N-[3-(dimethoxymethylsilyl)propyl]ethylenediamine

Toxicity to soil macroorganisms except arthropods

Link to relevant study record(s)

Reference

Reference 1

Endpoint:

toxicity to soil macroorganisms except arthropods: short-term

Type of information:

experimental study

Adequacy of study:

key study

Study period:

2004-03-01 to 2004-04-02

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

guideline study

Remarks:

Guideline study. The study was conducted according to an appropriate OECD guideline, and in compliance with GLP, and was considered to be reliability 1 (reliable without restrictions). Read across to the registered substance is considered scientifically justified. Further information on read-across is given in the Aquatic toxicity endpoint summary.

Qualifier:

according to guideline

Guideline:

OECD Guideline 207 (Earthworm, Acute Toxicity Tests)

GLP compliance:

yes (incl. QA statement)

Analytical monitoring:

no

Vehicle:

yes

Details on preparation and application of test substrate:

The application solution for the highest test concentration was prepared by dissolving 13.900 g of the test substance completely in 50 ml of chloroform, resulting in a test item concentration of 278 mg/ml of chloroform. Aliquots of the application solution were diluted with chloroform to obtain the application solutions for the lower test concentrations: aliquots of 1.5, 2.67, 4.74 and 8.43 ml of the application solution of the highest test concentration were made up to 15 ml to obtain the application solutions of the nominal test concentrations of 100, 178, 316 and 562 mg/kg dry soil respectively.

For each test concentration, the volume of 10 ml of the corresponding application solution was applied to 50 g of sand in a mortar. The solvent was completely evaporated at room temperature under a hood for 30 minutes. The remainder (sand/test substance mixture) was intensively mixed by means of a pestle and then mixed in a roller for 30 minutes. The sand/test substance mixture was then divided into 10 g aliquots (corrected for the amount of test item applied to 10 g of sand) and filled into separate vials.

Immediately before the start of the test, aliquots of 10 g sand/test substance mixture were quantitatively incorporated into the four replicates of 546 g of artificial soil (dry weight) per test concentration by intense mixing in a laboratory mixer. The moisture content was brought to 35% by adding 186 ml of purified water.

A control was tested in parallel. The control was prepared in the same way as the treated soils. A 50 g sand portion was treated with 10 ml of chloroform (but without the test substance) in the same way as the application of the test substance in the treatment groups.

Test organisms (species):

Eisenia fetida

Animal group:

annelids

Details on test organisms:

The test organisms were obtained from breeding stock maintainedat RCC Laboratory. The worms are held in a temperature-controlled room and fed with suitable food (e.g. horse manure and potatoes).

For one day prior to the start of the test, the test oragnisms were acclimated to the artificial soil and the test temperature.

At the start of the test the mean body wet weight of the worms in the different treatment and control replicates ranged from 338 to 382 mg. The worms used were adults with a clitellum and were approximately 4 to 5 months old.

Study type:

laboratory study

Substrate type:

artificial soil

Limit test:

no

Total exposure duration:

14 d

Test temperature:

18.9 to 20.4°C

pH:

Initial pH: 6.2

pH at the end of the test: 5.5-6.3

Moisture:

Initial: 35%

At end of test: 33-34%

Details on test conditions:

TEST SYSTEM

- Test container (material, size): cylindrical glass vessels (10 cm diameter, 14 cm tall) with a volume of approximately 1 litre.

- Amount of soil or substrate: The test vessels were large enough to contain 556 g dry weight of artificial soil, corresponding to approximately 750 g wet weight.

- No. of organisms per container (treatment): 10

- No. of replicates per treatment group: 4

- No. of replicates per vehicle control: 4

SOURCE AND PROPERTIES OF SUBSTRATE (if soil)

- Type: artificial soil prepared in accordance with the test guideline

- Soil texture (if natural soil). The soil (air dry components without calcium carbonate) was prepared in a batch of 20 kg by intensely mixing the corresponding amounts of the constituents in a cement mixer.
- % sand: 70
- % peat: 10
- % clay: 20
- % calcium carbonate: 0.5%


OTHER TEST CONDITIONS

- Photoperiod: continuous

- Light intensity: 490-550 Lux

EFFECT PARAMETERS MEASURED (with observation intervals if applicable): mortality and any symptoms of toxicity were determined after 7 and 14 days. The wet weight of the worms (after washing) was measured at the start (individually) and end (all together from each test vessel) of the test.

VEHICLE CONTROL PERFORMED: yes

TEST CONCENTRATIONS

- Spacing factor for test concentrations: 1.8

Nominal and measured concentrations:

Nominal concentrations: 0 (Control), 100, 178, 316, 562 and 100 mg/kg dry weight

Reference substance (positive control):

no

Duration:

14 d

Dose descriptor:

LC50

Effect conc.:

> 1 000 mg/kg soil dw

Nominal / measured:

nominal

Conc. based on:

test mat.

Remarks:

but exposure will be to hydrolysis products

Basis for effect:

mortality

Duration:

14 d

Dose descriptor:

NOEC

Effect conc.:

>= 1 000 mg/kg soil dw

Nominal / measured:

nominal

Conc. based on:

test mat.

Remarks:

but exposure will be to hydrolysis products

Basis for effect:

mortality

Duration:

14 d

Dose descriptor:

NOEC

Effect conc.:

>= 1 000 mg/kg soil dw

Nominal / measured:

nominal

Conc. based on:

test mat.

Remarks:

but exposure will be to hydrolysis products

Basis for effect:

growth

Details on results:

- Mortality at end of exposure period: 0

Reported statistics and error estimates:

There were no effects on mortality and therefore an LC50 value could not be determined. The wet weights of the worms were analysed using a multiple Dunnett-test to determine whether there were any significant differences between treatments.

Table 1. Test results

 

Nominal test concentration (mg/kg dry weight)	Mean percentage mortality – Day 7	Mean percentage mortality – Day 14	Mean body weight per worm (+/-Std. Dev.) – Start of test	Mean body weight per worm (+/-Std. Dev.) – Day 14	Mean percentage decrease in body weight per worm over the test period
0 (Control)	0	0	362 (+/-15)	342 (+/-13)	-6
100	0	0	353 (+/-17)	353 (+/-17)	-7*
178	0	0	350 (+/-11)	317 (+/-10)	-9*
316	0	0	374 (+/-9)	348 (+/-5)	-7*
562	0	0	353 (+/-8)	324 (+/-11)	-8*
1000	0	0	348 (+/-12)	329 (+/-8)	-5*

*Mean decrease not significantly different to Control (p<0.05)

Validity criteria fulfilled:

yes

Conclusions:

A 14-day LC50 of >1000 mg/kg dry weight and NOEC of =1000 mg/kg dry weight have been determined for the effects of the test substance on mortality of Eisenia fetida. A NOEC of =1000 mg/kg dry weight has also been determined for effects on growth. It is likely that under the moist test conditions employed in the test that the test organisms were exposed to the hydrolysis products of the substance.

Reference 2

Endpoint:

toxicity to soil macroorganisms except arthropods: long-term

Type of information:

experimental study planned

Study period:

After approval by ECHA

Qualifier:

according to guideline

Guideline:

OECD Guideline 222 (Earthworm Reproduction Test (Eisenia fetida/Eisenia andrei))

Principles of method if other than guideline:

The study is to be conducted with the hydrolysis product of the registered substance, in view of its hydrolysis rate - see IUCLID Section 6.3, CSR Section 7.2, for further details of the risk assessment approach.
A tiered testing approach is proposed with the OECD 222 test to be conducted first in order to establish that stability and homogeneity is feasible for the earthworm study prior to conducting the OECD 208 plant test.

Reference 3

Endpoint:

toxicity to soil macroorganisms except arthropods: short-term

Type of information:

read-across from supporting substance (structural analogue or surrogate)

Adequacy of study:

key study

Justification for type of information:

See Ecotoxicological Information discussion in IUCLID, Section 7 of the CSR, for justification of read-across.

Reason / purpose for cross-reference:

read-across source

Duration:

14 d

Dose descriptor:

LC50

Effect conc.:

> 1 000 mg/kg soil dw

Nominal / measured:

nominal

Conc. based on:

test mat.

Remarks:

but exposure will be to hydrolysis products

Basis for effect:

mortality

Duration:

14 d

Dose descriptor:

NOEC

Effect conc.:

>= 1 000 mg/kg soil dw

Nominal / measured:

nominal

Conc. based on:

test mat.

Remarks:

but exposure will be to hydrolysis products

Basis for effect:

mortality

Duration:

14 d

Dose descriptor:

NOEC

Effect conc.:

>= 1 000 mg/kg soil dw

Nominal / measured:

nominal

Conc. based on:

test mat.

Remarks:

but exposure will be to hydrolysis products

Basis for effect:

growth

Description of key information

LC₅₀ (14-day): >1000 mg/kg dry weight, mortality, Eisenia foetida, read-across from CAS 1760-24-3 (RCC, 2004).

NOEC of =1000 mg/kg dry weight, mortality and growth, Eisenia foetida, read-across from CAS 1760-24-3 (RCC, 2004).

Additional information

A 14-day LC₅₀ of >1000 mg/kg dry weight and NOEC of =1000 mg/kg dry weight have been determined for the effects of the structurally analogous substance N-(3-(trimethoxysilyl)propyl)ethylenediamine on mortality of Eisenia foetida. A NOEC of =1000 mg/kg dry weight has also been determined for effects on growth. It is likely that under the moist test conditions employed in the test that the test organisms were exposed to the hydrolysis products of the test substance, N-(3-(trihydroxysilyl)propyl)ethylenediamine.

Further information on read-across is given in IUCLID Section 6 endpoint summary (CSR Section 7.0) and in the ecotoxicity RAAF attached in Section 13 of IUCLID.

The registration substance falls within soil hazard category 3 as defined in REACH R.7 (ECHA 2017); high persistence (DT₅₀ >180 days) but there is no indication that the substance is very toxic to aquatic organisms (E(L)C₅₀ <1 mg/l).

 

In this situation, a screening approach is applied: a confirmatory long-term terrestrial test in addition to the equilibrium partitioning approach with an extra factor of ten.

 

The PEC × 10 / PNECscreen based on the equilibrium partitioning method indicates the substance will have a risk characterisation ratio (RCR) >1. The highest terrestrial RCR based on PEC x 10 / PNEC is 4.69 related to deposition from air.

 

ECHA guidance Chapter R.7c, Table R.7.11—2 states the following (ECHA 2017): If PEC/PNECscreen > 1 or indication of risk from confirmatory long-term soil toxicity test: Conduct long-term toxicity tests according to the standard information requirements Annex X (invertebrates and plants), choose lowest value for derivation of PNECsoil.

 

A long-term toxicity to terrestrial invertebrates test in accordance with test guideline OECD 222 is therefore proposed. In view of the rapid hydrolysis rate of the registration substance, the relevant assessment entity is the silanol hydrolysis product N-[3-(dihydroxymethylsilyl)propyl]ethylenediamine. The parent substance should therefore be pre-hydrolysed prior to exposure of test organisms.

A tiered testing approach is proposed with the OECD 222 test to be conducted first in order to establish that stability and homogeneity is feasible for the earthworm study prior to conducting the plant test.

Details on how the PNEC and the risk characterisation ratio have been derived can be found in IUCLID Section 6.0, CSR Section 7, and Chapters 9 and 10 of the Chemical Safety Report, respectively.