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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:
13 -15 Feb 2012
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)
Version / remarks:
April 2004
Qualifier:
according to guideline
Guideline:
EU Method C.2 (Acute Toxicity for Daphnia)
Version / remarks:
May 2008
Qualifier:
according to guideline
Guideline:
ISO 6341 (Water quality - Determination of the Inhibition of the Mobility of Daphnia magna Straus (Cladocera, Crustacea))
Version / remarks:
Third Edition, 1996
GLP compliance:
yes (incl. QA statement)
Remarks:
Food and Consumer Product Safety Authority (VWA), Utrecht, The Netherlands
Analytical monitoring:
no
Remarks:
No suitable analytical method could be established to quantify the test substance in test medium.
Vehicle:
no
Details on test solutions:
PREPARATION AND APPLICATION OF TEST SOLUTION
- Method: Preparation of test solutions started with individually prepared loading rates of 1.0, 10 and 100 mg/L applying a 1 h period of magnetic stirring. The obtained mixtures containing undissolved material were allowed to settle for a period of 50 min after which the Water Accommodated Fractions were siphoned off and used as test solutions. The lowest test concentration was prepared as a 10-fold dilution of the WAF prepared at 1.0 mg/L.
- Eluate: no
- Differential loading: yes (except for the lowest loading rate)
- Controls: yes, test medium control
- Evidence of undissolved material (e.g. precipitate, surface film, etc.): The final test solutions were all clear and colourless.
Test organisms (species):
Daphnia magna
Details on test organisms:
TEST ORGANISM
- Common name: water flea
- Source: in-house culture
- Feeding during test: none

BREEDING
- Breeding conditions: same as test with newborn daphnids, i.e. less than 3 d old, by placing about 250 of them into 5 L of medium in an all-glass culture vessel. Maximum age of cultures was 4 weeks.
- Type and amount of food: suspension of fresh water algae
- Feeding frequency: daily
- Culture medium: M7 medium
Test type:
static
Water media type:
freshwater
Limit test:
no
Total exposure duration:
48 h
Hardness:
180 mg CaCO3/L
Test temperature:
20.5 °C (20.3 - 20.7 °C)
pH:
7.8 - 8.0
Dissolved oxygen:
8.8 - 9.6 mg O2/L
Nominal and measured concentrations:
nominal: control, 1, 10, 100 mg/L
Details on test conditions:
TEST SYSTEM
- Test vessel: All-glass beakers
- Material, size, headspace, fill volume: all-glass, 100 mL, headspace: 20 mL, fill volume: 80 mL
- Aeration: no
- No. of organisms per vessel: 5
- No. of vessels per concentration (replicates): 4 (highest concentrations), 2 (lower concentrations)
- No. of vessels per control (replicates): 4

TEST MEDIUM / WATER PARAMETERS
- Source/preparation of dilution water: tap water purified by Reverse Osmosis (ROwater, GEON Waterbehandeling, Berkel-Enschot, The Netherlands)
- Culture medium different from test medium: same as test
- Intervals of water quality measurement: The pH and dissolved oxygen was measured at the beginning and at the end of the test, for the highest concentration and the control. Temparature was measured continuously.

OTHER TEST CONDITIONS
- Adjustment of pH: no
- Photoperiod: 16 h light, 8 h darkness

EFFECT PARAMETERS MEASURED
- Mobility: measured after 24 and 48 h
Reference substance (positive control):
yes
Remarks:
potassium dichromate
Key result
Duration:
48 h
Dose descriptor:
EL50
Effect conc.:
> 100 mg/L
Nominal / measured:
nominal
Conc. based on:
test mat.
Remarks:
WAF
Basis for effect:
mobility
Key result
Duration:
48 h
Dose descriptor:
NOELR
Effect conc.:
>= 100 mg/L
Nominal / measured:
nominal
Conc. based on:
test mat.
Remarks:
WAF
Basis for effect:
mobility
Details on results:
- Inhibition of mobility in control: 0%
Results with reference substance (positive control):
- Results with reference substance valid? yes
- Limit test: no
- Dose-response test: yes
- ECx: EC50 (48 h): 0.28 mg/L (95% CI: 0.26 - 0.32 mg/L)
Reported statistics and error estimates:
No effects were recorded. Thus, no statistical analysis was considered to be necessary.

Analytical measurements

The test substance is an organic compound with the element tin (Sn) in its molecular structure. An ICP-MS method was developed for the determination of the test substance based on the element Sn. Validation of the analytical assay was carried out, however, it was found that the accuracies on test samples prepared with the test substance were inadequate. The ICP-MS method developed was considered to be the best possible for the determination of the test substance:

- Oxygen and helium gas were used to remove the organic and tetrahydrofuran (THF) content of the test substance and accuracy samples.

- The analytical sequence had a normal number of samples and the instrument was cleaned prior to use.

- The substance must be dissolved in THF since it was not directly soluble in (aqueous) strong acids such as HNO3.

According to the results obtained it was concluded that it is not possible to use the ICP-MS method for quantification of test samples to support physico-chemical- and (eco)toxicologal studies. Other analytical techniques such as GC, HPLC and UV-Vis were not suitable for the determination of the test substance due to its hydrophobic molecular structure.

Validity criteria fulfilled:
yes

Description of key information

EL50 (48 h) > 100 mg/L (nominal, OECD 202)

Key value for chemical safety assessment

Fresh water invertebrates

Fresh water invertebrates
Effect concentration:
100 mg/L

Additional information

One experimental study is available investigating the effects of the substance to freshwater invertebrates. The study was performed according to OECD 202 (GLP) with Daphnia magna under static conditions. Test solutions were prepared as loading rates of 0.1, 1.0, 10.0 and 100 mg/L by adding appropriate amounts of the substance to test medium followed by 1 h stirring, 50 min settling and siphoning off the soluble fraction to be used for testing. The lowest loading rate was prepared by serial dilution (10x) of 1 mg/L. All test solutions were clear and colorless throughout the test. Analytical measurements were not possible to be conducted since no suitable analytical method could be established (see also IUCLID section 5.1.2). No inhibition of mobility was recorded after 48 h resulting in an EL50 (48 h) of > 100 mg/L.