Sterilization is used to destroy all microbial life through physical or chemical processes. It is important for reducing deaths from infection, improving surgical techniques and health conditions. Sterility assurance levels define the probability of an item remaining non-sterile after sterilization. Common sterilization methods include heat, steam, radiation, filtration, ethylene oxide, and hydrogen peroxide. Regulations and standards from organizations like the ISO aim to harmonize sterilization practices globally.

1. Sterilization methods: regulation
Arti Ahluwalia
Open Source for
Biomedical Engineering - OS4BME

2. Sterilization
Sterilization means the use of a physical or chemical
procedure to destroy all microbial life including
resistant bacterial endospores.
It causes denaturation of
proteins, nucleic acids and
components of cellular
membrane.

3. Sterilization
The importance of sterilization :
- reduction of number of deaths
- improvement of surgical
techniques
- reduction of epidemic diseases
- improvement of health conditions

4. Sterilization
Sterility assurance level (SAL) is the probability of a
single unit being non-sterile after it has been
subjected to sterilization:
- 10-6
for tools operating on internal tissue (surgical
tools, implantable devices);
- 10-3
for tools operating on external tissue.
N = number of microorganisms
N0 = initial number of microorganisms
T = time
D = decay constant

5. Sterilization
Sterilization methods
Physical methods:
● dry heat
● steam sterilization
● gamma ray
● UV rays
● filtration
Chemical methods:
● ethylene oxyde (EtO)
● glutaraldehyde and
formaldehyde
● hydrogen peroxide
● paracetic acid

6. Sterilization: physical methods
Dry heat: can be done by baking and flaming.
Mainly used for metals and ceramics; practical and
cheap, but takes a long time.

7. Sterilization: physical methods
Steam sterilization: in Autoclave
Used for heat-stable materials
(generally not plastics).

8. Sterilization: physical methods
Gamma Radiation (usually Cobalt-60 or caesium-137)
Commonly used in biomedical device sterilization, it
does not produce radioactivity on the objects.
Very efficient but
expensive method.

9. Sterilization: physical methods
UV sterilization (wl = 230-280 nm, typically 254 nm)
Mainly used to sterilize water, air fluxes and surfaces.
Cheap and fast
system, but no
penetrating power
and not usable with
plastics.

10. Sterilization: physical methods
Filtration for liquid not tolerant to heat, rays, chemical
agents.
Membrane filters present
pores with diameters of
μm or nm to effectively
remove
microorganisms.

11. Sterilization: chemical methods
Ethylene Oxyde (EtO): highly
penetrating and efficient.
Generally used to sterilize
PVC, rubbers and devices
such as endoscopes.

12. Formaldehyde is used to preserve
anatomic specimens and to
prepare viral vaccines.
Sterilization: chemical methods
Glutaraldehyde and Formaldehyde: separately and in
solution. Method expensive and of low durability and
taking long time (>20h).
Glutaraldehyde is used for medical
devices such as endoscopes;
objects sterilized by it can not be
packed.

13. Sterilization: chemical methods
Hydrogen Peroxide is a strong oxidant.
It is used for heat
sensitive articles,
disinfecting soft contact
lenses and endoscopes.
Peracetic acid shows a rapid
action against all microorganisms (t < 30min).
It is used for surgical and dental instruments.

14. Sterilization: regulations &
standards
Differences between standards and regulations

15. Sterilization: regulations &
standards
It is not easy to understand which are the rules to
respect in designing and creating sterilization devices.

16. Sterilization: regulations &
standards
National regulation agencies
International regulation agencies for regulatory
harmonization in a specific area
International regulation agencies for global
harmonization
WHO, Harmonization Task Force (GHTF) , International Medical
Devices Regulatory Forum (IMDRF)

17. Sterilization: regulations &
standards
Goals: creating occasions to exchange information
about regulatory on medicine and biomedical fields to
reach a harmonization system.
In their sites there are sections with documentation
available.
www.amrh.org & www.pahwp.org

18. Sterilization: regulations &
standards
Non-governmental membership organization
The world's largest developer of voluntary
International Standards
Members from 165 countries and 3,368 technical
bodies to take care of standard development

19. Sterilization: regulations &
standards
www.iso.org

20. Sterilization: regulations &
standards
ISO Members

21. Sterilization: regulations &
standards
About sterilization of health care products...
Over 60 ISO rules!!!

22. Sterilization: regulations &
standards
Typical ISO standard rule structure:
I. Definition of application field
II. Definition of technical terms used in the
document
III. Regulatory references
IV. Technical regulations
V. Technical tables and appendixes

23. Sterilization: regulations &
standards
Choosing is fundamental
- to save time in consulting
- ISO rules are not free...

24. Sterilization: regulations &
standards
There is still a long way to go...

25. Sterilization: regulations &
standards
References
1. Guideline for Disinfection and Sterilization in Healthcare
Facilities – CDC
2. www.who.int
3. www.iso.org
4. Ultraviolet Germicidal Irradiation Handbook – W.
Kowalski
5. Final Report: Effectiveness of UV Irradiation for Pathogen
Inactivation in Surface Waters – EPA (USA)

26. Sterilization: regulations &
standards
Thank you for your
attention!