Carbamic acid, N-[(dimethoxymethylsilyl)methyl]-, methyl ester

Endpoint summary

Description of key information

Methyl-N-{[dimethoxy(methyl)silyl]methyl}carbamate (CAS 23432 -65 -7) and its hydrolysis products are not harmful to aquatic organisms.

Additional information

The registered substance methyl-N-{[dimethoxy(methyl)silyl]methyl}carbamate (CAS 23432 -65 -7) hydrolyses rapidly in contact with water (DT50 = 1.9 h at pH 7 and 20 – 25 °C, QSAR) to methyl-N-{[dihydroxy(methyl)silyl]methyl}carbamate and methanol. 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.

Data for the acute aquatic toxicity of the target substance methyl-N-{[dimethoxy(methyl)silyl]methyl}carbamate (CAS 23432 -65 -7) is available for all three trophic levels (fish, aquatic invertebrates, algae). Due to the duration and exposure scenario of the performed short-term toxicity studies (static set-up) and the rapid hydrolyses of the parent substance, it can be assumed that the organisms were mainly exposed to the hydrolysis products. All studies were performed according to accepted standard guidelines and GLP. No acute effects (LC/EC50 values) were observed towards the tested organisms of all three trophic levels up to a concentration of 100 mg/L.

The second hydrolysis product methanol 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 methanol are in excess of 1000 mg/l (OECD SIDS, 2004). Thus, methanol is not considered to contribute to the overall aquatic toxicity of the parent substance.

Table: Overview on aquatic effect values for methyl-N-{[dimethoxy(methyl)silyl]methyl}carbamate (CAS 23432 -65 -7) and its hydrolysis products.

	Parent	Silanol hydrolysis product	Other hydrolysis product
CAS	23432 -65 -7		67-56-1
	methyl-N-{[dimethoxy(methyl)silyl]methyl}carbamate	methyl-N-{[dihydroxy(methyl)silyl]methyl}carbamate	Methanol
Acute fish (LC 50)	> 100 mg/L	See parent	> 15000 mg/L*
Acute invertebrates (EC50)	> 100 mg/L	See parent	> 10000 mg/L*
Algae (ErC50)	117.42 mg/L	See parent	ca. 22000 mg/L*
Algae (NOErC)	33.5 mg/L	See parent	No data

* Source: OECD SIDS (2004)

 

No effects on activated sludge microorganisms were recorded up to a concentration of 1000 mg/L with the parent substance methyl-N-{[dimethoxy(methyl)silyl]methyl}carbamate (CAS 23432 -65 -7). The EC50 (3 h) was found to be > 1000 mg/L. On this basis, no toxic effects are anticipated by the parent substance and the degradation process in sewage treatment plants is not considered to be inhibited.

References:

OECD SIDS, 2004: SIDS Initial Assessment Report for Methanol, SIAM 19, Berlin, Germany, 19-22 October 2004, Methanol, CAS 67-56-1