Wisdom For Polyethylene vol.28
28. Gamma and Electron Beam Sterilization of Poly Bags
As awareness of safety and hygiene increases, sterilization of packaging materials has become a key focus.
Particularly in response to infectious disease outbreaks and food contamination issues, the food industry has strengthened its control systems, including HACCP implementation.
In the medical and pharmaceutical sectors, the demand for gamma and electron beam sterilization has surged due to the spread of disposable medical devices and limitations of conventional gas sterilization (EOG).
Sterilization Needs by Industry
- In aseptic manufacturing environments, not only containers and caps but also packaging materials brought into cleanrooms must be sterilized.
- With stricter GMP standards, the demand for sterilized packaging is growing.
- In Japan, radiation sterilization of certain formulations and APIs is approved and being implemented as a safety measure.
- The demand for fresh, unheated foods has increased, prompting the use of aseptic filling systems to prevent mold growth during storage.
- Common sterilization methods include:
- Hydrogen peroxide (H₂O₂) sterilization
- Ultraviolet (UV) sterilization
- Gas sterilization (EOG)
- However, concerns about residual chemicals, post-treatment, and wet sterilization processes have driven wider adoption of radiation sterilization, which leaves no residues.
- There have been incidents where products applied around the eyes were contaminated with Pseudomonas aeruginosa, leading to serious accidents.
- Sterilization of cosmetic containers and raw materials is now strongly recommended.
Comparison of Sterilization Methods
Method | Electron Beam | Gamma Ray | Gas Sterilization (EOG) | Autoclave |
Equipment | Large | Large | Small–Large | Small–Large |
Penetration | Low (packaging OK) | High (packaging OK) | Cannot penetrate sealed containers | Cannot penetrate sealed containers |
Applicable Materials | Radiation-resistant | Radiation-resistant | Pressure-resistant | Heat-/water-resistant |
Sterilization Temperature | Ambient | Ambient | 40–50°C | 121°C |
Process Type | Continuous | Continuous | Batch | Batch |
Processing Time | Tens of minutes | Several hours | Several hours | Several hours |
Post-treatment | None | None | Gas removal required | Drying |
Residuals | None | None | Gas residue | None |
Sterilization Verification | Dose measurement | Dose measurement | BI sterility test | BI sterility test |
- Medical devices
- Nonwoven fabrics, sanitary products
- Laboratory and clinical testing equipment
- Containers and packaging for pharmaceuticals and cosmetics
- Pharmaceutical, herbal, and cosmetic raw materials
- Food containers and packaging materials
- Laboratory animal feed, housing, and veterinary devices
Effects of Radiation on Packaging Materials
Material | Strength | Discoloration | Odor |
LDPE | ○ | △ | × |
HDPE | ○ | ○ | ○ |
PVC | ○ | × | ○ |
PET | ○ | ○ | ○ |
PS | △ | △ | ○ |
Demand and Importance of Radiation Sterilization
In recent years, radiation sterilization of various packaging materials and containers has attracted attention, and demand is rapidly increasing.
However, when utilizing radiation sterilization, it is essential to correctly understand both its advantages and disadvantages and respond appropriately. Prior confirmation of the effects of radiation exposure on materials—such as discoloration, odor generation, and strength degradation—is required, making careful material selection a critical factor when applying radiation sterilization.
Looking ahead, it is expected that more companies across industries will consider sterilization for products that have previously been used in a non-irradiated state.
From a risk management perspective, companies are increasingly adopting radiation sterilization to proactively prevent quality defects under their responsibility and to reduce complaints caused by microbial contamination.
In particular, polyethylene bags used in the pharmaceutical, food, and cosmetic industries demand even higher quality standards.
To meet these needs, our company has established a system capable of delivering most standard products—including “poly bags,” “clean poly bags,” and “laminate bags”—with gamma irradiation in small lots and short lead times.