Potential risk of exposure to radiation from nuclear moisture density gauge stolen in Drogheda

A Troxler Nuclear Moisture Density Gauge, containing a radioactive source was among the items taken from a van in Drogheda this week.

An Garda Síochána have been informed by the Environmental Protection Agency that members of the public should be aware that there is a potential risk of exposure to radiation if an individual comes into contact with this item. In particular, if the case is opened and the equipment is activated.

The theft occurred sometime between 6pm on Monday and 6.30am yesterday (Tuesday) morning, when gardaí were alerted to the theft of a number of items from a van parked in The Downs, Highlands, Drogheda .

Gardaí are appealing to anyone who may have information in relation to this incident and any person who may have witnessed any unusual activity in the Highlands area in that time to come forward to them.

Any person with information in relation to the theft or whereabouts of this item is asked to contact Drogheda Garda Station on (041) 987 4200, the Garda Confidential Line on 1800 666 111 or any Garda station.

The Department of Public Health HSE North East and the EPA's office of Environmental Enforcement are urging people to stay away and not to tamper with the stolen nuclear gauge device.

The device contains an encapsulated supply of caesium which is a radioactive source and may have health implications for anybody who might open, break or tamper with the container.

Dr Keith Ian Quintyne, Specialist in Public Health Medicine North East advises members of the public that if they find this device, to “avoid tampering with it, and to promptly link with the local Gardaí and the Environmental Protection Agency.” Dr Quintyne added that “radiation risks to the general public are low if container remains intact”.

The radioactive source of interest is Caesium-137 which is welded inside stainless steel capsules. These sealed capsules or sources are designed to prevent leakage of radioactive material under severe accident conditions.

The source is part of an instrument called a Nuclear Moisture Density gauge (or Nuclear Gauge) which is specifically designed to measure the moisture and density of soils, aggregates, cement, and lime treated materials, and to measure the density of asphalt concrete.

What is caesium?

Caesium is a naturally occurring element found combined with other elements in rocks, soil, and dust in low amounts. Naturally occurring caesium is not radioactive and is referred to as stable caesium.

Cs-137 is a man-made radioactive isotope that has a half-life of 32 years (i.e. it is a long-lived source that will be radioactive for a long time). Cs-137 emits radiation in the form of medium energy gamma rays, and to a lesser extent, high-energy beta particles, which can disrupt molecules in cells and deposits energy in tissues, causing damage.

How can caesium affect my health?

It is highly unlikely that you would be exposed to high enough amounts of stable caesium to cause harmful health effects. Laboratory animals given very large amounts of caesium compounds showed changes in behaviour, such as increased or decreased activity.

Exposure to large amounts of radioactive caesium can damage cells in your body from the radiation. You might also experience acute radiation syndrome, which includes nausea, vomiting, diarrhoea, bleeding, coma, and even death in cases of very high exposures.

The annual dose limit a member of the public can receive is set in the legislation and it is 1 millisievert (1 mSv/y). A person standing 1 metre away from the closed and secured transport case containing the stolen item (as showed in the picture) would exceed the annual dose limit for a member of the public in approximately 100 hours. A person sitting on top of the closed and secured transport case containing the stolen item would exceed the annual dose limit for a member of the public in approximately 10 hours. If the case is opened and the equipment is activated the person could exceed the annual dose limit for a member of the public in approximately 12 minutes.

To put the dose level into context it is also important to understand that we are all exposed to a certain level of background radiation from natural sources of radiation e.g. radon, radioactivity in food etc. (background radiation dose in Ireland is estimated to be 4 mSv per year). We can also receive additional radiation doses from for example, flying on a plane (cosmic radiation) or undergoing x-ray examinations or computed tomography (CT) scans.

In a scenario where this equipment is removed from the case and activated and an individual is in close proximity to it for an hour, they would receive a dose similar to having a CT scan.

How likely is caesium to cause cancer?

There are no studies regarding non-radioactive caesium and cancer. There are human studies that specifically associate exposure to radioactive caesium with increased cancer risk.

Because radioactive caesium emits ionising radiation, carcinogenic effects among individuals acutely exposed to very high levels of radiation from a radioactive caesium source.

What to do if the items are found?

• Members of the public should move away from them, and call their local Garda station or call the Environmental Protection Agency (EPA) at 01 268 0100. This will allow for co-ordination of appropriate assistance.

What to do if this item has already been handled?

• Members of the public should remain where they are and call their local Garda station or call the Environmental Protection Agency (EPA) at 01 268 0100. This will allow for co-ordination of both medical and technical assistance.

The owner of the item is on standby to collect the item as soon as it is deemed safe; the integrity of the item will be checked by technical experts (dose rate measurements and wipe test) and managed accordingly, in liaison with the licensee and the manufacturer.