Bis(triethoxysilylpropyl)amine

Endpoint summary

Additional information

The registered substance 3-(triethoxysilyl)-N-[3-(triethoxysilyl)propyl]-1-propanamine (CAS 13497-18-2) hydrolyses rapidly in contact with water (DT50 = 11.9 h at pH 7 and 20 °C, OECD 111) to 3-(trihydroxysilyl)-N-[3-(hydroxysilyl)propyl]-1-propanamine and ethanol. REACH guidance R.16 states that “for substances where hydrolytic DT50 is less than 12 h, environmental effects are likely to be attributed to the hydrolysis product rather than to the parent itself” (ECHA, 2016). TGD (EC, 2003) and REACH guidance R.16 (ECHA, 2016) also suggest that when the hydrolysis half-life is less than 12 h, the breakdown products, rather than the parent substance, should be evaluated for aquatic toxicity testing.

Short-term toxicity data of the three trophic levels (fish, aquatic invertebrates, algae) is available for the registered compound testing saltwater species. Due to the fast hydrolysis time (DT50 = 11.9 h at pH 7 and 20 °C) of the parent compound and the duration of the acute tests (48 to 96 hours), it is likely that the organisms were predominantly exposed to the hydrolysis products. The second hydrolysis product ethanol is well characterised in the public domain literature and is not hazardous at the concentrations relevant to the studies. The short-term EC50 and LC50 values for ethanol are in excess of 1000 mg/l (OECD SIDS, 2004). Thus, ethanol is not considered to contribute to the overall aquatic toxicity of the target substance. In consequence, data for ethanol are not presented specifically for each environmental toxicity endpoint within this dossier.

  

All aquatic studies were performed according to accepted standard guidelines and GLP criteria. No acute effects were observed towards marine fish and marine invertebrates up to the highest tested concentrations. Marine algae were the most sensitive species with an ErC50 (72 h) of 125 mg/L.

 

Table: Overview on aquatic effect values for 3-(triethoxysilyl)-N-[3-(triethoxysilyl)propyl]-1-propanamine and its hydrolysis products.

	Parent	Silanol hydrolysis product	Other hydrolysis product^a
CAS	13497-18-2	Not available	64-17-5
	3-(triethoxysilyl)-N-[3-(triethoxysilyl)propyl]-1-propanamine	3-(trihydroxysilyl)-N-[3-(hydroxysilyl)propyl]-1-propanamine	Ethanol
Acute fish (LC50)	> 200 mg/L	See parent	> 1100 mg/L
Acute Invertebrates (EC50)	> 151.9 mg/L	See parent	12340 mg/L
Algae (ErC50)	125 mg/L	See parent	10000 mg/L*
Algae (ErC10)	68 mg/L	See parent	No data

* 96-h EC50 for Selenastrum capricornumtum also known as Pseudokirchneriella subcapitata;^aSource = OECD SIDS (2004)

 

For the assessment of toxicity to activated sludge microorganism read-across to 3-(trimethoxysilyl)-N-[3-(trimethoxysilyl)propyl]-1-propanamine (CAS No. 82985-35-1) was performed. Additional information is given in the analogue justification attached to IUCLID chapter 13.2.

The study resulted in an EC10 (3 h) of 270 mg/L (nominal) and an EC50 (3 h) of 1000 mg/L. On this basis, no toxic effects are anticipated by the target substance and the degradation process in sewage treatment plants is not considered to be inhibited.

 

References:

OECD SIDS (2004): SIDS Initial Assessment Report for SIAM 19, Berlin, Germany, 19-22 October 2004, Ethanol, CAS 64-17-5.