Sodium O-ethyl dithiocarbonate

Long-term toxicity to aquatic invertebrates

Link to relevant study record(s)

Reference

Endpoint:

long-term toxicity to aquatic invertebrates

Type of information:

experimental study

Adequacy of study:

key study

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

guideline study

Justification for type of information:

Testing performed on substance to guidelines

Qualifier:

according to guideline

Guideline:

OECD Guideline 211 (Daphnia magna Reproduction Test)

Deviations:

no

GLP compliance:

yes (incl. QA statement)

Remarks:

SNAS 038/G-017

Analytical monitoring:

yes

Details on sampling:

During the test concentrations of test substance were determined once a week.Oxygen concentration, temperature, and pH values were measured once a week, in fresh andold medium, in the control(s) and in the highest tests substance concentration.Hardness in medium = control (M4) was measured once a week in fresh and old medium.

Details on test solutions:

NaOH, 1 mol/L: 40 g (1 mole) NaOH was dissolved in 1 L of water.Test medium: Elendt M4 (by OECD 211, Annex 2)M4 medium was prepared using stock solution II, the macro-nutrients and vitaminsThe combined vitamin stock was stored frozen in small aliquots. Vitamins were added to the mediumshortly before use. To avoid precipitation of salts when preparing the complete medium, the aliquotsof stock solution were added to about 500 – 800 mL deionised water and then filled up to 1 litre.Test solutions of the chosen concentrations had been prepared by dilution of a stock solution.Stock solutions had been prepared, without using any solvents or dispersants, by agitating the testsubstance in test medium using mechanical means (agitating).

Test organisms (species):

Daphnia magna

Details on test organisms:

The daphnids species: Daphnia magna, Straus.The source of daphnids species: own rearing, the original source Water Research Institute,Bratislava, Slovak Republic.At the start of the test, the animals were less than 24 hours old and weren’t first brood progeny.They were derived from a healthy stock (i.e. showing no signs of stress such as high mortality,presence of males and ephippia, delay in the production of the first brood, discoloured animals,etc.). The stock animals were maintained in culture conditions (light, temperature, medium,feeding and animals per unit volume) similar to those were used in the test.

Test type:

semi-static

Water media type:

freshwater

Limit test:

no

Total exposure duration:

21 d

Hardness:

Hardness was above 140 mg/L (as CaCO3).

Test temperature:

The temperature of the test media was in the range 18 – 22°C. The temperature didn’t vary by more than 2°C within these limits as daily range.

pH:

The pH was within the range 6 – 9 and it did not vary by more than 1.5 units in any one test.

Dissolved oxygen:

The dissolved oxygen concentration was above 3 mg/L at the beginning and during the test.

Nominal and measured concentrations:

In semi-static tests where the concentration of the test substance was expected to remainwithin ± 20 per cent of the nominal (i.e. within the range 80 - 120 per cent) as a minimum thehighest and lowest test concentrations was analysed when freshly prepared and at the time ofrenewal on one occasion during the first week of the test (i.e. analyses had been made on asample from the same solution - when freshly prepared and at renewal). These determinationswere repeated at least at weekly intervals thereafter.

Details on test conditions:

Duration. The test duration was 21 days.Loading. Parent animals were maintained individually, one per test vessel, with 50 mL of medium in each vessel.Test animals. 10 animals individually were held at each test concentration and 10 animals individually were held in the control series.Feeding. For semi-static tests, feeding was done three times per week (corresponding to media changes). A concentrated algal suspension was fed to the Daphnia to minimise the volume of algal culture medium transferred to the test vessels. Concentration of the algae was achieved by centrifugation followed by re-suspension in Daphnia culture medium.During the test, the diets of the parent animals were living algal cells of Chlorella sp. The supplied diet was based on the amount of organic carbon (C) provided to each parent animal. The ration was in the recommended range of 0.1 - 0.2 mg C/Daphnia/day at all times.Nomograph of algal cell number on mg C/L was created (Graph 1).Light. 16 hours light at intensity 860 – 980 lux was measured at the water surface of the vessel daily (not exceeding 1000 – 1500 lux).Temperature. The temperature of the test media was in the range 18 – 22°C. The temperature didn’t vary by more than 2°C within these limits as daily range.Aeration. The test vessels weren’t aerated during the test.

Duration:

21 d

Dose descriptor:

EC10

Effect conc.:

0.047 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

reproduction

Duration:

21 d

Dose descriptor:

EC50

Effect conc.:

0.372 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

reproduction

Validity criteria fulfilled:

yes

Conclusions:

Confirms classification Aquatic Chronic 2 when considering biodegradation outcome

Description of key information

Key study confirms classification as Aquatic Chronic 2

Later study performed on related xanthate suggests slightly lower toxicity

Key value for chemical safety assessment

Fresh water invertebrates

Fresh water invertebrates

Dose descriptor:

EC10

Remarks:

Semi-static

Effect concentration:

0.047 mg/L