Registration Dossier

Ecotoxicological information

Endpoint summary

Administrative data

Description of key information

Additional information

There are no reliable data for toxicity of the registration substance to aquatic organisms. The methoxysilane functional groups of 3-(trimethoxysilyl)propylamine (CAS 13822-56-5) undergo a rapid hydrolysis reaction (half-life 2.6 hours at pH 7) to form the hydrolysis product 3-aminopropylsilanetriol.

Reliable short-term toxicity tests results are available with the structural analogue 3-aminopropyltriethoxysilane (CAS 919-30-2) which also hydrolyses to form 3-aminopropylsilanetriol, and an analogous isocyanatopropyl trialkoxysilane, 3-(trimethoxysilyl)propyl isocyanate (CAS 15396-00-6), which undergoes a very rapid hydrolysis reaction (half-life <1 minute at pH 7) to form the registration substance as an intermediate hydrolysis product, with subsequent rapid hydrolysis to 3-aminopropylsilanetriol. Both of these substances are relevant surrogate substances; for read-across justification, please refer to the discussion of ecotoxicological information.

 

Reliable short-term toxicity tests conducted with 3-aminopropyltriethoxysilane (CAS 919-30-2) are available for species of freshwater fish (Brachydanio rerio), freshwater invertebrate (Daphnia magna) and fresh and marine water algae (Scenedesmus subspicatus and Skeletonema costatum) and are taken as key or weight of evidence data.

The hydrolysis rate of 3-aminopropyltriethoxysilane (CAS 919-30-2) (half-life 8.5 hours at pH 7 and 20-25 °C) and test media preparation methods and pH values mean it is likely that the test organisms in each test were exposed primarily to the hydrolysis products, 3-aminopropylsilanetriol and ethanol.

The relevant short term values are:

Fish: LC50 (96 h): >934 mg/l or >579 mg/l expressed in terms of concentration of the hydrolysis product, 3-aminopropylsilanetriol.

Daphnia: EC50 (48 h): 331 mg/l or 205 mg/l expressed in terms of concentration of the hydrolysis product, 3-aminopropylsilanetriol.

Algae: Freshwater: ErC50 (72 h): >1000 mg/l or >620 mg/l expressed in terms of concentration of the hydrolysis product, 3-aminopropylsilanetriol; ErC10 321 mg/l or 199 mg/l expressed in terms of concentration of the hydrolysis product, 3-aminopropylsilanetriol.

Marinewater: ErC50 (72 h): 863 mg/l, or 535 mg/l expressed in terms of concentration of the hydrolysis product, 3-aminopropylsilanetriol; NOEC for growth rate 40 mg/l or 25 mg/l, expressed in terms of concentration of the hydrolysis product, 3-aminopropylsilanetriol.

 

Reliable short-term toxicity tests conducted with 3-(trimethoxysilyl)propyl isocyanate (CAS 15396-00-6) are available for species of freshwater fish (rainbow trout) and invertebrate (Daphnia magna). L(E)C50 or EC50 values for the two organisms were >100 and >100 mg/L respectively. These limit values are taken as supporting data.

The test substance is susceptible to rapid hydrolysis and it is therefore likely that the test organisms were primarily exposed to the hydrolysis products of the substance.

 

A reliable long-term toxicity to aquatic invertebrates result is available for a structural analogue of the registration substance, N-(3-(trimethoxysilyl)propyl)ethylenediamine (CAS 1760-24-3).

The relevant results are: 21-day NOEC of =1 mg/l based on survival and reproduction of Daphnia magna. The hydrolysis half-lives of the registration substance and N-(3-(trimethoxysilyl)propyl)ethylenediamine indicate that, under conditions relevant to ecotoxicity assessment, both will hydrolyse to similar hydrolysis products 3-aminopropylsilanetriol and N-(3-(trihydroxysilyl)propyl)ethylenediamine, respectively, over the course of the test. The result is therefore equivalent to =0.8 mg/l when expressed in terms of silanol hydrolysis product.

 

Data waivers are applicable to long-term toxicity data for fish.

 

Refer to IUCLID Section 6 endpoint summary (CSR Section 7.0) for further discussion of the approach to chemical safety assessment and justification for read across.

There are no reliable data for toxicity of the registration substance to activated sludge microorganisms. A study of Pseudomonas putida respiration inhibition, resulting in a 5.75 hour EC50 of 43 mg/L and EC10 of 13 mg/L for effects on sewage treatment microorganisms, has been read-across from an analogous substance (3-aminopropyltriethoxysilane, CAS 919-30-2).