3-chloropropyltrimethoxysilane

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:

1993-05-25 to 1993-05-27

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:

1982

GLP compliance:

yes

Analytical monitoring:

yes

Details on sampling:

The dissolved organic carbon analysis (DOC) concentration of the stock solution used to prepare the test media was determined and used as the basis for setting the treatment levels.

Vehicle:

no

Details on test solutions:

PREPARATION AND APPLICATION OF TEST SOLUTION

- Method:The test substance was dissolved at 1 g/l in VE water and stirred for 18 h. The resulting stock solution was filtered and served as the initial solution for testing. 

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: None

ACCLIMATION

- Acclimation conditions (same as test or not): yes

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

- Feeding frequency: daily

Test type:

static

Water media type:

freshwater

Limit test:

no

Total exposure duration:

48 h

Hardness:

synthetic freshwater: ratio Ca2+ : Mg2+ = 4 : 1 Na+ : K+ = 10 : 1 (CaCl2.2H2O = 294 mg/L, MgSO4.7H2O = 123 mg/L, NaHCO3 = 63 mg/L, KCl = 5.5 mg/L)

Test temperature:

20±1ºC

pH:

7.4-7.5 at end of test

Dissolved oxygen:

6.9-8.2 mg/L at end of test

Salinity:

Not applicable

Nominal and measured concentrations:

The DOC content of the stock solution was determined to be 378.5 mg/l, corresponding to a test material concentration of 1046 mg/l.

Nominal concentrations based on DOC measured concentration in the stock solution: 0 (Control), 115, 167, 230, 335, 471, 669 and 941 mg/L

Details on test conditions:

TEST SYSTEM

The test vessels were glass cylinders graduated to 10 ml. 

Each concentration had 4 replicate vessels and each vessel contained 5 test organisms.  

The age of the test organisms was <24 hours and they were not fed during the test. 

Vessels were kept in the dark at 20ºC and not aerated during the  test.

The Daphnia were observed for immobilization after 24 and 48 hours of exposure.  

The synthetic water used for the study had the following components: CaCl2 x 2 H20 = 294 mg/l MgSO4 x 7 H20 = 123 mg/l NaHCO3 = 63 mg/l KCl = 5.5 mg/l

Reference substance (positive control):

yes

Remarks:

Potassium dichromate.

Key result

Duration:

48 h

Dose descriptor:

NOEC

Effect conc.:

669 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

mobility

Key result

Duration:

48 h

Dose descriptor:

EC50

Effect conc.:

869 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

mobility

Key result

Duration:

48 h

Dose descriptor:

EC100

Effect conc.:

> 941 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

mobility

Key result

Duration:

24 h

Dose descriptor:

EC50

Effect conc.:

> 941 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

mobility

Details on results:

- Immobilisation of control: 0

Results with reference substance (positive control):

EC50: >0.9, <1.9 mg/L

Reported statistics and error estimates:

The EC50 value was determined by Probit analysis. TheNOEC was determined by visual examination of the raw data.

Immobile organisms were observed only at the test substance concentration of 941 mg/l:

Concentration	24 hour			48 hour
	Mobile	Immobile	%	Mobile	Immobile	%
Control	20	0	0	20	0	0
115	20	0	0	20	0	0
167	20	0	0	20	0	0
230	20	0	0	20	0	0
335	20	0	0	20	0	0
471	20	0	0	20	0	0
669	20	0	0	20	0	0
941	19	1	5	7	13	65

Oxygen content and pH at the end of the test:
conc (mg/l)  O2 (mg/L)          pH
Control (0)       8.2                7.5
115                7.3                 7.5
167                7.2                 7.4
230                7.1                 7.4
335                6.9                 7.4
471                7.2                 7.4
669                7.4                 7.4
941                6.9                 7.4

Validity criteria fulfilled:

yes

Conclusions:

A 48-hour EC50 value of 869 mg/L and a NOEC of 669 mg/L have been determined for the effects of the test substance on mobility of Daphnia magna. It is likely that the test organisms were exposed to the hydrolysis products of the substance.

Description of key information

48-hour EC₅₀ 869 mg/l (measured based on DOC in the stock solution) (OECD guideline 202). The observations in this study are attributed to the exposure of test organisms to the silanol hydrolysis product, (3-chloropropyl)silanetriol, in the test system. The EC₅₀ is equivalent to 685 mg/l when expressed in terms of the silanol hydrolysis product.

Key value for chemical safety assessment

Fresh water invertebrates

Fresh water invertebrates

Effect concentration:

685 mg/L

Additional information

A 48-hour EC₅₀ value of 869 mg/l (measured) has been determined for the effects of the registered substance (3-chloropropyl)trimethoxysilane (CAS 2530-87-2) on mobility of Daphnia magna (Hüls, 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 of the stock solution. The results may be expressed in terms of concentration of the silanol hydrolysis product, (3-chloropropyl)silanetriol, by applying a molecular weight correction: (MW of silanol = 156.64 / MW of parent = 198.72) * 869 mg/l = EC₅₀ 685 mg/l.

 

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 mention of undissolved material (parent substance or precipitated products) in the study report for this test. 

In a supporting short-term toxicity to aquatic invertebrates test, conducted according to OECD TG 202 and in compliance with GLP, a 48 hour NOEC and EC₁₀ were concluded to be 4.64 and 10 mg/l respectively, and an EC₅₀ >100 mg/l, based on the mobility of Daphnia magna.

The measured concentrations at the start and after 48-hours were below 70% (in the first set) and 60% (in the second test set) of the nominal concentrations. This depended on undissolved test substance or water-insoluble condensation products, respectively. The undissolved test substance or water-insoluble condensation products tend to adsorb on the surface of the glass vessels used and were not detected by the DOC-method. Although not dissolved, the test substance was available in the stock solution of the nominal concentration of 100 mg/L. Because the reported DOC measurements are below the limit of quantitation, the reported biological results are related to the nominal concentrations. Due to the presence of undissolved test materials and DOC recoveries below the limit of quantitation, the results should be treated with caution (LPT, 2003).

Refer to the discussion in the Section 6 endpoint summary (Section 7.0 of CSR) for further discussion of the approach to chemical safety assessment for this registration substance.