Review Article

Radiation Accidents: Occurrence, Types, Consequences, Medical Management, and the Lessons to be Learned

István Turai1,2 and Katalin Veress3

1 “Frédéric Joliot-Curie” National Research Institute for Radiobiology and Radiohygiene, “Fodor József” National Center for Public Health, Budapest, Hungary
2 International Atomic Energy Agency, Vienna, Austria
3 Institute of Public Health, Faculty of Medicine, Semmelweis University, Budapest, Hungary

Corresponding author: Assoc. Prof. István Turai, MD, MPHM, PhD
    IAEA, POB.200,
    A-1400 Vienna, Austria
    E-mail: I.Turai@iaea.org

CEJOEM 2001, Vol.7. No.1.:3-14


Key words:
radiation accidents, causes of radiation accidents, diagnosis, education and training


Abstract:
The paper reviews the frequency, causes and occurrence of radiation accidents with some significant exposure to human. More detailed information is provided in tabulated form on the health consequences of those twenty severe radiation accidents that occurred in 1986-2000, world-wide. Reference is given to the very low cumulative incidence of significant radiation accidents, as during the last 57 years there were, in average, seven registered accidents annually in all countries of the world. Thus, the chance for most of the physicians to meet a patient with symptoms of acute radiation injury during their professional career is very low. Nevertheless, the probability of a case of radiation injury should not be ruled out, and hence, each physician has to have some basic knowledge to recognize and initially respond to radiation injuries. The paper aims at providing the key statistical data and information on these aspects, pointing to the necessity of strengthening the regular undergraduate and postgraduate training in radiohygiene and radiation medicine in all continents, but in particular in Central and Eastern Europe, where unauthorized possession and even smuggling of radiation sources is not uncommon which may result in accidental radiation injuries.



INTRODUCTION

An accident is: “Any unintended event including operating errors, equipment failures or other mishaps, the consequences or potential consequences of which are not negligible from the point of view of protection and safety” (IAEA et al., 1996b). A radiation accident is an unintended or unexpected event occurring with a radiation source or during a practice involving ionizing radiation, which may result in significant human exposure and/or material damage (IAEA and WHO, 1998a; IAEA, 1999a).
      Radiation accidents include radiological and nuclear accidents (IAEA, 2000a). The latter are caused by nuclear chain reaction. When, for example, plutonium powder is spilled in a laboratory, the probability of nuclear chain reaction can be singled out, thus, despite the involvement of a nuclear (fission) material, we cannot speak of a nuclear accident. It is also a radiological (and not a nuclear) accident if a worker is overexposed due to the fault of a radiograph while checking the quality of welding of a primer circuit tube in a nuclear power plant.


INCIDENCE OF RADIATION ACCIDENTS IN 1944–2000 AND THEIR MAIN HEALTH CONSEQUENCES

In 1944–2000, 417 radiation accidents led to significant overexposure of at least one person (when the absorbed dose to the whole body exceeded 0.25 Gy, or 6 Gy to skin, or 0.75 Gy to any other organ). Among 3000 overexposed persons 127 fatalities are registered in 57 years (ORISE, 2000). This latter number includes 28 operators and firemen who got fatal exposure in Chernobyl in April 1986 (IAEA et al., 1996a), and also those 7 cancer patients who (due to calibration errors) received an overdose for radiotherapy up to 60% in Costa Rica, in August–September 1996 (IAEA, 1998a).


WHERE DO RADIATION ACCIDENTS OCCUR?

Radiation accidents primarily occur with radiation devices, such as sealed sources (192Ir, 60Co, 137Cs) or X-ray devices for material testing (mainly radiography), in irradiation facilities or X-ray and radiotherapy devices (used in medicine or research).
      About one third of radiation accidents occurs in the industry, roughly each eighth of them in connection with the medical application of sources of ionizing radiation, while close to one third of them has unclear origin. Radiation accidents are the rarest in the transport and waste management or military application of radioactive materials or devices. About one half of radiation accidents are caused by 192Ir, and one quarter of them by 60Co, while the remaining 23% is due to 137Cs, radium, uranium, transuranic elements or unknown isotopes (Fig. 1).
      Accidents with unsealed radioisotopes (in isotope production facilities, nuclear medicine departments of hospitals and research) are much more rare. Criticality accidents in nuclear reactors or other critical assemblies are even less frequent. Radiation accidents during transportation of radioactive materials have never led to an overexposure of a single person.
      Analysing the frequency distribution of 405 radiation accidents with significant overexposure of at least one person in 1940–1999 (Fig. 2), one can conclude that accidents with radiation devices have become more frequent since 1970, reaching 40–45 events per five-year periods (ORISE, 2000). During the last 5-year period (1995–99) the accidents with sealed source became significantly less in number but more severe in outcome. The number of accidents with unsealed radioisotopes remained below ten except for the period of 1985–89, when they almost doubled compared to data of the previous interval. Since then a considerable decline could be observed. World-wide, the majority of the 22 criticality accidents during the last 60-years was registered before 1964. Since 1965 in five-year periods 0 to 2 criticality events were reported.

Fig. 1. Distribution of radiation accidents according to the type of facility and the radioisotopes involved, 1945–2000.

Number of accidents in 5-year periods

Fig. 2. Frequency distribution of radiation accidents world-wide, 1940–1999 (based on ORISE, 2000).


MAIN TYPES OF RADIATION ACCIDENTS

1. Radiation accidents depending on the population groups involved
1.1. 
Accidents may happen during work involving workers. The most frequent occurrence of this type of accident is observed in radiography, at irradiators (sealed sources and accelerators), and in nuclear research.
1.2. Accidental exposure of members of the public may occur due to loss of control over radiation sources used in radiotherapy, sterilizators, etc, and due to orphan sources.
1.3. Accidental exposure of patients during medical application of sources of ionizing radiation. In case of miscalibration of radiotherapy devices, accidental exposure may occur with large numbers of patients. However, more frequently, even a single patient may have an accidental exposure at an erroneous medical application (e.g., misadministration of the prescribed radiopharmacons).

2. Radiation accidents by type, time of recognition and management
2.1.  Radiation accidents of unknown origin and late recognition (e.g., Goiania, Brazil, 1987; Tammiku, Estonia, 1994; Lilo, Georgia, 1997; Istanbul, Turkey, 1998/99; Samut Prakarn, Thailand, 2000; Meet Halfa, Egypt, 2000)
2.2. Accidents of known radiation origin (e.g., Gilan, Iran, 1996; Yanango, Peru, 1999)
2.3. Accidental exposure in medical applications (e.g., Zarragosa, Spain, 1990; Costa Rica, 1996; Panorama, 2001)
2.4. Criticality accidents (e.g., Sarov, Russia, 1997; Tokaimura, Japan, 1999)
2.5. Nuclear accident with transboundary effects (Chernobyl, USSR, 1986).

3. Radiation accidents by scale
3.1.  Small-scale radiation accidents usually involve a small source term and a small number of individuals; they often come to light from observations by primary care physicians (mainly General Practitioners, and also by Occupational Physicians and Pediatricians).
3.2. Large-scale radiation accidents usually involve a large source term and a large number of persons may be irradiated and/or contaminated. They require treatment by specialist in both primary and secondary medical facilities and they can also lead to widespread public health actions to mitigate the effects of radioactive contamination.


WHY DO RADIATION ACCIDENTS OCCUR?

The main causes of radiation accidents in various application areas:
–  lack of information on usual physical appearance and possible harm of radiation sources which may lead to accidental overexposure in case of unauthorised possession;
– insufficiency of radiation protection and radiation safety regulations, or their deficient application;
– violation of radiation protection and radiation safety procedures;
– human error due to insufficient knowledge of radiation protection and radiation safety regulations;
– insufficient or inappropriate training of radiation protection and radiation safety rules and regulations;
– inappropriate application of gamma sources and X-ray machines in industrial radiography and production control;
– unauthorised repair of gamma sources and X-ray machines in industrial radiography and production control;
– misuse, including misadministration of ionizing radiation or radioactive substances for diagnostic radiology, nuclear medicine and radiotherapy (X-ray generating machines and gamma ray sources, particle accelerators, and sealed or unsealed radionuclide sources);
– misuse of gamma sources in the sterilization and preservation of foodstuff or for other purposes;
– negligent and/or unregulated disposal of radiation sources and/or radioactive waste.


HEALTH CONSEQUENCES OF THE SEVERE RADIATION ACCIDENTS SINCE CHERNOBYL

During the last 15 years 20 radiation accidents occurred world-wide leading to significant overexposure with clinical manifestation in at least one person per single event (Table 1). Acute clinical consequences of overexposure could be detected in 494 radiation accident patients, severe radiation injuries were observed in 316 cases that caused fatal outcome in 66 persons. Hence, radiation accidents during the last 15 years appeared with more severe consequences, as half of the cases of fatal outcome were observed in this interval within the 55-year period of observation.

Table 1. Radiation accidents in 1986–2000 and their health consequences

Place and date
(month
and/or year)

Type of facility and
main cause of the accident

Number of
exposed
persons with
acute clinical
consequences

Number of victims with severe radiation injury

Number of
deaths from
overexposure

Reference

Chernobyl,
Soviet Union,
April 1986

Nuclear power plant: loss of cooling and explosion of vapour due to multiple violation of safety rules


237


134

28
(+2 from
the vapour explosion)


IAEA et al.,
1996a

Goiania,
Brazil,
Sept.1987

Disposed 137Cs radio-
therapy source: breaking the stolen source


50


14


4

IAEA,
1998b,
1998c

San Salvador,
El Salvador,
1989

60Co irradiation facility: violation of safety rules during repair


3


3


1

IAEA,
1990

Soreq,
Israel,
1990

60Co irradiation facility: violation of safety rules during repair


1


1


1

IAEA,
1993a

Zarragosa, Spain, 1990

Radiotherapy accelerator: wrong calibration


27


27


11

IAEA,
2000b

Neswizh,
Belarus,
1991

60Co irradiation facility: violation of safety rules during repair


1


1


1

IAEA,
1993b

USA,
1991

Accelerator: violation of safety rules

1

1

–

IAEA,
2000b

Hanoi, Vietnam, 1992

Accelerator: violation of safety rules

1

1

–

IAEA,
1995

Jilin, China, 1992

60Co irradiation facility

8

8

3

Ye et al., 1997

USA,
1992

192Ir brachytherapy

1

1

1

IAEA and WHO, 1998a

Tammiku, Estonia,
1994

Disposed 137Cs source: steeling from waste repository


5


4


1

IAEA,
1998d

San Jose, Costa Rica, Aug-Sept. 1996

Radiotherapy: calibration error of dose rate of the new 60Co source


115


77


7

IAEA,
1998a

Gilan, Iran, July 1996

Radiography: loss of 192Ir source

1

1

–

IAEA,
2001a

Lilo, Georgia,
Dec. 1996–Apr. 1997

Military training site – possessing of the found unrecognized 137Cs source


11


11


–

IAEA and WHO,
2000a

Sarov, Russia,
June 1997

Criticality assembly: violation of safety rules

1

1

1

IAEA,
2001b

Istanbul, Turkey,
Dec. 1998

Unauthorized disposal and breakage of 60Co source transport container


10


10


–

IAEA,
2000c

Yanango, Peru,
Febr. 1999

Radiography: loss of
192Ir source

1

1

–

IAEA,
2000d

Tokaimura, Japan,
Sept. 1999

Radiochemical facility: criticality excursion due to violation of safety rules & procedures


3


3


2


IAEA,
1999b

Samut Prakarn, Thailand, Febr. 2000

Unauthorized disposal and breakage of radiotherapy heads with 60Co source


10


10


3


IAEA,
2001c

Meet Halfa,
Egypt,
May 2000

Radiography: loss of 192Ir source


7


7


2

Naggar & Mahmoud,
2000



THE MEDIC’S CONCERN – RECOGNITION OF AND RESPONSE TO RADIATION INJURIES

Hence, replying the first usual question of any single primary care physician, "How many radiation accidents can I yearly expect, in which I may be involved?" the most probable and justified answer can be zero, or perhaps one. Indeed, during the last 15 years there were 0–2 radiation accidents per year world-wide when the medical community had to face with the problem of treatment of a few persons having severe radiation injuries.
      Nevertheless, it cannot be excluded that an MD (mainly a GP) meets a patient who cannot explain the origin of his very general complaints or local symptoms reminding burn, blister or ulcer. The general symptoms, like nausea, vomiting, anorexia, diarrhoea, weakness, headache, dizziness and/or fatigue associated with lymphopenia appear in combination (within 2 days following an exposure of large part of the body). At a later stage (2–4 weeks after the accidental exposure to radiation source), they progress to simultaneous leuko- and thrombopenia, leading to gingival bleeding, epistaxis and petechiae as well as infectious complications (due to moderate to severe reduction or total loss of cellular immunity). In case of exposure of hairy parts of the body epilation may also develop in 2–4 weeks (IAEA, 1986; IAEA and WHO, 1998b; IAEA and WHO, 2000b).
      The second usual question of a physician – being as a rule, unfamiliar with the nature of the radiation hazard – "To what extent is a victim of a radiation accident dangerous for me and for my colleagues handling or treating such a patient?". Analysing the dosimetry and medical management records of the most recent radiation accident victims, it can be stated with certainty that the radiation accident patient does not present a health risk to the doctor or other responders. Thus, in case of combined injury or conventional illness, the priority and obligatory task of the primary care physician (first aid or ambulance staff) is to save the life of the victim, not considering his/her radiation exposure or radioactive contamination. All MDs should be aware that radiation does not produce life threatening early symptoms, immediate death or immediate burns, and irradiation alone is not a medical emergency.


LESSONS IDENTIFIED FOR PREVENTION OF RADIATION ACCIDENTS

1. General recommendations:

2. The quality assurance programmes in radiotherapy, diagnostic radiology and nuclear medicine should include:

3. Preparedness of public health authority, medical institutions and their staff for management of radiation accidents


CONCLUSION

There is a low chance for most of the physicians to meet a patient with symptoms of acute radiation injury during their professional career. However, in case of observation of the above described non-specific symptoms and signs, it is necessary to bear in mind – besides the usually diagnosed intestinal infection, food poisoning, allergy, or insect bite – their radiation origin as an alternative cause. It can be suspected independently of the unawareness of the accidental exposure by the patient. Radiation injury should not be ruled out today when improper registration, loss of control, unauthorised possession, smuggling or even criminal and terrorist use of radiation sources might, and occasionally does, occur.
      Hence, each physician has to be prepared to recognize and initially respond to radiation injuries. Specialists of radiohygiene, radiation medicine and public health must take the lead in conducting regular postgraduate training and medical education to successfully compete with this task.


REFERENCES

IAEA (1986). What the General Practitioner (MD) Should Know About Medical Handling of Overexposed Individuals. IAEA-TECDOC-366. International Atomic Energy Agency, Vienna.

IAEA (1990). The Radiological Accident in San Salvador. International Atomic Energy Agency, Vienna.

IAEA (1993a). The Radiological Accident in Soreq. International Atomic Energy Agency, Vienna.

IAEA (1993b). The Radiological Accident in Neswizh. International Atomic Energy Agency, Vienna.

IAEA (1995). The Radiological Accident in Hanoi, International Atomic Energy Agency, Vienna.

IAEA (1998a). The Radiotherapy Accident in Costa Rica. International Atomic Energy Agency, Vienna.

IAEA (1998b). The Radiological Accident in Goiania. International Atomic Energy Agency, Vienna.

IAEA (1998c). Dosimetric and medical aspects of the radiological accident in Goiania in 1987. IAEA-TECDOC-1009. International Atomic Energy Agency, Vienna.

IAEA (1998d). The Radiological Accident in Tammiku. International Atomic Energy Agency, Vienna.

IAEA (1999a). Generic Procedures for Monitoring in a Nuclear or Radiological Emergency. IAEA-TECDOC-1092. International Atomic Energy Agency, Vienna.

IAEA (1999b). Report on the preliminary fact finding mission following the accident at the nuclear fuel processing facility in Tokaimura, Japan. International Atomic Energy Agency, Vienna.

IAEA (2000a). Safety Glossary. IAEA Working Material, Version 1.0. International Atomic Energy Agency, Vienna.

IAEA (2000b). Lessons Learned from Accidental Exposures in Radiotherapy. Safety Reports Series No.17. International Atomic Energy Agency, Vienna.

IAEA (2000c). The Radiological Accident in Istanbul. International Atomic Energy Agency, Vienna.

IAEA (2000d). The Radiological Accident in Yanango. International Atomic Energy Agency, Vienna.

IAEA (2001a). The Radiological Accident in Gilan. International Atomic Energy Agency, Vienna (accepted for publication).

IAEA (2001b). The Criticality Accident in Sarov. International Atomic Energy Agency, Vienna.

IAEA (2001c). The Radiological Accident in Samut Prakarn. International Atomic Energy Agency, Vienna (accepted for publication).

IAEA, European commission, and WHO (1996a). One Decade after Chernobyl – Summing up the Consequences of the Accident. Proc. Internat. Conf., Vienna, 8–12 April 1996. International Atomic Energy Agency, Vienna.

IAEA, FAO, ILO, OECD/NEA, PAHO, and WHO (1996b). International Basic Safety Standards for Radiation Protection against Ionizing Radiation and for the Safety of Radiation Sources. International Atomic Energy Agency, Vienna.

IAEA and WHO (1998a). Planning the Medical Response to Radiological Accidents. Safety Reports Series No.4. International Atomic Energy Agency, Vienna.

IAEA and WHO (1998b). diagnosis and Treatment of Radiation Injuries. Safety Reports Series No.2, International Atomic Energy Agency, Vienna.

IAEA and WHO (2000a). The Radiological Accident in Lilo. International Atomic Energy Agency, Vienna.

IAEA and WHO (2000b). How to Recognize and Initially Respond to an Accidental Radiation Injury. Leaflet and Poster, International Atomic Energy Agency, Vienna.

NAGGAR, A. M. and MAHMOUD, M. H. (2000). The Radiological Accident at Meet Halfa, Qaloubiya. Egyptian Atomic Energy Authority, Cairo.

ORISE-EHSD-REAC/TS (2000). Radiation Accident Registries, REAC/TS, Oak Ridge, USA.

YE GENYAO, WANG GUILIN, LUO QINGLIANG, YANG ZHIXIANG, and MAO BINGZHI (1997). “Joint report for the Jilin 192Ir accident.” Chin. J. Rad. Med. Prot. 17: 338–347.


Received:  19 February 2001
Accepted:  03 March 2001

| Back |