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Short-term toxicity to aquatic invertebrates

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Reference
Endpoint:
short-term toxicity to aquatic invertebrates
Type of information:
experimental study
Adequacy of study:
key study
Study period:
2001-08-30 to 2001-12-07
Reliability:
1 (reliable without restriction)
Rationale for reliability incl. deficiencies:
other: GLP guideline study
Qualifier:
according to guideline
Guideline:
OECD Guideline 202 (Daphnia sp. Acute Immobilisation Test)
Version / remarks:
adopted on April 1984
Deviations:
no
GLP compliance:
yes (incl. QA statement)
Remarks:
The Department of Health of the Government of the United Kingdom
Analytical monitoring:
yes
Details on sampling:
Sampling of test material was done at 0 (fresh media), 24 (old and fresh media) and 48 hours (old media). Samples were taken from the control (replicates R1-R2 pooled) and each test group (replicates R1-R2 pooled). Duplicate samples were taken and stored frozen (approximately -20°C) for further analysis if necessary
Vehicle:
no
Details on test solutions:
PREPARATION AND APPLICATION OF TEST SOLUTION (especially for difficult test substances)
- Method: 200 mg of the test substance was dissolved in reconstituted water with the aid of ultrasonication for approximately 1 minute and the volume adjusted to 2 litres to give the 100 mg/L test concentration from which dilutions were made to give the remainder of the test series. The test material was heated approximately 30°C to ensure homogeneity prior to use.
- Controls: Blank: water.
- Stock solution: 200 mg of the test substance was dissolved in reconstituted water and adjusted to 100 mg/L with 2 L water.
- Evidence of undissolved material (e.g. precipitate, surface film, etc): No

Range fining test: 100 mg test material was dissolved in reconstituted water with the aid of ultrasonication for approx. 1 min and the volume adjusted to 1 L to give the 100 mg/L test concentration from which dilutions were made to give the series of test concentrations. The test material was heated approx. 30 °C, to ensure homogeneity prior to use. Each prepared concentration was inverted several times to ensure adequate mixing and homogeneity.
Test organisms (species):
Daphnia magna
Details on test organisms:
TEST ORGANISM
- Common name: Water Flea
- Strain: Daphnia magna
- Source: SafePharm, Derby, United Kingdom
- Age at study initiation (mean and range, SD): ist instar (< 24 h)
- Method of breeding: Cultures of daphnia are maintained in polypropylene vessels containing approx. 2 L of reconstituted water at 21°C.The lighting cycle was controlled to give a 16 hours light and 8 hours darkness cycle with 20 minute dawn and dusk transition periods. Each culture was fed daily with a suspension of algae (Chlorella sp.). Culture conditions ensured that reproduction was by parthenogenesis.
- Pretreatment: 24 hours before the start of the test gravid daphnia are isolated so that the young daphnia produced overnight (0-24h of age) are retained for the test.
- Feeding during test: none
Test type:
semi-static
Water media type:
freshwater
Limit test:
no
Total exposure duration:
48 h
Hardness:
250 mg CaCO3/L
Test temperature:
21 °C
pH:
6.3 - 7.9
Dissolved oxygen:
8.1 - 8.4 mgO2/L
Nominal and measured concentrations:
Nominal: 1.0, 1.8, 3.2, 5.6, 10, 18, 32, 56 and 100 mg/L

Time weighted mean measured: 0.52, 0.71, 1.7, 2.8, 5.3, 9.0, 16, 28 and 52 mg/L
Details on test conditions:
TEST SYSTEM
- Test vessel: 250 mL covered glass jars containing 200 ml solution per jar
- Aeration: None during the test.
- Renewal rate of test solution (frequency/flow rate): 24 h
- No. of organisms per vessel: 10
- No. of vessels per concentration (replicates): 4
- No. of vessels per control (replicates): 4
- No. of vessels per vehicle control (replicates): 2

TEST MEDIUM / WATER PARAMETERS
- Source/preparation of dilution water: Reconstituted water according to the guideline. ( reconstituted water: 11.76 g/L CaCl2.2H2O, 4.93 g/L MgSO4.7H2O, 2.59 g/L NaHCO3, 0.23 g/L KCL; an aliquot (25 mL) of each of the solutions was added to each liter (final volume) of deionised water with a conductivity of < 5µS/cm. The reconstituted water had a pH of 7.8 ± 0.2 adjusted (if necessary) with NaOH or HCl and was aerated until the dissolved oxygen concentration was approx. air-saturation value.)
- Intervals of water quality measurement: oxygen, pH, temperature daily (in separate vessels at the start of the test)

OTHER TEST CONDITIONS
- Photoperiod: Fluorescent light, 16 hours daily with 20 m dusk and dawn transition period

EFFECT PARAMETERS MEASURED: Immobilization

TEST CONCENTRATIONS
- Spacing factor for test concentrations: ca. 1.8
- Test concentrations: 9
- Range finding study
Test concentrations: 0.1, 1.0, 10 and 100 mg/L
Results used to determine the conditions for the definitive study: No immobilisation was observed at the test concentrations of 0.10, 1.0 and 10 mg/L. However immobilisation was observed at 100 mg/L. Based on this definitve test concentrations were selected between 1.0 and 100 mg/L
Reference substance (positive control):
not specified
Duration:
48 h
Dose descriptor:
EC50
Effect conc.:
16 mg/L
Nominal / measured:
meas. (TWA)
Conc. based on:
test mat.
Basis for effect:
mobility
Remarks on result:
other: 95% CL 14 -19 mg/L
Duration:
48 h
Dose descriptor:
EC50
Effect conc.:
33 mg/L
Nominal / measured:
nominal
Conc. based on:
test mat.
Basis for effect:
mobility
Remarks on result:
other: 95% CL: 29 - 37 mg/L
Duration:
48 h
Dose descriptor:
NOEC
Effect conc.:
9 mg/L
Nominal / measured:
meas. (TWA)
Conc. based on:
test mat.
Basis for effect:
mobility
Duration:
48 h
Dose descriptor:
NOEC
Effect conc.:
18 mg/L
Nominal / measured:
nominal
Conc. based on:
test mat.
Basis for effect:
mobility
Details on results:
- Test preparations were observed to be clear, colourless solutions throughout the test
- Mortality of control: 0 % mortality was observed in the control and the solvent control.
Reported statistics and error estimates:
The EC-50 values were calculated according to the trimmed Spearman-Karber method (Hamilton et al. 1977)
EC-values were calculated using nominal and the time-weighted mean measured test concentrations

Table: Cumulative immobilisation data in the definitve test:

Nominal Concentration (mg/L)

Cumulative immobilised Daphnia (initial population: 10 per replicate)

24 hours

48 hours

R1

R2

Total

%

R1

R2

Total

%

Control

0

0

0

0

0

0

0

0

1.0

0

0

0

0

0

0

0

0

1.8

0

0

0

0

0

0

0

0

3.2

0

0

0

0

0

0

0

0

5.6

0

0

0

0

0

0

0

0

10

0

0

0

0

0

0

0

0

18

0

0

0

0

0

0

0

0

32

0

0

0

0

5

4

9

45

56

0

0

0

0

10

10

20

100

100

10

9

19

95

10

10

20

100

Analysis of the fresh test solutions taken at 0 and 24 hours showed the measured test concentrations to range from 83% to 99% of the nominal concentrations. Analysis of the old or expired test media sampled at 24 and 48 hours showed a marked decline in the measured test concentrations. The values were shown to range from less than the Limit of Quantitation (LOQ) of the analytical method to 29% of the nominal. Given that the test material was unstable over each 24 -hour dosing period it was considered appropriate to calculate the results of the definitive test based on the time-weighted mean measured test concentrations in order to give a "worst case" analysis of the data.

Description of key information

The determined EC50(48 h) value for D. magna was 16 mg/L (TWA).

Key value for chemical safety assessment

Fresh water invertebrates

Fresh water invertebrates
Effect concentration:
16 mg/L

Additional information

The acute toxicity of 1,3-propanesultone was tested in a guideline test according to OECD 202. The 48–hr-acute toxicity of the test item to Daphnia magna was studied under semi-static conditions with a renewal of the test medium after 24 hours. Daphnids were exposed to control, and test item at nominal concentration of 1.0, 1.8, 3.2, 5.6, 10, 18, 32, 58 and 100 mg/L for 48 hr.  The test substance concentrations were verified analytically. The analytical verification showed a decline in the test concentrations due to the hydrolysis of the test substance to concentrations <30% of nominal. The effect concentrations were therefore based on the time-weighted mean measured test concentrations. Mortality/immobilization and sublethal effects were observed daily.  The 48–hr EC50 was 16 mg/L (TWA). The 48–hr NOEC based on immobilization was 9.0 mg/L (TWA). This study is classified as acceptable and satisfies the guideline requirements for an acute toxicity study with freshwater invertebrates.