Chinese Medical Device Regulations
Chinese medical device regulations have strict provisions on additives in silicone products. Fumed silica, as a key additive, must meet the following requirements:

**Safety First Principle:**
Additives must be "pharmacologically inactive," only capable of providing physical, mechanical, or chemical auxiliary functions.
**They must not possess pharmacological activity for treating diseases or regulating physiological functions.**
**Safety must be adequately guaranteed; it must be non-toxic, non-irritating, and non-sensitizing.**

**Ingredient Restrictions:**
All ingredients must be directly related to the intended use of the product.
**Ingredients unrelated to the function (such as pigments, fragrances, and other unnecessary additives) are prohibited.
**Must comply with GB 4806.16-2025 "National Food Safety Standard for Silicone Rubber Materials and Products for Food Contact"**

**Quality Control:**
Supplier qualifications and COA reports are required.
**12 categories of substances, including lead chromate yellow (PbCrO₄), are prohibited.
**Total phthalate limit ≤ 0.1%**

**International Standard Requirements:**
FDA Regulations
Must comply with FDA 21 CFR Requirements for Silica Gel Materials (177.2600):
* Fumed silica must be FDA food-grade certified.
* Medical-grade silica raw material purity must be ≥99.9%, impurities (metal ions, oligomers) ≤10ppm.
* A raw material traceability report (full chain record from silica sand to finished product) is required.
* EU Regulations:
* Must comply with (EU) No 10/2011 regulations for food contact materials.
* Must pass a full set of ISO 10993 biocompatibility tests, including cytotoxicity (ISO 10993-5), sensitization (ISO 10993-10), irritation and systemic toxicity (ISO 10993-11).
* Must meet the requirements of the EU REACH regulation for chemical substances.
* Safety Standards for Fumed Silica:
* Material Properties:
* Purity ≥99.5%, chloride ions <30ppm
* Particle size <50nm, specific surface area 150-380m²/g
* Thermal weight loss <1% to 300℃
* Biocompatibility:
* Must pass ISO 10993 biocompatibility tests. 10993 Series Biocompatibility Testing: Cytotoxicity must reach Grade 0. Sensitization, irritation, and systemic toxicity tests must be qualified.

Toxicological Assessment:
Acute oral toxicity test (survival rate in mice at 5g/kg dose for 14 days):
Skin irritation index ≤0.44 (0-8 scale);
Eye irritation index ≤1.0 (0-110 scale)
Production Process Compliance Requirements:

Production Environment:
Requires a Class 10,000 cleanroom (particle count ≤352,000/m³). Some implants require a Class 100 laminar flow hood (local particle count ≤3,520/m³). Personnel must wear sterile full-body suits and undergo air shower disinfection (for at least 30 seconds).

Equipment and Tools:
Copper or easily rusting tools are prohibited.
Molds must be made of 316L stainless steel (medical grade).
High-precision testing equipment (such as a surface roughness meter) is required.

Quality Control:
A complete quality control system must be established. Traceability System
Each batch of products must undergo migration testing and accelerated aging testing.
Key parameters (such as compression set) must be monitored regularly.
Application Recommendations
Material Selection:

Preferably use fumed silica (particle size <50nm).
Surface treatment agents recommended: HMDZ or silane coupling agents.
Purity requirements: SiO₂ content >99.5%, chloride ions <30ppm.
Formulation Design:

Addition amount controlled within the range of 5-8wt%. Synergistic optimization with vulcanization systems, reinforcing agents, and other components is required.
It is recommended to determine the optimal formulation through experiments.
Certification Preparation:

Plan FDA/CE certification in advance.
Prepare complete toxicology and biocompatibility test reports.
Establish a production quality management system that meets GMP requirements.
By strictly adhering to the above compliance points, the safety and effectiveness of using fumed silica in medical-grade silicone products can be ensured, meeting medical device regulatory requirements.