The immediate and long-term impact of a radiation dispersal event (RDE) on the health and wellbeing of a population, as well as the country’s food chain, drinking water, property and national critical infrastructure mark out such an event from other emergencies requiring medical response.

As well as acute physical injury an RDE from a bomb or nuclear facility explosion would also contaminate affected persons externally and internally – due to the spread of radioactive emission through the surrounding area and potentially, beyond – depending on weather conditions, wind direction and level and locations of particle deposition. The use of even an improvised radiological weapon could affect an entire country or region for a long time, economically, medically, and psychologically.

An RDE caused by an exploding device, facility leak or meltdown, or other release is therefore a complex event for rescue/healthcare systems – and radiation protection authorities, police and the joint command chain – to deal with.

Differing effects

The harm caused depends on the type of radioisotope used and the type of ionizing radiation emitted. To assess this, the isotope would have to be identified very quickly. Gamma emitters (e.g. cesium-137*) penetrate body tissue and may be lethal; beta emitters (e.g. strontium-90**) can penetrate and burn the skin; and alpha emitters (e.g. plutonium-239***; polonium-210****) have to be ingested or inhaled, and once they are, may be lethal.

*used in medicine and industry

**emitted in the Windscale fire

***weapons-grade material for nuclear weapons

****used to kill Alexander Litvinenko

Effects depend on the absorbed dose and range. At the high end, Acute Radiation Syndrome (ARS) is caused by a high dose (4-6 Gy), with victims showing severe symptoms within hours. As well as vomiting and diarrhoea, which could be mistaken for severe food poisoning, the clinchers are hair loss, skin redness, burns and moist peeling, haemorrhaging, then necrosis (cell death) and multiple organ failure. Many more people could be exposed to a mild to moderate dose (1-4 Gy) within days or weeks, with no symptoms but a heightened risk of cancer, which as one of the world’s most common illnesses is hard to attribute.

Precedent is rare – but catastrophic

The chief case studies of health effects are major catastrophes – the 1945 atomic bombings; Chernobyl and Fukushima; atomic veterans and nuclear workers. Since the fire in the Windscale nuclear reactor in Cumbria, northern England in October 1957, there have been no major radiation emergencies in the UK – that is, until the poisoning of the Russian dissident Alexander Litvinenko with the alpha-emitting radioisotope polonium-210 in November 2006 in London.

Effects caused by lower-level releases are sometimes overlooked. The Inquiry Chairman, Sir Robert Owen, described the Litvinenko incident as a “miniature nuclear attack on the streets of London which put many hundreds of people at risk.” The UK capital’s first RDE affected dozens of contacts and potential contacts as well as the murder victim and required varied levels of decontamination of 20 premises.

The cause of Litvinenko’s demise was only nailed when an AWE scientist recognised a small spike in the read-out of one of the victim’s urine samples. Alpha emissions are very short range and therefore, hard to detect. Agencies expected to respond to another nuclear accident, or a bomb. The then Director of the Health Protection Agency, Dr Pat Troop, admitted she needed “a crash course in what polonium-210 was and what problems it could cause. It was quite clear that what was unfolding was unprecedented.” 

Measuring exposure

The graphic depicts a theoretical RDD deposition scenario following the bombing of Bishopsgate, London, by the IRA on 24 April 1993 (which was not a RDD). Based on 1 tonne ammonium nitrate plus 1 kg cesium-137 powder, the simulation is based on dust dispersal and weather patterns on that day ten minutes after the explosions, using a model with archived meteorological data from the Air Resources Laboratory of the US National Oceanic and Atmospheric Administration (NOAA).

The next RDE may be totally different from either Litvinenko or Windscale and possibly more challenging, especially as health services are now under such extreme pressure. If by a terrorist group, it could involve multiple devices or releases. Coordination with police and specialist agencies from Porton Down and elsewhere would be vital from the start – to ascertain the source, type, and delivery method of the radiation.

Even if a radioactive source has been identified, to deliver an effective and nationally consistent response to any radiation emergency, responders would have to consider the symptoms of victims, depending on exposure. Internal exposure comes from particles small enough to be inhaled or ingested with contaminated food or fluid, which leads to a build-up of dose. This may result from direct contact with a liquid or solid substance which gets transferred to skin, eyes, hair, or clothing.

The body may retain the material for some time, for example, radioactive iodine in the thyroid gland. So the time a radioactive material will continue to emit radiation is crucial: its ‘half-life’ – the time taken for around half the material to decay (become stable) on average – varies considerably. Materials with a long half-life emit radiation at a slower rate but remain radioactive for longer periods.

Therefore, emergency plans go beyond administering triage and treating the injured as far as is possible depending on severity, but also attempting to minimise lifetime health risks and further spread of contamination.

Procedures

In a major release, people would be evacuated from the area of external and internal exposure. Administration of potassium iodate tablets to counter uptake of radioactive iodine-(a countermeasure around nuclear power facilities) would accompany controls and advice on the consumption of contaminated food or drink. People would be relocated from buildings and areas that require decontamination or left until safe to reoccupy.

All casualties – whether injured or not – who could be contaminated, would receive decontamination at the scene. Decontaminating externally contaminated persons protects their health as well as that of others. Most types of radioactive material do not readily cross through the skin; a beta emitter causes skin burns and systemic contamination if it penetrates burned skin. Wounds may facilitate entry of radioactive material into the bloodstream. Everyone affected would also need psychological support.

Gross decontamination after a radiological incident involves the removal of all patient clothing and full-body irrigation. But simple measures such as flannel use and vigorous towel-drying greatly improve the removal of agents. Emergency medical care takes priority over decontamination.

In a radiological or nuclear emergency in the UK, Public Health England’s Centre for Radiation, Chemical and Environmental Hazards (CRCE) is required to maintain emergency response arrangements, radiation monitoring and public health advice to government agencies and the NHS. Emergency response is coordinated from the Chilton Emergency Operations Centre in Oxfordshire. It has long been accepted that planning, organization, equipment, and training at local community and regional, national, and international levels are vital to mitigate the health effects of a radiological release.

To monitor the consequences for the UK of nuclear incidents abroad, 96 nuclear radiation monitoring and nuclear emergency response (RIMNET) sites around the UK collect radiation dose rate readings every hour. An abnormal increase indicating a nuclear incident would result in a national alert.