Triethyl borate

Toxicity to aquatic algae and cyanobacteria

Link to relevant study record(s)

Reference

Reference 1

Endpoint:

toxicity to aquatic algae and cyanobacteria

Type of information:

experimental study

Adequacy of study:

key study

Study period:

1996

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

other: see 'Remark'

Remarks:

Acceptable, study with sufficient documentation to demonstrate that study meets basic scientific principles and contains enough detail to be able to judge the results reliable as a contribution to the understanding of the toxicity to algae of this substance. Test longer than ideal to ensure exponential growth but sufficient information available at interim periods to overcome this.

Qualifier:

equivalent or similar to guideline

Guideline:

OECD Guideline 201 (Alga, Growth Inhibition Test)

Deviations:

yes

Remarks:

, see text below

Principles of method if other than guideline:

The method followed the basic principles of an OECD 201 guideline but there was no detail on the medium used (just a cross reference to an unavailable test method) and no data on initial cell density used.

GLP compliance:

not specified

Analytical monitoring:

no

Vehicle:

no

Details on test solutions:

PREPARATION AND APPLICATION OF TEST SOLUTION (especially for difficult test substances)
- Method: not described

Test organisms (species):

Chlorella vulgaris

Details on test organisms:

TEST ORGANISM
- Common name: green algae
- Strain: Chlorella vulgaris
- Source (laboratory, culture collection): Isolated from Lake Geneva in 1980
- Age of inoculum (at test initiation): no data
- Method of cultivation: Axenic using Algal assay Procedure (1971) medium with 15 mg/l NaHCO3 and 12 mg/l K2HPO4 in 500 ml flasks containing 250 ml algal suspension.

Test type:

static

Water media type:

freshwater

Limit test:

no

Total exposure duration:

5 d

Test temperature:

21 +/- 1 deg C

pH:

Water chemistry (pH) on test: Not described.

Nominal and measured concentrations:

Test design: Ethanol was tested three times at each concentration (0, 0.05, 0.1, 0.3, 0.5 and 1% v/v).
Method of calculating mean measured concentrations: Only nominal concentrations were used.

Details on test conditions:

TEST SYSTEM
- Test vessel: 20 x 125 mm test tubes containing 20 ml of suspension, medium and ethanol.
- Type: closed
- Initial cells density: Initial chlorophyll content standardised at 5ug/l
- Control end cells density: Final chlorophyll content approx 290ug/l
- Cell density at each flask/each measuring point: Not given but chlorophyll measurements available in graphical form
- No. of vessels per concentration (replicates): 3 Tubes per test concentration were used including for control.
- Aeration: no

GROWTH MEDIUM
- Detailed composition if non-standard medium was used: Algal assay Procedure (1971) medium with 15 mg/l NaHCO3 and 12 mg/l K2HPO4.

OTHER TEST CONDITIONS
- Light intensity and quality: continuous illumination at 100 microE/m^2-sec except when reduced to 1.5 microE/m^2-sec 20 min before and during measurement of chlorophyll content by fluorescence.

EFFECT PARAMETERS MEASURED (with observation intervals if applicable) : Measurements made daily
- Determination of cell concentrations: fluorimeter: Turner model 111 equipped with a blue light source, blue excitation and red emission filters.
- Chlorophyll measurement: Yes with calibration curves prepared to correlate fluorescence and chlorophyll measurements in ug/l.

Reference substance (positive control):

no

Duration:

4 d

Dose descriptor:

EC10

Effect conc.:

86 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

growth rate

Remarks on result:

other: Based on graphical extrapolation of results.

Duration:

4 d

Dose descriptor:

EC50

Effect conc.:

675 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

growth rate

Remarks on result:

other: Based on graphical interpolation of results.

Duration:

3 d

Dose descriptor:

EC10

Effect conc.:

11.5 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

growth rate

Remarks on result:

other: Based on graphical extrapolation of results.

Duration:

3 d

Dose descriptor:

EC50

Effect conc.:

275 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

growth rate

Remarks on result:

other: Based on graphical extrapolation of results.

Duration:

3 d

Dose descriptor:

EC100

Effect conc.:

14 200 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

growth rate

Remarks on result:

other: Based on graphical extrapolation of results.

Details on results:

- Exponential growth in the control (for algal test): yes, up to day 3, then started to flatten out.
- Observation of abnormalities (for algal test):
- Cells removed before measurement: cells were not removed.
Biological observations:
- +Growth curves: Chlorophyll content plotted over time for each concentration, including control.
- Percent biomass/growth rate inhibition per concentration
- Tabulated observations at 394, 789, 1580, 3950 and 7890 mg/l, the growth inhibition was 37%, 54%, 69%, 86% and 95% respectively on day 4 (no data on confidence intervals.)
- Information obtained from graphical presentation at day 3 (when controls still in exponential growth) , inhibition

Growth was significantly inhibited (p=0.05) at all concentrations of ethanol and showed a VERY shallow dose response curve. A linear curve could be fitted to a plot of the data with a log transformation of the concentration (R>0.99) allowing very reliable interpolation and reasonably reliable extrapolation. Fitted curve for the 4 day data was:

% inhibition = 19.42 x LN (concentration) + 57.6

A similar curve could be fitted to the 3 day data with the following parameters

% inhibition = 12.64 x LN (concentration) + 66.4 (R>0.99)

The EC50 and EC10 values quoted above are calculated with these functions.

Validity criteria fulfilled:

yes

Remarks:

controls in exponential growth at day 3, control growth >16x.

Conclusions:

Ethanol causes is slightly toxic to green algae

Executive summary:

In a study which followed the basic principles of a guideline study, the green algae Chlorella vulgaris was exposed to ethanol at sufficient concentrations to enable an EC50 to be established. Exposure was carried out over 5 days with daily measurements of growth characterised by chlorophyll measurement. The dose response curve obtained was very shallow. The four day data presented showed some evidence that the control had passed the exponential growth phase. Basing the results on the 3 day measurements when exponential growth was still clearly evident, ethanol showed slight toxicity to this species. The results are shown below.

Synopsis

EC10 (72hr) = 11.5mg/l

EC50 (72hr) = 275mg/l

Reference 2

Endpoint:

toxicity to aquatic algae and cyanobacteria

Type of information:

experimental study

Adequacy of study:

supporting study

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

other: see 'Remark'

Remarks:

Acceptable, study with sufficient documentation to demonstrate that study meets basic scientific principles and contains enough detail to be able to judge the results reliable as a contribution to the understanding of the algal toxicity of this substance.

Qualifier:

no guideline followed

Principles of method if other than guideline:

Study to determine the sensitivity of a marine diatom to ethanol by established the EC50 over a 4-5 day exposure period using a particle counting method to ascertain growth rates. Method close to OPPTS 850.5400 for a one species test.

GLP compliance:

not specified

Analytical monitoring:

not specified

Vehicle:

no

Details on test solutions:

PREPARATION AND APPLICATION OF TEST SOLUTION (especially for difficult test substances)
- Method: Stock solutions prepared with double-distilled sterile water.

Test organisms (species):

Skeletonema costatum

Details on test organisms:

TEST ORGANISM
- Source: Bigelow Lab. for Ocean Sciences, West Boothbay Harbour, Maine, USA.
- Common name: marine diatom
- Strain: clone SKEL

CULTURING CONDITIONS
- temperature: 20 +/-2C
- light: 4304 lux +/- 161/day.
- photoperiod (ligh/dark hrs): 14/10
- medium: Provasoli ASP-12., revised
- Vessel: 150ml Erlenmeyer flask with Shimadzu closures.
- Vessel content :100ml
- Habitat maintenance:
- frequency of transfer (days): 7
- culture chamber: incubator
- amount of transfer cells: 109x10E6
- Culture agitation: Agitated daily
- Acclimation period: 4 weeks
- Health criteria: growth of 9x10E6 in 7 days

Test type:

static

Water media type:

saltwater

Limit test:

no

Total exposure duration:

5 d

Hardness:

not applicable (salt water)

Test temperature:

19.5-20.6 degC. (average 19.9C)

pH:

Without growth: mean 8.17 (+/-0.27); range 7.7 - 9.0
With growth: mean 8.25 (+/-0.24); range 7.8 - 8.9

Salinity:

See details of medium below

Nominal and measured concentrations:

Method of calculating mean measured concentrations: Only nominal concentratiuons used.
Statistical methods: Not described.

Details on test conditions:

TEST SYSTEM
- Test vessel: 100 ml covered with parafilm; each concentration tested in triplicate.
- No. of vessels per concentration (replicates): replicated 3 times
- No. of vessels per control: 1
- Initial cells density: 10E5

GROWTH and TEST MEDIUM/WATER PARAMETERS
- Detailed composition of medium as used:
MgSO4.7H2O 8.75g/l
MgCl2.6H2O 5g/l
CaCl2.2H2O 1.834 g/l
NaCl 28g/l
KCl 0.693g/l
NaNO3 99mg/l
K3PO4 9.9mg/l
Na2SiO3.9H2O 297mg/l
Na2 glycerophosphate.5H2O 9.9mg/l (omitted for test medium)
FeCl3.6H2O: 0.484mg/l
EDTA-Na salt 10mg/l
H3BO3 11.438mg/l
MnCl2.4H2O 1.441mg/l
ZnCl2 0.10422mg/l
CoCl2.6H2O 46.37ug/l
Na2SeO4 4.79ug/l
CuCl2.2H2O 67.07ug/l
NaBr 12.878mg/l
SrCl2.6H2O 4.441mg/l
RbCl 0.282mg/l
LiCl 1.22178 mg/l
Na2MoO4.2H2O 1.26095mg/l
KI 13.08ug/l
Cyanocobalamine 0.4ug/l
Biotin 1ug/l
Thiamine 0.1mg/l
Tris 1g/l (omitted for test medium)
Nitrilotriacetic acid 0.4g/l (omitted for test medium)

test medium adjusted for pH to 8.0-8.2 then sterilised (autoclave 15mins @ 15psi).

OTHER TEST CONDITIONS
- Photoperiod: 14 h light/10 h dark cycle.
- Light intensity and quality: Mean lux 4304 +/- 8.2

TEST CONCENTRATIONS
- 5 or more concentrations based on an initial ranger finder test (logarithmic concentrations in range 0.1 to 1000mg/l)

OTHER:
- septic conditions: axenic

EFFECT PARAMETERS MEASURED (with observation intervals if applicable) : daily
- Determination of cell concentrations: Coulter counter

Reference substance (positive control):

no

Duration:

5 d

Dose descriptor:

NOEC

Effect conc.:

5 400 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

growth rate

Remarks on result:

other: based on total cell volume count.

Duration:

5 d

Dose descriptor:

EC50

Effect conc.:

11 619 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

growth rate

Remarks on result:

other: based on total cell volume count. 95% CI: 7923 - 15314

Duration:

5 d

Dose descriptor:

NOEC

Effect conc.:

3 240 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

growth rate

Remarks on result:

other: based on total cell volume volume

Duration:

5 d

Dose descriptor:

EC50

Effect conc.:

10 943

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

growth rate

Remarks on result:

other: based on total cell volume volume. 95% CI: 7061 - 14826

Details on results:

Biological observations:
- #Cell density at each flask at each measuring point: Not given.
- #Growth curves: Not given but growth was stimulated before inhibition began.
- Percent biomass/growth rate inhibition, observations: Not given.

Note that regression equations for curves based on both total cell count and total cell volume are given (in mg/l):
- Cell count method: Total cell count = 1237663 - 57xconcentration (R=0.956)
- Cell volume method: Total cell volume = 8444 - 0.3xconcentration (R=0.950)
Both methods give a virtually identical EC50 of around 10800mg/l

Validity criteria fulfilled:

yes

Remarks:

based on adequate growth

Conclusions:

The authors state that, using EPA criteria, ethanol can be judged 'practically nontoxic, by this test. Ethanol was used as a carbon source, stimulating growth before inhibition began.

Executive summary:

In a well described study, the marine diatom Skeletonema costatum was exposed to ethanol for a period of 5 days and at concentrations sufficient to derive both an EC50 value and a NOEC. From the results, ethanol was practically non-toxic to this species.

Synopsis

NOEC (5 days): 3240mg/l

EC50 (9 day): 10940 mg/l

Reference 3

Endpoint:

toxicity to aquatic algae and cyanobacteria

Type of information:

experimental study

Adequacy of study:

supporting study

Study period:

1996

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

other: see 'Remark'

Remarks:

Acceptable, study with sufficient documentation to demonstrate that study meets basic scientific principles and contains enough detail to be able to judge the results reliable as a contribution to the understanding of the toxicity to algae of this substance. Test longer than ideal to ensure exponential growth but sufficient information available at interim periods to overcome this.

Qualifier:

equivalent or similar to guideline

Guideline:

OECD Guideline 201 (Alga, Growth Inhibition Test)

Deviations:

yes

Remarks:

, see text below

Principles of method if other than guideline:

The method followed the basic principles of an OECD 201 guideline but there was no detail on the medium used (just a cross reference to an unavailable test method) and no data on initial cell density used.

GLP compliance:

not specified

Analytical monitoring:

no

Vehicle:

no

Details on test solutions:

PREPARATION AND APPLICATION OF TEST SOLUTION (especially for difficult test substances)
- Method: not described

Test organisms (species):

Pseudokirchneriella subcapitata (previous names: Raphidocelis subcapitata, Selenastrum capricornutum)

Details on test organisms:

TEST ORGANISM
- Common name: green algae
- Strain: Selenastrum capricornutum
- Source: Obtained from EPA at Corville, OR.
- Age of inoculum (at test initiation): no data
- Method of cultivation: Axenic using Algal assay Procedure (1971) medium with 15 mg/l NaHCO3 and 12 mg/l K2HPO4 in 500 ml flasks containing 250 ml algal suspension.

Test type:

static

Water media type:

freshwater

Limit test:

no

Total exposure duration:

5 d

Test temperature:

21 +/- 1 deg C

pH:

Water chemistry (pH) on test: Not described.

Nominal and measured concentrations:

Test design: Ethanol was tested three times at each concentration (0, 0.05, 0.1, 0.3, 0.5 and 1% v/v).
Method of calculating mean measured concentrations: Only nominal concentrations were used.

Details on test conditions:

TEST SYSTEM
- Test vessel: 20 x 125 mm test tubes containing 20 ml of suspension, medium and ethanol.
- Type: closed
- Initial cells density: Initial chlorophyll content standardised at 5ug/l
- Control end cells density: Final chlorophyll content approx 200ug/l
- Cell density at each flask/each measuring point: Not given but chlorophyll measurements available in graphical form
- No. of vessels per concentration (replicates): 3 Tubes per test concentration were used including for control.
- Aeration: no

GROWTH MEDIUM
- Detailed composition if non-standard medium was used: Algal assay Procedure (1971) medium with 15 mg/l NaHCO3 and 12 mg/l K2HPO4.

OTHER TEST CONDITIONS
- Light intensity and quality: continuous illumination at 100 microE/m^2-sec except when reduced to 1.5 microE/m^2-sec 20 min before and during measurement of chlorophyll content by fluorescence.

EFFECT PARAMETERS MEASURED (with observation intervals if applicable) : Measurements made daily
- Determination of cell concentrations: fluorimeter: Turner model 111 equipped with a blue light source, blue excitation and red emission filters.
- Chlorophyll measurement: Yes with calibration curves prepared to correlate fluorescence and chlorophyll measurements in ug/l.

Reference substance (positive control):

no

Duration:

4 d

Dose descriptor:

EC10

Effect conc.:

0.33 g/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

growth rate

Remarks on result:

other: Based on graphical extrapolation of results.

Duration:

4 d

Dose descriptor:

EC50

Effect conc.:

11.2 g/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

growth rate

Remarks on result:

other: Based on graphical interpolation of results.

Duration:

3 d

Dose descriptor:

EC10

Effect conc.:

0.44 g/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

growth rate

Remarks on result:

other: Based on graphical extrapolation of results.

Duration:

3 d

Dose descriptor:

EC50

Effect conc.:

12.9 g/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

growth rate

Remarks on result:

other: Based on graphical extrapolation of results.

Details on results:

- Exponential growth in the control (for algal test): yes, up to day 3, then started to flatten out.
- Observation of abnormalities (for algal test):
- Cells removed before measurement: cells were not removed.
Biological observations:
- +Growth curves: Chlorophyll content plotted over time for each concentration, including control.
- Percent biomass/growth rate inhibition per concentration
- Tabulated observations at 394, 789, 1580, 3950 and 7890 mg/l, the growth inhibition was 37%, 54%, 69%, 86% and 95% respectively on day 4 (no data on confidence intervals.)
- Information obtained from graphical presentation at day 3 (when controls still in exponential growth) , inhibition.

Growth was inhibited (p=0.05) at least slightly at all concentrations of ethanol and showed a VERY shallow dose response curve. A linear curve could be fitted to a plot of the data with a log transformation of the concentration (R>0.99) allowing very reliable interpolation and reasonably reliable extrapolation. Fitted curve for the 4 day data was:

% inhibition = 11.34 x LN (concentration) + 22.61

A similar curve could be fitted to the 3 day data with the following parameters

% inhibition = 11.82 x LN (concentration) + 19.78 (R~0.99)

The EC50 and EC10 values quoted above are calculated with these functions which actually differed little between the 3 and 4 day information.

Validity criteria fulfilled:

yes

Remarks:

controls in exponential growth at day 3, control growth >16x.

Conclusions:

Ethanol is practically non-toxic to green algae

Executive summary:

In a study which followed the basic principles of a guideline study, the green algae Selenastrum capricornutum was exposed to ethanol at sufficient concentrations to enable an EC50 to be established. Exposure was carried out over 5 days with daily measurements of growth characterised by chlorophyll measurement. The dose response curve obtained was very shallow. The four day data presented showed some evidence that the control had passed the exponential growth phase. Basing the results on the 3 day measurements when exponential growth was still clearly evident, ethanol showed virtually no toxicity to this species. The results are shown below.

Synopsis

EC10 (72hr) = 440mg/l

EC50 (72hr) = 12900mg/l

Reference 4

Endpoint:

toxicity to aquatic algae and cyanobacteria

Type of information:

experimental study

Adequacy of study:

supporting study

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

other: Reasonably well reported study which focusses on development of the method as much the results. Short of some method details. Not a standardised test method.

Principles of method if other than guideline:

During reproduction the shedding of motile cells is associated with a visible change in thallus colour, from yellow-green to dark olive and to white, reflecting the release of reproductive cells. Inhibition of reproductive cell release can be assessed by estimating the percent area of thallus shedding reproductive cells. Inhibition of spore release is assessed as the end-point.

GLP compliance:

not specified

Analytical monitoring:

not specified

Vehicle:

no

Test organisms (species):

other: Ulva Pertusa

Details on test organisms:

TEST ORGANISM
- Common name: Ulva Pertusa Kjellman
- Source (laboratory, culture collection): Collected from near Ahnin, Korea
- Method of cultivation: Disks were cut from the margins of thalli and distributed to plastic cell plates containing 10 ml of artificial seawater to which 1 mM KNO3 and 0.1 mM K2HPO4 had been added. Material was cultured under optimal environmental conditions for spore production (see Han and Choi, 2005) - light flux: 80-100 umol photons.m-2 .s-1. , 12:12 hr Light/dark; 15 C).

Test type:

static

Water media type:

saltwater

Limit test:

no

Total exposure duration:

96 h

Nominal and measured concentrations:

0, 5, 10, 20, 40, 80ml/L

Details on test conditions:

EFFECT PARAMETERS MEASUREMENT: Image analysis under a 400x microscope

Reference substance (positive control):

not required

Duration:

96 h

Dose descriptor:

EC50

Effect conc.:

17.9 other: ml/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

other: spore release inhibition

Remarks on result:

other: CI:8.4-26.5. EC50 equivalent to 14.1g/l

Duration:

96 h

Dose descriptor:

EC0

Effect conc.:

5 other: ml/l

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

other: spore release inhibition

Remarks on result:

other: EC0 equivalent to 3.9g/l

Validity criteria fulfilled:

not applicable

Executive summary:

In a study designed to assess the 96hr acute toxicity to marine algae Ulva, ethanol was found to have an EC50 of 14.1g/l and an EC0 of 3.9g/l when assessed using an end point of spore release inhibition.

Reference 5

Endpoint:

toxicity to aquatic algae and cyanobacteria

Type of information:

experimental study

Adequacy of study:

supporting study

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

other: Basic data given. Results only available in graphical form but information appears to be reliable and useable as supportive information.

Principles of method if other than guideline:

From basic description given, method followed that of 1981 OECD guideline, with some minor deviations in method and data analysis. The purpose of the study was to assess the toxicity to marine algae of candidate solvents for use as carrier solvents in aquatic toxicity studies.

GLP compliance:

not specified

Analytical monitoring:

not specified

Vehicle:

no

Test organisms (species):

other: Heterosigma akashiwo

Details on test organisms:

TEST ORGANISM
- Source (laboratory, culture collection): Microbial culture collection, National Institute for Environmental Studies, Environmental Agency, Japan.
- Method of cultivation: Erlenmeyer flask containing 200ml of f/2 medium (Guillard and Ryther 1962) in stock culture. The algae were cultured at a
temperature of 20+/-1°C, under illumination of 3,500–4,500 lux and a 14:10 h light and dark cycle.

Test type:

static

Water media type:

saltwater

Limit test:

no

Total exposure duration:

96 h

Nominal and measured concentrations:

17 to 40000ppm (ul/l)

Details on test conditions:

TEST SYSTEM
- Test tubes containing growth medium into which solvents were mixed at appropriate concentrations and 0.6 ml of algal stock solution at
exponential growth phase were inoculated into the growth media. Initial chl a concentrations in the growth media were below 10 ng/ml.
- No. of vessels per concentration (replicates): 3. Whole experiment also repeated twice.

GROWTH MEDIUM
- Standard medium used: yes. Guillard & Ryther f/2 medium

OTHER TEST CONDITIONS
- Sterile test conditions: yes. All growth medium were autoclaved at 121°C for 20 min
- Photoperiod: 14:10 h light and dark cycle.
- Temperature: 20+/-1°C
- Light intensity and quality: 3,500–4,500 lux

EFFECT PARAMETERS MEASURED (with observation intervals if applicable) :
- The growth of the algae was monitored daily by in vivo fluorescence using a fluorescence meter.

Duration:

96 h

Dose descriptor:

EC50

Effect conc.:

2 400 other: ppm

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

biomass

Remarks on result:

other: equivalent to 1900mg/l

Reported statistics and error estimates:

Comparison of microalgal sensitivity was analyzed using the Friedman test, a nonparametric statistical method.

Executive summary:

In a study designed to assess the toxicity of common solvents recommended for aquatic toxicity tests, ethanol was found to exhibit an EC50 of 1900mg/l for the marine algal species Heterosigma akashiwo.

Reference 6

Endpoint:

toxicity to aquatic algae and cyanobacteria

Type of information:

experimental study

Adequacy of study:

supporting study

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

other: Basic data given. Results only available in graphical form but information appears to be reliable and useable as supportive information.

Principles of method if other than guideline:

From basic description given, method followed that of 1981 OECD guideline, with some minor deviations in method and data analysis. The purpose of the study was to assess the toxicity to marine algae of candidate solvents for use as carrier solvents in aquatic toxicity studies.

GLP compliance:

not specified

Analytical monitoring:

not specified

Vehicle:

no

Test organisms (species):

other: Tetraselmis tetrathele

Details on test organisms:

TEST ORGANISM
- Source (laboratory, culture collection): Marine Ecology Research Institute, Japan.
- Method of cultivation: Erlenmeyer flask containing 200ml of f/2 medium (Guillard and Ryther 1962) in stock culture. The algae were cultured at a
temperature of 20+/-1°C, under illumination of 3,500–4,500 lux and a 14:10 h light and dark cycle.

Test type:

static

Water media type:

saltwater

Limit test:

no

Total exposure duration:

96 h

Nominal and measured concentrations:

17 to 40000ppm (ul/l)

Details on test conditions:

TEST SYSTEM
- Test tubes containing growth medium into which solvents were mixed at appropriate concentrations and 0.6 ml of algal stock solution at
exponential growth phase were inoculated into the growth media. Initial chl a concentrations in the growth media were below 10 ng/ml.
- No. of vessels per concentration (replicates): 3. Whole experiment also repeated twice.

GROWTH MEDIUM
- Standard medium used: yes. Guillard & Ryther f/2 medium

OTHER TEST CONDITIONS
- Sterile test conditions: yes. All growth medium were autoclaved at 121°C for 20 min
- Photoperiod: 14:10 h light and dark cycle.
- Temperature: 20+/-1°C
- Light intensity and quality: 3,500–4,500 lux

EFFECT PARAMETERS MEASURED (with observation intervals if applicable) :
- The growth of the algae was monitored daily by in vivo fluorescence using a fluorescence meter.

Duration:

96 h

Dose descriptor:

EC50

Effect conc.:

19 000 other: ppm

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

biomass

Remarks on result:

other: equivalent to 15000mg/l

Reported statistics and error estimates:

Comparison of microalgal sensitivity was analyzed using the Friedman test, a nonparametric statistical method.

Executive summary:

In a study designed to assess the toxicity of common solvents recommended for aquatic toxicity tests, ethanol was found to exhibit an EC50 of 15000mg/l for the marine algal species Tetraselmis tetrathele.

Description of key information

FRESHWATER - RELIABLE
Chlorella vulgaris; EC50 (72hr) = 275mg/l; EC10 (72hr) = 11.5mg/l
Selenastrum capricornutum EC50 (72hr) = 12900mg/l; EC10 (72hr) = 440mg/l
Chlamydomonas eugametos: EC50 (48hr) ~ 18000mg/l NOEC (48hr) = 7900mg/l 
SEAWATER  -RELIABLE
Skeletonema costatum: EC50 (9 day): 10940 mg/l; NOEC (5 days): 3240mg/l 
Ulva pertusa: EC50 (96hr): 14900mg/l, NOEC: 3900mg/l
Skeletonema costatum (96hr) EC50: 7000mg/l.
Dunaliella tertiolecta (96hr) EC50:12000mg/l.
Heterosigma akashiwo (96hr) EC50: 1900mg/l.
Tetraselmis tetrathele (96hr) EC50: 15000mg/l.
Isochrysis galbana (96hr) EC50: 12000mg/l.
Chaetoceros calcitrans (96hr) EC50: 5500mg/l.
Pavlova lutheri (96hr) EC50:  9000mg/l.

Key value for chemical safety assessment

EC50 for freshwater algae:

275 mg/L

EC50 for marine water algae:

1 900 mg/L

EC10 or NOEC for freshwater algae:

11.5 mg/L

EC10 or NOEC for marine water algae:

1 580 mg/L

Additional information

In a study which followed the basic principles of a guideline study, two green algae Chlorella vulgaris and Selenastrum capricornutum were exposed to ethanol at sufficient concentrations to enable EC50 values to be established. Exposure was carried out over 5 days with daily measurements of growth characterised by chlorophyll measurement. The dose response curve obtained was very shallow. The four day data presented showed some evidence that the control had passed the exponential growth phase. Basing the results on the 3 day measurements when exponential growth was still clearly evident, ethanol showed slight toxicity to the Chlorella species but not to the Selenastrum species. EC10 (72hr) values were= 11.5mg/l and 440mg/l respectively.  EC50 (72hr) values were 275mg/l and 12900mg/l respectively.

In a well described study, the marine diatom Skeletonema costatum was exposed to ethanol for a period of 5 days and at concentrations sufficient to derive both an EC50 value and a NOEC. From the results, ethanol was not toxic to this species.

In a study designed to assess the 96hr acute toxicity to marine algae Ulva, ethanol was found to have an EC50 of 14.1g/l and an EC0 of 3.9g/l when assessed using an end point of spore release inhibition.