III. Previous Research

This section of the PHA summarizes research previously conducted on Vieques that is directly related to the fish and shellfish sampling conducted by ATSDR and EPA/ERT. The next section of the PHA (Section IV) provides more details about ATSDR's sampling effort.

1. Biomagnification of Carcinogenic Metals in Crab Tissue, Vieques, Puerto Rico by Arturo Massol Deyá, Ph.D. and Elba Díaz, M.S. Casa Pueblo de Adjuntas and Universidad de Puerto Rico. January 12, 2000.

Summary

In November 1999, researchers from Casa Pueblo de Adjuntas, in cooperation with the Biology Department of Recinto Mayaguez at the University of Puerto Rico, sampled male fiddler crabs (Uca pugnax rapax) from Icacos and Anones Lagoons in the LIA and from Puerto Mosquito just east of Esperanza. The purpose of the research was to assess the potential transport of metals from the impact area to other ecosystems.

Researchers collected "close to 35" fiddler crabs at each location. They analyzed the extremities (levers and legs) separately from the body (shell and internal contents) for cadmium, chromium, cobalt, copper, lead, manganese, nickel, and zinc. Please see Table 2 for a summary of the results. The researchers compared the levels of the heavy metals detected in fiddler crabs in Icacos Lagoon to the levels in the sediments and reported that biomagnification (see text box for definition) of cadmium was occurring. They also noted that the average cadmium concentration exceeds the critical levels of concern for cadmium ingestion according to the US Food and Drug Administration (FDA) and the World Health Organization (WHO).

Conclusions

This research established that fiddler crabs contained evidence of heavy metals. However, fiddler crabs are not known to be a species that are eaten by the residents of Vieques. While the data from this report may be useful to evaluate ecological contamination, it has limited utility when trying to extrapolate into the human food chain. To evaluate human exposures to edible land-based shellfish, ATSDR sampled and analyzed land crabs (a species known to be consumed by the residents) during the fish and shellfish investigation in July 2001. The remainder of this PHA details ATSDR's sampling effort (Section IV) and evaluates whether eating land crabs, among other fish and shellfish species, would result in harmful health effects (Section V).

1. Toxicological Survey of Heavy Metals in Fish Populations, Vieques Island
   by Doris A. Caro, Ph.D.; Mei-Ling Nazario; and Noel Diaz. Universidad Metropolitana. June 2000.

Summary

Between December 1999 and April 2000, researchers from the School of Environmental Matters, Universidad Metropolitana, collected fish from fish markets on the northern and southern (Esperanza) coasts of Vieques and from the Parquera fish market in Lajas on the western side of the mainland of Puerto Rico. The focus of the research was to identify potential heavy metal contamination in fish species that are commonly eaten by the residents of Vieques.

To identify the most frequently consumed species, researchers administered a questionnaire to Vieques residents asking about their dietary habits. Fifty-one residents responded to the questionnaire. Of these, 10 people (19.6%) reported to eat fish never or occasionally, 24 people (47%) 1-2 times a week, 9 people (17.6%) 3-4 times a week, and 8 people (15.7%) five or more times a week. Based on responses to the questionnaire, the most commonly consumed species of fish include: colirrubia (yellow tail snapper, Ocyurus chrysurus), mero cabrilla (red hind, Epinephelus guttatus), peje puerco (triggerfish, Balistes sp.), sierra (cero, Scomberomorus regalis), capitán (not identified), cotorro (parrotfish, Scaridae family), chapín (trunkfish, Lactophrys sp.), bonito (skipjack tuna, Euthynnus pelamis), negra (blackfin snapper, Lutjanus buccanella), dolorado (not identified), chillo (silk snapper, Lutjanus vivanus), boquicolorao/ronco (white grunt, Haemulon plumieri), and sama (mutton snapper, Lutjanus analis).

Researchers collected a total of 78 fish--35 fish from fish markets in northern Vieques, 17 fish from fish markets in Esperanza, and 26 fish from fish markets in the Parquera area on the mainland of Puerto Rico. Species included: arrayao (lane snapper, Lutjanus synagris), boquicolorao, colirrubia, cotorro azul (blue parrotfish, Scarus coeruleus), cotorro rojo (stoplight parrotfish, Sparisoma viride), cotorro verde (redband parrotfish, Sparisoma aurofrenatum), mero cabrilla, mero mantequilla (coney, Epinephelus fulvus), and salmorete de altura (goatfish, Mullidae family). Fish fillet and skin samples were tested for arsenic, cadmium, lead, mercury, selenium, and zinc.

The researchers concluded that "based on the data obtained...we were not able to verify our hypothesis of potential bioaccumulation in the fish...there is no clear relationship between fish weight and size and their metal content" (Caro et al. 2000). They reported "high concentrations" of arsenic, mercury, selenium, and zinc; but low or no concentrations of cadmium and lead in the fish tissue samples. Please see Tables 3 and 4 for a summary of their analytical results.

Conclusions

This research provided valuable information about the dietary habits of the residents of Vieques, specifically how often people are eating fish and what species. This information was used throughout ATSDR's public health evaluation. In addition, ATSDR evaluated whether the concentrations reported would result in harmful health effects for people consuming fish from the sampled fish markets⁽²⁾. Based on this data, ATSDR determined that it is safe to eat fish from the fish markets in northern Vieques, Esperanza, and the Parquera area on the mainland of Puerto Rico on a daily basis (i.e., all of the concentrations reported by Universidad Metropolitana are too low to be of health concern). Please see Section V. Evaluation of Fish and Shellfish from Vieques and Appendix D for more details on the methods and assumptions ATSDR used to estimate human exposure doses and determine health effects.

1. Contaminant levels in crabs from two solid waste management units on Vieques National Wildlife Refuge (October 4, 2002)

Summary

In July 2001, US Fish and Wildlife Service (FWS) personnel sampled land crabs and fiddler crabs from two solid waste management units (SWMUs) in west Vieques (the former NASD) and from Sandy Point National Wildlife Refuge in St. Croix, as a control. The samples are whole body and were analyzed for pesticides and metals. The purpose of the research was to collect preliminary data about the level of contamination in the prey base (land crabs and fiddler crabs) for some aquatic birds (e.g., herons and egrets). FWS provided the analytical data to ATSDR for inclusion in this health assessment (FWS 2001a, 2001b). Please see Tables 5 and 6 for summaries of the fiddler crab and land crab data, respectively.

Conclusions

This research established that fiddler crabs and land crabs contained some heavy metals and pesticides. The results were not available prior to ATSDR's sampling in July 2001. In accordance with the objectives of this research, the data from the report are useful to evaluate ecological contamination. However, this research cannot easily be converted for evaluating human health because fiddler crabs are not a species that are eaten by people. Also, the concentrations may not be applicable to what people eat because the whole body was analyzed (e.g., included in the analysis were parts that are not eaten, such as the shell)⁽³⁾. To evaluate potential exposure to people, ATSDR sampled and analyzed edible portions (i.e., the meat) of the land crabs during the July 2001 fish and shellfish investigation. The remainder of this PHA details ATSDR's sampling effort (Section IV) and evaluates whether eating land crabs, among other fish and shellfish species, would result in harmful health effects (Section V).

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² It was not noted in the study by Caro et al. 2000 if the concentrations were reported as wet weight concentrations or dry weight concentrations, ATSDR is assuming they are wet weight concentrations.