Plasma: the 1st non-toxic sterilant
A sterilant is a physical or chemical means used in a sterilization process. Its objective is to reduce to 0.000001% (1 in 1 million) the probability of finding pathogenic microorganisms on a medical device.
We therefore expect a sterilant to be biocidal. Thus, by definition, it presents a threat to living organisms, and therefore to human health and the environment.
But thanks to Aurora, the world of health now has plasma with a non-toxic sterilant that does not present a danger to health or the environment.
Saturated water vapour: risk of explosion and burns
Water vapor saturated at 134°C is the oldest and best known sterilant. It is implemented in autoclaves, sealed enclosures under pressure of 2 bars. The process is well controlled. It refers to the sterilization of reusable medical devices in healthcare centers and hospitals.
In addition to its high energy consumption, it presents a danger of explosion and burns. Recent questions have been raised about its effectiveness in certain long and narrow lights. Above all, such temperatures damage many heat-sensitive materials. The autoclave is therefore reserved for robust medical devices.
However, saturated water vapor leaves no residue. It does not require a desorption phase. Its precursor, liquid water, is also safe if it is cold. This is not the case with the following sterilants.
Ionizing radiation requires the safety of nuclear facilities
Ionizing radiation is another family of sterilants. It is made up of gamma rays, X-rays, and beta rays.
The advantage of ionizing rays is to sterilize cold. They can thus process a wider range of materials.
Ionizing rays sterilize by transferring energy to the molecules they pass through. They thus damage the components of the cells they pass through, creating lesions that can cause cell death if the dose is high enough.
Sterilization with ionizing radiation must therefore be implemented with the precautions that apply to nuclear activities. Ionizing rays can cause skin burns, vomiting and internal pain. In the long term they increase the risk of cancer.
The most common ionizing sterilant is Cobalt 60. It accounts for 40% of cold sterilization of medical devices worldwide. This cobalt isotope is obtained by exposure of this metal in the heart of certain nuclear reactors.
In a sterilization plant, the source of Co60 is isolated from its surroundings by thick concrete walls. It is immersed in a vast pool of water when the sterilization cycle is interrupted.
Capacities are not adapted to the increase in demand
These industrial constraints are justified because the gamma rays of Cobalt 60 are the only ones which make it possible to cold sterilize materials in their mass. Indeed, the gamma rays of Cobalt 60 are able to cross consistent thicknesses.
Irradiation has the effect of altering the polymer chains. This is an effect that can be desired in modifying materials. In general, it is rather a consequence that one wants to avoid, because it produces an accelerated aging of the materials and damages them.
Due to industrial constraints, it is complicated for manufacturers to extend their sterilization capacities to ionizing radiation. Producing Cobalt 60 in the future will pose challenges as the reactors capable of generating it are nearing the end of their life.
The use of chemical sterilants encounters similar problems.
Ethylene oxide: a gas under political pressure
The two main chemical sterilants used in sterilization are ethylene oxide and hydrogen peroxide.
The latter (H2O2) is well suited to the reprocessing of reusable devices in hospitals and in care centers which perform their own sterilization. With some protection (gloves and goggles) to avoid skin burns and a desorption phase so as not to harm the patient, one can quite simply mitigate its toxicity.
This is not the case with ethylene oxide (C2H4O), explosive, irritant, carcinogenic and mutagenic.
Still used for hospital sterilization in some countries, it was banned for this use in European hospitals 10 years ago. It is now reserved for industrial sterilization, i.e. contract sterilization of single-use medical devices.
It has, however, come under increased scrutiny since 2019, when the US Environment Agency shut down two ethylene oxide sterilization plants in the US, following environmental releases, considered to be a threat to the health of local residents. In agreement with the FDA, these factories were reopened because of the disruption that the supply disruptions of certain devices were causing in health establishments. The use of ethylene oxide has become a political issue in the states of Illinois and Georgia, as well as during the 2020 presidential elections.
European authorities joined these concerns at the end of 2020, calling or the dissemination of technologies to replace ethylene oxide in sterilization due to the toxicity of this product.
Oxygen plasma: clean and safe
Aurora Oxygen Plasma is the first sterilant that does not pose a hazard to human health or the environment.
This is because Aurora’s sterilant is obtained by transforming small amounts of gaseous oxygen (O2) into plasma, via a low-power RF electromagnetic source. Reactive oxygen species have very short lifespans (of the order of a second at most). When the electromagnetic source is cut, the plasma is instantly recomposed into O2.
The method does not pose any cytotoxicity problems.
The residues of the microorganisms eliminated by the plasma are volatilized in the form of carbon dioxide or nitrogen dioxide, without danger to health or the environment in the quantities produced, and in the ventilated environment of a sterilization department.
Finally, the Aurora process does not require a major energy source: the Aqsaniit sterilizer plugs into a simple socket.