Decontamination of sensitive items

One abiding aspect of warfare and terrorism involving chemical, biological, radiological, and nuclear (CBRN) weapons is that many of them persist for a long time after use. Many, but not all, CBRN materials can pose a contamination hazard for hours, days, weeks, or even months, depending on the material used, the material contaminated, and environmental conditions. This means that CBRN materials could cause injury or death long after their initial use. Some CBRN agents, such as persistent chemical warfare agents like Sulfur mustard and the nerve agent VX, to name two of many, are principally intended to cause harm over a longer period of time well after their employment.

At the time of the dawn of chemical warfare in the First World War, military equipment was generally not sensitive and delicate. The most sensitive thing in the trenches in the First World War was the soldier himself. His rifle was easily decontaminated, abandoned, or replaced. He had no electronics. By contrast, the modern battlefield is riddled with sophisticated equipment and systems ranging from small personal electronic devices all the way up to aircraft and combat vehicles full of sensitive components. We have little to no experience in CBRN warfare with modern electronic systems. How do we deal with a touch-screen, an artillery fire control system, a main battle tank interior, or a helicopter cockpit that has been contaminated? Small amounts of hazardous CBRN materials could lurk about inside or on the surface of a sensitive item, providing both a contact hazard and a possible respiratory hazard through the process of desorption.

CBRN contamination of sensitive items may involve those items emitting a small amount of hazard over a longer period of time. Substances lurking in the interior of an electronic system may desorb slowly over a long period of time or evaporate slowly as electronics heat up through use. Many CBRN hazards present types of damage to health that are cumulative over a period of time. Others provide health problems from slow chronic exposure to low levels over time that may not be well understood by modern medicine. Just because a vehicle or aircraft crew manages to not get immediately sick does not mean that there is no hazard present.

The challenges

The biggest challenge posed by sensitive equipment decontamination is the potential damage done to electronics by existing decontamination products and materials. The typical processes for decontamination of military materiel such as tanks and artillery pieces generally involve water (either plain or soapy), or caustic substances such as alkaline solutions. While hot soapy water or dilute bleach is fine for a tank or a critical bit of pavement on a bridge, it is injurious to electronic systems. Water causes havoc with electrical circuitry, and both water and caustic decontaminating solutions cause corrosion. Even the smallest bit of corrosion can render an electronic device useless due to disruptions in electronic circuits. It is not only electronics that suffer. Some components such as seals, gaskets, turbine blades, or propellor blades can fail due to damage. Finding a method that will cause some sort of useful reaction with a hazardous particle or droplet, but does so in a way that is not going to physical damage electronics is no mean feat.

Various schemes have been tried in the past to accomplish sensitive equipment decontamination with varying degrees of success and failure. In this correspondent’s own past, some of these schemes have ranged from the sublime to the ridiculous. One recalls meetings and briefings where bombardment with extremely high doses of gamma radiation or electron beams, or dipping entire aircraft into vast tanks of now-banned fluorocarbon refrigerants. A concept for a microwave plasma torch has been noted in the technical literature. These ideas may very well have ‘worked’ in that they would have got rid of the chemical or biological hazard. Yet they were also expensive, unsafe and/or environmentally unsound. Some are the CBRN equivalent of burning the village in order to save it.

Another challenge in sensitive item decontamination is best illustrated when we pose the question ‘how clean is clean enough?’ This question has plagued CBRN specialists for a long time. The layman might answer ‘clean enough is when all of the hazardous material is gone’ but such an answer is highly problematic. How do you prove a negative? You cannot. From a practical perspective, the answer is more likely to be ‘when we cannot detect the hazard any longer’, thus intertwining the issue with detection. Every detection instrument and technology, which have been discussed in this magazine numerous times, has constraints. So, to a certain extent, the quest for better decontamination is related to the quest for more sensitive detection methods.

Current approaches, products, and technologies

Absorption and adsorption are tactics that can be used in decontamination. If you could introduce a particle into electronics that could either absorb (act like a sponge) or adsorb (act like sticky tape) a bit of a hazard. Depending on the material used for this role, the resulting mix of adsorbent/adsorbent and threat material could be vacuumed away from the affected area. Decades ago, this was, approximately, the principle behind using Fuller’s Earth, a naturally occurring mineral powder, for skin or equipment decontamination. Now, imagine if a sorbent particle that would not harm or foul-up electronics and similar hardware.

This is the principle behind SX 34, a product fielded for about 15 years now by Cristanini, the Verona-based Italian decontamination firm. It remains one of the few truly specialist decontamination products in this niche. In full disclosure, this correspondent spilled simulated nerve agent (in the form of doctored olive oil) over his corporate laptop in 2010 and effectively decontaminated it with SX 34. The SX 34 material entraps the threat materials in a sorbent powder that is sprayed into affected equipment. The powder is then vacuumed out using a high efficiency particulate air (HEPA)-vacuum. Heavy contamination may need multiple applications, but it is very effective. More significantly, numerous rigorous trials involving live agents have occurred and decontamination targets as complex as aircraft cockpits have been tested by third-party laboratories. By virtue of this product, Cristanini remains the lead in this segment.

Fumigation remains a viable option, particularly for biological contamination but also for chemical contamination. Introducing something in a gas, vapour, or aerosol form that can permeate into and through materiel in a way that reacts with hazards. This can be particular effective in confined areas like computers or avionics. Such an approach has long been used in the medical sector, as various types of medical objects and equipment need sterilisation by methods that are not destructive to the material involved. For example, numerous medical and dental instruments, devices, and consumables are routinely decontaminated by fumigation with Ethylene oxide, a strong oxidant. Chlorine dioxide was used at the US Capitol after the 2001 anthrax incidents.

Fumigation as an approach to sensitive item decontamination came out of the healthcare sector. Ethylene oxide is more usable in an industrial setting, due to its numerous hazards. Chlorine dioxide is problematic with electronics. Yet vapourised Hydrogen peroxide can be used in a similar way with fewer issues. It is a strong oxidiser. The US firm Steris, which is a global leader in such technologies for the medical sector and has been seen in the defence space. Other firms, such as MW (Sweden) and Bioquell (UK) are involved in peroxide-based fumigation. Cristanini’s name pops up again in the fumigation space, using a variant on the same theme. Their LDV-X uses catalysed Hydrogen peroxide to fumigate a volume with Hydroxyl radicals. This system has done well in testing in military applications. With such fumigation techniques, the biggest constraint is typically the supply chain to keep these systems supplied with Hydrogen peroxide.

If the hazards being decontaminated are strictly biological as opposed to chemical, a broader arsenal of technologies is available for use. By irradiating the target bacteria, virus, or spore with some form of radiation, it could be possible to render a biological threat inert. This has been a principle in industrial sterilisation for decades and it could be achieved by gamma radiation from a radioisotope, high energy x-rays (difficult in practice), electron beams, or various types of ultraviolet (UV) radiation. In practice, the energy required to do this for chemical hazards ranges from impractically dangerous to science fiction death ray in concept, but for biological hazards this is a possibility. For electronics, this remains a bit problematic due to the density of the target material and, for UV, line of sight issues. However, irradiation should not be ignored for some applications.

Civil sector requirements

Although military CBRN specialists do not often realise it, there is a significant overlap between military and civil requirements in this specialist area. On a microscopic and molecular level, there is not a lot of difference between decontaminating a bit of aircraft avionics in a fighter cockpit and decontaminating a piece of electronic equipment in the back of a civilian ambulance. Indeed, as has been mentioned above, some of the technologies in this area already exist in the healthcare sector.

Competent planning for response to terrorism with CBRN materials and response to accidents involving hazardous materials needs to consider contamination of sensitive items as part of the possible threat environment. A broad range of scenarios is feasible. Personal electronics or vehicles used by responders, aircraft used in emergency response, laboratory equipment used in forensic laboratories, critical electronics in national infrastructure, or large server farms could all be contaminated by hazards. Postal contamination and contamination of offices is something that was a seriously expensive problem after the relatively small amount of anthrax spores was used in the USA in 2001.

One aspect of sensitive item decontamination is the threat of criminal damage to artifacts and relics. We have already witnessed ideologically-motivated vandalism of works of art. How does one deal with contamination of famous paintings, sculptures, an original flag, or a historic document? Simply put, can one decontaminate the Mona Lisa or Magna Carta without destroying it? As terrorism is about fear and ideas as much as, or even more than, actual practical impact, the social, cultural, psychological, and economic impacts of contaminating national treasures is an interesting line of inquiry.

The closest we have really come to this being a practical reality has been the anthrax spore contamination of various rooms in the US Capitol complex in 2001. Due to the location of those spores, no great items of historical or cultural importance were needed to be decontaminated, but some of that decontamination activity was very close to a number of such items. More investigation is needed in this arena. Interestingly, Cranfield University in the UK is advertising a paid PhD studentship for a scholar interested in investigating the detection of chemical hazards in archival materials. This is an indication that the subject is being taken seriously in some quarters.

Prospects

Sensitive item decontamination is certainly an area where there are more prospects for improvements to product lines and technologies. Some of these lines of enquiry are fundamentally low-tech, while others are high-tech.

Hardening is one approach that has not been fully exploited. This is a two-fold approach. First, can you make the equipment rugged enough that it can withstand the rigours of existing harsh decontaminants. Existing waterproofing and ruggedisation goes more than half the distance. If sixty years ago the US Army could design a radio that works in a tropical downpour in a Vietnamese rice paddy without shorting out, it is not beyond the realm of hope that a radio could be dunked in a bath of water with a bit of bleach in it to decontaminate hazards. By making it difficult for liquids or aerosols to effect ingress into a bit of equipment, the scope of contamination is reduced.

The other hardening approach is similar. If you can make the equipment resistant to decontamination, it follows that much of the same effort might end up with equipment that is actually resistant to contamination in the first place. In theory, there are many things that could be done to make various sensitive items more resistant to being contaminated in the first place. In order for contamination to physically occur, some hazardous material needs to actually be physically present inside or upon the item. There are ways to make individual items more resistant to contamination. One approach is coatings. There is precedent here with larger items. There has been a long history in the US Army of making combat vehicles more difficult to contaminate by painting them with expensive but effective chemical contamination-resistant paint. Advances in materials technology can make it more difficult for a sensitive item to absorb or adsorb a droplet of hazardous chemical. Therefore, one can look for the prospect of coatings or materials that do not afford CBRN materials the opportunity for entrapment.

A time-honoured decontamination tactic is one often euphemistically described as ‘ageing and weathering’. In practical terms, it means sitting the items somewhere out of the way and letting time and nature take its course. Humidity in the air, rain, sunshine, and the passage of time will have an effect on CBRN contamination. For some short-lived radioactive isotopes, the passage of time is probably the best option in many scenarios. For a tank contaminated with the nerve agent Sarin, a day in the hot sun may be a decontamination tactic that is safer and uses fewer resources than employing a squad of soldiers to wash it thoroughly, given the fact that Sarin degrades rapidly in open air at normal temperatures.

There are ways in which the mechanisms that make ageing and weathering effective can be promoted and exploited. Imagine a helicopter heavily contaminated with a persistent nerve agent, both inside and outside. If one were to park this helicopter on the end of a runway in the hot sun and let it sit for some weeks or months, the non-volatile but highly dangerous persistent nerve agent would eventually evaporate and degrade, due to both the evaporation of the agent and the gradual reaction of nerve agent with humidity in the air, assuming that it was not the driest of deserts. Yet what if the temperature, vapour pressure, and humidity could all be tweaked to increase the degradation of the nerve agent? If one were to stick the helicopter in a sufficiently-large greenhouse, thus increasing the humidity and temperature, a hazard that might take a week to abate might be gone in three days. This would work for chemical hazards, some biological hazards, but not radiological hazards.

By taking a more rigorous approach to this ‘greenhouse theory’ of chemical decontamination, it is not difficult to foresee a product line of greenhouses, tents, and large ovens that increase temperature. It would not need to be hot enough to reach the point of damaging hardware, but even 60°C would be a huge increase in evaporation. One could also, if needed, introduce more humidity. Likewise, atmospheric pressure could be lowered to increase the vapour pressure of liquids. The hothouse could be vented through appropriate filters to entrap the evaporated chemical warfare agents. This approach would not be likely to decontaminate a tank soaked in a Sulfur mustard in an hour – but could it do it in a day or two, with less hazard to decontamination crews? Perhaps it is possible.

Another approach that has been of interest for some years is enzymatic decontamination. The idea is that specific enzymes can be developed that react with specific chemical warfare agents to promote chemical reactions that neutralise said chemical warfare agents. Unlike, say, Chlorine or Hydroxide reactions where a single ion reacts with a single chemical warfare agent molecule, one molecule of an enzyme might make it possible for thousands of such reactions. This would mean that a relatively small amount of enzyme could do a lot of work. Although enzymes would likely be specific to a certain threat chemical, a decontamination solution could contain dozens or hundreds of them, as a little would go a long way. While this approach shows a lot of promise in other areas of decontamination, it is likely to be a bit problematic with sensitive items. So far, enzymatic decontamination has been aqueous – it needs water to be able to work. Even if that could be overcome, some of the decomposition products that are the daughters of enzymatic reactions could, in themselves, be injurious to electronics. However, for objects such as archival documents, historic furnishings, or oil paintings, a bit of water (and often not much is needed, possibly even a fine mist) is not the worst thing that could happen to them, and enzymes might prove useful in such scenarios.

Gradual progression in materials science may yield new frontiers. Sorbents, such as the fine white powder used in Cristanini’s SX 34 guide a path on the way to future possible improvements. With advances in materials technologies, particularly nanotechnology and nanoparticles, there is the prospect of new sorbent materials that could be used in decontamination.

Closing thoughts

Sensitive item decontamination is still a largely untested space. The institutional memory of chemical warfare operations is now quite dated, and dates to a period of time when militaries simply did not field electronics more complicated than a telegraph set or a field telephone. Avionics was not even a word. We do not even have a very good understanding of how big the problem may be in a future conflict that uses CBRN materials, nor are the logistics of massive CBRN sensitive item decontamination operations well thought-out. There is the distinct possibility that the hazard does not really matter so much. However, there is also the risk that key military systems could be rendered inoperable because their skilled operators cannot use them properly and that taking a critical system or two out of the battle for a few days could affect a battle or even a whole war. Sensitive item decontamination is, sadly, a necessary tool.

Dan Kaszeta