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Public Health Assessment
Fish and Shellfish Evaluation,
Isla de Vieques Bombing Range,
Vieques, Puerto Rico

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June 27, 2003
Prepared by:

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

IV. ATSDR'S Fish and Shellfish Sampling

The residents of Vieques are concerned that military training activities at the LIA are adversely affecting their health. Previous studies have reported "elevated" levels of heavy metals in fish and shellfish from Vieques (see Section III). People who regularly eat fish and shellfish may be exposed to these chemicals. The purpose of ATSDR's sampling and analysis activities was to determine whether the muscle tissues from commonly consumed fish and shellfish contain levels of heavy metals and explosives compounds that would adversely affect public health(4). To assist in the activities, ATSDR worked with the US Environmental Protection Agency's Environmental Response Team (EPA/ERT) to collect and analyze fish and shellfish from the coastal waters and near shore land on Vieques.

1. Sample Locations

Fish and shellfish were collected from six locations on Vieques (see Figure 3). The following locations were chosen to represent productive fishing areas surrounding the island (Ecology and Environment 1986 as cited in Navy 2000b):

  • Location 1. Fish and shellfish were collected from two small, near shore reefs to the north of the LIA on the east end of Vieques. The total area included in the sampling effort (the combined portions of each reef actually sampled by divers) was approximately 12,000 square meters. In addition, conch were collected from the sea grass bed and crabs were collected from the north end of the LIA.

  • Location 2 consisted of two sections of a former Navy vessel, located approximately 100 yards meters, that had been used for military target practice, near shore to the south of the LIA on the east end of Vieques. The total area included in the sampling effort was approximately 10,000 square meters. In addition, conch were collected from the sea grass bed and crabs were collected from the west coast of Bahia Salina del Sur in the AFWTF.

  • Location 3 consisted of three near shore reefs to the south of the town of Esperanza on the south shore of Vieques. Fish were collected at Bucky Reef and Patti Reef, and conch were collected from the seagrass bed north of Arena Reef. The total area included in the sampling effort was approximately 15,000 square meters.

  • Location 4. Fish were collected from two near shore reefs to the northwest of the town of Isabel Segunda on the north shore of Vieques and from Mosquito Pier to the west of Isabel Segunda (see Picture 10). The total area included in the sampling effort was approximately 15,000 square meters.

  • Location 5 was a fish market in the town of Isabel Segunda. No attempt was made to verify the area from which the fish and lobsters were caught, though the market staff stated that all fish and lobsters sold in the market were caught locally.

  • Location 6. Fish were collected from an unnamed near shore reef off the southwest end of Vieques, in the vicinity of the Monte Pirata Conservation Zone. Conch were collected from a seagrass bed 500 meters northeast of the reef. The total area included in the sampling effort was approximately 15,000 square meters. In addition, land crabs were collected from the Laguna Kiani Conservation Zone on the west end of Vieques.

2. Methods

Species Collected

At each location, field personnel attempted to catch (or purchase, in the case of the fish market) five individuals from the following types of fish targeted for analysis: yellowtail snapper (Ocyurus chrysurus)/mutton or lane snapper (Lutjanus sp.), grouper/red hind/rock hind/coney (Epinephelus sp.), grunt (Haemulon sp.), parrotfish (Scaridae family), and goatfish (Mullidae family). In addition, field personnel attempted to catch or purchase five individuals of queen conch (Strombus gigas) and spiny lobster (Panulirus argus) at each sampling location. These fish and shellfish were determined to be commonly caught and consumed by the residents of Vieques, based on research by Universidad Metropolitana (Caro et al. 2000), discussions with the petitioner and residents of Vieques, information provided in the Vieques Special Commission Report (Government of Puerto Rico 1999 as cited in Navy 2000b), and visits to local fish markets. In addition, to address a specific community concern, ATSDR collected one honeycomb cowfish (Lactophrys polygonia ) from the fish market.

Field personnel planned to collect a sufficient number of individuals of blue land crab (Cardisoma guanhumi) on shore, adjacent to Locations 1, 2, and 6 and fiddler crab (Uca sp.) adjacent to Locations 1 and 2 to meet the tissue mass requirements for five replicates of the desired chemical analyses(5) . For safety reasons, Navy technicians collected these crabs on the LIA and transferred them to field personnel the same day they were collected. Land crabs were determined to be a species eaten by the residents of Vieques, while fiddler crabs are not known to be a species that is eaten.

Table 7 summarizes the species of fish and shellfish that were collected from each sample location. For reference, Appendix E contains pictures of the species collected.

Quality Assurance and Quality Control

The data used in this investigation meets established EPA standards for adequate quality assurance and control measures for sampling procedures, chain-of-custody procedures, laboratory procedures, and data reporting. The analytical methods and detection limits established for this investigation were consistent with the study's objectives and were sufficient to enable a conservative evaluation of health implications. Appendix B contains more details concerning the sampling methods for ATSDR's fish and shellfish investigation.

3. Results

Organism General Health

All collected organisms were given a brief physical examination. However, the white grunts (H. plumieri) collected at the fish market had already had their gut cavities cleaned prior to sale; therefore, no internal examination was possible. All of the organisms collected from all of the sampling locations appeared to be healthy. Few had any obvious deformities or parasites, with the exception of the following.

  • One french grunt from Location 6 was observed to have a deformed anal fin. The cause of the deformity (injury or growth defect) could not be determined. A graysby collected fromLocation 3 was observed to have a sunken belly, the cause could not be determined.
  • External and internal parasites are common on reef fish, and in low numbers they are not an indication of a stressed system. A single fish was observed to have external parasites (isopods in the gill cavity of a bluestriped grunt from Location 3) and three fish were observed to have internal parasites (unidentified worms in the peritoneal cavity of two red hinds from the fish market and one coney from Location 6).

Chemical Analysis

Note of Explanation: Averages were calculated using detected concentrations only and do not take into account nondetected values. Even though this tends to overestimate the true average values, ATSDR chose to base its health evaluations on the more conservative averages to be more protective of public health.

Explosives compounds

Fish and shellfish tissues were analyzed for explosives compounds. No explosives compounds were detected in fish tissues from any sample location. Of the 42 shellfish samples, only fiddler crabs contained an explosives compound(6) (HMX; see Table 5). No explosives compounds were detected in conch, lobster, or land crab samples from any location (see Table 9).

Metals

Fish and shellfish tissues were analyzed for heavy metals. Finding heavy metals in fish and shellfish is not unique to Vieques. Depending on the geology and chemical composition of the area, a variety of metals can be found in varying concentrations (e.g., EPA 2001a). If the levels are too high and pose a health concern, health agencies issue advisories against eating fish or shellfish. Of the heavy metals, mercury is the chemical of concern in the largest number of states (EPA 2000).

  • Fish. Calcium, magnesium, potassium, selenium, and sodium were detected in every fish sample. Chromium, copper, and zinc were also frequently detected (in greater than 90% of the samples). Aluminum, arsenic, barium, and mercury were detected in 72-78% of the samples. Manganese and iron were detected in 65% and 60% of the samples, respectively. Lead and beryllium were detected in 35% and 19% of the samples, respectively. Cadmium, cobalt, nickel, silver, and vanadium were infrequently detected (in less than 10% of the samples) and antimony and thallium were not detected in fish. The ranges, averages, and frequency of detections are summarized in Table 8.
  • Shellfish. Calcium, copper, magnesium, potassium, selenium, sodium, and zinc were detected in every shellfish sample and chromium was also frequently detected (95% of the samples). Aluminum, arsenic, barium, iron, and manganese were detected in 64-89% of the samples. Cadmium, mercury, silver, and vanadium were detected in 34-55% of the samples. Beryllium, cobalt, and lead were less frequently detected (in less than 25% of the samples). Antimony, nickel, and thallium were not detected in shellfish. The ranges, averages, and frequency of detections are summarized in Table 9.
  • Fiddler crab. Antimony, beryllium, lead, mercury, and thallium were not detected in fiddler crabs and nickel was detected in 50% of the samples (7). The remaining metals were detected in every fiddler crab composite sample. The results are summarized under Live Impact Area in Table 5.

Methylmercury

One tissue sample from each of four species (red hind, white grunt, yellowtail snapper, and spiny lobster) collected from the fish market (Location 5) was analyzed for methylmercury. Methylmercury was detected in concentrations of 0.02-0.08 ppm (parts per million) in fish and 0.019 ppm in shellfish. Results are summarized in Tables 8 and 9.

Are the levels of mercury higher in fish from Vieques?
Because of its persistence in the environment and bioaccumulative property, mercury is the primary contaminant driving fish advisories—almost 75% of all fish advisories are related to mercury contamination (EPA 2002). In general, the levels of mercury measured in fish collected from Vieques were about the same as those from the mainland of Puerto Rico and the Virgin Islands. In Vieques, the average mercury level was 0.12 ppm. Average mercury levels found in the same species of fish from Puerto Rico and the Virgin Islands ranged from 0.07 to 0.70 (Burger et al. 1992). Average mercury levels in seafood species, collected nationwide, ranged from not detected to 1.45 ppm (FDA 2001b). It is also interesting to note that people who eat fish from Vieques would receive about as much mercury as people who eat canned tuna (according to a 1991 FDA survey, the average mercury concentration in canned tuna is 0.17 ppm; Yess 1993 as cited in ATSDR 1999a).


3 The National Academy of Science notes that there are limitations to the usefulness of assessing human health concerns from analyses performed on nonedible portions of organisms or on the whole body (EPA 2000).

4 The purpose of ATSDR's sampling and health evaluation is to address any potential chemical contamination in the fish and shellfish; therefore, this public health assessment does not focus on any potential biological conditions (e.g., naturally occurring toxins in fish, diseases, parasites, or bacteria) that may afflict the fish and shellfish of Vieques.

5 Originally, ATSDR planned to collected blue land crabs and fiddler crabs from all six sampling locations. However, due to time constraints and logistical problems encountered during sampling, it was decided to limit the collection to these key locations.

6 Rinsing fiddler crabs of sand and dirt was inadvertently omitted prior to placing them into sample containers. The concentrations detected may not accurately represent the levels of HMX in fiddler crabs, rather the concentrations could be artificially elevated due to the external sand and dirt contamination.

7 Rinsing fiddler crabs of sand and dirt was inadvertently omitted prior to placing them into sample containers. The concentrations detected may not accurately represent the levels of metals in fiddler crabs, rather the concentrations could be artificially elevated due to the external contamination.


 
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