Sodium ethanolate

Toxicity to aquatic plants other than algae

Administrative data

Endpoint:

toxicity to aquatic plants other than algae

Type of information:

migrated information: read-across from supporting substance (structural analogue or surrogate)

Adequacy of study:

key study

Study period:

1991

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

other: see 'Remark'

Remarks:

Acceptable, well reported guideline study with sufficient documentation to demonstrate that it meets key scientific principles and contains enough detail to be able to judge the results reliable as a contribution to the understanding of the acute toxicity of this substance. As there is no information on test substance loss (despite precautions to minimise this) it is rated reliable with restrictions.

Data source

Reference

Reference Type:

publication

Title:

The senisitivity of Lemna gibba G-3 and four clones of Lemna minor to eight common chemicals using a 7-day test

Author:

Cowgill, U., Milazzo, D., Landenberger, B.

Year:

1991

Bibliographic source:

Res. J. Water Pollut. Control Fed. 63:991-998.

Materials and methods

Test guideline

Test guideline 1

Qualifier:

according to guideline

Guideline:

EPA OTS 797.1160 (Aquatic Plant Toxicity Test using Lemna spp. Tiers I & II))

Deviations:

not specified

Test guideline 2

Qualifier:

equivalent or similar to guideline

Guideline:

EPA OPPTS 850.4400 (Aquatic Plant Toxicity Test using Lemna spp. Tiers I & II))

Deviations:

yes

Remarks:

, no renewal

GLP compliance:

not specified

Test material

Test material information

Constituent 1

Reference substance name:

Ethanol

EC Number:

200-578-6

EC Name:

Ethanol

Cas Number:

64-17-5

Molecular formula:

C2H6O

IUPAC Name:

ethanol

Details on test material:

- Analytical purity: 100% absolute dehydrated.
- Source: US Industrial chemicals

Sampling and analysis

Analytical monitoring:

no

Test solutions

Vehicle:

no

Details on test solutions:

PREPARATION AND APPLICATION OF TEST SOLUTION: Not described.

Test organisms

Test organisms (species):

Lemna gibba

Details on test organisms:

TEST ORGANISM
- Common name: duckweed
- Strain/clone: G-3
- Source (laboratory, culture collection): Smithsonian Institute, Washington DC
- Age of inoculum (at test initiation): Clone historically maintained axenically by weekly transfer of 15 fronds, 5 plants into fresh sterile medium.
- Method of cultivation:
- Temperature: 25 +/-2C
- Light: 6461 (+/-323) lux
- Photoperiod; continuous
- Medium: Revised Hoagland's, 100ml/vessel
- Septic conditions: axenic
- Vessel; Erlenmeyer 250ml glass flask, Shimadzu closure
- Habitat maintenance: weekly renewal
- Initial plant number: 5
- Frond/plant: 15

ACCLIMATION
- Acclimation period: Acclimation period was 8 weeks.
- Any deformed or abnormal cells observed: none reporte.
- Health criteria: Net plant and frond increase.

Study design

Test type:

static

Water media type:

freshwater

Limit test:

no

Total exposure duration:

7 d

Test conditions

Hardness:

Growth/test medium chemistry: Water hardness 636 mg/l as CaCO3.

Test temperature:

Maintained at 25 +/-0.7 degree C

pH:

Without growth: 4.5 - 5.0. With growth: 4.6 - 5.1

Nominal and measured concentrations:

Nominal concentrations 0, 1.0, 1.7, 2.8, 4.7, 7.8, 13, 21, 36, 60, 101, 168, 280, 467, 778, 1296, 2160, 3600, 6000, 10000, 16000, 21000mg/l
Method of calculating mean measured concentrations: Only nominal concentrations were used.

Details on test conditions:

TEST SYSTEM
- Test vessel: 250 ml Erlenmeyer flask.
- Type: closed, Shimadzu closures covered with parafilm to avoid evaporative loss.
- Fill volume: 100ml
- Type of cover:
- Aeration:
- No. of vessels per concentration (replicates): 3 times
- Initial plant number: 5
- Initial frond number: 15

TEST MEDIUM / WATER PARAMETERS
- Source/preparation of dilution water: Dilution water source not specified.
- Alkalinity: 23 mg/l as CaCO3
- Conductivity: 5000 micromhos/cm
- pH: 4.5 to 5.1.

GROWTH MEDIUM
- Standard medium used: yes, grown on Hoagland’s medium but omitting sugar, yeat extract, bactotyptone and EDTA.
- Medium was renewed weekly

OTHER TEST CONDITIONS
- Light intensity and quality: 5382 +/- 89 lux on test.
- Sterile test conditions: yes

EFFECT PARAMETERS MEASURED (with observation intervals if applicable) :
- Plant fronds counted visually.
- Determination of plant frond number: at end of study
- Determination of biomass: dry weight at end of study. Biomass measured by dry weight of plants and fronds
- Determination of frond area: no
- Other:

Reference substance (positive control):

yes

Remarks:

Potassium dichromate

Results and discussion

Effect concentrations

Effect concentrations 1

Duration:

7 d

Dose descriptor:

EC50

Effect conc.:

4 432 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

other: number of plants

Remarks on result:

other: 95% CI: 845 - 8018

Effect concentrations 2

Duration:

7 d

Dose descriptor:

EC50

Effect conc.:

4 816 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

frond number

Remarks on result:

other: 95% CI: 1635 - 7998

Effect concentrations 3

Duration:

7 d

Dose descriptor:

EC50

Effect conc.:

5 967 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

biomass

Remarks on result:

other: Dry weight. 95% CI: 1640 - 10293

Effect concentrations 4

Duration:

7 d

Dose descriptor:

NOEC

Effect conc.:

280 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

other: number of plants

Effect concentrations 5

Duration:

7 d

Dose descriptor:

NOEC

Effect conc.:

280 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

frond number

Effect concentrations 6

Duration:

7 d

Dose descriptor:

NOEC

Effect conc.:

1 296 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

biomass

Remarks on result:

other: Dry weight

Details on results:

- Observations: Results were not given for each of the 21 occurrences.
- Any visual signs of phytotoxicity (abnormalities): none reported
- Any stimulation of growth found in any treatment: none reported
- Any observations (e.g. precipitation) that might cause a difference between measured and nominal values: no
- Effect concentrations exceeding solubility of substance in test medium: no

Results with reference substance (positive control):

EC50 = 28-40mg/l depending on end point.

Reported statistics and error estimates:

Statistical method: EC50 - regression analysis;
NOEL: Dunnett's test.

Applicant's summary and conclusion

Validity criteria fulfilled:

not specified

Remarks:

Insufficient data on control response. Positive control responded appropriately.

Conclusions:

Ethanol is practically non-toxic to lemna

Executive summary:

In a well reported study that was carried out to guideline, Lemna minor (clone 7102) was exposed to ethanol over a concentration range of 1 to 21000mg/l over a 7 day period. The measures of growth inhibition used to assess toxicity were number of plants, number of fronds and total dry biomass at the end of the study compared to controls. The results for each measure are shown below:

Synopsis

Plant number: NOEC(7 day) = 280mg/l. EC50(7 day) = 4432mg/l

Frond number: NOEC(7 day) = 280mg/l. EC50(7 day) = 4816mg/l

Biomass: NOEC(7 day) = 1296mg/l. EC50(7 day) = 5967mg/l