Eesti keel   Русский   English



Medical Device Sterilization

Bioburden reduction of consumer goods:

  • cosmetics
  • spices
  • herbs
  • toiletries
  • pharmaceutical raw materials
  • food packaging
  • dyes and colorants

Industrial products processing



Background radiation measured on the exterior wall of Scandinavian Clinics Estonia OÜ´s plant (μSv/h):

(Natural background radiation in Estonia may reach up to 0,3 μSv/h)



Survey area: 0,12 µSv/h;
Control area: 0,10 µSv/h;
Pool: 0,08 µSv/h


The quality system ensures that all applicable standards are strictly followed. These are ISO 9001/2000 (basic Q/A rules), ISO 13485 (special Q/A rules for the medical industry, EN 552 (rules for irradiation), EN 556 (definition of the term sterility) and ISO 11137 (rules for a/o validation of products). In case of medicinal products, the rules in the Pharmacopoeia are also applied.The system will also be compatible with the FDA 21 CFR Part 820 QS Reg. GMP



A manufacturer may CE-mark his product and label it STERILE if he uses a validated sterilization process.

Firstly one must understand that it is impossible to prove that a product is sterile. It may sound strange. The explanation is that the so-called SAL (Sterility Assurance Level) shall be at least 10-6, which means that it in a batch of 1 million pieces is allowed to have only one single surviving micro organism. To statistically prove such a performance one must make at least 2 million tests, which of course is absurd. The tests are therefore made using 10-1 or 10-2 SAL-levels. Results on these levels are then re-calculated for 10-6. There are internationally accepted methods, described in ISO11137, for these validations.

The manufacturer is responsible for the quality of the product, including sterility. The contract sterilizer, we, assists in finding out the minimum dose required (Dmin) and the maximum tolerable dose ( Dmax). Dmin is related to the bioburden and the bioburden resistance. Dmax is set not to jeopardize the material properties in the product. In this validation process we will perform a so called dose mapping with the aims of finding where in the product package the minimum dose is to be found. Using dosimeters in a 3-dimensional grid makes this dose mapping. The process is then a base for routine production dosimetry.

The irradiation plant itself and the basic processes is annually calibrated against an international standard.

VDmax25 and Bioburden testing

Bioburden testing, Sterility testing and VDmax25 are handled together with our partner MIKROLAB AB in Sweden (Address: Kung Hans Väg 3, SE-192 68 SOLLENTUNA, SWEDEN. E-mail:; Mobile: +46-70 767 44 51 Office: +46-8-29 79 00)



The prevailing minimum dose given is 25 kGy, where Gy stands for Gray= 1 J/g absorbed radiation energy. There is an older unit, rad, where 1 Gy=100rad. 25 kGy is therefore the same as 2.5 Mrad. The standards allow for considerably lower doses, provided that one can prove the killing effect. Monitoring of the bioburden is therefore required. The method is sophisticated and costly and should only be used when the material , e.g. pharmaceuticals, cannot stand the normal 25 kGy.The maximum dose varies and depends on the product, but a rule of the thumb is that it might be double the minimum dose.



Each product must have a validation protocol, in which the detailed rules for production are written. After production, each individual batch will get a Certificate of Conformity.



We have acquired a cerificate for ISO 13485 (special Q/A rules for the medical industry that include basic Q/A rules of ISO 9001/2000) with reference to ISO 11137 (rules for validation of products). ISO 11137 also includes standards EN 552 (rules for irradiation) and EN 556 (definition of the term sterility). The system will also be compatible with the FDA 21 CFR Part 820 QS Reg. GMP. The certification company is Bureau Veritas Denmark.

The installation qualification (ISO 11137) has been conducted by Dr. Arne Miller as the head of the High Dose Reference Laboratory in Risö, Denmark.