Sodium ascorbate

Short-term toxicity to aquatic invertebrates

Link to relevant study record(s)

Reference

Endpoint:

short-term toxicity to aquatic invertebrates

Type of information:

experimental study

Adequacy of study:

key study

Study period:

2012-01-16 to 2012-02-16

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

guideline study

Qualifier:

according to guideline

Guideline:

OECD Guideline 202 (Daphnia sp. Acute Immobilisation Test)

Deviations:

no

Qualifier:

according to guideline

Guideline:

EU Method C.2 (Acute Toxicity for Daphnia)

Deviations:

no

GLP compliance:

yes (incl. QA statement)

Specific details on test material used for the study:

- CAS Number: 134-03-2

Analytical monitoring:

yes

Details on sampling:

- Concentrations: All concentrations were sampled
- Sampling method: Duplicate test medium samples were taken at the start and end of each test medium renewal period (concentrations of the test item were analysed in one of the duplicate test media samples with the exception of the nominal concentration of 10 mg/L and in the control).
- Sample storage conditions before analysis: Immediately after sampling, a 4% oxalic acid solution was added to each sample (1 mL acid per mL sample volume) to stabilise the sample during the storage period. Samples were stored deep-frozen (at about -20 °C) under nitrogen gas.

Vehicle:

no

Details on test solutions:

PREPARATION AND APPLICATION OF TEST SOLUTION (especially for difficult test substances)
- Method: Test medium of the highest nominal concentration of 220 mg/L was prepared by dissolving 440 mg of the test item in 2000 mL of test water and stirring intensely for 10 minutes at room temperature in the dark to avoid photolytic degradation of the test item. Adequate volumes of this medium were diluted with test water to prepare the lower concentrated test media. Test media were prepared just before introduction of the daphnids and prior to the renewals of medium.
- Controls: test water without test item
- Chemical name of vehicle (organic solvent, emulsifier or dispersant): not applicable
- Evidence of undissolved material (e.g. precipitate, surface film, etc): none reported

Test organisms (species):

Daphnia magna

Details on test organisms:

TEST ORGANISM
- Common name: Water flea
- Source: A clone of the species was originally supplied by the University of Sheffield, UK, in 1992 and the clone since then has been bred at the laboratory in reconstituted water
- Age at study initiation: 6 to 24 hours
- Method of breeding: Breeding occurs in reconstituted water of the same quality used in the test (with regard to pH, main ions and total hardness) and under temperature and light conditions identical to those of the test. Daphnids are fed three times a week with an algal suspension of the green alga Desmodesmus subspicatus CHODAT, strain No. 86.81 SAG (provided by SAG, Institute for Plant Physiology, University of Göttingen, Germany and cultivated at the laboratory under standardised conditions) or a mixture of the algal suspension and a commercial fish diet (Tetra Min Hauptfutter, TETRA-Werke, Melle, Germany)
- Feeding during test: Not applicable

Test type:

semi-static

Water media type:

freshwater

Limit test:

no

Total exposure duration:

48 h

Post exposure observation period:

Not applicable

Hardness:

250 mg/L as CaCO3

Test temperature:

20 to 21 °C

pH:

7.6 to 8.0

Dissolved oxygen:

5.8 to 8.8 mg/L

Salinity:

Not applicable

Nominal and measured concentrations:

Nominal: 0 (control), 10, 22, 46, 100 and 220 mg/L
Time weighted mean measured: < LOQ, not measured, 5.1, 24, 73 and 192 mg/L

Details on test conditions:

TEST SYSTEM
- Type: Covered with glass plates
- Material, size, headspace, fill volume: Glass beakers, 100 mL volume, filled with 60 mL of test medium
- Aeration: Prior to test water was aerated until oxygen saturation was reached; no aeration occurred during the test
- Renewal rate of test solution (frequency): Semi-static test was conducted and test medium was renewed every 12 hours
- No. of organisms per vessel: 5
- No. of vessels per concentration (replicates): 4
- No. of vessels per control (replicates): 4

TEST MEDIUM / WATER PARAMETERS
- Source/preparation of dilution water: Reconstituted test water according to ISO 6341
- Alkalinity: 0.8 mmol/L
- Ca/Mg ratio: 4/1
- Culture medium different from test medium: No

OTHER TEST CONDITIONS
- Photoperiod: Test was conducted as far as possible in the dark

EFFECT PARAMETERS MEASURED: immobilisation noted every 24 hours

Reference substance (positive control):

yes

Remarks:

potassium dichromate is tested twice a year

Duration:

48 h

Dose descriptor:

EC50

Effect conc.:

74 mg/L

Nominal / measured:

meas. (TWA)

Conc. based on:

test mat.

Basis for effect:

mobility

Remarks on result:

other: 95% CL: 52 to 107 mg/L

Details on results:

Not reported

Results with reference substance (positive control):

Results of the latest positive control in September 2011 (48-hour EC50 of 0.97 mg/L) showed that the sensitivity of the test organisms was within the internal historical range.

Reported statistics and error estimates:

Not specified.

Table 1: Effects of sodium ascorbate crystalline on the mobility of Daphnia magna

Nominal test concentration (mg/L)	TWA measured concentration (mg/L)	Number of daphnids tested	Immobilised daphnids after 24 hours		Immobilised daphnids after 48 hours
			Number	%	Number	%
Control	< LOQ	20	0	0	0	0
10	Not measured	20	0	0	0	0
22	5.1	20	0	0	0	0
46	24	20	0	0	2	10
100	73	20	3	15	10	50
220	192	20	14	70	17	85

Validity criteria fulfilled:

yes

Conclusions:

A 48-hour EC50 value of 74 mg/L was found in a valid semi-static study on the acute toxicity of the substance to Daphnia magna. This value was based on the measured time weighted average concentration as the substance was found to be relatively unstable under the conditions of the test.

Executive summary:

The acute toxicity of Sodium ascorbate to the aquatic invertebrate Daphnia magna was studied under GLP conditions in a semi-static 48-hour test according to OECD TG 402. The test was conducted with nominal concentrations of 10, 22, 46, 100 and 220 mg/L in reconstituted water. The test medium was exchanged every twelve hours. Due to the relative instability of the test substance, tests were performed in the dark as much as possible. The test temperature was kept constant at 20 to 21 °C, the pH ranged from 7.6 to 8.0 and the concentration of dissolved oxygen was at least 5.8 mg/L in all test vessels. The test concentrations were analysed by means of HPLC with UV detector. It was found that test concentrations were relatively instable over the course of twelve hour renewal period and time weighted average concentrations were therefore determined and used to calculate the effect levels. Five daphnids per vessel were tested in four replicates for each test concentration and the control. No immobilisation was seen with the nominal test concentration of 22 mg/L (TWA measured concentration of 5.1 mg/L) over the testing period of 48 hours. The 48-hour EC50 value (based on immobilisation) was 74 mg/L with a 95% confidence interval of 52 to 107 mg/L. All validity criteria of the test guidelines were fulfilled.

Description of key information

A 48-hour EC50 value of 74 mg/L (based on the measured time weighted average concentration) was found in a valid semi-static study on the acute toxicity of the substance to Daphnia magna.

Key value for chemical safety assessment

Fresh water invertebrates

Fresh water invertebrates

Effect concentration:

74 mg/L

Additional information

The acute toxicity of Sodium ascorbate to the aquatic invertebrate Daphnia magnawas studied under GLP conditions in a semi-static 48-hour test according to OECD TG 402. The test was conducted with nominal concentrations of 10, 22, 46, 100 and 220 mg/L in reconstituted water. The test medium was exchanged every twelve hours. Due to the relative instability of the test substance, tests were performed in the dark as much as possible. The test temperature was kept constant at 20 to 21 °C, the pH ranged from 7.6 to 8.0 and the concentration of dissolved oxygen was at least 5.8 mg/L in all test vessels. The test concentrations were analysed by means of HPLC with UV detector. It was found that test concentrations were relatively instable over the course of twelve hour renewal period and time weighted average concentrations were therefore determined and used to calculate the effect levels. Five daphnids per vessel were tested in four replicates for each test concentration and the control. No immobilisation was seen with the nominal test concentration of 22 mg/L (TWA measured concentration of 5.1 mg/L) over the testing period of 48 hours. The 48-hour EC50 value (based on immobilisation) was 74 mg/L with a 95% confidence interval of 52 to 107 mg/L. All validity criteria of the test guidelines were fulfilled.