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Petitioned Public Health Assessment
Soil Pathway Evaluation,
Isla de Vieques Bombing Range,
Vieques, Puerto Rico

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February 7, 2003
Prepared by:

Federal Facilities Assessment Branch
Division of Health Assessment and Consultation
Agency for Toxic Substances and Disease Registry

II. Background

Vieques is the largest offshore island in the Commonwealth of Puerto Rico. Vieques is 20 miles long, 4.5 miles at its widest point, and about 33,000 acres (or 51 square miles) in area. Figure 1 shows the location of Vieques and surrounding islands. As the figure illustrates, the nearest island to Vieques is the main island of Puerto Rico, approximately 7 miles to the west. The island of Culebra is roughly 9 miles north. St. Thomas, St. John, St. Croix, and other U.S. Virgin Islands are all at least 20 miles northeast and southeast from Vieques.

The highest point on the western half of Vieques is Monte Pirata (987 feet above sea level) and the highest point on the eastern half is Cerro Matias (450 feet above sea level). Other than these peaks, the Vieques terrain includes low rounded hills and an east-west ridge running through the center of the island. The average elevation of Vieques is approximately 246 feet above sea level (Cherry and Ramos 1995; Torres-Gonzalez 1989).

A. Land Use

The detailed map in Figure 2 illustrates land use in Vieques. The figure depicts the island in three separate sections, each of which is described in greater detail below:

  • Former NASD. Figure 2 identifies the western portion of Vieques as the "Former NASD." Prior to May 2001, the Navy owned the 8,200-acre Naval Ammunition Support Detachment (NASD). Most of the NASD is undeveloped and was used for limited Navy operations, including ammunition storage, a rock quarry, communication facilities, and Navy support buildings (IT Corporation 2000). Some NASD areas were leased to local farmers for cattle grazing and other agricultural purposes. In May 2001, the Navy transferred most of the NASD to la Isla de Vieques, the Puerto Rico Conservation Trust, and the U.S. Department of the Interior. The Navy retained about 100 acres for radar and communication facilities (Navy 2001a).
  • Residential Area. Figure 2 identifies the central portion of Vieques as the "Residential Area." This part of Vieques includes approximately 7,000 acres and currently borders Navy property only on the east. This section of the island houses the entire residential population of Vieques, mostly in the towns of Isabel Segunda and Esperanza. Section II.B of this assessment describes the demographics of Vieques in greater detail.

    Vieques land uses include residential, agricultural, commercial, and industrial. In the past, sugarcane was the principal crop. Other crops have included coconuts, grains, sweet potatoes, avocados, bananas, and papayas. In the 1960s and 1970s manufacturing was important for the economy, beginning with the 1969 construction of the General Electric plant (Bermudez 1998). But currently, only minimal manufacturing takes place on the island. Isabel Segunda and Esperanza, however, are home to commercial fishing fleets, and recently tourism has been increasing in economic importance.

  • Current Navy Property.
    Small arms ranges are designated areas where military personnel fire small arms (e.g., rifles and machine guns) at stationary and moving targets. Small arms ranges are not used for bombing exercises.
    The Navy currently owns roughly the eastern half of Vieques. As Figure 2 shows, these lands are further divided into two sections: the Eastern Maneuver Area (EMA) and the Atlantic Fleet Weapons Training Facility (AFWTF). The EMA includes approximately 11,000 acres located immediately east of the residential area. The Navy uses the EMA periodically for various combat training activities, such as conducting shore landing exercises and small arms training (CH2MHILL and Baker 1999; IT Corporation 2000). Camp Garcia, where Marine Corps and Naval personnel are temporarily stationed on Vieques, is within the EMA. Typically, no more than 100 military personnel reside at Camp Garcia, but this number increases during training exercises. Some EMA areas are leased to local farmers for cattle grazing and agriculture.

East of the EMA is the AFWTF (3,600 acres), which as Figure 2 shows, is further divided into three smaller sections of land:

  • The western part of AFWTF was formerly known as the Surface Impact Area. Prior to 1978, the area was used as an impact area for artillery. It is heavily vegetated and almost completely undeveloped, except for dirt roads, a few observation posts and towers, and the main observation post (OP-1), located on Cerro Matias.
  • The middle portion of AFWTF is the LIA, also commonly referred to as the bombing range. This roughly 900-acre tract contains the targets for aerial and naval bombardment. The LIA is sparsely vegetated, and contains no structures--only surplus equipment (e.g., tanks, small airplanes, and trailers) the Navy uses as targets. Section II.F of this report includes more detailed information about the Navy's training activities on Vieques.
  • The eastern tip of AFWTF is the Punta Este Conservation Zone. To preserve the unique upland forest scrub and evergreen scrub habitats, no Navy operations take place on this small piece of land. A variety of animals, including roseate terns and sea turtles, visit and nest there.
B. Demographics

ATSDR examines demographic data (i.e., population information) to determine the number of people potentially exposed to environmental chemicals, and to determine the presence of any sensitive populations, such as women of childbearing age, children, and the elderly. Demographic data also provide details on population mobility which, in turn, helps ATSDR evaluate how long residents might have been exposed to environmental chemicals.

Table 1 summarizes the 2000 US Census Bureau demographic data for Vieques. As the table shows, the 2000 Census reported that 9,106 people live on Vieques. This figure includes residents on both the residential area and Navy property. Table 1 also specifies the number of residents in three potentially sensitive populations: women of childbearing age, children, and the elderly. According to several anecdotal accounts, the population of Vieques is not highly mobile; many are lifelong residents of the island.

As noted previously, most of the residents of Vieques live in the two largest towns on the island, Isabel Segunda and Esperanza. Although these towns are located relatively close to the Navy property, they are several miles removed from the LIA. Approximately 7.9 miles (12.7 kilometers) of Navy owned land provides a buffer zone between the LIA and populated areas of Vieques.

C. Climate

Vieques lies in the path of the easterly trade winds (i.e., winds blowing from east to west). The climate is tropical-marine, with temperatures averaging about 79 Fahrenheit (26.3 Celsius). Annually, the temperature ranges from an average of 76 Fahrenheit (24.6 Celsius) in February to 82 Fahrenheit (28 Celsius) in August. The average amount of precipitation is about 45 inches a year. The western part of the island receives a higher amount of rainfall (about 50 inches a year) than the eastern section (about 25 inches a year). The rainy season is from August through November while the remainder of the year is drier. Tropical storms are common from June to November (NCDC 1985-1994; Torres-Gonzalez 1989).

African Dust Storms

Through the natural occurrence of African dust storms, Vieques, together with the mainland of Puerto Rico and the southeastern United States, receive in the summer an increase of airborne dust particles. Each year, large quantities of dust from the Sahara Desert and Sahel region in Africa are transported at high altitudes to the Caribbean Sea (USGS 2000). These dust storms can transport minerals, chemicals, bacteria, fungus spores--and possibly viruses and insects. African dust is comprised mainly of quartz, but also of other minerals, that are common in soil (Prospero 1999). Lead, iron, mercury, and beryllium have been detected in samples of African dust taken from the Virgin Islands, Barbados, Miami (Florida), and the Azores. Pesticides associated with pesticide spraying in the Sahel region have also been detected in the dust (Ballingrud 2000).

D. Geology

Alluvial deposits are sediment deposited by flowing water.
Vieques was formed from volcanic and other igneous rock. The island bedrock is mostly granodiorite, quartz diorite, and some lavas. Figure 3 is a generalized geologic map of Vieques identifying the island's geologic units (rock formations). On most of the western half as well as the central portion of the eastern half of the island, the bedrock is exposed and weathered. Because of the weathering of the bedrock, gravel, sands, and finer particles wash downhill during storms. Over the years this material has gathered in valleys near the ocean, forming alluvial deposits (see text box for definition). The alluvial sedimentary deposits generally consist of a mixture of gravel, sand, silt, and clay. Other portions of Vieques have ancient marine deposits from a time when the island was submerged. Today these deposits reveal areas with some limestone, sandstone, siltstone, and other sedimentary rocks at the surface.


Soils often form from the weathering and breakdown of the underlying rock or "parent material." Soils may be formed by the buildup of wind- or water-borne particles or by the addition of new minerals by naturally occurring chemical processes within the soil. There are many differing types of soil that form in different climates and on differing underlying parent materials. Five parameters, known as soil forming factors, contribute to the type of soil that can be found in an area: parent material (i.e., the geology that is present), relief (i.e., topography), organisms/microorganisms, climate, and time (Jenny and Hans 1941).

Analyzed as oxides, granodiorite and quartz diorite typically range from about: 61-66% silicon dioxide, 16-17% aluminum oxide, 2-3% ferric oxide, 2-4% ferrous oxide, 1-3% magnesium oxide, 3-6% calcium oxide, 3-4% sodium oxide, and 2-3% potassium oxide (after Travis 1955).
The natural soil on Vieques is a direct product of the island's bedrock, which as indicated above, is mostly granodiorite, quartz diorite, some volcanic lavas, and marine sedimentary deposits such as limestone. Soil type can vary according to topography or location. For example, because of differing soil-moisture conditions--which lead to differing rates and kinds of chemical and physical weathering and soil forming reactions--soil found on the top of a hill would be slightly different from that found in a valley. Organisms and microorganisms living in the soil participate in the soil formation process by extracting some chemicals, which they use as nutrients, and depositing others. Climate also affects the type of soil present. Soil found in a tropical-marine climate, such as Vieques, is different from soil in an arid climate. Soil is also a function of time, or how long the processes (e.g., erosion, deposition, weathering, and clay formation) have been at work.

Rocks are a natural source of the chemicals that are found in soil. Most rocks are formed from elements such as oxygen, silicon, aluminum, iron, magnesium, calcium, potassium, and sodium (USGS 1997). Chemical and physical processes break down the rocks and form minerals that are characteristic of the parent material. But human influences, such as agricultural processes and Navy training exercises at the LIA can also contribute to the chemicals found in the soil. Determining whether a chemical is present as a result of natural or human sources is sometimes difficult because frequently, it can be a combination of both.

Ninety-two elements occur naturally in our environment (USGS 2001a). Some of these elements are essential for life, such as iron and magnesium. Others are nonessential and can even be harmful if present in high enough concentrations (e.g., arsenic, cadmium, lead, and mercury). Some elements are required for life at certain levels, but can be harmful in concentrations that are too high (e.g., fluorine, copper, selenium, and molybdenum) (USGS 2001b).

E. Hydrogeology

All the groundwater on Vieques comes from rain that falls on the island. The rain runs downhill as intermittent stream runoff or it seeps into the soil and underlying deposits. Water is found in two main areas: (1) the upper portion of the bedrock and sedimentary rocks, and (2) the alluvial deposits. Water in pore space, cracks, and fractures in the bedrock eventually flows to the ocean or into alluvial deposits. Esperanza valley is the largest alluvial valley in Vieques and holds the most water.

Water Use

Most of the residents of Vieques currently receive their drinking water supply from the mainland of Puerto Rico through an underwater pipeline. The water is collected and treated on the main island of Puerto Rico, then piped into the distribution system through an underwater pipeline. This water originates in the mountains of the main island of Puerto Rico and is not affected by activities at the bombing range on Vieques. In addition, private groundwater wells and rainfall collection systems may still be used today to augment water supplies in some households and businesses.

F. Navy Operational History

The Navy has occupied portions of Vieques since 1941. In 1960, the Navy established targets on Vieques and began bombing practice (Navy 1990). The use of the LIA for air to ground and ship to shore training increased after the closing of the Culebra Island range in the mid-1970s. Currently, the Navy owns roughly the eastern half of the island--the EMA and AFWTF (see Figure 2). The Navy facilities are under the command of the Roosevelt Roads Naval Station on the mainland of Puerto Rico.

Ordnance Type and Use

Range utilization statistics data from 1983 to 1999 indicate that the Navy and other parties conducted exercises on Vieques between 159 and 228 days per year, with the total number of days not varying considerably from one year to the next. Generally, Navy training exercises were most frequent in February and August with fewer exercises in April, May, November, and December. The range utilization statistics suggest that, on average, 1,862 tons of ordnance were used at Vieques annually between 1983 and 1998. This ordnance, on average, contained 353 tons of high explosives (Navy 1999).

Live ordnance have not been used on Vieques since April 19, 1999, when two 500-pound bombs were accidentally dropped near OP-1, killing a civilian guard. In January 2000, the decision was made that the Navy could resume training on Vieques. The training is limited to 90 training days per year and the use of nonexplosive ordnance only. In May 2000, the Navy resumed training.

To varying degrees metals and metallic compounds are present in the munitions used on Vieques (see text box on the following page for descriptions of ordnance types). Rockets contain metals and metallic compounds in the initiator, igniter, propellant, and motor. A projectiles' body assembly and nose fuze are made of metals and metallic compounds. Both live and practice bombs contain metals and metallic compounds in the bomb body, base plug, suspension lug, fins, tail, fuze, and signal cartridge. The decoy, parachute, and simulator flares used on Vieques contain metals and metallic compounds in the ignition, first fire, flare slurry, friction material, and flare.

Certain pyrotechnic devices, such as illuminating flares and white phosphorous mortar rounds, are also used on Vieques for smoke generation. The flares contain sodium nitrate and magnesium, which when ignited produce magnesium oxide (magnesium hydroxide when wet), sodium oxide, nitrogen, carbon dioxide, carbon monoxide, and water. Upon contacting air, white phosphorous burns immediately, producing phosphorus pentoxide, which becomes phosphoric acid when wet (Young 1978).

Ordnance Types: The three types of flares used on Vieques are decoy, parachute, and simulator. All three are launched from aircraft. Decoy flares are fired during evasion tactics when the aircraft is threatened by enemy heat-seeking missiles. Parachute flares are launched to provide nighttime illumination of surface areas, often during search and attack operations. Simulator flares are designed to produce effects that imitate the appearance of combat weaponry. -- Illuminating projectiles are designed to eject a pyrotechnic candle to a certain point to allow visual observation. The projectiles that are now used on Vieques are inert target practice projectiles filled with an inert material without a signal (i.e., spotting) charge or a fuze. -- General purpose bombs are dropped from aircraft. They consist of a bomb body, nose and/or tail fuzing, and either a conical fin assembly or a retarded fin assembly. The explosive components of the bombs include 2,4,6-trinitrotoluene (TNT), cyclotrimethylene trinitramine (RDX), methyl-2,4,6-trinitrophenylnitramine (tetryl), cyclotetramethylene tetranitramine (HMX), ammonium picrate (Explosive D), and various combinations of these chemicals. -- Practice bombs are dropped from aircraft for target practice and are designed to simulate the ballistic properties of service bombs. They are manufactured with either solid cast-metal bodies or thin sheet metal containers that can be filled with sand or concrete. Practice bombs do not contain a main explosive load. They can, however, contain a small amount of explosive and reactive material in a signal cartridge (i.e., spotting charge) thus providing a visual indication of the impact. -- The Navy uses two rockets on Vieques. Both are aimed at the target and fired; once the rocket has been fired, the trajectory cannot be changed. A variety of warheads and fuzes were used on these rockets, depending on the tactical situation. Today, inert practice warheads are used for training and several smoke-producing warheads are used to mark the targets. -- Source: Navy 2001b

An explosive is any substance that can be made to produce a volume of rapidly expanding gas during a brief period.
Two types of explosives (see text box for definition), described below, were commonly used at Vieques, each with a different set of byproducts from the explosion reaction (Young 1978):

  • One explosive is made from organic nitrated compounds (i.e., only carbon, hydrogen, oxygen, and nitrogen). Examples include TNT, RDX, HMX, tetryl, Explosive D, Composition B (RDX and TNT), Octol (HMX and TNT), and Composition A-3 (RDX and wax). Carbon dioxide (35%), nitrogen (27%), and carbon monoxide (16%; which rapidly oxidizes to carbon dioxide) are the primary byproducts resulting from this type of explosive. Water (8%), ethane (5%), carbon (6%), and propane (2%) are other minor byproducts. Trace amounts (less than 1%) of ammonia, hydrogen, hydrogen cyanide, methane, methyl alcohol, and formaldehyde are also formed (Young 1978).
  • The other explosive contains aluminum in addition to organic nitrated compounds. Examples include Tritonal (TNT and aluminum), H-6 (TNT, RDX, and aluminum), and Torpex (TNT, RDX, and aluminum). The byproducts from a bomb made with this explosive include all the chemicals listed for the first type of explosive as well as acetylene, ethylene, phosphine, and aluminum oxide. The primary byproducts are aluminum oxide (38%), carbon monoxide (24%, which rapidly oxidizes to carbon dioxide), nitrogen (18%), and carbon (13%). Ethane (3%), water (1%), hydrogen (1%), and less than 1% of the remaining byproducts (i.e., carbon dioxide, ammonia, propane, hydrogen cyanide, methane, methyl alcohol, formaldehyde, acetylene, ethylene, and phosphine) are also formed (Young 1978).

During a February 19, 1999 training exercise, depleted uranium ammunition was inadvertently loaded aboard two U.S. Marine Corps aircraft (NRC 2000). The pilots fired 263 rounds of ammunition armed with depleted uranium penetrator projectiles on the LIA. The Navy has committed to recover all detectable depleted uranium penetrators, and as of August 2002 reported to have recovered 116 equivalent units. During June 6-15, 2000, the Nuclear Regulatory Commission (NRC) conducted an inspection of Vieques to determine whether the depleted uranium rounds contaminated the environment, thus creating a potential source of radiation exposure for Vieques residents. The NRC concluded that depleted uranium had not spread to areas outside the LIA. Thus the public had not been exposed to depleted uranium contamination or other radiation above normal background (naturally occurring) levels (NRC 2000). ATSDR has reviewed the NRC report and concludes that the background levels of radiation detected on Vieques do not present a public health hazard.

G. ATSDR Involvement at Vieques

Since its 1999 receipt of the petition requesting an evaluation of public health issues on Vieques, ATSDR has worked extensively to characterize and to respond to community needs. The following is a summary of ATSDR's past Vieques involvement:

  • Site visits. Since 1999, teams of ATSDR scientists and community involvement specialists have visited Vieques more than 10 times. These visits included site familiarization, identification of health concerns, and collection of fish and shellfish for analysis. During two of the site visits, ATSDR personnel extensively toured the former NASD, EMA, and AFWTF, which included a ground and aerial tour of the LIA.
  • Community involvement. Defining community concerns is an essential step in the public health assessment process. To define specific environmental health issues of concern, ATSDR met several times with individuals, families, and many other residents of Vieques. ATSDR is also working with elected officials, physicians, nurses, school educators, fishermen, leaders of women's groups, pharmacists, and businessmen. Among other discussion topics, ATSDR inquired how the agency can most effectively provide public health information to the community. ATSDR plans to continue such community involvement activities at Vieques at least into calendar year 2002.
  • Health education. Throughout the community involvement process, ATSDR has worked with physicians, nurses, and school officials to provide educational materials and to support the overall public health of Vieques residents. To date, the agency has hosted four physician workshops and one nurses' training workshop covering the various aspects of environmental health, including procedures for taking an exposure history. The agency has also facilitated community education sessions on cancer. ATSDR intends to provide additional education sessions that will address topics such as air quality and asthma, nutrition and wellness, and environmental health.
H. Summary of the Available Soil Sampling on Vieques

In 1972, personnel from US Geological Survey (USGS) and the Puerto Rico Department of Natural Resources (PRDNR) jointly surveyed surface soil across Vieques to evaluate the metallic resource potential of the island (see Figure 4 for soil sample locations) (Learned et al. 1973). A total of 420 soil samples were taken and analyzed semi-quantitatively for metals (1). In 1992, USGS released a reconnaissance geochemical survey with analytical results for stream sediment and soil samples from the Puerto Rican mainland, Culebra, and Vieques (Marsh 1992). The source for the Vieques soil data was the 1972 USGS and PRDNR survey. The sediment data for the mainland of Puerto Rico was generated through a cooperative sampling effort between USGS and PRDNR that began in the 1970s. A total of 2,852 stream sediment samples were analyzed for metals (2) .

In May 1978, the Naval Surface Weapons Center obtained and analyzed soil samples for explosive compounds from two areas within the EMA and four areas within the LIA (Hoffsommer and Glover 1978). At the same time, soil collected from one area within the EMA and five areas within the LIA was analyzed for explosion combustion products (Lai 1978) (3).

In October 1998, to document existing environmental conditions at a section of the former NASD's buffer zone proposed for expansion of the Vieques Municipal Airport, a contractor for the Navy collected five soil samples (see Figure 4 for locations) (PMC 1998). These samples were analyzed for volatile organic compounds, semivolatile organic compounds, pesticides, polychlorinated biphenyls, and metals.

In August 1999, a contractor for the Navy collected and analyzed for explosive compounds 32 surface soil samples along EMA's western border (see Figure 4 for soil sample locations) (CH2MHILL and Baker 1999). Twenty-one of the samples were collected from storm drains (i.e., culverts that are normally dry and only contain water during rain events); the remaining 11 were from areas adjacent to the monitoring wells.

From May 1999 to April 2000, personnel from Servicios Científicos y Téchnicos, Inc. (Garcia et al. 2000) collected and analyzed soil and sediment samples from 55 Vieques locations for metals and other inorganic compounds (Garcia et al. 2000). Of these, 44 samples were collected from the LIA; specifically, areas of direct impact, targets areas, and nearby areas. Five were collected from the Punta Este Conservation Zone and six were taken from the residential area. But ATSDR does not have access to the entire sampling data set. Only the highest and second-highest concentrations were reported for a total of 25 sample locations within the LIA (4) (see Figures 4 and 5 for soil sample locations).

In June 2000, at ATSDR's request, a Navy contractor collected and analyzed 37 surface soil samples within the LIA (specifically, from targets and drainage features and low lying areas which would collect stormwater runoff) and within conservation zones immediately adjacent to the LIA (see Figures 4 and 5 for locations) (CH2MHILL 2000a). Five of the sites specifically represented areas where the protestors lived from April 1999 to May 2000. The samples were analyzed for metals and explosive compounds.

In December 2000, a Navy contractor conducted a background (naturally occurring) sampling program in support of the Navy's Installation Restoration Program at the former NASD (CH2MHILL 2001). Samples of surface and subsurface soils, groundwater, surface water, and sediment were collected at various locations in the former NASD thought to be unaffected by man's activities. A total of 26 surface soil samples were collected and analyzed for metals (see Figure 4). A draft report summarizing the results of that investigation was released June 15, 2001.

I. Quality Assurance and Quality Control

To prepare this PHA, ATSDR reviewed and evaluated information provided in the referenced documents. The environmental data are from reports produced by many parties, including USGS in cooperation with PRDNR, the Navy, and Servicios Científicos y Téchnicos, Inc. The limitations of these data have been identified in the associated reports, and are restated in this document, as appropriate. The sampling procedures, analytical methods, and detection limits established for those investigations were consistent with the studies' objectives. Quality assurance and quality control measures were not available for the older data (i.e., Learned et al. 1973; Hoffsommer and Glover 1978; and Lai 1978) and data collected by Servicios Científicos y Téchnicos, Inc. (Garcia et al. 2000). ATSDR determined that the quality of environmental data available in the Vieques site-related documents constitutes an adequate basis for public health decisions. All available soil sampling data was considered during the public health assessment process.

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