degradation test Day 14.

TEST MEDIUM / WATER PARAMETERS
- Source/preparation of dilution water: water samples from Veolia Water Technologies-AnoxKaldnes were tested. No further details on the water samples was provided.

OTHER TEST CONDITIONS
- Adjustment of pH: yes, samples which fell outside the pH range of 6.8-7.2 were adjusted to fall within this range, using NaOH or unspecified acid. Original pH was 3.7 for the original sample and acetone and 7.2-7.4 for the degraded samples.

EFFECT PARAMETERS MEASURED: EC20 and EC50 values were determined.
The light emitted by the bacteria was registered after 5, 15 and 30 minutes of incubation with the various concentrations of the sample. Based on these results, a dose-response relationship was obtained and used to calculate EC20 and EC50 values. EC20 and EC50 values indicate the concentrations at which illumination by the bacteria is reduced by 20% and 50%, respectively.

EVALUATION OF RESULTS:
EC50 values, after 15 minutes of exposure, were assessed as follows: >70%: low toxicity, 20 -70%: medium toxicity, <20%: high toxicity.

Reference substance (positive control):

no

Results and discussion

Effect concentrations

Effect concentrations 1

Key result

Duration:

15 min

Dose descriptor:

EC50

Effect conc.:

0.1 other: (% v/v)

Nominal / measured:

nominal

Conc. based on:

other: spiked original sample in test water

Basis for effect:

other: Inhibition of luminescence

Effect concentrations 2

Key result

Duration:

15 min

Dose descriptor:

EC50

Effect conc.:

0.1 other: (% v/v)

Nominal / measured:

nominal

Conc. based on:

other: Acetone (non-spiked original sample)

Basis for effect:

other: Inhibition of luminescence

Effect concentrations 3

Key result

Duration:

15 min

Dose descriptor:

EC50

Effect conc.:

72.1 other: (% v/v)

Nominal / measured:

nominal

Conc. based on:

other: non-spiked sample in test water after 14 days degradation

Basis for effect:

other: Inhibition of luminescence

Effect concentrations 4

Key result

Duration:

15 min

Dose descriptor:

EC50

Effect conc.:

93.1 other: (% v/v)

Nominal / measured:

nominal

Conc. based on:

other: spiked sample in test water after 14 days degradation

Basis for effect:

other: Inhibition of luminescence

Effect concentrations 5

Key result

Duration:

15 min

Dose descriptor:

EC50

Effect conc.:

43.9 other: (% v/v)

Nominal / measured:

nominal

Conc. based on:

other: spiked sample in test water after 14 days of degradation

Basis for effect:

other: Inhibition of luminescence

Details on results:

- Full table of results is provided in 'Overall remarks'.
- Based on the results, the originally prepared samples are determined to be highly toxic to Vibrio fischeri (EC50 <20% concentration). However, when the samples have undergone 14 days of degradation, they show medium to low toxicity to Vibrio fischeri. There is no significant difference between spiked and non-spiked degraded samples. Uncertainties in the Microtox test are relatively low and the samples have been run in parallels to rule out misreading (personal communication with the lab).

Results with reference substance (positive control):

Not performed.

Reported statistics and error estimates:

Not reported.

Applicant's summary and conclusion

Validity criteria fulfilled:

not specified

Conclusions:

Based on the results of a Microtoxicity study (ISO 11348-3) using the luminescent bacteria Vibrio fischeri, Fluoren-9-one can be considered highly toxic towards Vibrio fischeri. However, when the substance has undergone degradation (14 days), it shows low to medium toxicity towards Vibrio fischeri. These results can be used as a screening for ecotoxicology tests but cannot be extrapolated to other (aquatic) organisms.