Sodium O-isobutyl dithiocarbonate

Toxicity to other aquatic organisms

Link to relevant study record(s)

Reference

Reference 1

Endpoint:

toxicity to other aquatic vertebrates

Data waiving:

other justification

Justification for data waiving:

other:

Reference 2

Endpoint:

toxicity to other aquatic vertebrates

Type of information:

other: published data

Adequacy of study:

supporting study

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:

Carbon disulphide is both a reagent in the manufacture, as well as a decomposition product of xanthates. SIBX 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 SIBX.

Qualifier:

no guideline required

Principles of method if other than guideline:

Effects of different concentrations of carbon disulphide on the embryonic development of frog investigated.

GLP compliance:

no

Analytical monitoring:

no

Vehicle:

no

Test organisms (species):

Microhyla ornata

Details on test organisms:

Fresh, naturally fertilized eggs of the frog Microhyla ornata were obtained from a local, unpolluted pond. The jelly was removed with forceps and the eggs were transferred to aged tapwater. Eggs in early gastrulation (dorsal lip) were then used in experimentation as per the procedure described earlier (Ghate, 1980 & 1983 a). 50 Embryos per concentration expodes.

Test type:

static

Water media type:

freshwater

Limit test:

no

Total exposure duration:

96 h

Hardness:

NR

Test temperature:

NR

pH:

NR

Dissolved oxygen:

NR

Salinity:

NR

Nominal and measured concentrations:

SOLVENT
NAME: Ethanol
COMMENT: 1 ML CS2 TO 50 ML ALCOHOL

Details on test conditions:

4 µL CS2 / 100 mL aged tapwater: no mortality / Development normal
8 µL CS2 / 100 mL aged tapwater: no mortality / Hatching delayed by few hours / Tadpoles showed slightly abnormal notochord
12 µL CS2 / 100 mL aged tapwater: no mortality / Hatching delayed 50% failed to hatch even at 96 hrs. / All were oedematic with wavy notochord
16 µL CS2 / 100 mL aged tapwater: 90% mortality in 24 hrs. / All dead in 48 hrs.
20 µL CS2 / 100 mL aged tapwater: 100% mortality in 24 hrs.

Reference substance (positive control):

not specified

Duration:

24 h

Dose descriptor:

LC100

Effect conc.:

126 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

mortality

Details on results:

The embryonic development of frogs was disturbed at a concentration of 126 mg CS2/L, with no hatching taking place (100% mortality) .

4 µL CS2 / 100 mL aged tapwater: no mortality / Development normal

8 µL CS2 / 100 mL aged tapwater: no mortality / Hatching delayed by few hours / Tadpoles showed slightly abnormal notochord

12 µL CS2 / 100 mL aged tapwater: no mortality / Hatching delayed 50% failed to hatch even at 96 hrs. / All were oedematic with wavy notochord

16 µL CS2 / 100 mL aged tapwater: 90% mortality in 24 hrs. / All dead in 48 hrs.

20 µL CS2 / 100 mL aged tapwater: 100% mortality in 24 hrs.

Validity criteria fulfilled:

not specified

Conclusions:

The embryonic development of frogs was disturbed at a concentration of 126 mg CS2/L, with no hatching taking place (100% mortality) .

Description of key information

Expert Judgement

Xanthates are used in the mining industry as flotation agents in the recovery of metal sulphides. The amount of xanthate used is very small relative to the quantity of ore treated, being approximately 250 to 350 g/tonne of ore.

During use, the solid SIBX is mixed with water to form a dilute aqueous solution and typically concentrations in the order of 10% are used. The pH of the solution ranges from 7 to 11.

The flotation process is fully automated. The process takes place in open tanks and there is the potential for formation of carbon disulphide vapour. However, the concentration of SIBX in the flotation tank is low and, therefore, the release of carbon disulphide would be expected to be low. Air monitoring data, although limited and of poor quality, indicate that the atmospheric levels of carbon disulphide are below 10 ppm in the flotation areas. The risk to workers during the flotation process is considered to be low.

Due to the absence of chemical groups or other structural alerts this substance is not considered to exhibit an high hazard potential.

The results suggest for SIBX that direct and indirect exposure of other aquatic organisms is unlikely.

Therefore testing for Toxicity to other aquatic organisms does not need to be performed.

Additional information

Expert Judgement

Xanthates are used in the mining industry as flotation agents in the recovery of metal sulphides. The amount of xanthate used is very small relative to the quantity of ore treated, being approximately 250 to 350 g/tonne of ore.

During use, the solid SIBX is mixed with water to form a dilute aqueous solution and typically concentrations in the order of 10% are used. The pH of the solution ranges from 7 to 11.

The flotation process is fully automated. The process takes place in open tanks and there is the potential for formation of carbon disulphide vapour. However, the concentration of SIBX in the flotation tank is low and, therefore, the release of carbon disulphide would be expected to be low. Air monitoring data, although limited and of poor quality, indicate that the atmospheric levels of carbon disulphide are below 10 ppm in the flotation areas. The risk to workers during the flotation process is considered to be low.

Due to the absence of chemical groups or other structural alerts this substance is not considered to exhibit an high hazard potential.

The results suggest for SIBX that direct and indirect exposure of other aquatic organisms is unlikely.

Therefore testing for Toxicity to other aquatic organisms does not need to be performed.