Reaction products of [3-(2,3-epoxypropoxy)propyl]trimethoxysilane and triacetoxyvinylsilane.

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:

November 12 1999 to April 12 2000

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:

yes

Remarks:

Adjustment of pH

Qualifier:

according to guideline

Guideline:

EU Method C.2 (Acute Toxicity for Daphnia)

GLP compliance:

yes (incl. QA statement)

Analytical monitoring:

yes

Details on sampling:

- Concentrations: 0, 100, 178, 317, 562 and 1000 ppm
- Sampling method: Two 50 ml aliquots were collected from each stock solution at 0 h (before addition of Daphnia) and 48 h (after removal of Daphnia) and one aliquot was collected from each test vessel at 48 h. The aliquots were transferred from the pipettes into 50 ml propylene centrifuge tubes with screw-on lids, for silicon analysis by ICP-OES
- Sample storage conditions before analysis: Not reported

Details on test solutions:

PREPARATION AND APPLICATION OF TEST SOLUTION
- Method: Test article was weighed into tared glass weighing caps which were added into 1 litre beakers containing 950 ml of aerated well water. An empty glass weighing cap was added into the control beaker. All solutions were then brought to to 1 litre volume and stirred briefly (~2 min). The solutions were then put in the environmental incubator to hydrolyse for ~ 4 hours. pH was then measured and adjusted to the approximate pH of the control using 1N NaOH. Solutions were then brought up to 1 litre again with well water and final pH measured. Test article was added to achieve nominal concentrations of 0, 100, 178, 317, 562 and 1000 ppm. Daphnia were added to the test vessels immediately after the test solutions were added to the test vessels.
- Controls: Well water without test article
- Evidence of undissolved material: None reported

Test organisms (species):

Daphnia magna

Details on test organisms:

TEST ORGANISM
- Common name: Daphnia magna
- Strain: Straus
- Source: In house cultures from an initial stock culture received from Aquatic Biosystems Inc., Fort Collins, Colorado, December 1997.
- Age at study initiation (mean and range, SD): Neonate < 24 hrs old
- Weight at study initiation (mean and range, SD): Not reported
- Length at study initiation (length definition, mean, range and SD): Not reported
- Valve height at study initiation, for shell deposition study (mean and range, SD): Not reported
- Peripheral shell growth removed prior to test initiation: Not reported
- Method of breeding: Not reported
- Feeding during test: None

ACCLIMATION
- Acclimation period: Test conditions same as culture conditions except the organisms were not fed during the tests and the test vessels were not aerated

- Type and amount of food: Ankistrodesmus convolutus Corda and yeast, Ceophyl and Trout chow (YCT).
- Feeding frequency: Three to four times per week.
- Health during acclimation: Only adult daphnia cultures >12 d old, free of ephippia and having <20% mortality during the previous 48 h were used as a source of neonates.

Test type:

static

Water media type:

freshwater

Limit test:

no

Total exposure duration:

48 h

Hardness:

Ca 19.7 mg/L, Mg 8.7 mg/L

Test temperature:

19.4 - 19.5 °C

pH:

8.1 - 8.3 at 0 h and 7.9 - 8.0 at 48 h

Dissolved oxygen:

8.6-8.7 at 0 h and 7.7-8.7 at 48 h (60 - 105 % saturation)

Salinity:

Sodium concentration 71.3 mg/L

Nominal and measured concentrations:

0, 100, 178, 317, 562, 1000 ppm nominal
0, 98.5, 178, 323, 567 and 986 ppm measured

Details on test conditions:

TEST SYSTEM
- Test vessel: 250 mL glass beakers
- Type: open / closed: Covered with a watch glass
- Material, size, headspace, fill volume: Glass, 250 mL containing 200 mL test solution
- Aeration: None
- Type of flow-through: Static
- Renewal rate of test solution (frequency/flow rate): Static
- No. of organisms per vessel: 9
- No. of vessels per concentration (replicates): 2
- No. of vessels per control (replicates): 2
- Biomass loading rate: Not reported

TEST MEDIUM / WATER PARAMETERS
- Source/preparation of dilution water: Well water obtained at 1809 Salzberg Rd, Bay Co. MI
- Total organic carbon: Not reported
- Particulate matter: Not reported
- Metals: Not reported
- Pesticides: Not reported
- Chlorine: Not reported
- Alkalinity: From weekly measurements of well water during culture and test period: 160-182 mg/L as CaCo3
- Ca/mg ratio: 1.4:1
- Conductivity: From weekly measurements of well water during culture and test period: 508-552 µmho/cm
- Culture medium different from test medium: No
- Intervals of water quality measurement: Temp, pH, dissolved oxygen and light recorded at 0 and 48 h.
No contaminants reported

OTHER TEST CONDITIONS
- Adjustment of pH: Yes
- Photoperiod: 16 h light, 8 h dark
- Light intensity: GE Cool White and Mod-U-Line E fluorescent lighting, intensity of 190-213 foot candles (2045-2293 lux).

EFFECT PARAMETERS MEASURED (with observation intervals if applicable) : Mortality at 0, 24 and 48 hours

TEST CONCENTRATIONS
- Spacing factor for test concentrations: 1.78

Duration:

48 h

Dose descriptor:

EC50

Effect conc.:

583 mg/L

Nominal / measured:

meas. (arithm. mean)

Conc. based on:

other: hydrolysis products according to the study authors

Basis for effect:

mobility

Remarks on result:

other: 95% CI 512-665 mg/l

Duration:

48 h

Dose descriptor:

NOEC

Effect conc.:

323 mg/L

Nominal / measured:

meas. (arithm. mean)

Conc. based on:

other: hydrolysis products according to the study authors

Basis for effect:

mobility

Remarks on result:

other: 95% CI 512-665 mg/l

Reported statistics and error estimates:

Trimmed Spearman Karber Method

Table 1: Test Substance Concentrations (mg/l) Measured During Daphnia Study

Loading Level (mg/l)	Time = 0 hrs		Time = 48 hrs
	Sample 1	Sample 2	Chamber 1	Chamber 2
100	97	96	100	101
178	174	174	182	182
316	318	316	327	331
562	565	565	568	571
1000	970	989	997	986

Table 2: Statistical Results

Time Period (hours)	NOEC (mg/l)	EC50 (mg/l)	95% Confidence Interval (mg/l)
0	986	>997	ND
24	567	933	ND
48	323	583	512 -665

*ND = Not determinable

Table 3: Test System Observations

Concentration mg/l	Test Vessel #	Observations*
		0 -h	24 -h	48 -h
Control 0 ppm	1	9 N	9 N	8 N, 1 D**
	2	9 N	9 N	9 N
98.5 ppm	3	9 N	9 N	9 N
	4	9 N	9 N	9 N
178 ppm	5	9 N	9 N	9 N
	6	9 N	9 N	9 N
323 ppm	7	9 N	9 N	9 N
	8	9 N	9 N	9 N
567 ppm	9	9 N	9 N	6 N, 3 D
	10	9 N	9 N	4 N, 5 D
986 ppm	11	9 N	6 N, 3 D	9 D
	12	9 N	2 N, 7 D	9 D

* Observations are coded as: N = Normal, D = Dead, M = Moribund

** One dead organism in control due to surface entrapment

Validity criteria fulfilled:

yes

Conclusions:

A 48-h EC50 value of 583 mg/L and a NOEC of 323 mg/L have been reported for the effects of the tested substance (CAS 154518-41-9) on mobility of Daphnia magna. It is likely that the test organisms were exposed to a mixture of the parent substance and hydrolysis products.

Description of key information

Short-term toxicity to invertebrates: 48 hour EC₅₀ 583 mg/l (measured (total Si), arithmetic mean) (OECD Guideline 202 (Daphnia sp. Acute Immobilisation Test)). It is not feasible to reinterpret this test result in terms of the silanol hydrolysis products (Dow Corning Corporation, 2000).

Key value for chemical safety assessment

Fresh water invertebrates

Fresh water invertebrates

Effect concentration:

583 mg/L

Additional information

A 48-h EC₅₀ value of 583 mg/l and NOEC of 323 mg/l (measured (based on total silicon), arithmetic mean) have been determined for the effects of Reaction mass of 3-(2,3-epoxypropoxy)propyltrimethoxysilane and triacetoxyvinylsilane (CAS 154518-41-9) on mortality of Daphnia magna. In view of the test media preparation method/exposure regime it is likely that the test organisms were exposed predominantly to the hydrolysis products of the tested substance. It is not feasible to reinterpret this test result in terms of the silanol hydrolysis products (Dow Corning Corporation, 2000).

The constituents of the registration substance hydrolyse rapidly (half-life <12 hours at pH 7 and 25°C) to [3-(2,3-epoxypropoxy)propyl]silanetriol, vinylsilanetriol, acetic acid/acetates and methanol.

Refer to the discussion in the Section 6 endpoint summary for further discussion of the approach to chemical safety assessment for this registration substance.