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Ecotoxicological information

Toxicity to aquatic algae and cyanobacteria

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Description of key information

The lowest  72-hour EC50 (118 mg/L) has been determined for the effects of read-across substance dimethylsilanediol (CAS No. 1066-42-8) on growth rate of Pseudokirchnerella subcapitata.  This study is considered to be reliable without restrictions and, therefore, may be used to conclude that dimethylsilanediol and dichloro(dimethyl)silane are not acutely toxic to algae.  Dichloro(dimethyl)silane makes up 20 - 35% of MS-Silane and it is used to read-across to all constituents of MS-Silane.

Key value for chemical safety assessment

EC50 for freshwater algae:
118 mg/L

Additional information

No data for toxicity to aquatic algae and cyanobacteria are available for MS-Silane. However a study on toxicity to algae is available for the hydrolysis product of dichloro(dimethyl) silane (CAS No. 75-78-5). Dichloro(dimethyl) silane hydrolyses to dimethylsilanediol (CAS No. 1066-42-8). Data are also available for trimethylsilanol (CAS 1066 -40 -6). 72 -hour EC50 values for the hydrolysis products are 118 mg/L and >750 mg/L, respectively. These 2 constituents comprise 20 - 40% of MS-Silane. The hydrolysis half-life of chlorosilanes indicate that, under conditions relevant to ecotoxicity assessment, they will rapidly hydrolyze to silanol. The other hydrolysis product is hydrogen chloride; the properties of this substance are well characterised. Its effects on aquatic organisms are limited to those that result from changes to pH in unbuffered media and are discussed in the CSR.

The following information is taken into account for acute algal toxicity for the derivation of PNEC:

The lowest 72-hour EC50 (118 mg/L) has been determined for the effects of read-across substance dimethylsilanediol (CAS No. 1066-42-8) on growth rate of Pseudokirchnerella subcapitata. This study is considered to be reliable without restrictions and, therefore, may be used to conclude that dimethylsilanediol and dichloro(dimethyl)silane are not acutely toxic to algae and cyanobacteria. Dichloro(dimethyl)silane makes up 20 - 35% of MS-Silane and it is used to read-across to all constituents of MS-Silane.