Justin Tyas examines a case in which an employee suffered radiation burns after being exposed to nearly 50 times the legal radiation limit.

An employee was working for a company that provided industrial radiography services, which included the use of high energy ionising radiation to test and look inside metal structures. He was working with x-ray equipment in a radiation bay; a designated danger area. A separate team of employees was testing safety equipment and warning beacons, which also required the use of the high energy x-rays.

The other employees had devised an ad hoc test method that involved turning off safety access controls and the warning alarms for the radiation bays. During a test, the employee remained in a radiation bay carrying out tests on safety equipment while the x-ray was energised, and the fingertips on his right hand were irradiated.

The equivalent dose was 23,000 milliSieverts (mSV), which is 46 times the legal dose of 500 mSV in a calendar year. The dose received caused his right hand to swell up with severe tissue damage to the middle, ring and little fingers. He had to undergo surgery and his fingers remain numb, with occasional tingling.

Radiation

Radioactivity has been known about since the 1890s and now has a wide range of scientific and industrial applications, including agriculture, medicine and electrical production. Ionising radiation is high energy radiation which has sufficient energy to cause ionisation of matter. Examples are alpha particles, beta particles, gamma rays, x-rays and neutrons. When these radiation types pass through the human body they have sufficient energy to damage DNA.

Exposure to radiation can damage tissues in the body and increase the risk of cancer. The more a person is exposed to radiation, the greater the risk of permanent damage and cancer. The potential harm done to a person by exposure to radiation is measured by a quantity of radiation dose. This is measured in mSv and takes into account the harm done to the body by exposure to radiation. According to a briefing note from the n Environment Agency, the average individual exposure to all sources of radiation in the UK, including from medical exposure, is 2.6 mSV per year.

Radiography is the use of ionising radiation for non-destructive examination of the structure of materials. When the radiation penetrates the material, it produces a shadow image by blackening a sheet of photographic film that has been placed behind the material, and the differences in blackening suggest flaws and unevenness in the material. Radiography is widely used in medicine, and has significant use as a technique in science and industry.

Statutory requirements

The Ionising Radiations Regulations 1999 (IRR) apply to a wide range of workplaces where radioactive materials and electrical equipment emitting ionising radiation are used. They also apply to work with naturally occurring ionising radiation, such as work with radon gas and its decay products. Employers who work with ionising radiation are termed radiation employers and must comply with the IRR. These regulations have their own Approved Code of Practice: Work with Ionising Radiation (L121).

The IRR require employers to keep exposure to ionising radiations as low as reasonably practicable. Exposures must not exceed specified dose limits. Restriction of exposure should be achieved first by means of engineering control and design features. Where this is not reasonably practicable employers should introduce safe systems of work and only rely on the provision of personal protective equipment as a last resort.

Dose limits are intended to reduce the risk of the occurrence of serious effects, such as cancer, and are in place to protect the eyes, skin and extremities against other forms of damage. Dose limits are defined in UK legislation and can be found in schedule 4 of the IRR, which set out the classes of person to whom the dose limits apply. “Effective dose” relates to the whole body, while the “equivalent dose” relates to the dose received by a tissue or part of the body such as skin or the eye.

For employees of 18 years of age or above (excluding women of reproductive capacity) the limit on effective dose shall be 20 mSv in any calendar year; the limit on equivalent dose for the hands, forearms, feet and ankles shall be 500 mSv in a calendar year.

Regulation 7 (Prior risk assessment etc) of the IRR requires that before a radiation employer commences a new activity involving work with ionising radiation, a suitable and sufficient risk assessment must be made for the purpose of identifying the control measures required to restrict exposure to employees or other persons. This regulation complements regulation 3 (Risk assessment) of the Management of Health and Safety at Work Regulations 1999.

Regulation 13 (Radiation protection adviser) requires the appointment of a suitably competent person or body to provide advice to employers on compliance with the IRR.

Regulation 17 (Local rules and radiation protection supervisors) requires the writing of local rules, identifying the key working instructions intended to restrict exposure to ionising radiation. Local rules for a controlled area should include the arrangements for restricting access to that area. This regulation also requires the appointment of one or more suitable Radiation Protection Supervisors, who have a crucial role in helping compliance with arrangements made under the IRR, and in particular, supervising arrangements made under local rules.

Breaches

The company involved in this accident pleaded guilty to breaching s. 2(1) of the Health and Safety at Work, etc Act (HSWA) 1974 and regulation 11(1) of the IRR. It was fined £30,000 and ordered to pay £4930 in costs.

Section 2(1) of the HSWA states: “It shall be the duty of every employer to ensure, so far as is reasonably practicable, the health, safety and welfare at work of all his employees”.

Regulation 11(1) of the IRR states: “every employer shall ensure that his employees and other persons within a class specified in schedule 4 are not exposed to ionising radiation to an extent that any dose limit specified in part 1 of that schedule for such class of person is exceed in any calendar year.”

Failings

The Health and Safety Executive’s investigation identified that the workers had not previously used the x-rays to test the safety equipment, and that no procedures had been developed to enable the testing to be completed safely. As a result, they had developed their own ad hoc test method, which had led to several important safety devices being switched off. It was also found that staff widely ignored an instruction to remove a key operating the x-ray equipment when they left to go on a break.

This accident demonstrates the failure to implement effective risk management, with a lack of suitable controls to effectively reduce exposure. There was a breakdown of management control including cooperation and coordination, with no effective supervision.

Lessons learned

This was a foreseeable accident that should not have occurred. It resulted in a worker being exposed to high energy ionising radiation. The level of radiation to which the worker was exposed was sufficient to cause serious ill health, including the potential for death if the high energy x-rays had passed into vital organs in his body.

Risk assessment should have been used to ensure that effective controls were in place to reduce exposure. Local rules should contain clear working instructions to be followed by everyone to keep the dose of radiation to as low as is reasonably practicable. They should reflect actual working practices, and be specific to the working environment. Finally, to be effective, local rules and subsequent working practices need to be managed by radiation protection supervisors to ensure employers have suitable arrangements in place to comply with the IRR.

Further information

L121 Work with Ionising Radiation

Briefing Note, Environment Agency

Last reviewed 25 June 2014