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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 main application for our plant is sterilization of medical supplies. The term "sterilization" is defined by international bodies and is highly regulated. The definition is that a sterilized product may not have more than one surviving micro organism per one million articles, e.g. syringes. This is an extremely hard demand and an excellently working Quality Assurance management is needed. Note that it is mathematically impossible to test that a product has achieved this high degree of cleanliness. To make a test that gives significance, one will need at least two million tests, which certainly is impossible. Instead the bioburden is tested at a very small dose and the result at the normal sterilization dose is then calculated. However, it illustrates the importance of Quality Assurance.

Normally the customer has own routines for bioburden checking. Nevertheless, if the customer prefers we are happy to organize such testing in co-operation with a certified laboratory in Tallinn or Stockholm (Sweden).



Our irradiator is a gamma irradiator. It is a high capacity equipment for radiation processing of various products. The Cobalt-60 source encapsulated in a stainless steel capsule is a man-made radioisotope emitting gamma rays.

The irradiation technique is a product-overlapped system operating with stainless steel tote boxes with inside dimensions of 84 x 48 x 150 cm (600 litres). The product transport system moves the tote boxes through the process. An automatic conveyor system transfers the tote boxes into the irradiation room where a source pass mechanism moves them around the Cobalt-60 source in two passes on two levels. Then the automatic conveyor system transfers the tote boxes back to the storage area for unloading.

NB! Our irradiator contains also a unique additional system for the treatment of packaging materials and other products of special shapes and measures not suiting the tote box dimensions. This enables for example treatment of large rolls of packing materials or any other similar products.



The term decontamination indicates that we intend to somewhat decrease the bioburden but not go as far as sterilization and  thereby comply with the strict regulations in that field. Instead the user, according to his own needs, defines himself the degree of microbial reduction. One example is that packing material, though already  rather clean from the mechanical manufacturing process, can be processed down to 1/100 or 1/1000 of the original bioburden. And at small doses compared to sterilization. Perhaps it is enough with 2 kGy instead of 25 as normally  required for sterilization. The gain for the user is that the total bioburden in his plant may decrease a significant factor, which may mean that he will be more attractive for demanding customers. The increased cleanliness will thereby be paid for.

To satisfy the need for large scale decontamination we will install an unusual feature  in our gamma plant, aimed at handling very large objects at small doses. E.g. a paper roll with diameter 1 meter and length 2 meters.



The treatment of your products will exactly follow the routines that the customer demands and that we have accepted. Thereafter the goods will be shipped back or further to the customers own customers or maybe stored for a while.



There are three steps:

The first step is material testing. All types of materials have to be tested including glue and packaging material. A normal testing scheme is 0, 25, 50, 75 and 100 kGy. The zero-dose sample shall join the other samples during the whole trip to avoid unexpected influence caused by the transport cycle, e.g. changes due to temperature variations. Note that it is not enough to test on 25 kGy only, because the absorbed dose in the goods may vary from 25 kGy up to perhaps 50 kGy. Also, it is important for the supplier of irradiation to know what to do if he, for technical reasons, must run part of the goods twice. These parts will then get a double dose. Most medical articles can stand that, but there are exceptions.

The next step is to make a qualification. This procedure shall be carried out when the product is almost ready for production. The packing material may be the only thing remaining. In the qualification a dose mapping of the goods in the preferred packing pattern will be made. This gives information about where the minimum dose is to be expected. In many cases it will however be revealed that the goods are not optimally packed, and the alternatives are therefore discussed and a final decision can be made.

The last step is the validation. Validation takes place when the product is ready for the market. Here the place of the earlier found minimum dose will be certified. Dose mapping is again used. For statistical reasons the procedure is repeated several times. The end product is a validation document that is a part of the commercial contract. This document is also an important legal document, which you need for registration in all countries.

After running of each batch or lot a Certificate of Conformity is issued. This document is the legal means to release the product for the market.