Silicon dioxide (E551)

Names on a label

• E551
• E 551
• Silicon dioxide

Labels outside Europe often print the number on its own, without the E.

What it’s used for

The FDA lists these uses in food: anticaking agent or free-flow agent; antioxidant; color or coloring adjunct; drying agent; emulsifier or emulsifier salt; flavoring agent or adjuvant; formulation aid; humectant; lubricant or release agent.¹

What regulators and scientists say

• The FDA lists it as generally recognized as safe (GRAS) for its intended use in food (21 CFR 182.90).¹
• IARC classifies it as not classifiable as to its carcinogenicity to humans (Group 3, 1997).²

IARC’s groups “indicate the strength of the evidence as to whether an agent is capable of causing cancer,” but they don’t measure how likely cancer is at a given level of exposure.³