(3-chloropropyl)triethoxysilane

Long-term toxicity to aquatic invertebrates

Link to relevant study record(s)

Reference

Endpoint:

long-term toxicity to aquatic invertebrates

Type of information:

experimental study

Adequacy of study:

key study

Study period:

1994-10-07 to 1994-10-28

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

guideline study

Qualifier:

according to guideline

Guideline:

other: OECD Guideline 202, Part II

GLP compliance:

yes (incl. QA statement)

Analytical monitoring:

yes

Details on sampling:

Samples of the test media without algae or Daphnia were taken for analysis on days 0, 3, 5, 7, 10, 12, 14, 17 and 19.

Samples of old test media, that had contained algae and daphnia were taken for analysis on days 3, 5, 7, 9, 10, 12, 14, 17, 19 and 21.

Vehicle:

no

Details on test solutions:

A stock solution of the test substance was prepared in Elendt M4 medium at a nominal concentration of 1000 mg/L by mixing for 18 hours followed by filtration. Further treatments were prepared by dilution of the stock solution.

Test organisms (species):

Daphnia magna

Details on test organisms:

TEST ORGANISM

- Common name: Daphnia magna

- Strain: Clone 5

- Source: Stock culture

- Age at study initiation (mean and range, SD): <24 h

- Method of breeding: Parthenogenetic reproduction

- Feeding during test: The daphnids were fed with algae (Scenedesmus subspicatus) at the rate of 0.7x10E7 cells/daphnid per day from days 0-6 and then at the rate of 1.0x10E7 cells/daphnid per day from days 7-21.


ACCLIMATION

- Acclimation conditions: same as test

- Type and amount of food: sufficient to be consumed each day leaving no residue

- Feeding frequency: daily

Test type:

semi-static

Water media type:

freshwater

Limit test:

no

Total exposure duration:

21 d

Hardness:

The Elendt M4 medium contained 222 mg/L of CaCl2, 114 mg/L of MgSO46H2O and 64 mg/L of NaHC03

Test temperature:

20-23ºC

pH:

7.8-8.2

Dissolved oxygen:

94-99% ASV

Salinity:

Not applicable

Nominal and measured concentrations:

Nominal concentrations: 0 (Control), 12, 20, 35, 60 and 100 mg/L

Measured DOC concentrations in fresh test media that did not contain algae or daphnia were within 20% of nominal.

Measured concentrations in old test media that had contained algae and daphnia were significantly lower than nominal.

The test results are interpreted with reference to the nominal concentrations.

Details on test conditions:

TEST SYSTEM

- Test vessel: 150 mL glass beakers containing 80 mL of test medium.

- Aeration: none

- Renewal rate of test solution: semi-static, renewal every 2 or 3 days

- No. of organisms per vessel: 1

- No. of vessels per concentration (replicates): 10

- No. of vessels per control (replicates): 10

- Biomass loading rate: 1 daphnid/80 mL of test medium


TEST MEDIUM / WATER PARAMETERS

- Source/preparation of dilution water: Elendt M4 medium

- Intervals of water quality measurement: At test medium renewal


OTHER TEST CONDITIONS

- Adjustment of pH: no

- Photoperiod: 19 h light, 8 h dark

- Light intensity: 600/100 lux


EFFECT PARAMETERS MEASURED (with observation intervals if applicable): Survival and reproduction on days of test medium renewal and at the end of the test.

VEHICLE CONTROL PERFORMED: yes

Reference substance (positive control):

no

Key result

Duration:

21 d

Dose descriptor:

NOEC

Effect conc.:

>= 100 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

other: reproduction and mortality

Key result

Duration:

21 d

Dose descriptor:

LOEC

Effect conc.:

> 100 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

other: reproduction and mortality

Key result

Duration:

21 d

Dose descriptor:

NOEC

Effect conc.:

>= 66 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Remarks:

as silanol hydrolysis product

Basis for effect:

other: reproduction and mortality

Reported statistics and error estimates:

Statistical methods not reported

Table 1. Test results

Nominal concentration (mg/L)	Mean measured concentration in fresh test media (mg/L)	Percentage mortality at end of test	Mean number of young per female at end of test (+/-SD)	Percentage difference in mean number of young relative to Control
0 (Control)	-	0	72 (+/-12)	-
12	11.3	10	77 (+/-14)	-8*
20	18.8	0	81 (+/-8)	-13*
35	33.5	0	66 (+/-16)	8**
60	56.0	0	70 (+/-22)	3**
100	93.5	0	68 (+/-26)	6**

*Higher than Control

**Not significantly different from Control

The test results have been recalculated as 66 mg/L by the reviewer in terms of the arithmetic mean measured concentration of the test substance. The resulting NOEC is =66 mg/L.

Validity criteria fulfilled:

yes

Conclusions:

A 21-day NOEC of =100 mg/L has been determined for the effects of the test substance on mortality and reproduction of Daphnia magna. The result has been reinterpreted by the reviewer in terms of the mean measured concentration of the test substance to give a NOEC of =66 mg/L.

Description of key information

21-day NOEC =100 mg/l (nominal) (OECD 202, Part II). The NOEC is equivalent to =66 mg/l when expressed in terms of the silanol hydrolysis product, (3-chloropropyl)silanetriol.  

Key value for chemical safety assessment

Fresh water invertebrates

Fresh water invertebrates

Dose descriptor:

NOEC

Effect concentration:

66 mg/L

Additional information

A 21-day NOEC value of =100 mg/l (nominal) (highest concentration tested) has been determined for the effects of the registration substance (3-chloropropyl)triethoxysilane (CAS 5089-70-3, EC 225-805-6) on the reproduction of Daphnia magna (Evonik, 1994). In view of the test media preparation method and exposure regime it is likely that the test organisms were exposed predominantly to the hydrolysis products of the tested substance. The nominal test concentrations are supported by DOC analysis. 

The results may be expressed in terms of concentration of the hydrolysis product, (3-chloropropyl)silanetriol by applying a molecular weight correction: (MW of silanol = 156.64 / MW of parent = 198.72) * =100 mg/l = =66 mg/l. This value is read across to (3-chloropropyl)silanetriol without further correction.  

 

Above a concentration of approximately 1000 mg/l, dimeric / oligomeric, cyclic or cross-linked condensation products could potentially form over time in the aqueous test media. There was no report of undissolved material (parent substance or precipitated products) indicated in the study report for this test. 

Refer to the discussion in the Section 6 endpoint summary (Section 7.0 of CSR) and IUCLID Section 13 for further discussion of the approach to chemical safety assessment for this registration substance, and justification for read-across used.