Radiation
Sterilization
Sterility and bioburden reduction through irradiation
Radiation
Radiation sterilization: Safe sterilization through ionizing radiation
One of the most important industrial sterilization processes worldwide is sterilization with ionizing radiation. Irradiation safely destroys pathogenic germs, molds and spores on the products within a short time. The radiation damages the DNA of microorganisms so that they reliably lose their ability to reproduce and become harmless. Gamma rays are used frequently for sterilization and disinfection, and increasingly electron beam (E-Beam). X-ray systems (X-ray) are being developed, some of the first commercial systems are currently in operation.
As a physical process, sterilization with electron and gamma radiation is residue-free, takes place without any significant increase in temperature and enables products to be sterilized in their sealed final packaging.
Because the entire product is irradiated, radiation sterilization is also recommended for complex geometric shapes, although there are limits to electron irradiation depending on the structure and density of the product.
After dosimetric release, the products are ready for delivery and can be used immediately – without further tests or storage and waiting times. These numerous advantages make radiation sterilization a simple, effective and environmentally friendly alternative to other methods. For sterilization and bioburden reduction, we at BGS use gamma radiation as well as electron radiation.
The main difference lies in the ability to penetrate a material and the dose rate:
- E-Beam: high dose rate and limited penetration depth
- Gamma rays: relatively low dose rate and high penetration depth
Sterilization with radiation: Application areas
Medical devices
Sterility is essential for medical devices and in diagnostics and is defined by various standards, laws and regulations. At BGS, we have been supporting our customers in this sensitive process for decades – from the sterilization of packaging and consumables to highly sensitive medical devices such as endoprosthetics or implants.
Biotechnology
Sterile working materials and consumables are also essential in biotechnology and pharmacy to ensure controlled conditions for sampling, testing or research and to prevent contamination with microorganisms. Radiation sterilization is an indispensable step in the manufacturing process of these products.
Packaging material
In many industries, bioburden reduction is a prerequisite for reproducible and high-quality production results. This is why radiation sterilization is used for packaging materials and processing aids for the cosmetic and pharmaceutical industries as well as for food packaging.
Fight the pathogens: Sterility vs. Bioburden reduction
Sterility and bioburden reduction are two terms that are not synonymous! Sterility is defined and standardized. According to DIN EN 556, the sterility assurance level (SAL) for medical devices, must be at least 10-6 . This means that no more than one viable microorganism may be detected on one million products whose sterilization has been validated using a suitable procedure. A medical device is therefore only sterile if the theoretical probability of finding one living microorganism per object is no more than 1:1,000,000. Bioburden reduction, on the other hand, means that the quantity of microorganisms is below a limit that is considered safe for a specific application. For example, products can be labeled as bioburden-reduced if they have undergone a treatment process in which the theoretical probability of finding one surviving microorganism per item is less than 1:1,000 (SAL 10-3).
Radiation sterilization: Methods
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More InformationContact radiation sterilization
Are you interested in sterilization or bioburden reduction? We would be happy to check your request for the irradiation of your products.
Validation process: From non-sterile to sterile product
The path to a sterile product requires legally prescribed validation. For radiation sterilization processes, this is regulated by the standard DIN EN ISO 11137. Validation is a complex process in the course of which proof is provided that the normative requirements for the production of a medical device have been met. In principle, every sterilization is preceded by a validation process. It is required for
- the market launch of a product,
- the qualification of a second source,
- the qualification of a second supplier while retaining the selected sterilization process, and
- a change from an established sterilization process to another, for example from gamma to E-Beam.
Validation consists of three parts, namely microbiological, dosimetric and application-related validation, which are interdependent.
1. Microbiological
validation
In the microbiological validation, the irradiation dose that converts a non-sterile product into a sterile one is determined. For this purpose, the initial bioburden – number and type of microorganisms – is determined. For this validation, we work closely with independently accredited microbiology laboratories that determine the microbial load (bioburden) on the products. Based on these results and our advice, we work with you to determine the parameters for the ionizing radiation in order to achieve the desired sterility level. We also carry out the revalidation (dose audits) of your products in cooperation with these laboratories.
2. Dosimetric validation
The aim of dosimetric validation, also known as dose mapping, is to show the dose distribution in relation to a defined product arrangement in the packaging during irradiation. The results of this analysis are used to determine the minimum and maximum dose positions of the product and the resulting dose range for the routine monitoring positions. We support and advise you in the development of your products and definition of your packaging configuration schemes and prepare the reports and dossiers for irradiation in accordance with current regulatory requirements and standards.
3. Application validation
During application validation, the properties of the medical device and its primary packaging are evaluated after all manufacturing processes have been completed. Since irradiation with E-Beam and gamma rays not only kills microorganisms, but can also change the properties and functions of materials, packaging and products, these changes must be investigated. Changes to the product often correlate with the irradiation dose – it is therefore essential that you involve our experts.
Material resistance: Overview of frequently requested polymers
Group | Polymers | Resistance | Remarks |
|---|---|---|---|
Thermoplastics | Polystyrene (PS) | ** | Very resistant; discolouration possible in transparent types; impact-proof types less resistant |
Acrylonitrile butadiene styrene (ABS) | ** | Breaks down at about 100 kGy; avoid high doses in impact-resistant settings | |
Polycarbonate (PC) | ** | Discolouration possible; special types with reduced yellowing obtainable; discolouration may disappear after annealing | |
Aromatic polyesters (PET/PETG/PBT) | ** | Extremely stable, retains its very good transparency; be sure to pre-dry prior to processing! | |
Polyethylene (LDPE/HDPE/LLDPE/MDPE) | ** | Crosslinked to higher strengths, at the same time reduction of elongation at break; LDPE most resistant | |
Polymethyl methacrylate (PMMA) | * | Discolouration at about 20-40 kGy | |
Cycloolefin copolymer (COC) | * | Retains its good transparency and impact strength | |
Polyvinylchloride (PVC) | * | Standard types not suitable, release of corroding gases; special types with higher radiation resistance obtainable, discolouration possible | |
Polypropylene (PP) copolymer | * | More stable than PP homopolymers; specially stabilised qualities are recommended | |
Polyacetal (POM) | o | Not recommended, extremely brittle | |
Polytetrafluorethylene (PTFE) | o | Breaks down rapidly, creates corroding gases, not suited | |
Elastomers | Ethylene propylene diene rubber (EPDM) | ** | Possibly crosslink products in addition |
Ethylene vinyl acetate (EVA) | ** | Possibly crosslink products in addition | |
Silicones | * | Increase in shore hardness possible | |
Butyl and halobutyl rubbers | * | Breaks down, sterilization only possible in very low dose windows |
Brochure radiation sterilization
Our technical brochure answers central questions on technology, procedures and process integration.
FAQ: Radiation sterilization: Frequently asked
Both types of radiation, electron beam & gamma rays, can achieve the same result. Before switching to E-Beam, our experts will check the suitability of your products in terms of density and packing scheme. Subsequently, the changeover requires a new performance validation (PQ) and parts of the microbiological validation.
No, the radiation in the BGS systems can only cause chemical reactions in the products due to their physical properties. The energies used are too low to generate radioactivity.
After irradiation, we check the dose using the dosimeter attached to the product. The product can then be placed on the market immediately.
Radiation sterilization is generally unsuitable for products with microelectronic components, as irradiation would destroy the electronics.
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