Disodium disilicate

Toxicity to aquatic algae and cyanobacteria

Description of key information

Two studies examined the effect of disodium disilicate (delta-crystalline) on green algae (Scenedesmus subspicatus) for 72 hours in a growth inhibition test. In both studies the 72 hours NOEC value was 18 mg/L and the EbC50 according to the key study 44.1 mg/L.

Key value for chemical safety assessment

EC50 for freshwater algae:

44.1 mg/L

Additional information

Two studies examined the effect of disodium disilicate (delta-crystalline) on green alga (Scenedesmus subspicatus) for 72 hours in a growth inhibition test. In the key study (CE90/021) and in the supporting study (CE90/011) the cultures were exposed to nominal concentrations of 0, 10, 18, 32, 56 and 100 mg/L of the test substance. Only in the supporting study the cultures were also exposed in the second part of the study to higher nominal concentrations of 100, 180, 320, 560 and 1000 mg/L with pH adjustment (to pH 7.6). Both studies were under static conditions and in accordance with the OECD 201 guideline.

The 72 hour NOEC value was determined according to the results of the key study and the first part of the supporting study (not pH adjusted) was 18 mg/L. The EbC50 in the key study and in the supporting study were determined to be: 44.1 (32 -56) mg/L, 51.6 (32-56) mg/L, 179 (100-320) mg/L (pH adjusted) respectively. The NOEC and the EbC50 values were based on cell concentration measurements.