Silicone rubbers were developed in the 1950s for military and industrial applications, and from the mid-1960s onwards, they began to be used in the medical, pharmaceutical, and food sectors. Despite their inherent biocompatibility, not all silicone rubbers are the same. They can be classified into the following categories:
- Industrial use
- Food-grade
- Medical or pharmaceutical use (for contact with the human body fluids for less than 30 days)
- Implantable use
Food-grade silicones are regulated by each country, with the most commonly used regulations being FDA CFR 177 2006 in the United States or Section 15 of the German BFR. These regulations share common points, such as the requirement for ingredients used in polymer or compound manufacturing to be on a positive list. They also establish limits for the extractable volatile substances after conducting tests under various time and temperature conditions using different reference liquids for silicone.
Silicones for medical and pharmaceutical use refer to the USP (United States Pharmacopeia) and European Pharmacopoeia regulations. They differ from food-grade silicones in having lower volatile substance content and undergoing in vivo biocompatibility tests, usually for at least five days intramuscularly. However, both categories share the best practice of carrying out appropriate post-vulcanization cycles by following specific mathematical formulas.
How to choose one type of silicone over another and when is
it necessary to produce it in a cleanroom?
The choice depends on the application’s
requirements, requiring specific reference to the relevant regulations.
Specific regulation references, such as FDA or USP Class 6, are required. There
are different solutions for a cleanroom, and it is crucial to define the
required class. ISO 14644-1 standard defines the class difference, typically
ranging from Class 1 to Class 100,000, which determines the maximum accepted
level of dust particles larger than 0.5 microns per cubic meter of air.
Selecting the right class is highly important, as cost management depends on
it; the lower the class, the higher the costs.
Regarding precautions to be taken in a cleanroom environment, personnel selection and training are essential. Staff members need to be informed about the procedures and behavior to be maintained in this environment, which is completely different from an industrial setting. “Good Manufacturing Practices” (GMP) must be implemented in cleanroom operations and can be summarized into five elements to achieve a sustainable and consistently high-quality product:
- People
- Working environment
- Processes
- Procedures
- Instructions