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Ecotoxicological information

Toxicity to birds

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Description of key information

The NOAEL in turkey after repeated oral administration of sodium metasilicate over 4 weeks was greater than 270 ppm Si (Read across to sodium metasilicate).

Key value for chemical safety assessment

Long-term EC10, LC10 or NOEC for birds:
2 039 mg/kg food

Additional information

No studies with disodium disilicate (delta-crystalline) are available for repeated dose exposure. Read across to soluble silicates (sodium metasilicate) was done instead. Disodium disilicate (delta-crystalline) differs from the soluble silicates only in the crystal structure and the molar ratio of sodium and silicate. When dissolved in water so called waterglas is formed from both components. Thus read across is justified in this case.

Kayongo-Male and Jia (1999) studied the effect of various silica sources added to diets of turkeys. Parameters examined were body weight, organ weight (liver and heart), hemoglobin, hematocrit, and mineral concentrations in blood plasma and organ tissues (liver and heart). Turkeys exposed to 270 ppm Si (corresponding to 2039 ppm sodium metasilicate, pentahydrate) for 4 weeks in did not exhibit significant effects on body and organ weights. Plasma P was increased and Cu was decreased. Minerals in heart and liver tissue were unaffected.