Silicon dioxide

E number E551INS 551CAS 7631-86-9

Used as an anticaking agent — Codex also lists it as antifoaming agent, carrier.

Silicon dioxide is the anticaking agent in powdered products — spice blends, powdered drinks, grated cheese and salt — where it absorbs moisture and keeps particles separate.

Where it is and isn’t permitted

Status of Silicon dioxide by jurisdiction. Every jurisdiction this site covers is listed, including those where the substance does not appear.
JurisdictionStatusScope and limitsCitation
United StatesFood and Drug AdministrationPermitted, with conditions21 CFR 172.480retrieved 2026-09-07
Codex AlimentariusCodex Alimentarius Commission / JECFAPermitted, with conditions

13 food categories

highest permitted level 15,000 mg/kg

Show every food category
  • 01.5.1 Milk powder and cream powder (plain) — GMP
  • 01.6.1 Unripened cheese — GMP
  • 01.6.2.1 Ripened cheese, includes rind — GMP
  • 01.8.2 Dried whey and whey products, excluding whey cheeses — 10,000 mg/kg
  • 11.1.2 Powdered sugar, powdered dextrose — 15,000 mg/kg
  • 12.1.1 Salt — GMP
  • 12.1.2 Salt substitutes — GMP
  • 12.2.1 Herbs and spices — GMP
  • 13.1.1 Infant formulae — 10 mg/kg
  • 13.1.2 Follow-up formulae — 10 mg/kg
  • 13.1.3 Formulae for special medical purposes for infants — 10 mg/kg
  • 13.2 Complementary foods for infants and young children — 2,000 mg/kg
  • 14.1.5 Coffee, coffee substitutes, tea, herbal infusions, and other hot cereal and grain beverages, excluding cocoa — GMP
CXS 192-1995 Table Three, INS 551and 13 further provisionsretrieved 2026-09-07

What it is made from

Produced synthetically by precipitation or flame hydrolysis, giving a very fine amorphous powder. This is amorphous silica, which regulators treat separately from crystalline silica.

  • Vegan
  • Vegetarian
CAS registry number
7631-86-9
InChIKey
VYPSYNLAJGMNEJ-UHFFFAOYSA-N
PubChem
CID 24261

Every name it appears under

68 recorded names. A label may use any of them.

E number

  • E551

INS number

  • 551

CAS registry number

  • 7631-86-9

As it appears in regulation

  • Silicon dioxide

Other names

  • Acticel
  • Aerogel 200
  • Aerosil 200
  • Aerosil 300
  • Aerosil 380
  • Aerosil A 300
  • Aerosil E 300
  • Aerosil K 7
  • Amorphous silica dust
  • Cab-o-sil M-5
  • Carplex
  • Carplex 30
  • Carplex 80
  • colloidal silica
  • Corasil II
  • Diatomaceous silica
  • Dioxosilane
  • Dri-Die
  • E 551
  • ETJ7Z6XBU4
  • Extrusil
  • INS NO.551
  • Ludox hs 40
  • Manosil vn 3
  • Min-U-Sil
  • Nalfloc N 1050
  • Neosil
  • Neosyl
  • Porasil
  • Positive sol 130M
  • Positive sol 232
  • Quartz (SiO2)
  • Quso 51
  • Quso G 30
  • Santocel
  • Silanox 101
  • Silica
  • Silica crystalline quartz
  • Silica, amorphous
  • Silica, colloidal
  • Silicic anhydride
  • Silicium dioxide
  • Silicon dioxide
  • Silicon dioxide (amorphous)
  • Silicon dioxide, fumed
  • Silicone dioxide
  • Silikil
  • Sillikolloid
  • Siloxid
  • Sipernat
  • Snowtex 30
  • Snowtex O
  • Syton 2X
  • Tokusil TPLM
  • Ultrasil VH 3
  • Ultrasil VN 3
  • Vitasil 220
  • Vulkasil S
  • Wessalon
  • White carbon
  • Zeofree 80
  • Zipax
  • Zorbax sil

Systematic names

  • dioxosilane

Hazard reference values

Values set by assessing bodies. A body that has not set a value is not listed here.
TypeValuePopulationAssessed byOpinion
ADI1consumersEFSA FAF2024

Evidence and how bodies read it

Studies, and the differing conclusions regulators drew from them, are curated by hand rather than machine-read, and none has been written for this substance yet.

Sources for this page

  • ecfr retrieved 2026-09-07
  • gsfa retrieved 2026-09-07

Full licence terms and publisher details on Sources. How this page is built and updated: Method.

Machine-readable:/api/v1/additives/silicon-dioxide.json