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Long-term toxicity to aquatic invertebrates

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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:
meas. (arithm. mean)
Conc. based on:
test mat.
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

Daphnia: 21-day NOEC ≥100 mg/l, effects on mortality and reproduction of Daphnia magna, read across from (3-chloropropyl)triethoxysilane (CAS 5089-70-3).

Key value for chemical safety assessment

Additional information

No long term toxicity to aquatic invertebrates data are available with the registration substance (3-chloropropyl)trimethoxysilane (CAS 2530-87-2).

Data have been read across from the analogous substance (3-chloropropyl)triethoxysilane (CAS 5089-70-3). Both substances hydrolyse to the same hydrolysis product (3-chloropropyl)silanetriol. Although the hydrolysis half-life of (3-chloropropyl)triethoxysilane (CAS 5089-70-3) (35 hours at pH 7 and 20°C) is slower than that of the registration substance (4.5 hours at pH 7 and 20°C), the test solution preparation time (18 hours stirring) and pH (pH 7.8-8.2) indicate that the organisms would have been exposed to a mixture of the parent substance and the hydrolysis products (3-chloropropyl)silanetriol and ethanol.

A 21-day NOEC of ≥100 mg/l (nominal concentration) (highest concentration tested) has been determined for the effects of the read-across substance, (3-chloropropyl)triethoxysilane (CAS 5089-70-3), on mortality and reproduction of Daphnia magna (Hüls 1994), in accordance with OECD Guideline 202 Part II and in compliance with GLP.

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 = 240.8) * ≥100 mg/ = ≥65 mg/l.