Environment

The map shown in Figure 1 illustrates the location of the Republic of the Marshall Islands (RMI) relative to the other islands, island groups, and larger land masses in the Pacific Ocean. Figure 2 shows the position of the different island chains, atolls, and islands of the RMI (in this report the RMI will often be referred to simply as the "Marshall Islands", as has become common practice). The Marshall Islands consists of two chains of atolls running north-northwest to south-southeast: the western, Ralik ("sunset") chain and the eastern Ratak ("sunrise") chain are clearly differentiated in Fig. 2. The number of islands in the republic exceeds 1,200. Only five are considered single islands; the others are sets of islets grouped into 29 atolls, of which Rongelap Atoll is one. The areas of the various atolls range from about 0.5 to 16 km², and those of the lagoons from about 8.5 to 2,500 km². The capital of the republic, Majuro, is on an atoll that lies approximately 3,800 km southwest of Honolulu and 2,700 km north of Fiji.

Figure 1.

Central Pacific Ocean.

Figure 2.

Republic of the Marshall Islands

The climate of the Marshall Islands is tropical. The average daily temperature is 27ºC (81ºF), and the typical relative humidity is about 80%. The islands are low-lying and therefore do not influence local weather patterns substantially. Rainfall has a wide gradient, from 350 cm (138 in.) a year in the southern islands to only about 110 cm (43 in.) in the northernmost; this accounts for the heavier vegetation in the South. The wettest months are September through November, the driest January through March. During the wet season, intense rain squalls are frequent. Full-blown tropical storms and typhoons are rare, but they can be devastating when they do occur and cross these unprotected islands.

The soils and vegetation of the Marshall Islands have been studied extensively (see, e.g., Fosberg and Carroll, 1965). Virtually all the islands have white sand (coral) beaches. Soils of the deep-ocean atolls consist almost solely of sandy and coarser particles of calcium carbonate as calcite and aragonite and contain small amounts of substituted magnesium and strontium. Silicate clays appear undetectable, although trace amounts presumably occur from accumulation of global dust. Organic matter is relatively high in the surface layer but decreases abruptly through a narrow transition zone. The organic content of the surface layer varies from a trace to more than 10% and is the sole source of cation-exchange capacity. Calculated ratios of the carbon to nitrogen content of the soils vary from about 10:1 to 13:1 and indicate advanced stages of organic decomposition. Phosphorus content represents input by nesting sea birds at some time in the past and varies highly in amount from site to site. The make-up of the island soils and sub-soils contribute to very low natural background radiation exposure rates; there are no naturally occurring rock formations that would contribute to such otherwise commonly occurring radiation backgrounds such as that due to radon.

Most of the original vegetation of the northern Marshall Islands, especially the larger islands, has been replaced by coconut plantations. These plantations range in density from almost complete cover in the moister regions to sparseness in the dry northern atolls. The ground cover under the trees ranges from grass and other herbs to a thick tangle of bushes, vines, and trees, depending on the particular atoll climate and how diligently the plantations are tended. A belt of scrub forest is sometimes left around the plantations for protection from wind and salt spray. The thick scrub forests along the fringe of the islands can give the appearance of impenetrability. In undisturbed areas, pure stands of the soft-wooded trees Pisonia, Pandanus, or umbrella-like Ochrosia are found with mixed stands of several hardwood species. The forests usually have dense canopies and little undergrowth.

Rongelap Atoll is in the Ratak Chain about 670 km northwest of Majuro and about 200 km southeast of Bikini Atoll. It comprises about 50 low-lying islands with a total area of about 9 km² surrounding a lagoon of about 1,000 km². The largest and by far the most important island is Rongelap, with an area of about 0.8 km². The atoll has moderate yearly rainfall, about 150-180 cm (60-70 in.). The mean air temperature is about 27ºC (82ºF), and the prevailing wind is east to north. The islands are covered with vegetation—some coconuts and much native brush and woodland; however, the lack of rainfall during the long dry season limits the kinds of plants that can be grown. Fourteen bird species are known on Rongelap Atoll: eight sea birds, four shore birds, one heron, and one domestic fowl (Amerson, 1969).

Culture

Anthropologists estimate that the residents of the Republic of the Marshall Islands first arrived on the shores of their coral-atoll homes about 2,000 years ago. Until the latter half of the nineteenth century, they subsisted on seafoods and breadfruit, pandanus, coconut, and arrowroot. The Marshall Islands were never unified under a single leader, although one chief often controlled several atolls, and at times virtually the entire Ralik chain was under a single chief. Chiefs had absolute authority, but their wealth and power depended on the loyalty and tribute payments of the commoners.

European cultural influences were absent from the islands until Alvaro de Saavedra landed in the western part of the Marshall Islands in 1529. Although other Spanish expeditions landed in the Marshall Islands during the 1500s, Spain did not attempt to colonize the area actively. Substantial interest in the area by British and Europeans generally was not shown until the 1830s and 1840s, when whalers began to frequent the area. The islands are named after the English sea captain John Marshall, who visited the islands in 1788, but it was the Russian explorer Otto von Kotzebue who was chiefly responsible for extensive exploration of the region between 1815 and 1825 and whose efforts resulted in the first good maps of the islands.

Whalers and traders began to expand their efforts in the Pacific early in the 1800s, but tended to avoid the Marshall Islands because of its widespread reputation for violence. Responding to European and American abuse of island women and to the killing of sacred chiefs and valued commoners, the previously friendly Marshall Islands natives became, for westerners, the most feared people in Micronesia. Violence was declining, however, by the westerners, the most feared people in Micronesia. Violence was declining, however, by the time the first Protestant missionaries arrived on Ebon Atoll in the 1850s. Missionaries were given a mixed reception by local people but within a few years had attracted a core of converts. In the 1860s and 1870s, copra production replaced whaling as the primary European industrial interest in the area. The copra industry employed local chiefs as intermediaries and greatly increased their power, stability, and influence (Carucci, 1988).

Germany purchased the Marshall Islands from Spain in 1885 and left the administration of island affairs to a group of German trading companies that further stabilized the position of the ruling chiefs. German government officials did not arrive on the scene until 1906. In the interim, a series of struggles over the terms of western domination took place between American missionaries, German traders, and independent "local" European traders. In 1917, the Japanese took control of the Marshall Islands under a League of Nations mandate. They assumed control of the copra business and, unlike the Germans, purchased copra directly from the people, using groups of resident Japanese traders, rather than relying solely on local chiefs. This policy, with the Japanese institutionalization of positions for a group of local political elites, began to undermine the unquestioned authority that island chiefs had gained during the copra era. In 1933, when it broke from the League of Nations, Japan declared ownership of Micronesia. It developed and fortified large military bases on several atolls, using local labor from throughout the Marshall Islands and Korean and Okinawan expatriates. The United States defeated Japan in decisive battles on Kwajalein and Enewetok Atolls in 1944 liberating the Marshall Islands, and ruled the area through a naval military government until it was given authority by the United Nations after World War II to administer the scattered islands and atolls of Micronesia as the Trust Territory of the Pacific Islands. Administration of the trust territory shifted from the U.S. Navy to the Department of the Interior in 1951 and remained in effect until the Republic of the Marshall Islands gained political, if not economic, independence under the Compact of Free Association that was signed with the United States in 1983 and approved under U.S. Public Law 99-239 on January 14, 1986.

Ebon, Jaluit, Majuro, Kwajalein, and Enewetok were Marshall Islands locations of interest to Japanese, European, and American colonizers from the 1850s to the 1950s, but it was not until the U.S. nuclear-testing era after World War II that Rongelap, Bikini, and Utirik joined Enewetok as locations of major consideration. The United States began nuclear tests in 1946 on Bikini Atoll and expanded them to Enewetok late in 1947.

The consequences of the contamination of Rongelap Atoll and exposure of its inhabitants owing to substantial amounts of radiation from radioactive fallout on the life-style of the people of Rongelap are summarized in Table 1-1. On March 1, 1954, the BRAVO test on Bikini exploded with 3 times the projected intensity. The unexpectedly extensive fallout traveled eastward of the test site and subjected the residents of Rongelap Atoll (including Ailinginae and Rongerik) and Utirik Atoll to substantial amounts of radioactive contamination. Within about 5 h after the nuclear test, a fine white powdery substance began to rain on Rongelap and its inhabitants. There had been no warning, so the children were allowed to play in the "snow"; only later did the inhabitants of Rongelap learn that this "snow" was dangerously radioactive. On March 3, 1954, 2 days after the test, 64 residents of Rongelap and 18 of Ailinginae were evacuated to Kwajalein; then on March 4, 159 residents of Utirik were evacuated. Including fetuses, 252 residents of these Atolls suffered whole-body exposure, with the people of Rongelap receiving estimated external gamma-ray doses of 190 rem and substantial internal and external exposure from beta-emitting radionuclides (Conard, 1992). The later development of nodular thyroid diseases, including some malignancies, resulted in understandable concern in Rongelap community about long-term health.

Table 1-1.

Summary of Residences of Rongelap Community Since BRAVO Test.

The people of Rongelap returned to their home atoll on June 29, 1957, after a decision was made that it was safe for them to return under continuing radiological surveillance. Later, they came to feel that ''safe" was relative when unanticipated medical problems began to surface.² Concern was intensified by release of additional government reports, including a Marshallese language discussion of the radiation levels in the Northern molls of the Marshall Island (Bair, et al., 1982), that the people of Rongelap interpreted as indicating greater levels of contamination on their homelands than they had previously been made aware of by the U. S. Department of Energy. This report was interpreted as indicating that their atoll was contaminated to the same degree as Bikini which was generally considered "unsafe" for habitation. In addition to these concerns, urine samples analyzed by Brookhaven National Laboratory in 1984 had shown higher levels of plutonium than had been expected (Conard, 1992). On May 22, 1985, the Rongelap people, having lost confidence in the advice provided by the department of Energy,³ left their home atoll for a new location on Mejatto Island in Kwajalein Atoll. The increased plutonium concentrations now appear to have resulted from urine-collection procedures that resulted in spurious high plutonium levels (Conard, 1992) and the levels of radionuclide contamination on Rongelap have proven to be lower than those on Bikini. However, the Rongelap people now wish to eliminate all doubts about the habitability of their homeland before they return and have chosen to stay on Mejatto Island until they are assured of the radiological safety of Rongelap Island.

The review of DOE's effort in the radiological assessment of Rongelap by this National Research Council committee is aimed at determining whether the methods and practices undertaken by DOE and its contractors are scientifically sound.

Radiation Exposure and Dose

Radiation doses that might be received in the future by persons of all ages are important issues related to the resettlement of the Rongelap people. Assessments of these doses provide important bases for estimating the possible health risks associated with residual radionuclides on Rongelap Island. Sources of radiation can be external, internal, or both. For example, some of the Rongelap inhabitants exposed directly to the BRAVO fallout material in March 1954 received, in a matter of a few days, bums on their skin as a result of beta radiation emitted by radionuclides deposited on skin, whereas other effects of the early exposures, such as damage to the thyroid, were not manifest for several years. Effects on the thyroid, including cancer, were produced by radionuclides of iodine (¹³¹I,¹³³I,¹³⁵I) that were absorbed into the body, were deposited preferentially in the thyroidal tissue, and became sources of chronic internal radiation exposure.

Because of radioactive decay and natural weathering, many of the radionuclides in the initial fallout material are no longer present. Resettlement decisions must include consideration of which radionuclides are present and the extent to which current and future radionuclide inventories will contribute to radiation doses that the Rongelap people might receive from external and internal sources. Of the radionuclides originally deposited as fallout from the BRAVO detonation, only 5 radionuclides are still present in sufficient quantities to contribute significant doses to individuals. These include cesium-137, strontium-90, plutonium-239, plutonium-240, and americium-241. Of the total dose estimated for residents resettling the atolls, 90% is from cesium-137 and over 70% of that will come from ingestion of the native foods (Kercher and Robison, 1993). Possible exposure pathways by which radiation doses might be received are listed in Table 3. Strontium is the second most significant nuclide contributing to the estimated dose, also from ingestion in foodstuffs, and might account for as much as 2-5% of the dose. The transuranic radionuclides are estimated to contribute less than 5% of the estimated dose over 50 and 70 y. Estimated doses from stochastic source terms and the uncertainties in such calculations have recently been discussed in detail by Kercher and Robison (1993).

Measurements and analyses of the exposure pathways and the wide array of factors that can influence both the exposures and the radiation doses received from these exposures have been made by several different organizations during the last 40 years. Periodic medical examinations of the Rongelap people began soon after their evacuation in March 1954; the examinations have been carried out by medical staff of BNL and health-service personnel from the Marshall Islands. In addition to performing medical examinations on persons exposed to the initial BRAVO fallout, the BNL medical staff initiated, in 1958, periodic whole-body counting to determine the extent to which photon-emitting radionuclides from the internal exposure sources shown in Table 1-2 were being incorporated in people. Responsibility for monitoring internal deposition of radionuclides was transferred in 1978 to the BNL Safety and Environmental Protection Division, which continues to carry out whole-body counting and radionuclide-content analysis of urine and feces.

Table 1-2.

Pathways of Exposure to Radiation.

On-site environmental surveys have also involved several other organizations. Most of the early surveys were conducted by personnel of the U.S. Naval Radiological Defense Laboratory and the Radiation Ecology Laboratory of the University of Washington College of Fisheries. In 1978, personnel from EG&G Corporation performed an extensive airborne radiological survey of the northern Marshall Islands in the BRAVO fallout path; in conjunction with this extensive survey program, scientists from LLNL conducted land-based environmental surveys of water, soil, vegetation, and marine species. Additional sampling trips were made in 1986-1993.

This committee has focused in large part on requirements specified in the MOU related to annual radiation doses, soil concentrations of transuranic radionuclides (alpha radiation), and measurements needed before and after resettlement. Thus, the measurements, analyses, and dose estimates made by scientists from LLNL and BNL lie at the heart of the committee's concerns and responsibilities. The approaches used by both organizations are illustrated in Fig. 3. LLNL scientists obtain information on the radionuclide content of the various samples shown, and then calculate possible radionuclide intakes on the basis of the amounts of intake of air, water, and food. This information is then coupled with models of radionuclide metabolism and dosimetry to calculate the internal deposition and retention of these radionuclides and the resulting internal radiation dose. Such an approach makes it possible to estimate the accumulation of radionuclides and the consequent internal dose in the Rongelap people after resettlement.

Figure 3.

Internal dose assessments for Rongelap people.

The measurements on individuals by BNL scientists provide direct information on the presence of radionuclides in the body. Whole-body counting provides information on the total-body content of radionuclides that emit photons of sufficient energy to escape the body and be detected by the whole-body counter. Analyses of radionuclides excreted in urine and feces indicate which radionuclides are present in the body on a given day, regardless of whether they emit alpha, beta, or gamma radiation. Metabolic models are used to compute the total-body content of each radionuclide measured. Once the total-body content has been estimated by whole-body counting or excretion analyses, metabolic and dosimetric models are used to compute the radiation dose resulting from this body burden.

The LLNL approach can be used to estimate either past or future environmental exposure of persons on Rongelap Atoll; the BNL measurements provide estimates of the current body content of radionuclides of interest. The measurements and modeling approaches used by the two laboratories are related and can be used to obtain comparable data. The BNL measurements of total-body radionuclide content at a reference time should provide dose estimates that agree with the prediction for the same time yielded by the LLNL models based on environmental pathways.

It is obvious that many scientific variables are associated with each approach. To provide the best information on radionuclide exposure and radiation dose, these variables must be dealt with in scientifically acceptable and defensible ways. This committee has reviewed what has been done about dose assessment in the past and what further should be done before resettlement of the Rongelap people. In particular, the Committee has directed its efforts to five related subjects:

• Environmental sampling and analysis.
• Diet models.
• Measurements on humans.
• Dosimetry and its application.
• Uncertainty and variability in dose projection.

Each of those subjects is explored in detail in subsequent chapters of this report.

Footnotes

2

According to testimony of Senator Jeton Anjain before the Subcommittee on Insular and International Affairs, Washington, D.C., November 16, 1989.

3

As related by Senator Anjain in his testimony to the House Committee on Appropriations, May 9, 1991.