Description, Sources, Mechanisms

Apart from the transportation of radioactive materials, there are three settings in which radiation accidents can occur:

• use of nuclear reactions to produce energy or arms, or for research purposes

• industrial applications of radiation (gamma radiography, irradiation)

• research and nuclear medicine (diagnosis or therapy).

Radiation accidents may be classified into two groups on the basis of whether or not there is environmental emission or dispersion of radionuclides; each of these types of accident affects different populations.

The magnitude and duration of the exposure risk for the general population depends on the quantity and the characteristics (half-life, physical and chemical properties) of the radionuclides emitted into the environment (table 1). This type of contamination occurs when there is rupture of the containment barriers at nuclear power plants or industrial or medical sites which separate radioactive materials from the environment. In the absence of environmental emissions, only workers present onsite or handling radioactive equipment or materials are exposed.

Table 1. Typical radionuclides, with their radioactive half-lives

^* y = years; d = days.

Exposure to ionizing radiation may occur through three routes, regardless of whether the target population is composed of workers or the general public: external irradiation, internal irradiation, and contamination of skin and wounds.

External irradiation occurs when individuals are exposed to an extracorporeal radiation source, either point (radiotherapy, irradiators) or diffuse (radioactive clouds and fallout from accidents, figure 1). Irradiation may be local, involving only a portion of the body, or whole body.

Figure 1. Exposure pathways to ionizing radiation after an accidental release of radioactivity in the environment

Internal radiation occurs following incorporation of radioactive substances into the body (figure 1) through either inhalation of airborne radioactive particles (e.g., caesium-137 and iodine-131, present in the Chernobyl cloud) or ingestion of radioactive materials in the food chain (e.g., iodine-131 in milk). Internal irradiation may affect the whole body or only certain organs, depending on the characteristics of the radionuclides: caesium-137 distributes itself homogeneously throughout the body, while iodine-131 and strontium-90 concentrate in the thyroid and the bones, respectively.

Finally, exposure may also occur through direct contact of radioactive materials with skin and wounds.

Accidents involving nuclear power plants

Sites included in this category include power-generating stations, experimental reactors, facilities for the production and processing or reprocessing of nuclear fuel and research laboratories. Military sites include plutonium breeder reactors and reactors located aboard ships and submarines.

Nuclear power plants

The capture of heat energy emitted by atomic fission is the basis for the production of electricity from nuclear energy. Schematically, nuclear power plants can be thought of as comprising: (1) a core, containing the fissile material (for pressurized-water reactors, 80 to 120 tonnes of uranium oxide); (2) heat-transfer equipment incorporating heat-transfer fluids; (3) equipment capable of transforming heat energy into electricity, similar to that found in power plants that are not nuclear.

Strong, sudden power surges capable of causing core meltdown with emission of radioactive products are the primary hazards at these installations. Three accidents involving reactor-core meltdown have occurred: at Three Mile Island (1979, Pennsylvania, United States), Chernobyl (1986, Ukraine), and Fukushima (2011, Japan) [Edited, 2011].

The Chernobyl accident was what is known as a criticality accident—that is, a sudden (within the space of a few seconds) increase in fission leading to a loss of process control. In this case, the reactor core was completely destroyed and massive amounts of radioactive materials were emitted (table 2). The emissions reached a height of 2 km, favouring their dispersion over long distances (for all intents and purposes, the entire Northern hemisphere). The behaviour of the radioactive cloud has proven difficult to analyse, due to meteorological changes during the emission period (figure 2) (IAEA 1991).

Table 2. Comparison of different nuclear accidents

Source: UNSCEAR 1993.

Figure 2. Trajectory of emissions from the Chernobyl accident, 26 April-6 May 1986

Contamination maps were drawn up on the basis of environmental measurements of caesium-137, one of the main radioactive emission products (table 1 and table 2). Areas of Ukraine, Byelorussia (Belarus) and Russia were heavily contaminated, while fallout in the rest of Europe was less significant (figure  3 and figure 4 (UNSCEAR 1988). Table 3 presents data on the area of the contaminated zones, characteristics of the exposed populations and routes of exposure.

FIgure 3. Caesium-137 deposition in Byelorussia, Russia and Ukraine following the Chernobyl accident.

Figure 4. Caesium-137 fallout (kBq/km2) in Europe following the Chernobyl accident

Table 3. Area of contaminated zones, types of populations exposed and modes of exposure in Ukraine, Byelorussia and Russia following the Chernobyl accident

* Individuals participating in clean-up within 30 km of the site. These include fire-fighters, military personnel, technicians and engineers who intervened during the first weeks, as well as physicians and researchers active at a later date.

^** Caesium-137 contamination.

Source: UNSCEAR 1988; IAEA 1991.

The Three Mile Island accident is classified as a thermal accident with no reactor runaway, and was the result of a reactor-core coolant failure lasting several hours. The containment shell ensured that only a limited quantity of radioactive material was emitted into the environment, despite the partial destruction of the reactor core (table 2). Although no evacuation order was issued, 200,000 residents voluntarily evacuated the area.

Finally, an accident involving a plutonium production reactor occurred on the west coast of England in 1957 (Windscale, table 2). This accident was caused by a fire in the reactor core and resulted in environmental emissions from a chimney 120 metres high.

Fuel-processing facilities

Fuel production facilities are located “upstream” from nuclear reactors and are the site of ore extraction and the physical and chemical transformation of uranium into fissile material suitable for use in reactors (figure 5). The primary accident hazards present in these facilities are chemical in nature and related to the presence of uranium hexafluoride (UF₆), a gaseous uranium compound which may decompose upon contact with air to produce hydrofluoric acid (HF), a very corrosive gas.

Figure 5. Nuclear fuel processing cycle.

“Downstream” facilities include fuel storage and reprocessing plants. Four criticality accidents have occurred during chemical reprocessing of enriched uranium or plutonium (Rodrigues 1987). In contrast to accidents occurring at nuclear power plants, these accidents involved small quantities of radioactive materials—tens of kilograms at most—and resulted in negligible mechanical effects and no environmental emission of radioactivity. Exposure was limited to very high dose, very short term (of the order of minutes) external gamma ray and neutron irradiation of workers.

In 1957, a tank containing highly radioactive waste exploded at Russia’s first military-grade plutonium production facility, located in Khyshtym, in the south Ural Mountains. Over 16,000 km² were contaminated and 740 PBq (20 MCi) were emitted into the atmosphere (table  2 and table 4).

Table 4. Surface area of the contaminated zones and size of population exposed after the Khyshtym accident (Urals 1957), by strontium-90 contamination

Research reactors

Hazards at these facilities are similar to those present at nuclear power plants, but are less serious, given the lower power generation. Several criticality accidents involving significant irradiation of personnel have occurred (Rodrigues 1987).

Accidents related to the use of radioactive sources in industry and medicine (excluding nuclear plants) (Zerbib 1993)

The most common accident of this type is the loss of radioactive sources from industrial gamma radiography, used, for example, for the radiographic inspection of joints and welds. However, radioactive sources may also be lost from medical sources (table 5). In either case, two scenarios are possible: the source may be picked up and kept by a person for several hours (e.g., in a pocket), then reported and restored, or it may be collected and carried home. While the first scenario causes local burns, the second may result in long-term irradiation of several members of the general public.

Table 5. Accidents involving the loss of radioactive sources and which resulted in exposure of the general public

^* Individuals exposed to doses capable of causing acute or long-term effects or death.
^** Among individuals receiving high doses.

Source: Nénot 1993.

The recovery of radioactive sources from radiotherapy equipment has resulted in several accidents involving the exposure of scrap workers. In two cases—the Juarez and Goiânia accidents—the general public was also exposed (see table 5 and box below).

The Goiвnia Accident, 1987

Between 21 September and 28 September 1987, several people suffering from vomiting, diarrhoea, vertigo and skin lesions at various parts of the body were admitted to the hospital specializing in tropical diseases in Goiânia, a city of one million inhabitants in the Brazilian state of Goias. These problems were attributed to a parasitic disease common in Brazil. On 28 September, the physician responsible for health surveillance in the city saw a woman who presented him with a bag containing debris from a device collected from an abandoned clinic, and a powder which emitted, according to the woman “a blue light”. Thinking that the device was probably x-ray equipment, the physician contacted his colleagues at the hospital for tropical diseases. The Goias Department of the Environment was notified, and the next day a physicist took measurements in the hygiene department’s yard, where the bag was stored overnight. Very high radioactivity levels were found. In subsequent investigations the source of radioactivity was identified as a caesium-137 source (total activity: approximately 50 TBq (1,375 Ci)) which had been contained within radiotherapy equipment used in a clinic abandoned since 1985. The protective housing surrounding the caesium had been disassembled on 10 September 1987 by two scrapyard workers and the caesium source, in powder form, removed. Both the caesium and the fragments of the contaminated housing were gradually dispersed throughout the city. Several people who had transported or handled the material, or who had simply come to see it (including parents, friends and neighbours) were contaminated. In all, over 100,000 people were examined, of whom 129 were very seriously contaminated; 50 were hospitalized (14 for medullary failure), and 4, including a 6-year-old girl, died. The accident had dramatic economic and social consequences for the entire city of Goiânia and the state of Goias: 1/1000 of the city’s surface area was contaminated, and the price of agricultural produce, rents, real estate, and land all fell. The inhabitants of the entire state suffered real discrimination.

Source: IAEA 1989a

The Juarez accident was discovered serendipitously (IAEA 1989b). On 16 January 1984, a truck entering the Los Alamos (New Mexico, United States) scientific laboratory loaded with steel bars triggered a radiation detector. Investigation revealed the presence of cobalt-60 in the bars and traced the cobalt-60 to a Mexican foundry. On January 21, a heavily contaminated scrapyard in Juarez was identified as the source of the radioactive material. Systematic monitoring of roads and highways by detectors resulted in the identification of a heavily contaminated truck. The ultimate radiation source was determined to be a radiotherapy device stored in a medical centre until December 1983, at which time it was disassembled and transported to the scrapyard. At the scrapyard, the protective housing surrounding the cobalt-60 was broken, freeing the cobalt pellets. Some of the pellets fell into the truck used to transport scrap, and others were dispersed throughout the scrapyard during subsequent operations, mixing with the other scrap.

Accidents involving the entry of workers into active industrial irradiators (e.g., those used to preserve food, sterilize medical products, or polymerize chemicals) have occurred. In all cases, these have been due to failure to follow safety procedures or to disconnected or defective safety systems and alarms. The dose levels of external irradiation to which workers in these accidents were exposed were high enough to cause death. Doses were received within a few seconds or minutes (table 6).

Table 6. Main accidents involving industrial irradiators

* EA: electron accelerator CI: cobalt-60 irradiator.

Source: Zerbib 1993; Nénot 1993.

Finally, medical and scientific personnel preparing or handling radioactive sources may be exposed through skin and wound contamination or inhalation or ingestion of radioactive materials. It should be noted that this type of accident is also possible in nuclear power plants.

Public Health Aspects of the Problem

Temporal patterns

The United States Radiation Accident Registry (Oak Ridge, United States) is a worldwide registry of radiation accidents involving humans since 1944. To be included in the registry, an accident must have been the subject of a published report and have resulted in whole-body exposure exceeding 0.25 Sievert (Sv), or skin exposure exceeding 6 Sv or exposure of other tissues and organs exceeding 0.75 Sv (see "Case Study: What does dose mean?" for a definition of dose). Accidents that are of interest from the point of view of public health but which resulted in lower exposures are thus excluded (see below for a discussion of the consequences of exposure).

Analysis of the registry data from 1944 to 1988 reveals a clear increase in both the frequency of radiation accidents and the number of exposed individuals starting in 1980 (table 7). The increase in the number of exposed individuals is probably accounted for by the Chernobyl accident, particularly the approximately 135,000 individuals initially residing in the prohibited area within 30 km of the accident site. The Goiânia (Brazil) and Juarez (Mexico) accidents also occurred during this period and involved significant exposure of many people (table 5).

Table 7. Radiation accidents listed in the Oak Ridge (United States) accident registry (worldwide, 1944-88)

^* 0.25 Sv for whole-body exposure, 6 Sv for skin exposure, 0.75 Sv for other tissues and organs.

Potentially exposed populations

From the point of view of exposure to ionizing radiation, there are two populations of interest: occupationally exposed populations and the general public. United Nations Scientific Committee on the Effects of Atomic Radiation (UNSCEAR 1993) estimates that 4 million workers worldwide were occupationally exposed to ionizing radiation in the period 1985-1989; of these, approximately 20% were employed in the production, use and processing of nuclear fuel (table 8). IAEA member countries were estimated to possess 760 irradiators in 1992, of which 600 were electron accelerators and 160 gamma irradiators.

Table 8. Temporal pattern of occupational exposure to ionizing radiation worldwide (in thousands)

^* Production and reprocessing of fuel: 40,000; reactor operation: 430,000.
^** including 190,000 shipboard personnel.

Source: UNSCEAR 1993.

The number of nuclear sites per country is a good indicator of the potential for exposure of the general public (figure 6).

Figure 6. Distribution of power-generating reactors and fuel  reprocessing plants in the world, 1989-90

Health Effects

Direct health effects of ionizing radiation

In general, the health effects of ionizing radiation are well known and depend on the dose level received and the dose rate (received dose per unit of time (see "Case Study: What does dose mean?").

Deterministic effects

These occur when the dose exceeds a given threshold and the dose rate is high. The severity of the effects is proportional to the dose, although the dose threshold is organ specific (table 9).

Table 9. Deterministic effects: thresholds for selected organs

Source: ICRP 1991.

In the accidents such as those discussed above, deterministic effects may be caused by local intense irradiation, such as that caused by external irradiation, direct contact with a source (e.g., a misplaced source picked up and pocketed) or skin contamination. All these result in radiological burns. If the local dose is of the order of 20 to 25 Gy (table 6, "Case Study: What does dose mean?") tissue necrosis may ensue. A syndrome known as acute irradiation syndrome, characterized by digestive disorders (nausea, vomiting, diarrhoea) and bone marrow aplasia of variable severity, may be induced when the average whole-body irradiation dose exceeds 0.5 Gy. It should be recalled that whole-body and local irradiation may occur simultaneously.

Nine of 60 workers exposed during criticality accidents at nuclear fuel processing plants or research reactors died (Rodrigues 1987). Decedents received 3 to 45 Gy, while survivors received 0.1 to 7 Gy. The following effects were observed in survivors: acute irradiation syndrome (gastro-intestinal and haematological effects), bilateral cataracts and necrosis of limbs, requiring amputation.

At Chernobyl, power plant personnel, as well as emergency response personnel not using special protective equipment, suffered high beta and gamma radiation exposure in the initial hours or days following the accident. Five hundred people required hospitalization; 237 individuals who received whole-body irradiation exhibited acute irradiation syndrome, and 28 individuals died despite treatment (table 10) (UNSCEAR 1988). Others received local irradiation of the limbs, in some cases affecting over 50% of the body surface and continue to suffer, many years later, multiple skin disorders (Peter, Braun-Falco and Birioukov 1994).

Table 10. Distribution of patients exhibiting acute irradiation syndrome (AIS) after the Chernobyl accident, by severity of condition

Source: UNSCEAR 1988.

Stochastic effects

These are probabilistic in nature (i.e., their frequency increases with received dose), but their severity is independent of dose. The main stochastic effects are:

• Mutation. This has been observed in animal experiments but has been difficult to document in humans.

• Cancer. The effect of irradiation on the risk of developing cancer has been studied in patients receiving radiation therapy and in survivors of the Hiroshima and Nagasaki bombings. UNSCEAR (1988, 1994) regularly summarizes the results of these epidemiological studies. The duration of the latency period is typically 5 to 15 years from the date of exposure depending on organ and tissue. Table 11 lists the cancers for which an association with ionizing radiation has been established. Significant cancer excesses have been demonstrated among survivors of the Hiroshima and Nagasaki bombings with exposures above 0.2 Sv.

• Selected benign tumours. Benign thyroid adenomas.

Table 11. Results of epidemiological studies of the effect of high dose rate of external irradiation on cancer

+ Cancer sites studied in the Hiroshima and Nagasaki survivors.
* Positive association with ionizing radiation.
¹ Cohort (incidence or mortality) or case-control studies.

Source: UNSCEAR 1994.

Two important points concerning the effects of ionizing radiation remain controversial.

Firstly, what are the effects of low-dose irradiation (below 0.2 Sv) and low dose rates? Most epidemiological studies have examined survivors of the Hiroshima and Nagasaki bombings or patients receiving radiation therapy—populations exposed over very short periods to relatively high doses—and estimates of the risk of developing cancer as a result of exposure to low doses and dose rates depends essentially on extrapolations from these populations. Several studies of nuclear power plant workers, exposed to low doses over several years, have reported cancer risks for leukaemia and other cancers that are compatible with extrapolations from high-exposure groups, but these results remain unconfirmed (UNSCEAR 1994; Cardis, Gilbert and Carpenter 1995).

Secondly, is there a threshold dose (i.e., a dose below which there is no effect)? This is currently unknown. Experimental studies have demonstrated that damage to genetic material (DNA) caused by spontaneous errors or environmental factors are constantly repaired. However, this repair is not always effective, and may result in malignant transformation of cells (UNSCEAR 1994).

Other effects

Finally, the possibility of teratogenic effects due to irradiation during pregnancy should be noted. Microcephaly and mental retardation have been observed in children born to female survivors of the Hiroshima and Nagasaki bombings who received irradiation of at least 0.1 Gy during the first trimester (Otake, Schull and Yoshimura 1989; Otake and Schull 1992). It is unknown whether these effects are deterministic or stochastic, although the data do suggest the existence of a threshold.

Effects observed following the Chernobyl accident

The Chernobyl accident is the most serious nuclear accident to have occurred to date. However, even now, ten years after the fact, not all the health effects on the most highly exposed populations have been accurately evaluated. There are several reasons for this:

• Some effects appear only many years after the date of exposure: for example, solid-tissue cancers typically take 10 to 15 years to appear.

• As some time elapsed between the accident and the commencement of epidemiological studies, some effects occurring in the initial period following the accident may not have been detected.

• Useful data for the quantification of the cancer risk were not always gathered in a timely fashion. This is particularly true for data necessary to estimate the exposure of the thyroid gland to radioactive iodides emitted during the incident (tellurium-132, iodine-133) (Williams et al. 1993).

• Finally, many initially exposed individuals subsequently left the contaminated zones and were probably lost for follow-up.

Workers. Currently, comprehensive information is unavailable for all the workers who were strongly irradiated in the first few days following the accident. Studies on the risk to clean-up and relief workers of developing leukaemia and solid-tissue cancers are in progress (see table 3). These studies face many obstacles. Regular follow-up of the health status of clean-up and relief workers is greatly hindered by the fact that many of them came from different parts of the ex-USSR and were redispatched after working on the Chernobyl site. Further, received dose must be estimated retrospectively, as there are no reliable data for this period.

General population. The only effect plausibly associated with ionizing radiation in this population to date is an increase, starting in 1989, of the incidence of thyroid cancer in children younger than 15 years. This was detected in Byelorussia (Belarus) in 1989, only three years after the incident, and has been confirmed by several expert groups (Williams et al. 1993). The increase was particularly noteworthy in the most heavily contaminated areas of Belarus, especially the Gomel region. While thyroid cancer was normally rare in children younger than 15 years, (annual incidence rate of 1 to 3 per million), its incidence increased tenfold on a national basis and twentyfold in the Gomel area (table 12, figure 7), (Stsjazhko et al. 1995). A tenfold increase of the incidence of thyroid cancer was subsequently reported in the five most heavily contaminated areas of Ukraine, and an increase in thyroid cancer was also reported in the Bryansk (Russia) region (table 12). An increase among adults is suspected but has not been confirmed. Systematic screening programmes undertaken in the contaminated regions allowed latent cancers present prior to the accident to be detected; ultrasonographic programmes capable of detecting thyroid cancers as small as a few millimetres were particularly helpful in this regard. The magnitude of the increase in incidence in children, taken together with the aggressiveness of the tumours and their rapid development, suggests that the observed increases in thyroid gland cancer are partially due to the accident.

Table 12. Temporal pattern of the incidence and total number of thyroid cancers in children in Belarus, Ukraine & Russia, 1981-94

* Incidence: the ratio of the number of new cases of a disease during a given period to the size of the population studied in the same period.

Source: Stsjazhko et al. 1995.

Figure 7. Incidence of cancer of the thyroid in children younger than 15 years in Belarus

In the most heavily contaminated zones (e.g., the Gomel region), the thyroid doses were high, particularly among children (Williams et al. 1993). This is consistent with the significant iodine emissions associated with the accident and the fact that radioactive iodine will, in the absence of preventive measures, concentrate preferentially in the thyroid gland.

Exposure to radiation is a well-documented risk factor for thyroid cancer. Clear increases in the incidence of thyroid cancer have been observed in a dozen studies of children receiving radiation therapy to the head and neck. In most cases, the increase was clear ten to 15 years after exposure, but was detectable in some cases within three to seven years. On the other hand, the effects in children of internal irradiation by iodine-131 and by short half-life iodine isotopes are not well established (Shore 1992).

The precise magnitude and pattern of the increase in the coming years of the incidence of thyroid cancer in the most highly exposed populations should be studied. Epidemiological studies currently under way should help to quantify the association between the dose received by the thyroid gland and the risk of developing thyroid cancer, and to identify the role of other genetic and environmental risk factors. It should be noted that iodine deficiency is widespread in the affected regions.

An increase in the incidence of leukaemia, particularly juvenile leukaemia (since children are more sensitive to the effects of ionizing radiation), is to be expected among the most highly exposed members of the population within five to ten years of the accident. Although no such increase has yet been observed, the methodological weaknesses of the studies conducted to date prevent any definitive conclusions from being drawn.

Psychosocial effects

The occurrence of more or less severe chronic psychological problems following psychological trauma is well established and has been studied primarily in populations faced with environmental disasters such as floods, volcanic eruptions and earthquakes. Post-traumatic stress is a severe, long-lasting and crippling condition (APA 1994).

Most of our knowledge on the effect of radiation accidents on psychological problems and stress is drawn from studies conducted in the wake of the Three Mile Island accident. In the year following the accident, immediate psychological effects were observed in the exposed population, and mothers of young children in particular exhibited increased sensitivity, anxiety and depression (Bromet et al. 1982). Further, an increase in depression and anxiety-related problems was observed in power-plant workers, compared to workers in another power plant (Bromet et al. 1982). In the following years (i.e., after the reopening of the power plant), approximately one-quarter of the surveyed population exhibited relatively significant psychological problems. There was no difference in the frequency of psychological problems in the rest of the survey population, compared to control populations (Dew and Bromet 1993). Psychological problems were more frequent among individuals living close to the power plant who were without a social support network, had a history of psychiatric problems, or who had evacuated their home at the time of the accident (Baum, Cohen and Hall 1993).

Studies are also under way among populations exposed during the Chernobyl accident and for whom stress appears to be an important public health issue (e.g., clean-up and relief workers and individuals living in a contaminated zone). For the moment, however, there are no reliable data on the nature, severity, frequency and distribution of psychological problems in the target populations. The factors that must be taken into account when evaluating the psychological and social consequences of the accident on residents of the contaminated zones include the harsh social and economic situation, the diversity of the available compensation systems, the effects of evacuation and resettlement (approximately 100,000 additional people were resettled in the years following the accident), and the effects of lifestyle limitations (e.g., modification of nutrition).

Principles of Prevention and Guidelines

Safety principles and guidelines

Industrial and medical use of radioactive sources

While it is true that the major radiation accidents reported have all occurred at nuclear power plants, the use of radioactive sources in other settings has nevertheless resulted in accidents with serious consequences for workers or the general public. The prevention of accidents such as these is essential, especially in light of the disappointing prognosis in cases of high-dose exposure. Prevention depends on proper worker training and on the maintenance of a comprehensive life-cycle inventory of radioactive sources which includes information on both the sources’ nature and location. The IAEA has established a series of safety guidelines and recommendations for the use of radioactive sources in industry, medicine and research (Safety Series No. 102). The principles in question are similar to those presented below for nuclear power plants.

Safety in nuclear power plants (IAEA Safety Series No. 75, INSAG-3)

The goal here is to protect both humans and the environment from the emission of radioactive materials under any circumstance. To this end, it is necessary to apply a variety of measures throughout the design, construction, operation and decommissioning of nuclear power plants.

The safety of nuclear power plants is fundamentally dependent on the “defence in depth” principle—that is, the redundancy of systems and devices designed to compensate for technical or human errors and deficiencies. Concretely, radioactive materials are separated from the environment by a series of successive barriers. In nuclear power production reactors, the last of these barriers is the containment structure (absent on the Chernobyl site but present at Three Mile Island). To avoid the breakdown of these barriers and to limit the consequences of breakdowns, the following three safety measures should be practised throughout the power plant’s operational life: control of the nuclear reaction, cooling of fuel, and containment of radioactive material.

Another essential safety principle is “operating experience analysis”—that is, using information gleaned from events, even minor ones, occurring at other sites to increase the safety of an existing site. Thus, analysis of the Three Mile Island and Chernobyl accidents has resulted in the implementation of modifications designed to ensure that similar accidents do not occur elsewhere.

Finally, it should be noted that significant efforts have been expended to promote a culture of safety, that is, a culture that is continually responsive to safety concerns related to the plant’s organization, activities and practices, as well as to individual behaviour. To increase the visibility of incidents and accidents involving nuclear power plants, an international scale of nuclear events (INES), identical in principle to scales used to measure the severity of natural phenomena such as earthquakes and wind, has been developed (table 12). This scale is not however suitable for the evaluation of a site’s safety or for performing international comparisons.

Table 13. International scale of nuclear incidents

Principles of the protection of the general public from exposure to radiation

In cases involving the potential exposure of the general public, it may be necessary to apply protective measures designed to prevent or limit exposure to ionizing radiation; this is particularly important if deterministic effects are to be avoided. The first measures which should be applied in emergency are evacuation, sheltering and administration of stable iodine. Stable iodine should be distributed to exposed populations, since this will saturate the thyroid and inhibit its uptake of radioactive iodine. To be effective, however, thyroid saturation must occur before or soon after the start of exposure. Finally, temporary or permanent resettlement, decontamination, and control of agriculture and food may eventually be necessary.

Each of these countermeasures has its own “action level” (table 14), not to be confused with the ICRP dose limits for workers and the general public, developed to ensure adequate protection in cases of non-accidental exposure (ICRP 1991).

Table 14. Examples of generic intervention levels for protective measures for general population

Source: IAEA 1994.

Research Needs and Future Trends

Current safety research concentrates on improving the design of nuclear power-generating reactors—more specifically, on the reduction of the risk and effects of core meltdown.

The experience gained from previous accidents should lead to improvements in the therapeutic management of seriously irradiated individuals. Currently, the use of bone marrow cell growth factors (haematopoietic growth factors) in the treatment of radiation-induced medullary aplasia (developmental failure) is being investigated (Thierry et al. 1995).

The effects of low doses and dose rates of ionizing radiation remains unclear and needs to be clarified, both from a purely scientific point of view and for the purposes of establishing dose limits for the general public and for workers. Biological research is necessary to elucidate the carcinogenic mechanisms involved. The results of large-scale epidemiological studies, especially those currently under way on workers at nuclear power plants, should prove useful in improving the accuracy of cancer risk estimates for populations exposed to low doses or dose rates. Studies on populations which are or have been exposed to ionizing radiation due to accidents should help further our understanding of the effects of higher doses, often delivered at low dose rates.

The infrastructure (organization, equipment and tools) necessary for the timely collection of data essential for the evaluation of the health effects of radiation accidents must be in place well in advance of the accident.

Finally, extensive research is necessary to clarify the psychological and social effects of radiation accidents (e.g., the nature and frequency of, and risk factors for, pathological and non-pathological post-traumatic psychological reactions). This research is essential if the management of both occupationally and non-occupationally exposed populations is to be improved.

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Massive contamination of agricultural lands by radionuclides occurs, as a rule, due to large accidents at the enterprises of nuclear industry or nuclear power stations. Such accidents occurred at Windscale (England) and South Ural (Russia). The largest accident happened in April 1986 at the Chernobyl nuclear power station. The latter entailed intensive contamination of soils over several thousands of square kilometres.

The major factors contributing to radiation effects in agricultural areas are as follows:

• whether radiation is from a single or a long-term exposure

• total quantity of radioactive substances entering the environment

• ratio of radionuclides in the fallout

• distance from the source of radiation to agricultural lands and settlements

• hydrogeological and soil characteristics of agricultural lands and the purpose of their use

• peculiarities of work of the rural population; diet, water supply

• time since the radiological accident.

As a result of the Chernobyl accident more than 50 million Curies (Ci) of mostly volatile radionuclides entered the environment. At the first stage, which covered 2.5 months (the “iodine period”), iodine-131 produced the greatest biological hazard, with significant doses of high-energy gamma radiation.

Work on agricultural lands during the iodine period should be strictly regulated. Iodine-131 accumulates in the thyroid gland and damages it. After the Chernobyl accident, a zone of very high radiation intensity, where no one was permitted to live or work, was defined by a 30 km radius around the station.

Outside this prohibited zone, four zones with various rates of gamma radiation on the soils were distinguished according to which types of agricultural work could be performed; during the iodine period, the four zones had the following radiation levels measured in roentgen (R):

• zone 1—less than 0.1 mR/h

• zone 2—0.1 to 1 mR/h

• zone 3—1.0 to 5 mR/h

• zone 4—5 mR/h and more.

Actually, due to the “spot” contamination by radionuclides over the iodine period, agricultural work in these zones was performed at levels of gamma irradiation from 0.2 to 25 mR/h. Apart from uneven contamination, variation in gamma radiation levels was caused by different concentrations of radionuclides in different crops. Forage crops in particular are exposed to high levels of gamma emitters during harvesting, transportation, ensilage and when they are used as fodder.

After the decay of iodine-131, the major hazard for agricultural workers is presented by the long-lived nuclides caesium-137 and strontium-90. Caesium-137, a gamma emitter, is a chemical analogue of potassium; its intake by humans or animals results in uniform distribution throughout the body and it is relatively quickly excreted with urine and faeces. Thus, the manure in the contaminated areas is an additional source of radiation and it must be removed as quickly as possible from stock farms and stored in special sites.

Strontium-90, a beta emitter, is a chemical analogue of calcium; it is deposited in bone marrow in humans and animals. Strontium-90 and caesium-137 can enter the human body through contaminated milk, meat or vegetables.

The division of agricultural lands into zones after the decay of short-lived radionuclides is carried out according to a different principle. Here, it is not the level of gamma radiation, but the amount of soil contamination by caesium-137, strontium-90 and plutonium-239 that are taken into account.

In the case of particularly severe contamination, the population is evacuated from such areas and farm work is performed on a 2-week rotation schedule. The criteria for zone demarcation in the contaminated areas are given in table 1.

Table 1. Criteria for contamination zones

When people work on agricultural lands contaminated by radionuclides, the intake of radionuclides by the body through respiration and contact with soil and vegetable dusts may occur. Here, both beta emitters (strontium-90) and alpha emitters are extremely dangerous.

As a result of accidents at nuclear power stations, part of radioactive materials entering the environment are low-dispersed, highly active particles of the reactor fuel—“hot particles”.

Considerable amounts of dust containing hot particles are generated during agricultural work and in windy periods. This was confirmed by the results of investigations of tractor air filters taken from machines which were operated on the contaminated lands.

The assessment of dose loads on the lungs of agricultural workers exposed to hot particles revealed that outside the 30 km zone the doses amounted to several millisieverts (Loshchilov et al. 1993).

According to the data of Bruk et al. (1989) the total activity of caesium-137 and caesium-134 in the inspired dust in machine operators amounted to 0.005 to 1.5 nCi/m³. According to their calculations, over the total period of field work the effective dose to lungs ranged from 2 to
70 cSv.

The relation between the amount of soil contamination by caesium-137 and radioactivity of work zone air was established. According to the data of the Kiev Institute for Occupational Health it was found that when the soil contamination by caesium-137 amounted to 7.0 to 30.0 Ci/km² the radioactivity of the breathing zone air reached 13.0 Bq/m³. In the control area, where the density of contamination amounted to 0.23 to 0.61 Ci/km³, the radioactivity of work zone air ranged from 0.1 to 1.0 Bq/m³ (Krasnyuk, Chernyuk and Stezhka 1993).

The medical examinations of agricultural machine operators in the “clear” and contaminated zones revealed an increase in cardiovascular diseases in workers in the contaminated zones, in the form of ischaemic heart disease and neurocirculatory dystonia. Among other disorders dysplasia of the thyroid gland and an increased level of monocytes in the blood were registered more frequently.

Hygienic Requirements

Work schedules

After large accidents at nuclear power stations, temporary regulations for the population are usually adopted. After the Chernobyl accident temporary regulations for a period of one year were adopted, with the TLV of 10 cSv. It is assumed that workers receive 50% of their dose due to external radiation during work. Here, the threshold of intensity of radiation dose over the eight-hour work day should not exceed 2.1 mR/h.

During agricultural work, the radiation levels at workplaces can fluctuate significantly, depending on the concentrations of radioactive substances in soils and plants; they also fluctuate during technological processing (siloing, preparation of dry fodder and so on). In order to reduce dosages to workers, regulations of time limits for agricultural work are introduced. Figure 1 shows regulations which were introduced after the Chernobyl accident.

Figure 1. Time limits for agricultural work depending on intensity of gamma-ray  radiation at workplaces.

Agrotechnologies

When carrying out agricultural work in conditions of high contamination of soils and plants, it is necessary to strictly observe measures directed at prevention of dust contamination. The loading and unloading of dry and dusty substances should be mechanized; the neck of the conveyer tube should be covered with fabric. Measures directed at the decrease of dust release must be undertaken for all types of field work.

Work using agricultural machinery should be carried out taking due account of cabin pressurization and the choice of the proper direction of operation, with the wind at the side being preferable. If possible it is desirable to first water the areas being cultivated. The wide use of industrial technologies is recommended so as to eliminate manual work on the fields as much as possible.

It is appropriate to apply substances to the soils which can promote absorption and fixation of radionuclides, changing them into insoluble compounds and thus preventing the transfer of radionuclides into plants.

Agricultural machinery

One of the major hazards for the workers is agricultural machinery contaminated by radionuclides. The allowable work time on the machines depends on the intensity of gamma radiation emitted from the cabin surfaces. Not only is the thorough pressurization of cabins required, but due control over ventilation and air conditioning systems as well. After work, wet cleaning of cabins and replacement of filters should be carried out.

When maintaining and repairing the machines after decontamination procedures, the intensity of gamma radiation at the outer surfaces should not exceed 0.3 mR/h.

Buildings

Routine wet cleaning should be done inside and outside buildings. Buildings should be equipped with showers. When preparing fodder which contains dust components, it is necessary to adhere to procedures aimed at prevention of dust intake by the workers, as well as to keep the dust off the floor, equipment and so on.

Pressurization of the equipment should be under control. Workplaces should be equipped with effective general ventilation.

Use of pesticides and mineral fertilizers

The application of dust and granular pesticides and mineral fertilizers, as well as spraying from aeroplanes, should be restricted. Machine spraying and application of granular chemicals as well as liquid mixed fertilizers are preferable. The dust mineral fertilizers should be stored and transported only in tightly closed containers.

Loading and unloading work, preparation of pesticide solutions and other activities should be performed using maximum individual protective equipment (overalls, helmets, goggles, respirators, rubber gauntlets and boots).

Water supply and diet

There should be special closed premises or motor vans without draughts where workers can take their meals. Before taking meals workers should clean their clothes and thoroughly wash their hands and faces with soap and running water. During summer periods field workers should be supplied with drinking water. The water should be kept in closed containers. Dust must not enter containers when filling them with water.

Preventive medical examinations of workers

Periodic medical examinations should be carried out by a physician; laboratory analysis of blood, ECG and tests of respiratory function are compulsory. Where radiation levels do not exceed permissible limits, the frequency of medical examinations should be not less than once every 12 months. Where there are higher levels of ionizing radiation the examinations should be carried out more frequently (after sowing, harvesting and so on) with due account of radiation intensity at workplaces and the total absorbed dose.

Organization of Radiological Control over Agricultural Areas

The major indices characterizing the radiological situation after fallout are gamma radiation intensity in the area, contamination of agricultural lands by the selected radionuclides and content of radionuclides in agricultural products.

The determination of gamma radiation levels in the areas allows the drawing of the borders of severely contaminated areas, estimation of doses of external radiation to people engaged in agricultural work and the establishing of corresponding schedules providing for radiological safety.

The functions of radiological monitoring in agriculture are usually the responsibility of radiological laboratories of the sanitary service as well as veterinary and agrochemical radiological laboratories. The training and education of the personnel engaged in dosimetric control and consultations for the rural population are carried out by these laboratories.

Back

A tragic industrial fire in Thailand has focused worldwide attention on the need to adopt and enforce state-of-the-art codes and standards in industrial occupancies.

On May 10, 1993, a major fire at the Kader Industrial (Thailand) Co. Ltd. factory located in the Nakhon Pathom Province of Thailand killed 188 workers (Grant and Klem 1994). This disaster stands as the world’s worst accidental loss-of-life fire in an industrial building in recent history, a distinction held for 82 years by the Triangle Shirtwaist factory fire that killed 146 workers in New York City (Grant 1993). Despite the years between these two disasters, they share striking similarities.

Various domestic and international agencies have focused on this incident following its occurrence. With respect to fire protection concerns, the National Fire Protection Association (NFPA) cooperated with the International Labour Organization (ILO) and with the Bangkok Police Fire Brigade in documenting this fire.

Questions for a Global Economy

In Thailand, the Kader fire has created a great deal of interest about the country’s fire safety measures, particularly its building code design requirements and enforcement policies. Thai Prime Minister Chuan Leekpai, who travelled to the scene on the evening of the fire, has pledged that the government will address fire safety issues. According to the Wall Street Journal (1993), Leekpai has called for tough action against those who violate the safety laws. Thai Industry Minister Sanan Kachornprasart is quoted as saying that “Those factories without fire prevention systems will be ordered to install one, or we will shut them down”.

The Wall Street Journal goes on to state that labour leaders, safety experts and officials say that the Kader fire may help tighten building codes and safety regulations, but they fear that lasting progress is still far off as employers flout rules and governments allow economic growth to take priority over worker safety.

Because the majority of the shares of Kader Industrial (Thailand) Co. Ltd. are owned by foreign interests, the fire has also fuelled international debate about foreign investors’ responsibilities for ensuring the safety of the workers in their sponsoring country. Twenty per cent of the Kader shareholders are from Taiwan, and 79.96% are from Hong Kong. A mere 0.04% of Kader is owned by Thai nationals.

Moving into a global economy implies that products are manufactured at one location and used at other locations throughout the world. Desire for competitiveness in this new market should not lead to compromise in fundamental industrial fire safety provisions. There is a moral obligation to provide workers with an adequate level of fire protection, no matter where they are located.

The Facility

The Kader facility, which manufactured stuffed toys and plastic dolls primarily intended for export to the United States and other developed countries, is located in the Sam Phran District of Nakhon Pathom Province. This is not quite halfway between Bangkok and the nearby city of Kanchanaburi, the site of the infamous Second World War railroad bridge over the River Kwai.

The structures that were destroyed in the blaze were all owned and operated directly by Kader, which owns the site. Kader has two sister companies that also operate at the location on a lease arrangement.

The Kader Industrial (Thailand) Co. Ltd. was first registered on 27 January 1989, but the company’s licence was suspended on 21 November 1989, after a fire on 16 August 1989 destroyed the new plant. This fire was attributed to the ignition of polyester fabric used in the manufacture of dolls in a spinning machine. After the plant was rebuilt, the Ministry of Industry allowed it to reopen on 4 July 1990.

Between the time the factory reopened and the May 1993 fire, the facility experienced several other, smaller fires. One of them, which occurred in February 1993, did considerable damage to Building Three, which was still being repaired at the time of the fire in May 1993. The February fire occurred late at night in a storage area and involved polyester and cotton materials. Several days after this blaze a labour inspector visited the site and issued a warning that pointed out the plant’s need for safety officers, safety equipment and an emergency plan.

Initial reports following the May 1993 fire noted that there were four buildings on the Kader site, three of which were destroyed by the fire. In a sense this is true, but the three buildings were actually a single E-shaped structure (see figure 1), the three primary portions of which were designated Buildings One, Two and Three. Nearby was a one-storey workshop and another four-storey structure referred to as Building Four.

Figure 1. Site plan of the Kader toy factory

The E-shaped building was a four-storey structure composed of concrete slabs supported by a structural steel frame. There were windows around the perimeter of each floor and the roof was a gently sloped, peaked arrangement. Each portion of the building had a freight elevator and two stairwells that were each 1.5 metres (3.3 feet) wide. The freight elevators were caged assemblies.

Each building at the plant was equipped with a fire alarm system. None of the buildings had automatic sprinklers, but portable extinguishers and hose stations were installed on outside walls and in the stairwells of each building. None of the structural steel in the building was fireproofed.

There is conflicting information about the total number of workers at the site. The Federation of Thai Industries had pledged to help 2,500 plant employees displaced by the fire, but it is unclear how many employees were at the site at any one time. When the fire occurred, it was reported that there were 1,146 workers in Building One. Thirty-six were on the first floor, 10 were on the second, 500 were on the third, and 600 were on the fourth. There were 405 workers in Building Two. Sixty of them were on the first floor, 5 were on the second, 300 were on the third and 40 were on the fourth. It is not clear how many workers                                                                                                                     were in Building Three since a portion of it was still being                                                                                                                                 refurbished. Most of the workers at the plant were women.

The Fire

Monday, May 10, was a normal workday at the Kader facility. At approximately 4:00 p.m., as the end of the day shift approached, someone discovered a small fire on the first floor near the south end of Building One. This portion of the building was used to package and store the finished products, so it contained a considerable fuel load (see figure 2). Each building at the facility had a fuel load composed of fabric, plastics and materials used for stuffing, as well as other normal workplace materials.

Figure 2. Internal layout of buildings one, two and three

Security guards in the vicinity of the fire tried unsuccessfully to extinguish the flames before they called the local police fire brigade at 4:21 p.m. Authorities received two more calls, at 4:30 p.m. and 4:31 p.m. The Kader facility is just beyond the jurisdictional boundaries of Bangkok, but fire apparatus from Bangkok, as well as apparatus from Nakhon Pathom Province, responded.

As the workers and security guards tried in vain to extinguish the fire, the building began filling with smoke and other products of combustion. Survivors reported that the fire alarm never sounded in Building One, but many workers grew concerned when they saw smoke on the upper floors. Despite the smoke, security guards reportedly told some workers to stay at their stations because it was a small fire that would soon be under control.

The fire spread rapidly throughout Building One, and the upper floors soon became untenable. The blaze blocked the stairwell at the south end of the building, so most of the workers rushed to the north stairwell. This meant that approximately 1,100 people were trying to leave the third and fourth floors through a single stairwell.

The first fire apparatus arrived at 4:40 p.m., their response time having been extended because of the relatively remote location of the facility and the gridlock conditions typical of Bangkok traffic. Arriving fire-fighters found Building One heavily involved in                                                                                                                                 flames and already beginning to collapse, with people jumping                                                                                                                       from the third and fourth floors.

Despite the fire-fighters’ efforts, Building One collapsed completely at approximately 5:14 p.m. Fanned by strong winds blowing toward the north, the blaze spread quickly into Buildings Two and Three before the fire brigade could effectively defend them. Building Two reportedly collapsed at 5:30 p.m., and Building Three at 6:05 p.m. The fire brigade successfully kept the fire from entering Building Four and the smaller, one-storey workshop nearby, and the fire-fighters had the blaze under control by 7:45 p.m. Approximately 50 pieces of fire apparatus were involved in the battle.

The fire alarms in Buildings Two and Three reportedly functioned properly, and all the workers in those two buildings escaped. The workers in Building One were not so fortunate. A large number of them jumped from the upper floors. In all, 469 workers were taken to the hospital, where 20 died. The other dead were found during the post-fire search of what had been the north stairwell of the building. Many of them apparently succumbed to lethal products of combustion before or during the building’s collapse. According to the latest information available, 188 people, most of them female, have died as a result of this fire.

Even with the help of six large hydraulic cranes that were moved to the site to facilitate the search for victims, it was several days before all the bodies could be removed from the rubble. There were no fatalities among the fire-fighters, although there was one injury.

Traffic in the vicinity, which is normally congested, made transporting the victims to hospitals difficult. Nearly 300 injured workers were taken to the nearby Sriwichai II Hospital, although many of them were transferred to alternate medical facilities when the number of victims exceeded the hospital’s capacity to treat them.

The day after the fire, Sriwichai II Hospital reported that it had kept 111 fire victims. The Kasemrat Hospital received 120; Sriwichai Pattanana received 60; Sriwichai I received 50; Ratanathibet I received 36; Siriraj received 22; and Bang Phai received 17. The remaining 53 injured workers were sent to various other medical facilities in the area. In all, 22 hospitals throughout Bangkok and Nakhon Pathom Province participated in treating victims of the disaster.

Sriwichai II Hospital reported that 80% of their 111 victims suffered serious injuries and that 30% required surgery. Half of the patients suffered only from smoke inhalation, while the remainder also suffered burns and fractures that ranged from broken ankles to fractured skulls. At least 10% of the injured Kader workers admitted to Sriwichai II Hospital risk permanent paralysis.

Determining the cause of this fire became a challenge because the portion of the facility in which it began was totally destroyed and the survivors have provided conflicting information. Since the fire started near a large electrical control panel, investigators first thought that problems with the electrical system might have been the cause. They also considered arson. At this time, however, Thai authorities feel that a carelessly discarded cigarette may have been the source of ignition.

Analysing the Fire

For 82 years, the world has recognized the 1911 Triangle Shirtwaist factory fire in New York City as the worst accidental loss-of-life industrial fire in which the fatalities were limited to the building of fire origin. With 188 fatalities, however, the Kader factory fire now replaces the Triangle fire in the record books.

When analysing the Kader fire, a direct comparison with the Triangle fire provides a useful benchmark. The two buildings were similar in a number of ways. The arrangement of the exits was poor, the fixed fire protection systems were insufficient or ineffective, the initial fuel package was readily combustible, and the horizontal and vertical fire separations were inadequate. In addition, neither company had provided its workers with adequate fire safety training. However, there is one distinct difference between these two fires: the Triangle Shirtwaist factory building did not collapse and the Kader buildings did.

Inadequate exit arrangements were perhaps the most significant factor in the high loss of life at both the Kader and the Triangle fires. Had the exiting provisions of NFPA 101, the Life Safety Code, which was established as a direct result of the Triangle fire, been applied at the Kader facility, substantially fewer lives would have been lost (NFPA 101, 1994).

Several fundamental requirements of the Life Safety Code pertain directly to the Kader fire. For example, the Code requires that every building or structure be constructed, arranged and operated in such a way that its occupants are not placed in any undue danger by fire, smoke, fumes or the panic that may occur during an evacuation or during the time it takes to defend the occupants in place.

The Code also requires that every building have enough exits and other safeguards of the proper size and at the proper locations to provide an escape route for every occupant of a building. These exits should be appropriate to the individual building or structure, taking into account the character of the occupancy, the capabilities of the occupants, the number of occupants, the fire protection available, the height and type of building construction and any other factor necessary to provide all the occupants with a reasonable degree of safety. This was obviously not the case in the Kader facility, where the blaze blocked one of Building One’s two stairwells, forcing approximately 1,100 people to flee the third and fourth floors through a single stairwell.

In addition, the exits should be arranged and maintained so that they provide free and unobstructed egress from all parts of a building whenever it is occupied. Each of these exits should be clearly visible, or the route to every exit should be marked in such a way that every occupant of the building who is physically and mentally able readily knows the direction of escape from any point.

Every vertical exit or opening between the floors of a building should be enclosed or protected as necessary to keep the occupants reasonably safe while they exit and to prevent fire, smoke and fumes from spreading from floor to floor before the occupants have had a chance to use the exits.

The outcomes of both the Triangle and the Kader fires were significantly affected by the lack of adequate horizontal and vertical fire separations. The two facilities were arranged and built in such a way that a fire on a lower floor could spread rapidly to the upper floors, thus trapping a large number of workers.

Large, open work spaces are typical of industrial facilities, and fire-rated floors and walls must be installed and maintained to slow the spread of fire from one area to another. Fire also must be kept from spreading externally from the windows on one floor to those on another floor, as it did during the Triangle fire.

The most effective way to limit vertical fire spread is to enclose stairwells, elevators, and other vertical openings between floors. Reports of features such as caged freight elevators at the Kader factory raise significant questions about the ability of the buildings’ passive fire protection features to prevent vertical spread of fire and smoke.

Fire Safety Training and Other Factors

Another factor that contributed to the large loss of life in both the Triangle and Kader fires was the lack of adequate fire safety training, and the rigid security procedures of both companies.

After the fire at the Kader facility, survivors reported that fire drills and fire safety training were minimal, although the security guards had apparently had some incipient fire training. The Triangle Shirtwaist factory had no evacuation plan, and fire drills were not implemented. Furthermore, post-fire reports from Triangle survivors indicate that they were routinely stopped as they left the building at the end of the work day for security purposes. Various post-fire accusations by Kader survivors also imply that security arrangements slowed their exit, although these accusations are still being investigated. In any case, the lack of a well-understood evacuation plan seems to have been an important factor in the high loss of life sustained in the Kader fire. Chapter 31 of the Life Safety Code addresses fire drills and evacuation training.

The absence of fixed automatic fire protection systems also affected the outcome of both the Triangle and the Kader fires. Neither facility was equipped with automatic sprinklers, although the Kader buildings did have a fire alarm system. According to the Life Safety Code, fire alarms should be provided in buildings whose size, arrangement or occupancy make it unlikely that the occupants themselves will notice a fire immediately. Unfortunately, the alarms reportedly never operated in Building One, which resulted in a significant delay in evacuation. There were no fatalities in Buildings Two and Three, where the fire alarm system functioned as intended.

Fire alarm systems should be designed, installed and maintained in accordance with documents like NFPA 72, the National Fire Alarm Code (NFPA 72, 1993). Sprinkler systems should be designed and installed in accordance with documents like NFPA 13, Installation of Sprinkler Systems, and maintained in accordance with NFPA 25, Inspection, Testing, and Maintenance of Water-Based Fire Protection Systems (NFPA 13, 1994; NFPA 25, 1995).

The initial fuel packages in both the Triangle and Kader fires were similar. The Triangle fire started in rag bins and quickly spread to combustible clothing and garments before involving wood furnishings, some of which were impregnated with machine oil. The initial fuel package at the Kader plant consisted of polyester and cotton fabrics, various plastics, and other materials used to manufacture stuffed toys, plastic dolls, and other related products. These are materials that can typically be ignited easily, can contribute to rapid fire growth and spread, and have a high heat release rate.

Industry will probably always handle materials that have challenging fire protection characteristics, but manufacturers should recognize these characteristics and take the necessary precautions to minimize associated hazards.

The Building’s Structural Integrity

Probably the most notable difference between the Triangle and Kader fires is the effect they had on the structural integrity of the buildings involved. Even though the Triangle fire gutted the top three floors of the ten-storey factory building, the building remained structurally intact. The Kader buildings, on the other hand, collapsed relatively early in the fire because their structural steel supports lacked the fireproofing that would have allowed them to maintain their strength when exposed to high temperatures. A post-fire review of the debris at the Kader site showed no indication that any of the steel members had been fireproofed.

Obviously, building collapse during a fire presents a great threat to both the building’s occupants and to the fire-fighters involved in controlling the blaze. However, it is unclear whether the collapse of the Kader building had any direct effect on the number of fatalities, since the victims may have already succumbed to the effects of heat and products of combustion by the time the building collapsed. If the workers on the upper floors of Building One had been shielded from the products of combustion and heat while they were trying to escape, the building’s collapse would have been a more direct factor in the loss of life.

Fire Focused Attention on Fire Protection Principles

Among the fire protection principles on which the Kader fire has focused attention are exit design, occupant fire safety training, automatic detection and suppression systems, fire separations and structural integrity. These lessons are not new. They were first taught more than 80 years ago at the Triangle Shirtwaist fire and again, more recently, in a number of other fatal workplace fires, including those at the chicken-processing plant in Hamlet, North Carolina, USA, that killed 25 workers; at a doll factory in Kuiyong, China, that killed 81 workers; and at the electrical power plant in Newark, New Jersey, USA, that killed all 3 workers in the plant (Grant and Klem 1994; Klem 1992; Klem and Grant 1993).

The fires in North Carolina and New Jersey, in particular, demonstrate that the mere availability of state-of-the-art codes and standards, such as NFPA’s Life Safety Code, cannot prevent tragic losses. These codes and standards must also be adopted and rigorously enforced if they are to have any effect.

National, state and local public authorities should examine the way they enforce their building and fire codes to determine whether new codes are needed or existing codes need to be updated. This review should also determine whether a building plan review and inspection process is in place to ensure that the appropriate codes are followed. Finally, provisions must be made for periodic follow-up inspections of existing buildings to ensure that the highest levels of fire protection are maintained throughout the life of the building.

Building owners and operators must also be aware that they are responsible for ensuring that their employees’ working environment is safe. At the very least, the state-of-the-art fire protection design reflected in fire codes and standards must be in place to minimize the possibility of a catastrophic fire.

Had the Kader buildings been equipped with sprinklers and working fire alarms, the loss of life might not have been so high. Had Building One’s exits been better designed, hundreds of people might not have been injured jumping from the third and fourth floors. Had vertical and horizontal separations been in place, the fire might not have spread so quickly throughout the building. Had the buildings’ structural steel members been fireproofed, the buildings might not have collapsed.

Philosopher George Santayana has written: “Those who forget the past are condemned to repeat it.” The Kader Fire of 1993 was unfortunately, in many ways, a repeat of the Triangle Shirtwaist Fire of 1911. As we look to the future, we need to recognize all that we need to do, as a global society, to prevent history from repeating itself.

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This article was adapted, with permission, from Zeballos 1993b.

Latin America and the Caribbean have not been spared their share of natural disasters. Almost every year catastrophic events cause deaths, injuries and enormous economic damage. Overall, it is estimated that the major natural disasters of the last two decades in this region caused property losses affecting nearly 8 million people, some 500,000 injuries and 150,000 deaths. These figures rely heavily on official sources. (It is quite difficult to obtain accurate information in sudden-onset disasters, because there are multiple information sources and no standardized information system.) The Economic Commission for Latin America and the Caribbean (ECLAC) estimates that during an average year, disasters in Latin America and the Caribbean cost US$1.5 billion and take 6,000 lives (Jovel 1991).

Table 1 lists major natural disasters that struck countries of the region in the 1970-93 period. It should be noted that slow- onset disasters, such as droughts and floods, are not included.

Table 1. Major disasters in Latin America and the Caribbean, 1970-93

Source: PAHO 1989; OFDA (USAID),1989; UNDRO 1990.

Economic Impact

In recent decades, ECLAC has carried out extensive research on the social and economic impacts of disasters. This has clearly demonstrated that disasters have negative repercussions on social and economic development in developing countries. Indeed, the monetary losses caused by a major disaster often exceed the total annual gross income of the affected country. Not surprisingly, such events can paralyze affected countries and foster widespread political and social turmoil.

In essence, disasters have three kinds of economic impacts:

• direct impacts on the affected population’s property

• indirect impacts caused by lost economic production and services

• secondary impacts that become apparent after the disaster—such as reduced national income, increased inflation, foreign trade problems, heightened financial expenses, a resulting fiscal deficit, decreased monetary reserves and so on (Jovel 1991).

Table 2 shows the estimated losses caused by six major natural disasters. While such losses might not seem particularly devastating for developed countries with strong economies, they can have a serious and lasting impact on the weak and vulnerable economies of developing countries (PAHO 1989).

Table 2. Losses due to six natural disasters

Source: PAHO 1989; ECLAC.

The Health Infrastructure

In any major disaster-related emergency, the first priority is to save lives and provide immediate emergency care for the injured. Among the emergency medical services mobilized for these purposes, hospitals play a key role. Indeed, in countries with a standardized emergency response system (one where the concept of “emergency medical services” encompasses provision of emergency care through the coordination of independent subsystems involving paramedics, fire-fighters and rescue teams) hospitals constitute the major component of that system (PAHO 1989).

Hospitals and other health care facilities are densely occupied. They house patients, personnel and visitors, and they operate 24 hours a day. Patients may be surrounded by special equipment or connected to life-support systems dependent on power supplies. According to project documents available from the Inter-American Development Bank (IDB) (personal communication, Tomas Engler, IDB), the estimated cost of one hospital bed in a specialized hospital varies from country to country, but the average runs from US$60,000 to US$80,000 and is greater for highly specialized facilities.

In the United States, particularly California, with its extensive experience in seismic-resistant engineering, the cost of one hospital bed can exceed US$110,000. In sum, modern hospitals are highly complex facilities combining the functions of hotels, offices, laboratories and warehouses (Peisert et al. 1984; FEMA 1990).

These health care facilities are highly vulnerable to hurricanes and earthquakes. This has been amply demonstrated by past experience in Latin America and the Caribbean. For example, as table 3 shows, just three disasters of the 1980s damaged 39 hospitals and destroyed some 11,332 hospital beds in El Salvador, Jamaica and Mexico. Besides damage to these physical plants at critical times, the loss of human life (including the death of highly qualified local professionals with promising futures) needs to be considered (see table 4 and table 5).

Table 3. Number of hospitals and hospital beds damaged or destroyed by three major natural disasters

Source: PAHO 1989; OFDA(USAID) 1989; ECLAC.

Table 4. Victims in two hospitals collapsed by the 1985 earthquake in Mexico

Source: PAHO 1987.

Table 5. Hospital beds lost as a result of the March 1985 Chilean earthquake

Source: Wyllie and Durkin 1986.

At present the ability of many Latin American hospitals to survive earthquake disasters is uncertain. Many such hospitals are housed in old structures, some dating from Spanish colonial times; and while many others occupy contemporary buildings of appealing architectural design, lax application of building codes makes their ability to resist earthquakes questionable.

Risk Factors in Earthquakes

Of the various types of sudden natural disasters, earthquakes are by far the most damaging to hospitals. Of course, each earthquake has its own characteristics relating to its epicentre, type of seismic waves, geological nature of the soil through which the waves travel and so on. Nevertheless, studies have revealed certain common factors that tend to cause death and injuries and certain others that tend to prevent them. These factors include structural characteristics related to building failure, various factors related to human behaviour and certain characteristics of nonstructural equipment, furnishings and other items inside buildings.

In recent years, scholars and planners have been paying special attention to identification of risk factors affecting hospitals, in hopes of framing better recommendations and norms to govern the building and organization of hospitals in highly vulnerable zones. A brief listing of relevant risk factors is shown in table 6. These risk factors, particularly those related to the structural aspects, were observed to influence patterns of destruction during a December 1988 earthquake in Armenia that killed some 25,000 people, affected 1,100,000 and destroyed or severely damaged 377 schools, 560 health facilities and 324 community and cultural centres (USAID 1989).

Table 6. Risk factors associated with earthquake damage to hospital infrastructure

Damage on a similar scale occurred in June 1990, when an earthquake in Iran killed about 40,000 people, injured 60,000 others, left 500,000 homeless, and collapsed 60 to 90% of buildings in affected zones (UNDRO 1990).

To address these and like calamities, an international seminar was held in Lima, Peru, in 1989 on the planning, design, repair and management of hospitals in earthquake-prone areas. The seminar, sponsored by PAHO, Peru’s National University of Engineering and the Peruvian-Japanese Center for Seismic Research (CISMID), brought together architects, engineers and hospital administrators to study issues related to health facilities located in these areas. The seminar approved a core of technical recommendations and commitments directed at carrying out vulnerability analyses of hospital infrastructures, improving the design of new facilities and establishing safety measures for existing hospitals, with emphasis on those located in high-risk earthquake areas (CISMID 1989).

Recommendations on Hospital Preparedness

As the foregoing suggests, hospital disaster preparedness constitutes an important component of PAHO’s Office of Emergency Preparedness and Disaster Relief. Over the last ten years, member countries have been encouraged to pursue activities directed toward this end, including the following:

• classifying hospitals according to their risk factors and vulnerabilities

• developing internal and external hospital response plans and training personnel

• developing contingency plans and establishing safety measures for the professional and technical hospital staffs

• strengthening lifeline backup systems that help hospitals to function during emergency situations.

More broadly, a principal aim of the current International Decade for Natural Disaster Reduction (IDNDR) is to attract, motivate and commit national health authorities and policy-makers around the world, thereby encouraging them to strengthen the health services directed at coping with disasters and to reduce the vulnerability of those services in the developing world.

Issues Concerning Technological Accidents

During the last two decades, developing countries have entered into intense competition to achieve industrial development. The main reasons for this competition are as follows:

• to attract capital investment and to generate jobs

• to satisfy domestic demand for products at a lower cost and to alleviate dependency on the international market

• to compete with international and subregional markets

• to establish foundations for development.

Unfortunately, efforts made have not always resulted in obtaining the intended objectives. In effect, flexibility in attracting capital investment, lack of sound regulation with respect to industrial safety and environmental protection, negligence in the operation of industrial plants, use of obsolete technology, and other aspects have contributed to increasing the risk of technological accidents in certain areas.

In addition, the lack of regulation regarding the establishment of human settlements near or around industrial plants is an additional risk factor. In major Latin American cities it is common to see human settlements practically surrounding industrial complexes, and the inhabitants of these settlements are ignorant of the potential risks (Zeballos 1993a).

In order to avoid accidents such as those that occurred in Guadalajara (Mexico) in 1992, the following guidelines are suggested for the establishment of chemical industries, to protect industrial workers and the population at large:

• selection of appropriate technology and study of alternatives

• appropriate location of industrial plants

• regulation of human settlements in the neighbourhood of industrial plants

• security considerations for technology transfer

• routine inspection of industrial plants by local authorities

• expertise provided by specialized agencies

• role of workers in compliance with security rules

• rigid legislation

• classification of toxic materials and close supervision of their use

• public education and training of workers

• establishment of response mechanisms in case of emergency

• training of health workers in emergency plans for technological accidents.

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