Sodium O-ethyl dithiocarbonate

Sediment toxicity

Administrative data

Endpoint:

sediment toxicity: short-term

Data waiving:

study scientifically not necessary / other information available

Justification for data waiving:

other:

Justification for type of information:

The substance rapidly hydrolyses under environmental conditions, including seawater and is also noted as being rapidly biodegradable in screening tests.
The key hydrolysis products are carbon disulphide and respective alcohols that are themselves biodegradable.
Exposure to sediment is considered unlikely and would only be transitory.

Cross-reference

Reason / purpose for cross-reference:

data waiving: supporting information

Reference

Endpoint:

biodegradation in water: ready biodegradability

Type of information:

experimental study

Adequacy of study:

key study

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

guideline study

Qualifier:

according to guideline

Guideline:

EU Method C.4-A (Determination of the "Ready" Biodegradability - Dissolved Organic Carbon (DOC) Die-Away Test)

Deviations:

no

GLP compliance:

yes (incl. QA statement)

Remarks:

GLP certificate no. 4/2010/DPL

Oxygen conditions:

aerobic

Inoculum or test system:

activated sludge, non-adapted

Details on inoculum:

Activated sludge from aeration tank of sewage treatment plant. The sludge was cleaned by multiple sedimentation and washing with water. The sludge after separation on filter, than was dried at 1050C.

Duration of test (contact time):

28 d

Details on study design:

Number of flask in the test:Flasks FT-3 and FT-4: test solutionFlasks FB-1 and FB-2: inoculum blankFlask FC: procedure control

Reference substance:

ethylene glycol

Test performance:

Into each of the 1000cm3 conical flasks FT-3 and FT-4 introduce 482 cm3 of nutrient solution and 13 cm3 of water solution (concentration 10g/dm3) test substance to give the DOC concentration 10-40g/dm3 of chemical equivalent. Inoculate the flasks with 5 cm3 to give 28.6 mg suspended solids/dm3, and make up to 500 cm3 with distilled water. Into each of the 1000cm3 conical flasks FB-1 and FB-2 introduce 495 cm3 of nutrient solution. Inoculate the flasks with 5 cm3 to give 28.6 mg suspended solids/dm3, and make up to 500 cm3 with distilled water.Into the 1000cm3 conical flasks FC introduce 495 cm3 of nutrient solution, and 51.9 mg of reference substance. Inoculate the flasks with 5 cm3 to give 28.6 mg suspended solids/dm3, and make up to 500 cm3 with distilled waterThe test, blank and reference solutions were inoculated and incubated under aerobic conditions in diffuse light at 20-250C, pH = 7.4+/- 0.2, concentration of dissolved oxygen >2mg/dm3.Degradation is followed by DOC analysis at frequent intervals over a 28-day period. First DOC measurement was after 3h+/-30min,and than after 2, 5, 7, 12, 14, 19, 22, 26 and 28 days of the test. The culture medium was mixed thoroughly before sampling. The samples before analysis were filtered using a membrane filter (0.45µm pores size). Activity of the inoculum was checked by parallel biodegradation run of reference substance (ethylene glycol).Degradation measures by means of DOC determinationDegradation is calculated using the following equation:Dt = {1 - (Ct.- Cbt)/(Co - Cbo)}Where:Dt% degradation at time tComean DOC concentration in the flask FT at 3h+/-30min [mgDOC/dm3]Ctmean DOC concentration in the flask FT at time t [mgDOC/dm3]Cbomean DOC concentration in the flask FB at 3h+/-30min [mgDOC/dm3]Cbtmean DOC concentration in the flask FB at time t [mgDOC/dm3]

Parameter:

% degradation (DOC removal)

Value:

100

St. dev.:

1.4

Sampling time:

28 d

Results:

Tabel .Results of DOC measurements, study of biodegradibilty of sodium ethyl xanthate
	Mean DOC concentration(mg/l)
	3h±30 min	2 days	5 days	7 days	12 days	14 days	19 days	22 days	26 days	28 days
Flasks FT-3 and FT-4 test solution	44,29 ± 0,13	39,56 ± 0,23	21,78 ± 0,11	17,81 ± 0,20	15,77 ± 0,23	14,95 ± 0,22	14,40 ± 0,30	14,09 ± 0,20	14,07 ± 0,21	12,09 ± 0,38
Flasks FB-1 and FB-2 inoculum blank	7,91 ± 0,27	9,20 ± 0,09	11,86 ± 0,24	8,48 ± 0,11	13,54 ± 0,37	12,14 ± 0,22	10,08 ± 0,26	10,58 ± 0,37	13,24 ± 0,30	16,35 ± 0,41
Falsk FC procedure control	51,21 ± 0,01	51,06 ± 0,06	16,31 ± 0,11	14,55 ± 0,34	17,58 ± 0,38	13,83 ± 0,12	13,70 ± 0,14	14,91 ± 0,29	15,18 ± 0,30	9,10 ± 0,39

Interpretation of results:

readily biodegradable

Conclusions:

After 28 days biodegradation of sodium ethyl xanthate: D28days = 100%
The results indicate that sodium ethyl xanthate (CAS# 140-90-9) is ready biodegradable - pass level, according to OECD 301:-
Pass value in the 10 day window (form 1 day to 11 day) is 89% removal of DOC,