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Short-term toxicity to aquatic invertebrates

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Endpoint:
short-term toxicity to aquatic invertebrates
Type of information:
experimental study
Adequacy of study:
key study
Study period:
1994-04-27 to 1994-04-29
Reliability:
1 (reliable without restriction)
Rationale for reliability incl. deficiencies:
guideline study
Qualifier:
according to
Guideline:
EU Method C.2 (Acute Toxicity for Daphnia)
Deviations:
no
GLP compliance:
yes
Analytical monitoring:
yes
Details on sampling:
- Concentrations: 500 mg/l nominal treatment

- Sampling method: Samples of test media were taken at the start and end of the test

- Sample storage conditions before analysis: Refrigerated
Vehicle:
no
Details on test solutions:
PREPARATION AND APPLICATION OF TEST SOLUTION

- Method: A 500 mg/l nominal concentration of the test substance was prepared by stirring overnight.

- Controls: Dilution water
Test organisms (species):
Daphnia magna
Details on test organisms:

- Type and amount of food: Chlorella vulgaris at 500000 cells/ml

- Feeding frequency: Daily
Test type:
static
Water media type:
freshwater
Limit test:
yes
Total exposure duration:
48 h
Hardness:
204 mg/l as CaCO3
Test temperature:
20.3 - 21.7ºC
pH:
7.4 - 8.1
Dissolved oxygen:
99 - 100% ASV
Nominal and measured concentrations:
Nominal: 0(Control), 500 mg/l

Measured concentration at start of test: 405 mg/l

Measured concentration at end of test: 436 mg/l

Mean measured concentration: 420 mg/l

Mean measured concentration as a percentage of nominal: 84.1%

The test results are presented and interpreted with reference to nominal concentrations.
Details on test conditions:
TEST SYSTEM

- Test vessel: Conical flasks

- Type: closed

- Material, fill volume: Glass, 150 ml of test medium

- Aeration: none

- 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 freshwater prepared by mixing (1:1) treated mains water and proprietary mineral water (Ashbourne, Still Natural Water (Nestle, UK. Limited).

- Culture medium different from test medium: no

- Chlorine: <0.1 mg/l (Total)

- Alkalinity: 134 mg/l as CaCO3

- Conductivity: 404 μS/cm

OTHER TEST CONDITIONS

- Adjustment of pH: no

EFFECT PARAMETERS MEASURED (with observation intervals if applicable) : Immobilization after 24 and 48 h
Reference substance (positive control):
no
Key result
Duration:
48 h
Dose descriptor:
EC50
Effect conc.:
> 500 mg/L
Nominal / measured:
nominal
Conc. based on:
test mat.
Remarks:
but exposure is to hydrolysis product
Basis for effect:
mobility
Duration:
48 h
Dose descriptor:
NOEC
Effect conc.:
>= 500 mg/L
Nominal / measured:
nominal
Conc. based on:
test mat.
Remarks:
but exposure is to hydrolysis products
Basis for effect:
mobility
Details on results:
- Mortality of control: 0
Reported statistics and error estimates:
No toxic effects were observed in the test media, the test results were therefore not subject to statistical analysis.
Validity criteria fulfilled:
yes
Conclusions:
A 48-hour EC50 value of >500 mg/l and NOEC of ≥500 mg/l have been determined for the effects of the test substance on mobility of Daphnia magna based on nominal concentration of the substance. However it is likely that the test organisms were primarily exposed to the hydrolysis products of the substance.
Endpoint:
short-term toxicity to aquatic invertebrates
Type of information:
experimental study
Adequacy of study:
supporting study
Study period:
not reported
Reliability:
4 (not assignable)
Rationale for reliability incl. deficiencies:
secondary literature
Remarks:
The result is sourced from secondary literature (company data). The original reference was not available for review and no further information is available.
GLP compliance:
not specified
Analytical monitoring:
not specified
Vehicle:
not specified
Test organisms (species):
Palaemonetes pugio
Test type:
static
Water media type:
saltwater
Limit test:
no
Total exposure duration:
48 h
Duration:
48 h
Dose descriptor:
LC50
Effect conc.:
58 mg/L
Nominal / measured:
not specified
Conc. based on:
not specified
Basis for effect:
mortality
Validity criteria fulfilled:
not specified
Conclusions:
A 48 h LC50 value of 58 mg/L has been determined for the effects of the test substance on mortality of Palemonetes pugio. It is likely that the test organisms were exposed to the hydrolysis products of the substance. The study was from a secondary source. As no further details of the test are available, the reliablility of the study could not be determined.
Endpoint:
short-term toxicity to aquatic invertebrates
Type of information:
experimental study
Adequacy of study:
supporting study
Reliability:
4 (not assignable)
Rationale for reliability incl. deficiencies:
secondary literature
Remarks:
The result is reported in a peer reviewed secondary source, however there is insufficient information to fully assess its reliability.
Principles of method if other than guideline:
No guideline specified.
Analytical monitoring:
no
Vehicle:
not specified
Test organisms (species):
Daphnia magna
Test type:
not specified
Water media type:
not specified
Duration:
48 h
Dose descriptor:
EC50
Effect conc.:
> 1 000 mg/L
Nominal / measured:
not specified
Conc. based on:
test mat.
Remarks:
but exposure is to hydrolysis products
Basis for effect:
mobility
Conclusions:
An EC50 value of >1000 mg/L has been reported for the test substance to Daphnia magna. The result is reported in a peer reviewed secondary source. It is likely that the test organisms were exposed to the hydrolysis products of the substance.
Endpoint:
short-term toxicity to aquatic invertebrates
Type of information:
calculation (if not (Q)SAR)
Remarks:
Migrated phrase: estimated by calculation
Adequacy of study:
supporting study
Reliability:
2 (reliable with restrictions)
Rationale for reliability incl. deficiencies:
other: The result was obtained by an appropriate predictive method.
Principles of method if other than guideline:
The ECOSAR ‘neutral organics’ QSARs for acute data have been applied and the effect concentrations calculated using log Kow and molar mass as input variables. An additional factor of *0.2 has been applied to the results.

The USEPA model ECOSAR was used as the basis for the estimation. This method is well-validated for ‘neutral organics’, i.e. those which act by a general narcotic mechanism, the potency of which is usually related to log Kow. Its scope is acute and long-term effects for the three standard trophic levels.

The method was validated for use with organosilicon compounds with a high weight percent of Si and limited or no additional functionality. Many of the reliable data for the category are limit values, therefore, the data were considered in terms of the range of the E(L)C 50, in accordance with normal classification bands:    

E(L)C50 < 1 mg/l;
E(L)C50 in the range > 1 mg/l to 10 mg/l;
E(L)C50 in the range > 10 mg/l to 100 mg/l;
E(L)C50 > 100 mg/l.

In general ECOSAR predicted correctly for most substances for each trophic level. However, performance was improved significantly by application of a factor of 0.2 to each predicted value (expressed in mg/l). The organosilicon substances are slightly more toxic than the general ECOSAR ‘neutral organics’ regression lines, although still well within the range of each model. The factor of 0.2 is applicable to fish,Daphniaand algae, across the whole range of log Kowvalues. It is concluded that the acute effects of the substances in the sub-category can therefore be predicted from ECOSAR, with a minor modification.
Duration:
48 h
Dose descriptor:
LC50
Effect conc.:
29 600 mg/L
Conclusions:
A 48 h LC50 value of 29600 mg/L was obtained for the hydrolysis product of the submission substance using an appropriate calculation method. The results are considered to be reliable.

Description of key information

(48-hour) EC50: >500 mg/l mobility Daphnia magna, reliability 1
(48-hour) LC50: 29600 mg/l mortality, hydrolysis product (using an appropriate calculation method), reliability 2

Key value for chemical safety assessment

Additional information

A 48-hour EC50 value of >500 mg/l and NOEC of ≥500 mg/l have been determined for the effects of the test substance on mobility of Daphnia magna based on nominal concentration of the substance. The study was conducted according to a standard guideline (EU Method C.2, Acute Toxicity for Daphnia) and GLP and was selected as key study (1994). Two other results are available from secondary literature and therefore of lower reliability; an EC50 value of >1000 mg/l for Daphnia magna and an LC50 value of 58 mg/l for Palaemonetes pugio (marine species) were reported.

As the substance hydrolyses rapidly (half-life approximately 5.5 hours), it is very likely that the test organisms were primarily exposed to the hydrolysis product, methylsilanetriol, retained in the test media. An LC50 of 29600 mg/l was derived for the hydrolysis product using an appropriate calculation method (2011).