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Public Health Assessment
Air Pathway Evaluation,
Isla de Vieques Bombing Range,
Vieques, Puerto Rico
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August 26, 2003
Federal Facilities Assessment Branch
Division of Health Assessment and Consultation
Agency for Toxic Substances and Disease Registry
An integral part of the public health assessment process is addressing community concerns related to environmental health. Throughout this process, ATSDR has been working with, and will continue to work with, the Vieques community to define specific health issues of concern. On multiple trips to the island, ATSDR has met with numerous individuals and organizations, including local officials, physicians, nurses, pharmacists, leaders of women's groups, teachers, students, fishermen, businessmen, and families. Meeting with community members was critical to identifying and understanding residents' health concerns.
This PHA has addressed four key questions that community members have repeatedly asked about inhalation exposures to contaminants from the Navy's bombing range at Vieques. ATSDR's other PHAs have addressed, or will address, community concerns regarding levels of contamination in other environmental media, including water, soils, and food items. These documents address the main concerns that ATSDR has received since first working on the island of Vieques.
In addition to the four key questions pertaining to air contaminants released from the LIA (see Section V), ATSDR has identified other community concerns that are relevant to the air exposure pathway. These additional concerns are summarized below in three questions, along with ATSDR's responses.
A. Is Water from Rainfall Collection Systems Safe to Drink?
ATSDR Response:The majority of residents on Vieques receive drinking water from the public water supply, which draws from surface water (Rio Blanco) on the main island of Puerto Rico. However, ATSDR has received accounts that some residents obtain drinking water using rainfall collection systems. The exact number of residents with such systems is not known. The following paragraphs address the public health implications of obtain drinking water from these rainfall collection systems.
Rainwater can be a safe and reliable source of drinking water and is used widely for this purpose throughout the Caribbean. However, the method of collecting and treating rainwater determines how safe the water is. Because rooftops are open to the air, a wide range of materials might settle on them. These materials include leaves, mold spores, dead insects, bird droppings, and particulate matter from local sources of air pollution. Some of these materials can contain significant bacterial contamination. Though dusts from the LIA might blow in the air for several miles and then settle on the rooftops in the residential areas of Vieques, analyses in Section V suggest that local sources of air pollution (e.g., motor vehicles) probably account for a majority of particulate matter in these areas.
The following discussion first outlines recommended sanitation practices for obtaining drinking water from rainfall collection systems and then presents ATSDR's specific comments on use of these systems on Vieques.
General Sanitation Practices
When rainwater falls on rooftops, it can wash the various materials that have settled onto the rooftops into the device used to collect the rainwater, usually a cistern or a storage tank. If residents consume the untreated water that first flows from the rooftops, they might be exposed to a wide range of disease-causing bacteria. As evidence of harmful exposures, scientists have suspected that an outbreak of salmonella in the West Indies resulted from residents drinking water from a rooftop collection system that was heavily contaminated with bird feces (Koplan et al. 1978). Many other accounts of diseases caused by water-borne pathogens have been attributed to use of poorly maintained rainfall collection systems. Therefore, consumption of untreated water from rooftop collection systems is not advised.
Various health and environmental agencies have published guidelines for ensuring that rainfall collection systems provide for a safe drinking water supply. Many of these guidelines involve minimal monetary investments to implement. The following suggestions are provided in several references on good sanitation practices for obtaining drinking water (e.g., Salvato 1982, Texas Water Development Board 1997, United Nations Environment Programme 1997):
- The water that initially flows from the rooftop likely contains the greatest amount of chemical and biological contamination, especially if the time between rainfalls is great. This water should be diverted from the water storage tank and should never be consumed. According to a United Nations document, ". . . water captured during the first 10 minutes of rainfall during an event of average intensity is unfit for drinking purposes" (United Nations Environment Programme 1997). Consumption of this water can be avoided by using diversion valves that cause the initial flow of water to bypass the storage tank.
- Some measures should be taken to periodically clean the various surfaces that might come into contact with the rainwater, including the rooftops and cisterns.
- The rainwater that is eventually collected should be filtered before entering the storage tank to remove gross impurities (e.g., leaves, insects). Separating and removing sediments in storage tanks is also recommended, as insoluble contaminants may pass through filters and then settle in the storage tanks. Finally, many agencies advise chemical treatment of collected water, such as chlorination.
By following these and other sanitation practices, residents of Vieques can ensure that drinking water provided by rainfall collection systems is relatively free of contamination, including contaminants from local sources (e.g., birds, insects, motor vehicles), as well as the much smaller quantities of contaminants that might transport from the LIA.
Information Specific to Vieques
Focusing specifically on Vieques, ATSDR has learned that some community members obtain drinking water from rooftop collection systems (Cherry and Ramos 1995), though detailed information on the extent to which this takes place is not available. It is ATSDR's understanding that most residents converted their collection systems into closed tanks that now store water provided by the public water supply, and not by local rainwater. However, some residents may still use rainwater from rainfall collection systems in addition to water from the public water supply. The main community concern about the rainfall collection systems is that dusts from the LIA might settle on rooftops and eventually contaminate the rainwater that is collected.
No sampling studies have been conducted to characterize the quality of water in rainfall collection systems on Vieques. Therefore, no firm conclusions can be drawn based on site-specific sampling data. ATSDR's response to this question addresses the general advantages and disadvantages of using rainfall as a source of drinking water. If good sanitation practices are followed, rainfall collection systems on Vieques are expected to provide clean water that does not pose health hazards.
ATSDR has collected many documents that list recommended sanitation practices for rainfall collection systems. Some of these documents address issues specific to water supplies in the Caribbean. For the residents' benefit, ATSDR has placed copies of two key documents in the records repositories for the Vieques site, which are located at Biblioteca Publica on Vieques, the Vieques Conservation and Historical Trust, and at the University of Puerto Rico School of Public Health.
B. Is Exposure to the Material in African Dust Unhealthy?
ATSDR's Response:The purpose of this PHA is to evaluate the public health implications of exposures to air contamination associated with the Navy's military training activities on Vieques. When evaluating this issue, however, some Vieques residents also expressed concern that "African dust storms" might influence air quality on the island. To be responsive to these concerns, ATSDR researched the potential impacts of these dust storms and reached the conclusions summarized below.
Public Health Implications of African Dust Storms
As Section III.E explains, many researchers have studied African dust storms, or events in which strong winds blow large amounts of dust from arid northern Africa soils into the air. Some dust clouds have been observed thousands of miles from Africa, including over areas in the Caribbean and the southeastern United States. ATSDR emphasizes that the presence of dust particles in the air does not imply that unhealthy exposures occur. The public health implications of the African dust storms depend on other factors, such as the amount of dust in the air, the duration of the storms, and the relative amounts of chemical and biological contaminants in these dusts.
Regarding the amount of dust in the air, authors of key studies on African dust storms have doubted that the levels of dust alone would exceed EPA's health-based standards for particulate matter (Prospero 1999a). However, they have hypothesized that the amount of African dust in the air, when added to particulate matter from local sources of air pollution, might lead to unhealthy levels of air pollution. This hypothesis has never been verified for Vieques. In fact, none of the particulate sampling studies conducted on Vieques (see Appendix C) have ever shown potentially unhealthy levels of particulate matter, as gauged by EPA's health-based National Ambient Air Quality Standards. Moreover, the historical record of particulate sampling along the eastern shore of the main island of Puerto Rico reveals a similar trend (see Appendix C). These consistent trends among the sampling studies suggest that levels of particulate matter on Vieques have not reached levels that could present a public health hazard, even during African dust storms. This finding should be verified by ongoing review of sampling data collected on the island.
Unfortunately, less information is available on the chemical and biological makeup of dust particles during these African dust storm events. ATSDR has identified studies indicating that the dust particles contain various minerals, and even traces of bacteria and viruses (Griffin et al. 2001). These studies have speculated about potential public health impacts, but no link between adverse health effects and the components of African dust has been established. ATSDR believes its recommendation for sampling of airborne metals (see Section IX) will address the data gap on the mineral content of African dust, and ATSDR supports further research into the type and amounts of biological material (e.g., bacteria, viruses) that may be transported with African dust.
Relative Amounts of Particulate Matter from African Dust Storms and from the LIA
Some community members have asked ATSDR to explain how it is possible that two different sources of air pollution located thousands of miles apart (i.e., the LIA and Africa) can have similar impacts on air quality at Vieques. The key to understanding this issue is that the LIA and African dust storms release dramatically different quantities of particulate matter.
Though emissions from both sources cannot be measured directly, emissions estimates suggest that African dust storms release far more particulate matter to the air than the Navy's military training exercises. Specifically, the Navy has estimated that its operations at Vieques release 70 tons of PM10 to the air per year (IT 2000). On the other hand, researchers have estimated that African dust storms release between 100,000,000 and 1,000,000,000 tons of particulate matter to the air per year (Shinn et al. 2000). Assuming the emissions estimates quoted above are reasonably accurate, the data suggest that African dust storms may release more than 1,000,000 times as much particulate matter as does the LIA.
Therefore, even though the source of African dust is several thousand miles away from Vieques, the fact that African dust storms release dramatically higher levels of particulate matter explains why they can have noticeable impacts on air quality in the Caribbean, even when local sources of air pollution (e.g., the Navy's military training exercises) might have little air quality impacts at distances as short as 7.9 miles from the source.
C. Can ATSDR Provide General Information on Asthma and Air Pollution?
ATSDR's Response:Asthma is a common, and potentially deadly, chronic (or long-term) lung disease. A person with asthma might suffer from "asthma attacks." These attacks can vary in frequency and severity. Some people with asthma have attacks often, while others have them rarely. Less severe asthma attacks result in difficultly breathing, tightness in the chest, coughing, and wheezing. More severe asthma attacks can be life-threatening if a person stops breathing. As a result, it is very important for a person with asthma to get help from a doctor to manage the disease. This is especially important for children with asthma, who have been found to be a sensitive sub-population for acute responses to outdoor air pollution (Clark et al. 1999).
No one has determined exactly what causes some people to have asthma and other people to not have the disease. However, scientists have identified many "asthma triggers" that are known to cause people with asthma to have asthma attacks. Different people are affected by different asthma triggers, and a doctor can help determine which asthma triggers appear to be a problem for a given person. The following list identifies some (but not all) of the known or suspected asthma triggers:
- Indoor air contaminants: mold, tobacco smoke, household chemicals, dust, and allergens from pets and insects.
- Outdoor air contaminants: particulate matter, pollen, and ozone.
- Other factors: sinus infections, certain medications, and food additives.
Though outdoor air pollution can trigger asthma attacks, the extent to which outdoor air pollution causes people to have asthma in the first place is unclear. As evidence of this, asthma occurs in areas with relatively low levels of air pollution. Further research is needed to understand to what extent outdoor air pollution affects whether or not a given person has asthma.
ATSDR notes that its review of outdoor air pollution on Vieques was based in part on EPA's health-based National Ambient Air Quality Standards. EPA developed these standards to protect public health, including the health of potentially sensitive populations, like asthmatics. Therefore, ATSDR's analyses found that levels of particulate matter on Vieques do not present a public health hazard, even for people who have asthma. However, ATSDR acknowledges that some asthmatics with extreme sensitivities might have attacks triggered by low levels of pollution. Recognizing that asthma is potentially serious and needs to be treated correctly, ATSDR urges all individuals with asthma–on Vieques and elsewhere in Puerto Rico and the United States–to work with a doctor to set up an asthma management plan. Following such a plan can help keep asthma under control.
Other Community Concerns:
ATSDR is committed to addressing additional community concerns relevant to environmental health issues, as these concerns arise. Vieques residents can direct their health concerns to ATSDR either in writing or via the telephone. Please submit written questions and inquiries to:
Program Evaluation, Records and Information Services Branch
ATSDR, Division of Health Assessment and Consultation
Attn: Isla de Vieques, Puerto Rico
1600 Clifton Road, NE (E-32)
Atlanta, GA 30333
Community members can also call ATSDR either by contacting our regional representatives in New York, New York, at (212) 637-4307 or by calling our toll-free telephone number, 1-888-42-ATSDR (or 1-888-422-8737).