Silicon Dioxide
Silicon dioxide, also called silica, is a fine, insoluble powder used mainly to keep dry foods free-flowing. Food additive forms are usually synthetic amorphous silica made as fumed silica, precipitated silica, silica gel or hydrous silica. Manufacturers use small amounts in powdered seasonings, salts, supplements and similar products to reduce clumping, carry ingredients or support processing.
- Concern
- Limited
- Function
- Other
- Updated
- Apr 23, 2026
What this is
Food-grade silicon dioxide is usually synthetic amorphous silica (SAS): fumed silica, precipitated silica, silica gel or hydrous silica. It differs from crystalline silica used in industrial contexts; the food question is mostly about oral exposure to amorphous particles and aggregates. EFSA’s 2018 review found no genotoxicity concern and no toxicity indication at reported use levels, but said particle-size specifications and some toxicology data were not adequate to confirm the old “ADI not specified.” In 2024, after new data and a nano-scale assessment, EFSA concluded E 551 does not raise a safety concern for any population group, including infants below 16 weeks, while still recommending better specifications for toxic-element impurities and particle characterization. JECFA has an ADI “not specified,” and major reviewed jurisdictions allow use under conditions. A Codex/JECFA safety re-evaluation request remains active, so this packet is marked for review rather than upgraded to a restriction tier.
Safety Review
The critical endpoints experts review in safety assessments. This is not a prediction of harm.
EFSA's 2024 follow-up concluded E551 does not raise a safety concern for any population group, while recommending better specifications for particle characterization and toxic-element impurities. Food-grade amorphous silica should be distinguished from industrial crystalline silica; the food issue is oral exposure to amorphous particles and aggregates.
Restaurant Usage
22 linked ingredient reports
State Policies
0 linked policies
No current state policy is listed for this ingredient in the policy tracker.
Federal Policies
0 linked policies
No direct federal policy is linked to this ingredient right now.
Sources
8 visible sources