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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
Federal Facilities Assessment Branch
Division of Health Assessment and Consultation
Agency for Toxic Substances and Disease Registry
V. Community Health Concerns
An integral part of the public health assessment process is addressing community concerns related to environmental health. ATSDR has been working with, and will continue to work with, the community to define specific health issues of concern. On multiple trips to the island, ATSDR has met with a variety of individuals and organizations, including local officials, physicians, nurses, pharmacists, leaders of women's groups, school educators, fishermen, and business people. ATSDR has also met with individual families. Meeting with a broad spectrum of community members is critical to determine health issues of concern and to assess the environmental health issues on Vieques.
General issues of health concern related to exposure to the soil on Vieques have been assessed in this PHA. In addition, ATSDR released a meeting summary report of an expert review panel who discussed the issue of whether an association existed between place of residence and morphological cardiovascular changes among fishermen (ATSDR and PSM 2001) and a PHA addressing Vieques groundwater and public water supply systems (ATSDR 2001b). Copies of these documents are available by contacting ATSDR (1-888-42-ATSDR) and from records repositories on Vieques. Public health issues related to exposure to chemicals in the air and in fish and shellfish were also evaluated by ATSDR. PHAs addressing these exposure pathways were released for public comment in October 2002.
This section of the PHA addresses additional community concerns relating to heavy metal uptake in plants and animals around Vieques and the state of the science of hair analysis.
Community members are concerned that heavy metals associated with the Navy's training activities are accumulating in agricultural plants and thereby, reaching the residents of Vieques through the food chain pathway.
In February and March 2000, researchers from Casa Pueblo and Recinto Universitario de Mayaguez (RUM), University of Puerto Rico, sampled the prevailing vegetation in the LIA (specifically Carrucho Beach, Monte David, and Gato and Icacos Lagoons) for heavy metals (Massol Deyá and Díaz 2000b). Reference populations of the same species were also collected in Bosque Seco de Guánica and RUM Alzamora Ranch. In addition, researchers from Casa Pueblo and University of Puerto Rico randomly collected agricultural and common vegetation from three sites within the residential section of Vieques: an agricultural area in Monte Carmelo, a section of Monte Carmelo that borders Camp Garcia, and an agricultural farm in Barrio Monte Santo, Gobeo sector (Massol Deyá and Díaz 2001). The authors reported that several species contained "excessive or toxic" levels of heavy metals and that these contaminants were moving through the food chain.
ATSDR determined through independent review with an agronomist with the US Department of Agriculture (USDA) that the studies provide insufficient evidence that heavy metals are accumulating in plants at a level that would cause harm to people.
First, many of the samples that were analyzed are not species that are eaten. In addition, when species that are eaten were sampled, the edible parts (e.g., pepper fruits, pumpkins, and seeds of pigeon peas) were not sampled, rather the stems and leaves were analyzed. Human exposures from locally grown foods can only be estimated from the edible portions of the food source (USDA 2002). In general, the edible portions of plants (e.g., fruits and berries) are less likely to accumulate metals from soil because of normal plant processes (e.g., physiological barriers that prevent contaminants from getting to the tops of plants) (ATSDR 2001a).
Second, without quality assurance samples, it is likely that errors occurred in the analysis process (USDA 2002). The reports lack the use of standard reference materials (e.g., orchard leaves available from the National Institute of Standards and Technology) to demonstrate that the results are accurate and background corrections for lead, cobalt, nickel, and cadmium to eliminate the effect of light scattering by non-element materials in the samples.
Third, research has shown that small soil particles can become embedded in the surface waxy layer of leaves and are difficult to remove (USDA 2002). Even with a thorough washing, soil particles will adhere to the plant materials. This adhered soil can actually carry more contaminants than what is taken up by the plant from the soil (ATSDR 2001a). When elements are present in plant samples as soil particles, they are often of low bioavailability and while the external contamination may also be ingested, the chemicals bound to soil are not usually in a form that can be absorbed by the body (USDA 2002). While there are methods to determine how much of a chemical concentration is adhered as soil and how much is in the plant tissue, these were not utilized by the researchers.
Because of these factors, ATSDR could not quantify exposures from these reports nor draw any health conclusions about whether consuming plants grown in Vieques would result in harmful health effects.
Community members expressed concern over the possibility that livestock are accumulating heavy metals by grazing on contaminated plants. In support, a study by Casa Pueblo de Adjuntas reports that heavy metals were found in the hair of goats. To address this concern, the Puerto Rico Department of Agriculture in cooperation with the Farmers Association of Puerto Rico (AAPR) sampled grass, fruit-bearing trees, and bovine livestock from Monte Carmelo, Martineau, Monte Santo, Esperanza, Lujan, Gubeo, and western Vieques for cadmium, cobalt, copper, lead, manganese, and nickel. They concluded that the agricultural products from Vieques are suitable for consumption and do not contain toxic levels of these contaminants (El Nuevo Día 2001).
To date, ATSDR has not been able to obtain the original data or report that support these findings. Once the information becomes available, ATSDR will also evaluate whether eating agricultural products grown on Vieques could lead to any potential health effects.
Community members expressed concern that they were being exposed to unhealthy levels of metals, as shown by hair analysis. However, the medical literature recommends that physicians not rely solely on hair analysis to diagnose or treat heavy metal toxicity (Frisch and Schwartz 2002).
In June 2001, ATSDR convened an expert panel to discuss the state of the science relating to analyzing hair for environmental exposure (ATSDR 2001c). The panel consisted of individuals who represented state and federal government agencies, academia, and private practice and whose expertise, interests, and experience covered a wide range of related technical disciplines.
The panelists agreed that "for most substances, insufficient data currently exist that would allow the prediction of a health effect from the concentration of the substance in hair. The presence of a substance in hair may indicate exposure (both internal and external), but does not necessarily indicate the source of exposure." They noted that a relationship between contaminant concentrations in hair and any kind of measurable outcome have only been established for methylmercury and to a limited extent for arsenic, provided external contamination can be ruled out.
The expert panel recognized that laboratory methods exist to measure the levels of some environmental contaminants in hair, but commented that procedures need to be standardized to help ensure more accurate and reliable results. They also identified several factors that limit the interpretation of even the most accurate, reliable, and reproducible laboratory results: (1) the lack of reference (or background) ranges in which to frame the interpretation of results, (2) difficulties in distinguishing internal from external contamination in hair, (3) a lack of understanding of how and to what extent environmental contaminants are incorporated into the hair, (4) the lack of correlation between levels in hair and blood and other target tissues, as well as the lack of epidemiologic data linking substance-specific hair levels with adverse health effects, and (5) little information is available pertinent to the study of environmentally relevant organic compounds in hair.
Copies of the meeting summary report are available by contacting ATSDR (1-888-42-ATSDR) and on ATSDR's Web site (http://www.atsdr.cdc.gov/HAC/hair_analysis/).
Community members can direct additional health concerns to:
Program Evaluation and Records Information Services Branch
ATSDR, Division of Health Assessment and Consultation
Attn: Isla de Vieques, Puerto Rico
1600 Clifton Road, NE (E-56)
Atlanta, Georgia 30333
Community members can also telephone the ATSDR regional representatives in New York, New York at (212) 637-4307 or call the toll-free telephone number, 1-888-42-ATSDR.