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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:
1999-09-21 to 1999-12-15
Reliability:
1 (reliable without restriction)
Rationale for reliability incl. deficiencies:
guideline study
Qualifier:
according to
Guideline:
OECD Guideline 202 (Daphnia sp. Acute Immobilisation Test)
Deviations:
no
Qualifier:
according to
Guideline:
EU Method C.2 (Acute Toxicity for Daphnia)
Deviations:
no
Qualifier:
according to
Guideline:
ISO 6341 (Water quality - Determination of the Inhibition of the Mobility of Daphnia magna Straus (Cladocera, Crustacea))
Deviations:
no
GLP compliance:
yes
Analytical monitoring:
yes
Details on sampling:
- Concentrations: Control and 100 mg/l (nominal)
- Sampling method: A 10 ml sample of test medium was taken from the approximate centre of the test vessels at the start and end of the test and analysed on the same day.
Vehicle:
no
Details on test solutions:
PREPARATION AND APPLICATION OF TEST SOLUTION (especially for difficult test substances)
- Method: The test media were prepared by direct addition of the substance to the dilution water followed by a short period of stirring with a magnetic stirrer to accelerate dispersion and solution. The resulting test media were clear and colourless.
- Controls: Dilution water
Test organisms (species):
Daphnia magna
Details on test organisms:
TEST ORGANISM
- Common name: water flea
- Strain: Straus, 1820
- Source: Laboratory stock culture
- Age at study initiation (mean and range, SD): <24 hours
- Feeding during test: none

ACCLIMATION
- Type and amount of food: Freshwater algae
- Feeding frequency: Daily
Test type:
static
Water media type:
freshwater
Limit test:
yes
Total exposure duration:
48 h
Hardness:
250 mg/l as CaCO3
Test temperature:
20.1 - 20.5ºC
pH:
7.7 - 8.0
Dissolved oxygen:
8.7 - 9.1
Nominal and measured concentrations:
Nominal Concentrations: 0(Contol) and 100 mg/l
Analysis of samples taken at the start of the test showed that the concentration based on component M2 was in agreement with nominal (93%). The concentrations of components M3 and M4 were 89 and 78% of nominal. After 48 hours the concentrations of components M2 and M3 had declined by 92 and 99% and component M4 could not be detected.
Details on test conditions:
TEST SYSTEM
- Test vessel:
- Material, size, headspace, fill volume: glass, 100 ml with 80 ml of test medium
- Aeration: none
- Renewal rate of test solution (frequency/flow rate): static
- No. of organisms per vessel: 10
- No. of vessels per concentration (replicates): 2
- No. of vessels per control (replicates): 2

TEST MEDIUM / WATER PARAMETERS
- Source/preparation of dilution water: ISO standard medium prepared with milli-RO water
- Intervals of water quality measurement: Start and end of the test

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

EFFECT PARAMETERS MEASURED (with observation intervals if applicable): Mobility after 24 and 48 hours

TEST CONCENTRATIONS
- Spacing factor for test concentrations: limit test
- Justification for using less concentrations than requested by guideline: range-finding test
- Range finding study
- Test concentrations: 0(Control) and 100 mg/l
- Results used to determine the conditions for the definitive study: no effects at 100 mg/l
Reference substance (positive control):
yes
Remarks:
potassium dichromate
Duration:
48 h
Dose descriptor:
EC50
Effect conc.:
> 100 mg/L
Nominal / measured:
nominal
Conc. based on:
test mat.
Basis for effect:
mobility
Duration:
48 h
Dose descriptor:
NOEC
Effect conc.:
>= 100 mg/L
Nominal / measured:
nominal
Conc. based on:
test mat.
Basis for effect:
mobility
Details on results:
- Mortality of control: 0
Results with reference substance (positive control):
- Results with reference substance valid? yes
- 48 h EC50: 0.56-1.0 mg/l
Reported statistics and error estimates:
Limit test and therefore no statistical analysis required

The project started with a pilot test with daphnia exposed to 100 mg/l in a static system but without analytical support. Exposure for 48 hours to 100 mg/l induced no effects on the mobility of the daphnids. Thereafter, a limit test was performed with daphnia exposed to 100 mg/l and a blank-control in a static system and samples for analysis of actual exposure concentrations were taken at the start and the end of the limit test.

Quantitative analyses were based on the three major components (NOTOX identification M2, M3 and M4) in A-1160 (methanol stripped). Analysis of the samples taken during the limits test showed that the concentration based on component M2 was in agreement with nominal at the start of the test period (93%). Concentrations based on components M3 and M4 were significantly below nominal at 89% and 78% of nominal, respectively. All three components degraded rather rapidly with degradation of M4>M3>>M2. Within 48 hours of exposure the concentration of M2 had decreased by 92%, the concentration of M3 by 99%, and the concentration of M4 had totally disappeared.

No immobility occurred during the 48-hour test period. Hence, the 48h-EC50daphnia exposed to A-1160 (methanol stripped) was > 100 mg/l in static system. The high rate of hydrolytic degradation of the three components indicated little relevance for testing in a semi-static or flow-through system. Instead, the assessment of the toxic potential of exposure of daphnia to A-1160 (methanol stripped) was considered to be more realistic when exposure to degradation products was included.

The result is considered to be reliable. The test organisms were exposed primarily to the hydrolysis products of the substance.

Validity criteria fulfilled:
yes
Conclusions:
A test mediaum prepared at a nominal concentration of 100 mg/l of ureidopropyltrialkoxysilane, mixed methoxy and ethoxy esters (CAS No. 119612-64-2) was not acutely toxic to Daphnia magna over 48 hours. The result is considered to be reliable. The test organisms were exposed primarily to the hydrolysis products of the substance.
Executive summary:

In an invertebrate acute toxicity study in which Daphnia magna were exposed to A-1160 (methanol stripped), no mortality occured at the limit concentration of 100 mg/L. The result is considered to be reliable. The test organisms were exposed primarily to the hydrolysis products of the substance.

Endpoint:
short-term toxicity to aquatic invertebrates
Type of information:
read-across from supporting substance (structural analogue or surrogate)
Adequacy of study:
key study
Justification for type of information:
Please refer to the attached justification below and the overall justification for grouping of substances attached in IUCLID Section 13.
Reason / purpose:
read-across source
Duration:
48 h
Dose descriptor:
EC50
Effect conc.:
> 100 mg/L
Nominal / measured:
nominal
Conc. based on:
test mat.
Basis for effect:
mobility

Description of key information

EC50 (48h) > 100 mg/L (nominal, OECD 202) based on read across from CAS 116912-64-2

Key value for chemical safety assessment

Additional information

No reliable data on the toxicity of [3-(trimethoxysilyl)propyl]urea (CAS 23843-64-3) to aquatic invertebrates are available. Therefore, good quality data from the analogous substance, Ureidopropyltrialkoxysilane, mixed methoxy and ethoxy esters (CAS 116912-64-2), have been read across. Details on read across justifications can be found in the attached justification in the respective target entry and in the overall justification for grouping of substances attached in IUCLID Section 13.

 

In a study (2000) according to the guideline OECD 202 and GLP standards, the short term toxicity of the read across substance ureidopropyltrialkoxysilane, mixed methoxy and ethoxy esters (CAS 116912-64-2) to aquatic invertebrates was tested. Daphnia magna as the test organism was exposed under static conditions for 48 h to a single nominal test item concentration of 100 mg/L and a blank control. The substance was analytically monitored and samples were collected at the beginning and at the end of the experiment. The substance degraded rapidly within 48 h due to hydrolysis. No toxic effects were observed in the study resulting in an EC50 (48 h) of > 100 mg/L (nominal). The substance was tested in a static system due to its high rate of hydrolytical degradation. With a static system an exposure to both the parent and the hydrolysis products was achieved while none caused toxic effects to fish. The result is considered to be reliable.

 

No toxic effects to aquatic invertebrates are expected by [3-(trimethoxysilyl)propyl]urea (CAS 23843-64-3) based on the results obtained for the read across substance.