Sodium O-ethyl dithiocarbonate

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:

other: published data

Adequacy of study:

weight of evidence

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

comparable to guideline study with acceptable restrictions

Justification for type of information:

Guideline study. SEX readily decomposes to carbon disulphide, especially in the presence of moisture/water. Therefore, the health effects of carbon disulphide (CS2) need to be considered in the assessment of SEX.

Qualifier:

according to guideline

Guideline:

OECD Guideline 201 (Alga, Growth Inhibition Test)

GLP compliance:

yes

Analytical monitoring:

not specified

Vehicle:

no

Test organisms (species):

Chlorella pyrenoidosa

Details on test organisms:

SPECIES #
(NAME): 426 Chlorella pyrenoidosa (Green Algae)
AGE: NR NR
LIFE STAGE: not reported, unknown
COMMENT: 10E+8 CELLS/100 ML

Test type:

static

Water media type:

freshwater

Limit test:

no

Total exposure duration:

96 h

Hardness:

90 mg CaCO3/L

Test temperature:

20 ± 1 °C

pH:

8.7 ± 0.2

Dissolved oxygen:

NR

Salinity:

NR

Details on test conditions:

The test was carried out in sealed flasks to prevent evaporation of CS2.
The medium contained major salts, urea, Ca-glycerophosphate, dextrose and trace elements. The complete composition of the test medium is given in Van Leeuwen and Maas, Environ. Pollution A37: 105-115 (1985).
The starting density of the cells was 1E5 cells/mL. The volume of test medium was 100 mL per flask. The medium was shaken under fluorescent light (7.5 W/m2).

Reference substance (positive control):

no

Duration:

96 h

Dose descriptor:

EC50

Effect conc.:

21 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

growth rate

Duration:

96 h

Dose descriptor:

EC50

Effect conc.:

39.8 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

growth rate

Remarks on result:

other: On a molecular weight scaled basis, the EC50 would be 39.8 mg/l. (21 x 144.19) /76.13 =39.8 mg/l

Details on results:

SEX readily decomposes to carbon disulphide, especially in the presence of moisture/water. Therefore, the health effects of carbon disulphide (CS2) need to be considered in the assessment of SEX.
On a molecular weight scaled basis, the EC50 would be 39.8 mg/l. (21 x 144.19) /76.13 =39.8 mg/l

Reported statistics and error estimates:

no data

Validity criteria fulfilled:

yes

Conclusions:

The 96-h EC50 of CS2 for the alga Chlorella pyrenoidosa in sealed flasks was 21 mg/L, based on the inhibition of growth rate.
SEX readily decomposes to carbon disulphide, especially in the presence of moisture/water. Therefore, the health effects of carbon disulphide (CS2) need to be considered in the assessment of SEX.
On a molecular weight scaled basis, the EC50 would be 39.8 mg/l. (21 x 144.19) /76.13 =39.8 mg/l

Executive summary:

SEX readily decomposes to carbon disulphide, especially in the presence of moisture/water. Therefore, the health effects of carbon disulphide (CS2) need to be considered in the assessment of SEX.

On a molecular weight scaled basis, the EC50 would be 39.8 mg/l. (21 x 144.19) /76.13 =39.8 mg/l

Reference 2

Endpoint:

toxicity to aquatic algae and cyanobacteria

Type of information:

(Q)SAR

Adequacy of study:

weight of evidence

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

results derived from a valid (Q)SAR model and falling into its applicability domain, with adequate and reliable documentation / justification

Justification for type of information:

QSAR prediction:US EPA accepted QSAR method for chemicals properties assessment.

Qualifier:

according to guideline

Guideline:

other: QSAR model

Principles of method if other than guideline:

ECOSAR Program(v1.00)

GLP compliance:

no

Analytical monitoring:

no

Vehicle:

no

Test organisms (species):

other: QSAR model

Details on test organisms:

not applicable. QSAR model

Test type:

other: QSAR model

Water media type:

freshwater

Limit test:

no

Total exposure duration:

96 h

Test temperature:

not applicable. QSAR model

pH:

not applicable. QSAR model

Dissolved oxygen:

not applicable. QSAR model

Salinity:

not applicable. QSAR model

Nominal and measured concentrations:

not applicable. QSAR model

Details on test conditions:

SMILES : S=C([S-])OCC.[Na+]
CHEM : Carbonodithioic acid, o-ethyl ester, sodium salt
MOL FOR: C3 H5 O1 S2 Na1
MOL WT : 144.18
Log Kow: 0.87 (used)
Wat Sol: 1.79E+004 mg/L (WskowWin estimate)

Reference substance (positive control):

no

Duration:

96 h

Dose descriptor:

EC50

Effect conc.:

129.387 mg/L

Nominal / measured:

not specified

Conc. based on:

not specified

Basis for effect:

not specified

Duration:

30 d

Dose descriptor:

NOEC

Effect conc.:

40.934 mg/L

Nominal / measured:

not specified

Conc. based on:

not specified

Basis for effect:

not specified

Remarks on result:

other: NOEC cited as a ChV value

Details on results:

Green Algae, 96-hr EC50 = 129.387 mg/L (ppm)
Green Algae, 30-day, NOEC cited as a ChV value = 40.934 mg/L(ppm)

Overview of QSARs estimations on aquatic toxicity of 

SEX

to Green algae

Method	Results	Remarks	Reference
QSAR estimate	Green Algae, 96-hr EC50 = 129.387 mg/L (ppm) Green Algae, 30-day, NOEC cited as a ChV value = 40.934 mg/L(ppm)	Reliable with restrictions, QSAR estimated data	ECOSAR Program (v1.00)

 

Green Algae, 96-hr EC50 = 129.387 mg/L (ppm)

Green Algae, 30-day, NOEC cited as a ChV value = 40.934 mg/L(ppm)

Validity criteria fulfilled:

yes

Remarks:

method for chemicals properties assessment.

Conclusions:

Green Algae, 96-hr EC50 = 129.387 mg/L (ppm)
Green Algae, 30-day, NOEC cited as a ChV value = 40.934 mg/L(ppm)

Executive summary:

The ECOSAR QSAR model predicts that 30-day, NOEC cited as a ChV value would to be 40.934 mg/L (ppm) Green Algae.

The ECOSAR QSAR model predicts that 96-hr EC50 value would to be 129.387 mg/L (ppm) for Green Algae.

Reference 3

Endpoint:

toxicity to aquatic algae and cyanobacteria

Type of information:

experimental study

Adequacy of study:

weight of evidence

Study period:

1996

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

study well documented, meets generally accepted scientific principles, acceptable for assessment

Justification for type of information:

Ethanol/ Ethyl Alcohol is both reagents used in the manufacture of sodium O-ethyl dithiocarbonate . Therefore, Ethanol/ Ethyl Alcohol need to be considered in the assessment of sodium O-ethyl dithiocarbonate

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.

Duration:

3 d

Dose descriptor:

EC10

Effect conc.:

36 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Remarks:

Sodium ethyl xanthate

Basis for effect:

growth rate

Remarks on result:

other: On a molecular weight scaled basis, theEC10 would be 36 mg/l. (11.5 x 144.19) /46.07=36mg/l

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:

A 3d EC10 of 11.5 mg/L has been determined for the effects of the test substance (Ethyl Alcohol ) on growth rate effect of the Chlorella vulgaris .
Ethyl Alcohol is both reagents used in the manufacture, as well as decomposition products of xanthates
On a molecular weight scaled basis, theEC10 would be 36 mg/l. (11.5 x 144.19) /46.07=36mg/l

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

On a molecular weight scaled basis, theEC10 would be 36 mg/l. (11.5 x 144.19) /46.07=36mg/l

Description of key information

The ECOSAR QSAR model predicts that 30-day, NOEC cited as a ChV value would to be 40.934 mg/L (ppm) Green Algae.
The ECOSAR QSAR model predicts that 96-hr EC50 value would to be 129.387 mg/L (ppm) for Green Algae.

Key value for chemical safety assessment

EC50 for freshwater algae:

129.934 mg/L

EC50 for marine water algae:

13 mg/L

EC10 or NOEC for freshwater algae:

40.934 mg/L

EC10 or NOEC for marine water algae:

4.09 mg/L

Additional information

The ECOSAR QSAR model predicts that 30-day, NOEC cited as a ChV value would to be 40.934 mg/L (ppm) Green Algae.

The ECOSAR QSAR model predicts that 96-hr EC50 value would to be 129.387 mg/L (ppm) forGreen Algae.

The available data for saltwater algae and cyanobacteria are limited and to obtaine the value for PNECs for saltwaters is taken account a assesment factor 10 to extrapolate to LC50 following the “Guidance on Information Requirement and Chemical Safety Assessment R.10: Characterisation of dose [concentration]- response for environment”and “Table R.10-5 Assessment factors proposed for deriving PNEC water for saltwater for different data sets”, to account for the possibility that greater taxonomic diversity in the marine environment makes it likely that some marine taxa may be more sensitive than the most sensitive freshwater taxa