Reaction products of sodium sulphide, sulphur, carbon disulphide and potassium hydroxide

Toxicity to aquatic algae and cyanobacteria

Link to relevant study record(s)

Reference

Endpoint:

toxicity to aquatic algae and cyanobacteria

Type of information:

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

Adequacy of study:

supporting study

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

other: Study carried out essentially according to a guideline, without detailed documentation. Incubation in sealed vessels due to volatility of CS2

Qualifier:

according to guideline

Guideline:

OECD Guideline 201 (Alga, Growth Inhibition Test)

Deviations:

yes

Remarks:

The test was carried out in sealed infusion bottles to prevent CS2 from escaping. The presence or absence of a headspace was not reported but is presumed to allow for sufficient CO2 for the biomass to grow normally.

GLP compliance:

no

Analytical monitoring:

no

Vehicle:

no

Details on test solutions:

not available

Test organisms (species):

Chlorella pyrenoidosa

Details on test organisms:

no data

Test type:

static

Water media type:

freshwater

Limit test:

no

Total exposure duration:

96 h

Hardness:

90 mg CaCO3/L

Test temperature:

20 +/- 1 deg C

pH:

8.7 +/- 0.2

Dissolved oxygen:

Not reported

Nominal and measured concentrations:

Nominal: 0 mg/l; 3.2 mg/l; 5.6 mg/l; 10 mg/l; 18.0 mg/l; 32 mg/l each presumed from Fig. 4 in the publication.

Details on test conditions:

The test was carried out in sealed infusion bottles to prevent evaporation of CS2. The presence or absence of a headspace was not reported but is presumed to allow for sufficient CO2 for the biomass to grow normally. 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 mediu 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:

act. ingr.

Basis for effect:

growth rate

Key result

Duration:

96 h

Dose descriptor:

EC50

Effect conc.:

554 mg/L

Nominal / measured:

estimated

Conc. based on:

other: EC# 944-003-3

Basis for effect:

growth rate

Remarks on result:

other: See attached background material

Reported statistics and error estimates:

no data

Validity criteria fulfilled:

not specified

Conclusions:

The 96-h EC50 of CS2 for the alga Chlorella pyrenoidosa in sealed infusion bottles was 21 mg/L, based on the inhibition of growth rate. From these data, the toxicity of the substance being registered (EC# 944-003-3) is estimated to be 554 mg/l.

Executive summary:

A test in sealed infusion bottles was carried out to determine the toxicity of CS2 to the alga Chlorella pyrenoidosa. The test was similar to the OECD Guideline 201, but was not carried out in compliance with GLP. The 96-h ErC50 for Chlorella pyrenoidosa was 21 mg/L. From these data, the toxicity of the substance being registered (EC# 944-003-3) is estimated to be 554 mg/l.

Description of key information

The substance degrades rapidly at pH <11 to form highly volatile Carbon disulphide (CS2). A test in sealed infusion bottles was carried out to determine the toxicity of CS2 to the alga Chlorella pyrenoidosa. The test was similar to the OECD Guideline 201, but was not carried out in compliance with GLP. The 96-h ErC50 for Chlorella pyrenoidosa was 21 mg/L. From these data, the toxicity of the substance being registered (EC# 944-003-3) is estimated to be 554 mg/l. The basis for this estimate is attached as background material in the supporting study (read-across to CS2).

Key value for chemical safety assessment

EC50 for freshwater algae:

554 mg/L

Additional information

The substance degrades rapidly at pH <11 to form highly volatile Carbon disulphide (CS2). A test in sealed infusion bottles was carried out to determine the toxicity of CS2 to the alga Chlorella pyrenoidosa. The test was similar to the OECD Guideline 201, but was not carried out in compliance with GLP. The 96-h ErC50 for Chlorella pyrenoidosa was 21 mg/L. From these data, the toxicity of the substance being registered (EC# 944-003-3) is estimated to be 554 mg/l. The basis for this estimate is attached as background material in the supporting study (read-across to CS2).