ISO 11137-2: How a Radiation Sterilization Dose Is Set
Radiation sterilization is one of the few ways a single-use item can be sterilized after it is sealed in its final packaging, and the dose that does the job is not a guess. ISO 11137-2 is the part of the series that explains how that dose is established and then kept current.
For a clinic buyer, the practical value is knowing which documents should exist behind a sterile claim.
What does ISO 11137-2 cover?
ISO 11137-2 gives the methods for establishing the sterilization dose for a product. It sits under the general requirements in Part 1, and it separates the question of what dose to use from the question of how the process is validated and controlled.
The standard offers more than one route to a dose. Some methods work from bioburden data and calculate a dose that delivers a sterility assurance level of 10 to the minus six. Others use fraction-positive testing. The VDmax approaches instead substantiate a preselected dose, most commonly 25 kGy.
How is the dose actually chosen?
| Route | Starting point | What the facility has to do |
|---|---|---|
| Method from bioburden | Counts of microorganisms on the product | Calculate the dose that reaches the target sterility assurance level |
| Fraction-positive method | Tests where part of the samples show growth | Derive the dose from the pattern of results |
| VDmax substantiation | A preselected dose such as 25 kGy | Run the prescribed verification testing for that dose |
| Dose audit | The established dose | Re-verify periodically that bioburden has not shifted |
Whichever route is used, the result is documented as a validated dose for that product and that packaging configuration. Change the material, the supplier or the packaging and the validation may need to be revisited.
Why does this matter for products a clinic buys?
Gloves, gowns and laboratory consumables arrive sterile or non-sterile depending on the intended use. When irradiation is the method, the documentation trail is what separates a validated product from an unverified claim. Ask for the sterilization validation summary and the most recent dose audit instead of accepting a certificate alone.
Which supplies carry that documentation?
For routine clinical use, items such as nitrile examination gloves, non-woven isolation gowns and specimen transport bags are produced in defined lots, which is what makes lot-level documentation possible in the first place. A supplier who can name the sterilization method, the dose and the audit date is easier to keep in your vendor file.
What should a buyer request before switching suppliers?
Ask three questions in writing. Which sterilization method is used, what dose was validated, and when the last dose audit was completed. Then ask for the reprocessing or storage instructions that come with the product, because a sterile claim only holds while the packaging stays intact. If any answer is missing, treat the switch as a project rather than a price comparison.
If you are consolidating a clinic or care home order and want the documentation bundled with it, start with the wholesale account, or request a wholesale quote and we will assemble the paperwork alongside the stock.
References
- ISO 11137-2:2013 - Sterilization of health care products - Radiation - Part 2: Establishing the sterilization dose (checked 19 September 2026)
- Public Health Ontario - infection prevention and control guidance for clinical settings (checked 19 September 2026)
- ASTM F2100 - Performance of materials used in medical face masks (checked 19 September 2026)
Related Reading
- Gloves for Canadian clinics and care homes
- Learning Hub - clinical and procurement guides
- Wholesale and multi-site ordering
- Sterilization modalities: ISO 17665, ISO 11135 and ISO 11137
- ISO 11737-1 and -2: bioburden and sterility testing explained
- ISO 14971 risk files: what clinic buyers can ask suppliers for
- free Ontario sterilization compliance log
- printable autoclave sterilization log sheet (free)
Frequently Asked Questions
What does radiation sterilization actually do to a device?
It uses ionising energy to damage the genetic material of microorganisms, so they cannot reproduce. The product stays inside its final packaging through the process, which is why the method suits single-use items such as gloves, gowns and laboratory consumables.
What is the difference between Method 1 and VDmax25?
Both live in ISO 11137-2, but they get to a dose in different ways. Method 1 works from bioburden data and calculates a dose that delivers the required sterility assurance level. VDmax25 starts from a preselected 25 kGy dose and provides the testing needed to substantiate that dose for the product.
What is a dose audit and why does it matter to a buyer?
After the initial dose is established, the standard expects periodic verification that the product's bioburden has not drifted. If the audit fails, the dose has to be re-established. A buyer asking for the audit history learns whether the dose behind the product is still current.
Does a sterile symbol on the pack prove the item was irradiated?
No. The symbol tells you the item is presented as sterile. The evidence is the validation report, the dose audit record and the certificate of processing, so ask for those documents rather than reading the artwork.
Last updated: September 2026. CliniEco Medical holds MDEL #35334 issued by Health Canada, and supplies clinics, long-term care homes and home-care programs across Canada.
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