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

Appendices

Appendix B: ATSDR Glossary of Environmental Health Terms

Absorption:

How a chemical enters a person's blood after the chemical has been swallowed, has come into contact with the skin, or has been breathed in.

Acute Exposure:

Contact with a chemical that happens once or only for a limited period of time. ATSDR defines acute exposures as those that might last up to 14 days.

Adverse Health Effect:

A change in body function or the structures of cells that can lead to disease or health problems.

ATSDR:

The Agency for Toxic Substances and Disease Registry. ATSDR is a federal health agency in Atlanta, Georgia that deals with hazardous substance and waste site issues. ATSDR gives people information about harmful chemicals in their environment and tells people how to protect themselves from coming into contact with chemicals.

Background Level:

An average or expected amount of a chemical in a specific environment. Or, amounts of chemicals that occur naturally in a specific environment.

Biota:

Used in public health, things that humans would eat - including animals, fish and plants.

Cancer:

A group of diseases which occur when cells in the body become abnormal and grow, or multiply, out of control

Carcinogen:

Any substance shown to cause tumors or cancer in experimental studies.

Chronic Exposure:

A contact with a substance or chemical that happens over a long period of time. ATSDR considers exposures of more than one year to be chronic.

Completed Exposure Pathway:

See Exposure Pathway.

Comparison Value:

Concentrations or the amount of substances in air, water, food, and soil that are unlikely, upon exposure, to cause adverse health effects. Comparison values are used by health assessors to select which substances and environmental media (air, water, food and soil) need additional evaluation while health concerns or effects are investigated.

Comprehensive Environmental Response, Compensation, and Liability Act (CERCLA):

CERCLA was put into place in 1980. It is also known as Superfund. This act concerns releases of hazardous substances into the environment, and the cleanup of these substances and hazardous waste sites. ATSDR was created by this act and is responsible for looking into the health issues related to hazardous waste sites.

Concern:

A belief or worry that chemicals in the environment might cause harm to people.

Concentration:

How much or the amount of a substance present in a certain amount of soil, water, air, or food.

Contaminant:

See Environmental Contaminant.

Dermal Contact:

A chemical getting onto your skin. (see Route of Exposure).

Dose:

The amount of a substance to which a person may be exposed, usually on a daily basis. Dose is often explained as "amount of substance(s) per body weight per day".

Dose / Response:

The relationship between the amount of exposure (dose) and the change in body function or health that result.

Duration:

The amount of time (days, months, years) that a person is exposed to a chemical.

Environmental Contaminant:

A substance (chemical) that gets into a system (person, animal, or the environment) in amounts higher than that found in Background Level, or what would be expected.

Environmental Media:

Usually refers to the air, water, and soil in which chemical of interest are found. Sometimes refers to the plants and animals that are eaten by humans. Environmental Media is the second part of an Exposure Pathway.

U.S. Environmental Protection Agency (EPA):

The federal agency that develops and enforces environmental laws to protect the environment and the public's health.

Epidemiology:

The study of the different factors that determine how often, in how many people, and in which people will disease occur.

Exposure:

Coming into contact with a chemical substance.(For the three ways people can come in contact with substances, see Route of Exposure.)

Exposure Assessment:

The process of finding the ways people come in contact with chemicals, how often and how long they come in contact with chemicals, and the amounts of chemicals with which they come in contact.

Exposure Pathway:

A description of the way that a chemical moves from its source (where it began) to where and how people can come into contact with (or get exposed to) the chemical.

ATSDR defines an exposure pathway as having 5 parts:

1. Source of Contamination,
2. Environmental Media and Transport Mechanism,
3. Point of Exposure,
4. Route of Exposure; and,
5. Receptor Population.
   
   

When all 5 parts of an exposure pathway are present, it is called a Completed Exposure Pathway. Each of these 5 terms is defined in this Glossary.

Frequency:

How often a person is exposed to a chemical over time; for example, every day, once a week, twice a month.

Hazardous Waste:

Substances that have been released or thrown away into the environment and, under certain conditions, could be harmful to people who come into contact with them.

Health Effect:

ATSDR deals only with Adverse Health Effects (see definition in this Glossary).

Indeterminate Public Health Hazard:

The category is used in Public Health Assessment documents for sites where important information is lacking (missing or has not yet been gathered) about site-related chemical exposures.

Ingestion:

Swallowing something, as in eating or drinking. It is a way a chemical can enter your body (See Route of Exposure).

Inhalation:

Breathing. It is a way a chemical can enter your body (See Route of Exposure).

MRL:

Minimal Risk Level. An estimate of daily human exposure - by a specified route and length of time -- to a dose of chemical that is likely to be without a measurable risk of adverse, noncancerous effects. An MRL should not be used as a predictor of adverse health effects.

NPL:

The National Priorities List. (Which is part of Superfund.) A list kept by the U.S. Environmental Protection Agency (EPA) of the most serious, uncontrolled or abandoned hazardous waste sites in the country. An NPL site needs to be cleaned up or is being looked at to see if people can be exposed to chemicals from the site.

NOAEL:

No Observed Adverse Effect Level. The highest dose of a chemical in a study, or group of studies, that did not cause harmful health effects in people or animals.

No Apparent Public Health Hazard:

The category is used in ATSDR's Public Health Assessment documents for sites where exposure to site-related chemicals may have occurred in the past or is still occurring but the exposures are not at levels expected to cause adverse health effects.

No Public Health Hazard:

The category is used in ATSDR's Public Health Assessment documents for sites where there is evidence of an absence of exposure to site-related chemicals.

PHA:

Public Health Assessment. A report or document that looks at chemicals at a hazardous waste site and tells if people could be harmed from coming into contact with those chemicals. The PHA also tells if possible further public health actions are needed.

Point of Exposure:

The place where someone can come into contact with a contaminated environmental medium (air, water, food or soil). For examples:
the area of a playground that has contaminated dirt, a contaminated spring used for drinking water, the location where fruits or vegetables are grown in contaminated soil, or the backyard area where someone might breathe contaminated air.

Population:

A group of people living in a certain area; or the number of people in a certain area.

Public Health Assessment(s):

See PHA.

Public Health Hazard:

The category is used in PHAs for sites that have certain physical features or evidence of chronic, site-related chemical exposure that could result in adverse health effects.

Public Health Hazard Criteria:

PHA categories given to a site which tell whether people could be harmed by conditions present at the site. Each are defined in the Glossary. The categories are:

1. Urgent Public Health Hazard
2. Public Health Hazard
3. Indeterminate Public Health Hazard
4. No Apparent Public Health Hazard
5. No Public Health Hazard

Receptor Population:

People who live or work in the path of one or more chemicals, and who could come into contact with them (See Exposure Pathway).

Recommended Dietary Allowance:

A set of estimated nutrient allowances established by the National Academy of Sciences. It is updated periodically to reflect current scientific knowledge.

Reference Daily Intake:

A set of dietary references base don the Recommended Dietary Allowances for essential vitamins and minerals and, in selected groups, protein. This term replaces the use of "Daily Reference Value."

Reference Dose (RfD):

An estimate, with safety factors (see safety factor) built in, of the daily, life-time exposure of human populations to a possible hazard that is not likely to cause harm to the person.

Route of Exposure:

The way a chemical can get into a person's body. There are three exposure routes:

- breathing (also called inhalation),
- eating or drinking (also called ingestion), and
- or getting something on the skin (also called dermal contact).

Safety Factor:

Also called Uncertainty Factor. When scientists don't have enough information to decide if an exposure will cause harm to people, they use "safety factors" and formulas in place of the information that is not known. These factors and formulas can help determine the amount of a chemical that is not likely to cause harm to people.

Source (of Contamination):

The place where a chemical comes from, such as a landfill, pond, creek, incinerator, tank, or drum. Contaminant source is the first part of an Exposure Pathway.

Statistics:

A branch of the math process of collecting, looking at, and summarizing data or information.

Toxic:

Harmful. Any substance or chemical can be toxic at a certain dose (amount). The dose is what determines the potential harm of a chemical and whether it would cause someone to get sick.

Toxicology:

The study of the harmful effects of chemicals on humans or animals.

Tumor:

Abnormal growth of tissue or cells that have formed a lump or mass.

Uncertainty Factor:

See Safety Factor.

Urgent Public Health Hazard:

This category is used in ATSDR's Public Health Assessment documents for sites that have certain physical features or evidence of short-term (less than 1 year), site-related chemical exposure that could result in adverse health effects and require quick intervention to stop people from being exposed.

PMC 1998 also sampled for volatile organic compounds, semivolatile organic compounds, pesticides, and polychlorinated biphenyls in the NASD near the Vieques Municipal Airport.

Appendix D: Responses to Public Comments

The Agency for Toxic Substances and Disease Registry (ATSDR) received the following comments during the public comment period (October 23 to December 31, 2001) for the Soil Pathway Evaluation for the Isla de Vieques Bombing Range Public Health Assessment (PHA) (October 2001). For comments that questioned the validity of statements made in the PHA, ATSDR verified or corrected the statements. The list of comments does not include editorial comments, such as word spelling or sentence syntax.

General

1. Comment: It is important that the available data relating to public health in Vieques be analyzed rigorously.

2. Response: ATSDR's exposure evaluation process carefully and thoroughly evaluates whether people are being exposed to hazardous substances and, if so, whether that exposure is harmful and should be stopped or reduced. As the first step in the process, ATSDR scientists review site environmental data to determine the types of contamination present, their quantity and location, and how people could come into contact with them. If the environmental data shows that people have or could come into contact with hazardous substances at the site, ATSDR scientists rigorously analyze the weight of evidence of existing scientific information, including the results of medical, toxicologic, and epidemiologic studies to determine if exposures are likely to result in harmful health effects.

3. Comment: Reading the PHA required a significant investment of time (56 hours). Is the PHA a document intended for broad public consumption or the product of an effort to compile and analyze data in a "scientific" manner?

4. Response: ATSDR relies on technical and scientific information to arrive at its health conclusions. This information is incorporated in the PHA, which is written for the general public rather than the scientific or regulatory communities. However, a PHA of this length is necessary in order to provide an evaluation of all available information.

5. Comment: ATSDR's concern with possible exposure pathways involving soil on the residential portions of Vieques is legitimate. However, exposure pathways involving trespassing onto the property of the federal government should be considered in a different light because there is no valid reason for people to trespass.

6. Response: While it is illegal to trespass onto the Navy's property, a health concern existed for those people who occupied portions of the Live Impact Area (LIA) from April 1999 to May 2000. ATSDR would have been remiss not to evaluate this exposure situation despite the illegal nature of the occupation.

7. Comment: It is absurd that ATSDR failed to find a problem with the soil on Vieques, given that many Vieques residents face serious health problems. The conclusions of the PHA are rejected and it is apparent that ATSDR is operating under the undue influence of the US Navy. ATSDR should cease its work on PHAs at Vieques.

8. Response: ATSDR is mandated by law [Comprehensive Environmental Response, Compensation, and Liability Act, (CERCLA)] to assess public health implications at sites on the National Priorities List (NPL). In addition, ATSDR can conduct public health assessments at the request of concerned individuals (i.e., through a petition). This PHA and related ATSDR public health actions currently underway in Vieques result from a petition submitted by a Vieques resident. It is under this mandate that ATSDR is conducting its investigation on Vieques.

9. Comment: Thank you for the time and effort spent developing PHAs at Vieques. Nevertheless, it is dubious that the PHA will dispel the controversy surrounding Naval activities at Vieques, since the root of the controversy relates to "economic development and not contaminant levels."

10. Response: Thank you for the comment.

11. Comment: The PHA's discussions of soil types and geology were very helpful in explaining the processes of natural soil formation and distribution in Vieques.

12. Response: Thank you for the comment.

ATSDR's Activities at Vieques

7. Comment: The PHA is in error where it claims that ATSDR held a "public availability session" in Vieques in March 2001, because the people of Vieques protested this meeting and thus, it cannot be said to have taken place.

8. Response: ATSDR's public availability sessions are typically good forums for community members to define specific health issues of concern that they would like ATSDR to address. They also provide a good opportunity for people to ask specific questions about ATSDR's health evaluation process and conclusions. Therefore, ATSDR commiserates with the commentator that the unfortunate protest by a few activists prevented the people of Vieques from having free access and exchange with ATSDR about their health concerns and questions during the public availability session held in March 2001.

9. Comment: ATSDR's conclusions were based on a biased sampling of pre-existing data rather than the collection of new data.

10. Response: The quality and extent of the existing information about the soil on Vieques is sufficient to support the public health decisions discussed in the document. ATSDR reviews all existing environmental data and exposure information that is available when drawing its conclusions and making its recommendations about public health.

11. Comment: If the relevant data are in some way less than adequate, ATSDR should simply state its data needs and speak no further.

12. Response: When evaluating public health hazards, ATSDR prefers to use as much information as possible when assessing environmental exposures. However, sometimes data are limited, particularly for past exposure scenarios. With limited data, ATSDR uses the available information about site conditions and the best professional judgement of ATSDR's scientists to draw conclusions and make appropriate recommendations. Following this approach, there was sufficient information to address the central question of whether residents of Vieques are being exposed to harmful levels of chemicals present in the soil.

13. Comment: ATSDR's provisions for public comment were imperfect. The comment form ATSDR provided with the PHA was restrictive in terms of the questions it asks and the amount of space it allots to answering them. In addition, a public comment period for December is when many people are preoccupied with holiday activities.

14. Response: In the letter accompanying the PHA, ATSDR solicited written comments about the PHA in addition to requesting that the reader complete the enclosed questionnaire (i.e., the Reader Evaluation form). Public comments that ATSDR receives are not limited to the Reader Evaluation form and are typically much more detailed. The public comment period (October 23 to December 31, 2001) was extended beyond the usual 30 days to account for holiday activities.

15. Comment: Hopefully ATSDR will respond to public comments on the soil PHA as successfully as they had responded to public comments on the previous drinking water PHA.

16. Response: Thank you for the comment.

17. Comment: The data presented in the PHA do not convincingly substantiate the PHA's conclusions about the past, current, and future health effects of the soil on Vieques. It would be inappropriate for ATSDR to produce further PHAs having to do with Vieques before correcting the errors in the soil PHA and the errors alleged to persist in the previous drinking water PHA. These PHAs are so rife with error that only two explanations seem plausible: either ATSDR is intentionally seeking to obscure public health risks in Vieques or ATSDR staff are not competent to evaluate public health risks in Vieques.

18. Response: Thank you for the comment. ATSDR appreciates objective comments and criticisms that can be used to contribute to the PHA. Before being released, the PHA was reviewed by qualified scientists from other federal agencies (e.g., USGS) that are not connected to ATSDR.

Soil Geology

13. Comment: Further consider the differences between the soils in the LIA and the soils elsewhere on Vieques. It is acceptable, based on the data presented in the PHA, that the composition of the two kinds of soils were different, but what is the scientific basis upon which the difference could be considered "slight" (and thus implicitly disregarded)? The PHA contains no statistical analysis of the difference between LIA and non-LIA soils. This omission is striking in light of the PHA's admission that there are indeed differences between soils from the two areas. Table 4 (Table 3 in the Public Comment PHA) should be subdivided into additional tables, each comparing samples of a particular soil type from within and outside the LIA.

14. Response: ATSDR concluded that the soil on the LIA differed slightly from the soil on the rest of Vieques after statistically comparing the chemical concentrations detected in each area. Comparisons were considered statistically significant (i.e., different) if there was less than 5% probability that the difference occurred by chance (i.e., p<0.05). Out of the 26 chemicals that were detected in both areas, only two chemicals (boron and calcium) showed any significant differences (see Table 4). Tables 5 and 6 have been added to the final release of the PHA to provide clarification to ATSDR's comparison of the Tl and Kv geologic units on the LIA to those on the rest of the island.

15. Comment: The PHA did not present sufficient evidence to support its conclusion that the metal concentrations observed in the soil of Vieques are consistent with ordinary expectations for soil associated with underlying igneous rock. This conclusion has limited application on Vieques, since some parts of the island are not associated with underlying igneous rock.

16. Response: ATSDR geologists determined that the mineralogy of the soils on Vieques is similar to naturally occurring soils that come from igneous/volcanic sources (that underlie a significant portion of the island). The areas that are not associated with underlying igneous rock would be expected to have a lower metal content. ATSDR considered the lower metal levels when determining that the mineralogy of Vieques is similar to soils elsewhere with a similar underlying geology.

    Moreover, ATSDR evaluated all soil analysis data available based upon the underlying geologic rock type (i.e., soil parent material). ATSDR's Vieques team scientists are trained in the factors influencing soil formation and expected, based upon long-established scientific principles, to see differences in the chemical make-up of the soils reflecting, at least in part, the nature of those parent materials.

Comparisons Between Soils on Vieques Island, Sediments on Puerto Rico Island, and Soils in the United States

15. Comment: Can one meaningfully evaluate whether soil metal concentrations on Vieques are normal by comparing them to sediment metal concentrations in Puerto Rico? The comparison is "dubious" because stream sediments are affected by human activity, stream transportation, and stream deposition. All of ATSDR's conclusions that rely upon using soil/sediment comparisons are "erroneous." ATSDR asserted that soil data were not available for Puerto Rico, however, ATSDR analyzed soil samples in several PHAs in Puerto Rico (Vega Baja, Guayama, and Humacao).

16. Response: As noted in the Section II.B of the PHA, only a generalized comparison can be made between the soil of Vieques and sediment in the mainland of Puerto Rico. Sampled stream sediments are generally representative of the soil and their parent material, however, several factors could introduce changes to the overall composition of the sediments as compared to the soil from which they were derived. Notwithstanding, ATSDR determined that comparing the soil on Vieques to the sediment on the mainland of Puerto Rico would still serve to point out generalized similarities or differences between the two areas.

    Ideally, ATSDR would compare the soil on Vieques to soil on the mainland. While the soil data available in previous PHAs in Puerto Rico provides some information about specific locations in Puerto Rico, they do not provide the area-wide perspective available in the stream sediment sampling data collected by the United Stated Geological Survey (USGS) and the Puerto Rico Department of Natural Resources (PRDNR) (Learned et al. 1973).

17. Comment: Vieques soil samples do not reflect the actual severity of metal contamination. At a certain point in Vieques' history (mid-1970s), there was an intensification of bombing activity on the island. If values prior to the intensification were lower, they would trigger a downward bias in average values. Therefore, one risks under-estimating the severity of contemporary metal contamination.

18. Response: 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. USGS and PRDNR collected soil samples from Vieques in 1972, prior to this intensification of training activity (Learned et al. 1973). However, as described in Section II.H, these data appear to be elevated by as much as 4-fold. Therefore, instead of triggering a downward bias in average values, these earlier data are actually causing an overestimation of average soil contamination, by as much as 4-fold.

    In addition, ATSDR's investigation of potential health effects from exposure to the soil on Vieques is a conservative evaluation, for the following reasons:

    • When evaluating health effects, ATSDR relied on data collected recently as well as data collected before an intensification of bombing activities. Chemicals were selected for further consideration based on the maximum concentration detected in any of the data sets, regardless of location or date of sampling.
    • 
      
      
    • ATSDR calculated averages using detected concentrations only, which overestimates the true average value; therefore, health evaluations were based on conservative averages.
    • 
      
      
    • ATSDR relied on highly conservative assumptions (e.g., high incidental ingestion rates) to estimate exposure.
    • 
      
      
    • ATSDR did not adjust the exposure doses to account for the low bioavailability of some of the metals in soil, which leads to overly conservative estimated exposure doses.
    • 
      
      
19. Comment: In those instances where the PHA finds a substance at greater concentrations in Vieques soil than in Puerto Rican sediment or United States soil, it does not venture any explanation of whether the Navy's activities are responsible.

20. Response: It is difficult to determine the source of an "elevated" chemical concentration, especially when dealing with heavy metals in soil because natural geology plays a significant role on the composition of soil. The important consideration is that there are no apparent health hazards associated with exposures to the soil on Vieques, regardless of the source.

Spatial and Chronological Patterns in Metal Levels

18. Comment: The PHA fails to furnish evidence which would allow the reader to independently arrive at the PHA's conclusion that there are no spatial patterns in the distribution of contaminants. The following are examples of information that would provide this evidence:
19. 
    
    
    • An explanation of the analytical methods ATSDR used to evaluate whether or not patterns exist.
    • 
      
      
    • A complete map and corresponding descriptive chart showing the spatial distribution of all sampling activities considered in the PHA.
    • 
      
      
    • Individual maps for each metal that show the spatial distribution of soil sampling results for that metal.
    • 
      
      

    Response: To provide further clarification to the spatial analyses, ATSDR included three figures (Figures 6-8) in the final release of the PHA that indicate the three types of patterns observed--western concentration, geologic association, and random distribution. As noted in Section III.D, none of the spatial maps depicted a progressive east to west trend. Thus, these analyses do not provide evidence of airborne transport of metals from the LIA to the residential area. Further analysis of this issue is being conducted by ATSDR using computer air transport models and will be presented in a separate air pathway evaluation (see Sections I and VIII).

20. Comment: Contrary to the PHA's conclusions, Figure 10 (Figure 5 in the Public Comment PHA) indicates that there is a spatial pattern of metal levels on the island of Vieques. The maximum levels of iron, vanadium, manganese, and chromium occur west of the LIA and the highest levels of lead, mercury, cadmium, and arsenic are located in the eastern end of the island, near or in the LIA, which is indicative of a spatial pattern in the distribution of metal levels. In addition, a report cited in the PHA (SCI 2000) mentions the existence of a spatial pattern in the distribution of metals.

21. Response: A spatial distribution of high chemical concentrations in the LIA (i.e., the presumed source) with decreasing concentrations tapering off to the west of the island for each chemical would have provided some indication that heavy metals from the LIA were migrating through the air towards the residential area. However, the distribution of each of the chemical concentrations do not illustrate such a pattern. Figures 6 to 8 show the spatial patterns (western concentration, geologic association, and random distribution) for the chemicals evaluated. For example, a western concentration of the highest levels of strontium detected is shown in Figure 6. Please see Section III.D for additional information about the trends that were observed. Further analysis of this issue is being conducted by ATSDR in a separate air pathway evaluation (see Sections I and VIII).

22. Comment: Explain how the current soil sampling data might relate to soil contamination present during past (or future) periods of live bombing.

23. Response: Soil sampling data collected during past periods of live bombing might differ from current sampling data in the level of explosive compounds detected since live munitions contains high explosives and practice munitions contain inert materials. However, high explosive compounds are designed to react during impact leaving only extremely small quantity of explosive compounds after detonation. ATSDR evaluated soil sampling data collected during periods of live bombing (e.g., Learned et al. 1973; Marsh 1992; Hoffsommer and Glover 1978; Lai 1978; and PMC 1998) and data that were collected up to 14 months after the cessation of live bombing (e.g., CH2MHILL and Baker 1999; Garcia et al. 2000; and CH2MHILL 2000a). At this time, ATSDR is unaware of any planned future activities involving the use of live ordnance.

24. Comment: A chronological link between Naval activities and contaminant concentrations is so much to be expected that ATSDR's failure to find such a link should raise suspicions about the PHA's methodology. ATSDR is not adequately motivated to review the quality of its own work in the face of surprising results.

25. Response: ATSDR objectively evaluated the data using accepted scientific methods. A chronological link is not something that can be assumed, but must be substantiated by relevant data. Scientific objectivity does not allow for any preconceived opinions to interfere with the evaluation. In non-laboratory sciences the theory of multiple working hypotheses must prevail. Induction and deduction lead the scientist by continual testing of ideas (hypotheses) to a conclusion. That conclusion will be subject to testing against new data, if and/or when it is developed and available.

26. Comment: Is it possible to determine whether or not there was a chronological pattern in certain metal levels (such as arsenic levels), given that earlier samples were made with instruments less sensitive than current instruments?

27. Response: Subsequent to the release of the public comment version of the PHA, ATSDR obtained a draft report that characterized the background levels of metals in the surface soils of the former NASD (CH2MHILL 2001). Given this new data, ATSDR compared the mean background soil concentrations from the former NASD (CH2MHILL 2001) to the mean soil concentrations for a subset (from the former NASD) of the earlier data (Learned et al. 1973), and found that the older data were 1.2 to 4 times higher than the background levels. Barium and calcium differ from this pattern for unknown reasons. In addition, the minimum values obtained during the earlier study were higher that the minimum values obtained during the recent background study, even though the minimum detection levels were higher than those used when the background analyses were performed. If there were no high-bias in the data reported in 1973 then several of the samples collected should have been reported as not detected.

    Since sampling locations from both events were from areas unaffected by the Navy training activities, it would appear that the older data is artificially elevated (i.e., higher than the true values), by as much as 4-fold. Therefore, in light of the newly acquired background data, the chronological evaluation became invalid and ATSDR revised this discussion in the final release of the PHA (see Section III.C).

28. Comment: The metal results obtained by Learned et. al (1973) were compared to those obtained by CH2MHILL (2000). The PHA found no significant difference between the 1972 and 2000 data with the exception of chromium, however, no data were presented to allow the reader to evaluate the values.

29. Response: In the public comment version of the PHA, ATSDR attempted to compare soil samples collected from the LIA in 1972 (Learned et al. 1973) to soil samples collected from the LIA in 2000 (CH2MHILL 2000a), to determine if this 28-year interval of Navy training had significantly increased the level of contamination at the LIA. However, new data (CH2MHILL 2001) received after the release of the public comment PHA indicated that the data collected in 1972 may be elevated by as much as 4-fold higher than the true values (as described in Section II.H). Therefore, this comparison became invalid and ATSDR revised this discussion in the final release of the PHA (see Section III.C).

30. Comment: Was the comparison between the soils of the United States and Vieques based on the entire United States or some other approach?

31. Response: Vieques soil samples were compared to soil samples taken from uncontaminated areas across the entire conterminous (i.e., contiguous) United States.

Soil Sampling

25. Comment: The 37 soil samples collected by CH2MHILL (for its June 2000 report) were too limited in scope and might have missed important areas of contamination. It is curious that only three of the 37 samples were taken in actual shooting target areas, while seven samples were taken in a conservation area where one would not expect pollutants to aggregate. In addition, the action of surface water might have organized metals into small, easily-missed pockets of contamination. This sampling pattern reflects a deliberate intent to avoid finding metal contamination.

26. Response: One of the goals of the sampling was to assess whether explosive compounds were present in the surface soil at the LIA (CH2MHILL 2000a). To meet this goal, CH2MHILL collected soil from 37 locations, including specific samples from drainage features and low lying areas which would collect stormwater runoff (19 samples), from within targets (7 samples), from known, protestor beach camps (4 samples), and from conservation zones upwind and downwind of the LIA (7 samples). Figure 5, which shows the sample locations, has been included in the final release of the PHA.

27. Comment: The PHA should have addressed the ways in which variation in soil sampling methodologies might affect comparisons between soil data from different reports.

28. Response: When variations in soil sampling methodologies affected a conclusion ATSDR noted this in the PHA. For example, the health evaluation for arsenic notes that exposure to arsenic is based on levels detected in the soil at the LIA and near the Vieques Municipal Airport because sampling conducted in the residential area was not sufficiently sensitive to detect the low levels of arsenic possibly existing in the residential area (see Section IV.C). Also, ATSDR noted in the final release of the PHA that the data collected by USGS and PRDNR (Learned et al. 1973) appears to be elevated above true values by up to 4-fold (see Section II.H); and described how this affected any evaluations, where appropriate (for example, see Section III.B).

29. Comment: ATSDR should reconcile its claim about the absence of harmful heavy metal concentrations in the soil with the facts stated in the US Navy/US Environmental Protection Agency (EPA) surface water discharge violation reports.

30. Response: EPA is a regulatory agency, whereas ATSDR is primarily an advisory agency. It is not unreasonable, in some cases, that a chemical concentration may be in violation of a regulatory level according to EPA, but may not be at a harmful level according to ATSDR. ATSDR's PHAs are driven by exposure, or contact. Even though chemicals may have been released into the environment, a release does not always result in exposure. People can only be exposed to a chemical if they come in contact with that chemical. If no one comes into contact with a chemical, then no exposure occurs, thus no health effects could occur.

    In addition, ATSDR considers the level of exposure. Exposure does not always result in harmful health effects. The type and severity of health effects that occur in an individual as the result of contact with a chemical depend on a number of factors, including the exposure concentration as well as the frequency and duration of exposure. ATSDR analyzes the weight of evidence of available toxicologic, medical, and epidemiologic data to determine whether exposures might be associated with harmful health effects. Taken together, these factors help determine if health effects could occur as a result of exposure to a chemical in the environment.

Explosives and Ordnance

28. Comment: The PHA's statement that the majority (82%) of the ammunition used in Vieques was non-explosive is erroneous. A July 15, 1999, Navy report provides contrary information--specifically, that only 39.64% of the ammunition was non-explosive.

29. Response: Thank you for the information. Since the PHA was written, ATSDR has acquired additional usage data. Section II.F Ordnance Type and Use has been updated in the final release of the PHA.

30. Comment: The PHA did not pay adequate attention to evaluating health risks associated with skin-permeable explosive chemicals (such as TNT, RDX, and tetryl). The very reports used by ATSDR in the PHA show significant levels of explosives in the Vieques environment. These compounds decompose relatively quickly in the environment, so the mere presence of the compounds indicates that they are being released on a continual basis.

31. Response: While five explosive compounds were detected in the soil on Vieques, all of them were detected at levels too low to be of health concern. As shown in Table 9, all concentrations of explosive compounds were below their respective health-based comparison values. Comparison values are derived using conservative exposure assumptions and reflect concentrations much lower than those known to cause harmful health effects. Thus, concentrations detected at or below these values do not warrant health concern. Furthermore, comparison values are protective of public health in all exposure situations, including dermal contact.

32. Comment: The PHA does not pay adequate attention to the presence of hazardous bombing debris and unexploded ordnance in the LIA.

33. Response: ATSDR's PHAs are driven by exposure. If no one can contact the hazard, then no exposures occur, and no harmful health effects can occur. Because the LIA is a restricted area, residents and visitors of Vieques who are engaged in legal activities are not being exposed to unexploded ordnance or bombing debris. ATSDR does agree that the people who willingly choose to illegally trespass onto Navy property are taking a risk because despite the Navy's efforts to locate unexploded ordnance, removal efforts tend to only be 75% effective (Wilcox 1997).

Comparison Values

31. Comment: The PHA did not adequately justify and explain its choice of comparison values. The PHA uses five different kinds of comparison values: Cancer Evaluation Guides (CREGs), Environmental Medical Evaluation Guides (EMEGs), Reference Dose Media Evaluation Guides (RMEGs), Risk Based Concentrations (RBCs), and Soil Screening Levels (SSLs). CREGs, EMEGs, and RMEGs were developed by ATSDR, but who developed the RBC and SSL values?

32. Response: Comparison values are developed by ATSDR and EPA from available scientific literature concerning exposure and health effects. Comparison values are media-specific and reflect an estimated chemical concentration that is not expected to cause harmful health effects for a given chemical. Thus, comparison values are protective of public health in essentially all exposure situations. CREGs, EMEGs, and RMEGs are non-enforceable, health-based comparison values developed by ATSDR for screening environmental contamination for further evaluation. RBCs and SSLs are non-enforceable, risk-based comparison values developed by EPA Region III to screen sites not yet on the NPL, respond rapidly to citizens inquiries, and spot-check formal baseline risk assessments. Definitions for these comparison values are provided in Appendix A.

33. Comment: What action would ATSDR recommend for those places (described in the PHA) where substances in the soil were found at levels above their comparison values?

34. Response: While concentrations at or below comparison values may reasonably be considered safe, it does not automatically follow that any environmental concentration that exceeds a comparison value would be expected to produce adverse health effects. It cannot be emphasized strongly enough that comparison values are not thresholds of toxicity. They represent chemical concentrations many times lower than levels at which no adverse effects were observed in experimental animal or human epidemiologic studies. The likelihood that harmful health effects will actually occur depends on site-specific exposure conditions, not an environmental concentration alone.

    Before recommending actions, ATSDR first examines potential exposures to the contaminants in the soil by following the process described in Section IV. Evaluation of the Soil Exposure Pathway. This process enables ATSDR to weigh the available evidence in light of uncertainties and offer perspective on the plausibility of harmful health outcomes under site-specific conditions. Using this process, ATSDR determined that no harmful health effects are expected to occur from exposure to the soil on Vieques. If ATSDR's exposure evaluation process would have identified a situation that could result in harmful health effects, ATSDR would have issued a public health advisory warning of the danger and urged regulators to take actions to prevent adverse human health effects resulting from exposure to hazardous substances in the soil.

Public Health Conclusions

33. Comment: How can ATSDR conclude that adults and children were not exposed to dangerous levels of chemical substances found in the soil of the LIA, since the PHA reported that concentrations of several chemical substances exceeded comparison values?

34. Response: As stated in our response to the previous comment, comparison values are derived using conservative exposure assumptions and reflect concentrations much lower than those observed to cause harmful health effects. While a concentration at or below the relevant comparison value could reasonably be considered safe, it does not necessarily follow that any environmental concentration exceeding a comparison value would produce harmful health effects. It cannot be emphasized too strongly that comparison values are not thresholds of toxicity. The likelihood that harmful health outcomes will actually occur depends on site-specific conditions and individual lifestyle, as well as factors affecting the route, magnitude, and duration of actual exposure--not an environmental concentration alone. Chemicals detected above comparison values are evaluated further by estimating exposure doses using site-specific exposure assumptions. ATSDR examines relevant toxicologic, medical, and epidemiologic data to determine whether these estimated doses are likely to result in harmful health effects. Although the concentrations of seven chemicals exceeded comparison values (see Table 9), after evaluating potential exposure doses, ATSDR determined that none of the chemicals are present at levels of health concern.

35. Comment: There is a discrepancy between the arsenic comparison values in Table 9 (Table 5 in the Public Comment PHA) and the health guidelines in Exhibit 3 (Exhibit 2 in the Public Comment PHA). The average arsenic concentration (8.91 ppm) is above the adult CREG (0.5 ppm), but below the child's EMEG (20 ppm) in Table 9. However, in Exhibit 3 the estimated exposure dose is below the minimal risk level (MRL) and reference dose (RfD) for adults, but above for children.

36. Response: No discrepancy exists between the values presented in Table 9 and Exhibit 3. The observation noted in the comment can be explained by further describing the distinction between cancer and noncancer screening values (e.g., comparison values and health guidelines) used by ATSDR in its public health assessment process.

    Comparison values represent concentrations of a substance (in this case arsenic in soil) to which humans may be exposed during a specified period of time without experiencing adverse health effects. Separate guidelines are available for cancer and noncancer effects. ATSDR typically compares the maximum detected concentration with the most conservative (i.e., protective) comparison value available for that chemical. This process enables ATSDR to quickly identify concentrations that are not of public health concern (i.e., those below comparison values) and those that might require further evaluation (i.e., those above comparison values).

    As shown in Table 9, ATSDR considered the CREG for cancer effects (i.e., the overall most conservative comparison value) and the child EMEG (i.e., the most conservative comparison value for noncancer effects) when evaluating health effects from exposure to the soil on Vieques. Even though only the child EMEG is reported in Table 9, an adult EMEG (200 ppm) also exists to evaluate noncancer health effects for adults. The maximum detected concentration of arsenic (36 ppm) exceeds the CREG (0.5 ppm) and the child EMEG (20 ppm), but not the adult EMEG; which is parallel to the comparison shown in Exhibit 3 (see next paragraph).

    The next step in the health evaluation process is to look more closely at those substances that exceed comparison values. In doing so, ATSDR estimates exposure doses for adults and children based on site-specific considerations and compares those doses with available health guideline values. Health guideline values for noncancer effects include MRLs and RfDs, as shown in Exhibit 3. Consistent with Table 9, the child dose (based on the maximum concentration) exceeds the MRL/RfD, but the adult dose does not.

    Exhibit 3 does not consider cancer effects because no health guideline value is available to evaluate cancer effects for arsenic, as there is for noncancer effects. Exceeding the CREG; therefore, has no bearing on the comparison of doses with MRLs. ATSDR addressed cancer health effects on a more qualitative basis in the arsenic evaluation in the PHA (see Section IV.C).

37. Comment: The PHA erroneously used a lineal equation to evaluate exposure doses because all such equations are questionable for use in live beings.

38. Response: An exposure dose is an estimate of how much of a substance a person may contact based on their actions and habits. Estimating an exposure dose requires identifying how much, how often, and how long a person may come in contact with a substance. The exposure dose equation described in Section IV.B of the PHA calculates a total dose accumulated over time, which is a useful number for health assessments (EPA 1992b). The standard equation that was used to estimate exposure doses in humans is an appropriate and conservative approach, consistent with ATSDR's Public Health Assessment Guidance Manual (ATSDR 1992a) and EPA's Superfund Risk Assessment Guidance (EPA 1989).

39. Comment: It is unrealistic to assume that a 6 year old child weighs 10 kilograms (kg), as 20 kg seems a more realistic weight.

40. Response: ATSDR based the calculations for childhood exposure on highly conservative assumptions. Even though a lower body weight tends to overestimate exposure, using 10 kg for a child's body weight is justified for very young children, who are more apt to ingest soil than older children. According to the National Health and Nutrition Examination Survey (NHANES), the average body weight for children 6 to 11 months old is 9.1 kg (NCHS 1987 as cited in EPA 1997).

41. Comment: When trying to reconstruct a dose calculation performed in the PHA the resulting answer differed from the PHA's by six orders of magnitude:

42. 

    The PHA reported 0.000720 mg/kg/day. Why is there a difference in the units and the value of the result?

    Response: The discrepancy between the two calculations appears to be due to unit conversions. Below is a detailed account of the unit conversions necessary to complete the dose calculation. As the equations show, the units below all cancel, thus ensuring that the calculation is correct. ATSDR clarified this calculation in the final release of the PHA.

    First calculate the soil concentration into units consistent with those for the other parameters:

    36 ppm of arsenic in soil	=	36 mg of arsenic 1 kg of soil	=	36 mg of arsenic 1,000,000 mg of soil

    (since ppm = mg/kg and 1 kg = 1,000,000 mg)

    Second, calculate the estimated exposure dose for arsenic using the equation and assumptions provided in the text of the PHA:

    

    

    The units cancel as shown below:

    

    Which results in an estimated dose of 0.00072 mg of arsenic / kg of body weight / day.

43. Comment: Clarify whether the PHA assumed an adult ingestion rate of 100 mg/day or 50 mg/day. If ATSDR is indeed using an ingestion rate of 100 mg/day, it is making a highly conservative (i.e., protective) assumption and should make note of that.

44. Response: ATSDR conservatively used an adult ingestion rate of 100 mg/day to evaluate exposures rather than EPA's recommended value of 50 mg/day. This ingestion rate is supported by a tracer study that found that adults ingested from 30 to 100 mg of soil a day (Calabrese et al. 1990 as cited in EPA 1997). ATSDR noted this in Section IV.B of the final release of the PHA.

45. Comment: The PHA's assumption that the primary mode of exposure to soil contaminants is through soil consumption is doubtful. It is absurd to assume that people are continually eating soil around Vieques, particularly in areas formerly occupied by the Navy.

46. Response: While it may seem doubtful, scientific evidence exists to support the ingestion rates of soil in adults and children (EPA 1997). ATSDR is not assuming that the people of Vieques are literally "eating" soil, rather people are incidentally (i.e., accidentally) ingesting soil when they eat food with their hands, smoke a cigarette, or put their fingers in their mouths. Soil or dust particles can adhere to food, cigarettes, and hands and result in incidental ingestion. Children are particularly sensitive to this phenomena and are more likely to ingest more soil than adults. Furthermore, during a normal phase of childhood, children display hand-to-mouth behavior which inadvertently results in consumption of soil.

47. Comment: The PHA should address the possibility of synergistic effects arising from the interaction of several low-level chemical exposures and the possibility of significant cumulative exposures occurring through several different contaminated media (e.g., soil, air, water, and foods).

48. Response: Most of the literature on the effects of chemical mixtures focus on relatively high exposures that may produce results such as synergism, additivity, and non-competitive inhibition. However, concentrations far in excess of typical environmental concentrations are generally required to produce such effects.

    Several studies, including those conducted by the National Toxicology Program (NTP) in the United States and the TNO Nutrition and Food Research Institute in the Netherlands, among others, generally support the conclusion that exposure to a mixture of chemicals is unlikely to produce any adverse health effects as long as the components of that mixture are present at levels well below their respective no observed adverse effects levels (NOAELs) (i.e., at concentrations that would have produced no adverse effects in animals treated individually with each component chemical; for reviews, see Seed et al. 1995; Feron et al. 1993). This observation appears to hold true whether the individual chemicals affect the same or different target organ(s) via different mechanisms and different exposure pathways (i.e., the situations that generally pertain to typical environmental mixtures). Even chemicals with the same or similar modes of action do not appear to exhibit either synergism or additivity, as long as the levels of exposure are well below the respective NOAELs of the individual chemicals; which is what was found for chemicals in the soil on Vieques.

    The entire public health assessment process is lengthy, especially when addressing complex environmental issues. ATSDR is evaluating each exposure pathway separately to be most responsive to the petitioner and the people of Vieques. After all the individual PHAs are completed, ATSDR will prepare a short summary of all the health issues evaluated at Vieques. This summary will present the results of ATSDR's media-specific PHAs and will also consider whether overall exposures to environmental chemicals pose a public health hazard.

49. Comment: The limitations of the sampling methodologies employed in the PHA also limit the applicability of the dose estimates reported. It would be far more helpful to directly assess health risks by taking hair and blood samples from residents of Vieques.

50. Response: ATSDR was prepared to take hair, blood, and urine samples from the residents of Vieques in 2001. To successfully complete the project ATSDR solicited the support and assistance of several Vieques physicians. However, the physicians have expressed reservation about whether the results will be reflective of actual exposures and have been unwilling to proceed. While the offer to collect hair, blood, and urine samples is still available, the project has been indefinitely postponed until the physicians are willing to assist.

    In June 2001, at ATSDR's invitation, seven experts in the fields of hair analysis, toxicology, and medicine met to discuss the utility of hair analysis in evaluating exposures and health effects at hazardous waste sites. The experts 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" (ATSDR 2001b). For more details, a discussion of hair analysis has been added to Section V. Community Health Concerns in the final release of the PHA.

51. Comment: The PHA speaks out of ignorance when it states that the protestors occupying the LIA from 1999 to May 2000 were not exposed to harmful levels of chemicals in the soil. Did ATSDR collect detailed information about the behavior patterns of the protestors (e.g., food preparation and consumption, daily hygiene, housing arrangements, daily forays throughout LIA)? It is not possible to arrive at an accurate exposure assessment without this data.

52. Response: While ATSDR did not collect detailed behavior information, the conservative assumptions that were used to evaluate exposures are expected to overestimate actual exposures under normal circumstances and more-accurately estimate exposures for the protestors who lived on the LIA for a year. ATSDR based the ingestion rates on the likelihood that the people occupying the LIA were incidentally ingesting a higher than normal amount of soil every day.

    EPA recommends using average ingestion rates of 100 mg/day for children and 50 mg/day for adults when calculating exposures, but notes that "200 mg/day for children may be used as a conservative estimate of the mean" (EPA 1997). In addition, ATSDR consulted the literature and found one study that estimated soil ingestion rates for children who were expected to have higher soil intake rates than normal (i.e., children vacationing at campgrounds). An average soil intake rate of 174 mg/day was reported (Van Wijnen et al. 1990 as cited in EPA 1997). Therefore, by using ingestion rates of 200 mg/day for children and 100 mg/day for adults, ATSDR took into consideration situations where people may incidentally consume more soil than under typical conditions (e.g., when the protestors lived on the LIA).

Additional Data

43. Comment: ATSDR does not compare the levels found in the soil of Vieques with background levels reported in "Draft Soil, Groundwater, Surface Water, and Sediment Background Investigation Report for U.S. Naval Ammunition Support Detachment, Vieques Island, Puerto Rico," that was published by CH2MHILL in June 2001. The data provided in the following table are consistent with the theory that the concentrations of heavy metals in the soil of Vieques have been enriched above natural levels by the activities of the U.S. Navy.
44. 
    
    

    Metal	Stated Background Concentration (CH2MHILL June 2001) units in ppm	Stated Average Soil Concentration (PHA) units in ppm	Stated Maximum Soil Concentration (PHA) units in ppm
    Arsenic	2.2	8.91	36
    Barium	364.5614	594	3,000
    Cadmium	0.04	1.6	31.3
    Chromium	74	58.2	700
    Copper	68	72.6	1,500
    Iron	9,360	45,600	150,000
    Lead	4.19	17.1	1,000
    Manganese	1,167.178	1,200	5,000
    Zinc	65.09994	78.5	3,000
    Mercury	0.04564024	0.0275	4.21
    Vanadium	183.6659	162	500

    Response: Thank you for bringing these data to ATSDR's attention. ATSDR was not aware of the report cited as it is in draft form and not yet available for release. Based upon an evaluation of this new data, ATSDR agrees with the commentator--the concentrations of metals at the LIA are indeed higher than background concentrations within the former Naval Ammunition Storage Detachment (NASD). ATSDR has revised Section III.C in the final release of the PHA to reflect this conclusion. It is important to note that even though the heavy metal concentrations are higher in the LIA than the former NASD, none of the levels are of health concern (see Section IV).

45. Comment: Additional soil sampling data (collected by the Navy in 2000) is available for non-range areas of the Eastern Maneuver Area (EMA)/Camp Garcia. An additional report published by C2HMHILL in October 2000 shows elevated metal concentrations in soil samples taken from western Vieques.

46. Response: ATSDR contacted the Navy and confirmed that all currently available data in the non-range areas of the EMA/Camp Garcia have already been incorporated into the PHA.

    The "Final Expanded Preliminary Assessment/Site Investigation, US Naval Ammunition Storage Detachment, Vieques, Puerto Rico" (CH2MHILL 2000b) investigated contamination at several solid waste management units (SWMUs) in the former NASD. Surface soil samples were collected and analyzed for organic compounds, metals, pesticides, polychlorinated biphenyls, and explosives. Contamination at these SWMUs is not associated with the Navy's bombing activities at the LIA, rather local sources at the former NASD (e.g., disposal sites and underground storage tanks) contributed to the contamination. Using the same procedures and methodologies described in the Evaluation of the Soil Exposure Pathway (Section IV) discussion of the PHA, ATSDR reviewed the surface soil data and determined that none of the SWMUs pose a public health hazard. The concentrations of chemicals at the SWMUs are not at levels of health concern for anyone exposed to the soil at these sites.

47. Comment: Because soil sampling was restricted to just the first six inches of soil, deeper samples should be taken before an assessment is made.

48. Response: ATSDR's PHAs are driven by exposure. People can only be exposed to a chemical if they come in contact with that chemical. If no one comes into contact with a chemical, then no exposures occur, thus no health effects could occur. When evaluating exposures to soil, ATSDR is most concerned with the top 6 inches of the soil because that is the layer that people can easily contact. Deeper soils are inaccessible and; therefore, no exposures of harmful health effects could occur from any chemicals present.

49. Comment: The PHA cannot justify its conclusions that there are no explosives contamination in the residential soil of Vieques and that there is no spatial pattern of explosives contamination on Vieques, given that it admits to lacking sampling data for the residential and western regions of Vieques.

50. Response: ATSDR carefully considered the possibility that explosive compounds might transport in the air and deposit on soils in downwind areas. First, ATSDR notes that explosive compounds in the bombs dropped on Vieques are largely destroyed upon impact. That is, explosive compounds react during impact, releasing large amounts of energy, and only a small quantity of the explosive compounds remain after detonation.

    Second, if long-range transport of explosive compounds occurred in appreciable amounts, then one would expect to find soils throughout the downwind areas with explosives contamination. However, the soil sampling data collected on the eastern edge of the residential area of Vieques found no evidence of explosive compounds. Specifically, explosives were not detected in 32 samples collected from storm drains along the border that receives runoff from the Navy's land (CH2MHILL and Baker 1999). It is unlikely that explosive compounds would be detected further downwind from this sampling area (e.g., in the soils of the residential area) if explosive compounds were not detected along this boundary zone between the residential area and the EMA. ATSDR's PHA on the air exposure pathway presents further information on atmospheric transport of contaminants from the LIA (see Sections I and VIII).

51. Comment: The PHA should consider soil samples collected near Open Burning/Open Detonation (OB/OD) areas and other Naval waste management areas. Elevated levels of metallic and organic contaminants have been recorded near these sites.

52. Response: ATSDR contacted the Navy and confirmed that all currently available data near OB/OD areas within the LIA have already been incorporated into the PHA; with the exception of data that were analyzed according to Toxicity Characteristic Leachate Procedure (TCLP) (personal communication with Atlantic Division Naval Facility Engineering Command personnel, March 2002). Samples are analyzed using TCLP to help regulators determine whether the soil qualifies as and should be disposed of as hazardous waste. Data analyzed according to TCLP confirm the potential presence of certain chemicals in the soil and their potential to leach, however, the results do not provide any indication as to the concentrations present. Remember that the presence of a chemical will not automatically result in harmful health effects. The type and severity of health effects that occur in an individual as the result of contact with a chemical depend on the exposure concentration (how much) and the frequency and duration of exposure (how long). Therefore, data that do not provide the concentration of the chemical in the soil do not provide useful information for an evaluation of public health exposures.

    This PHA is focused on addressing the petitioner's concerns about Naval bombing activities at the LIA. As noted in Comment 44, the Navy investigated contamination at several SWMUs in the former NASD, including one inactive OB/OD area (CH2MHILL 2000b). Surface soil samples were collected and analyzed for organic compounds, metals, pesticides, polychlorinated biphenyls, and explosives. Even though contamination at these SWMUs is not associated with the Navy's bombing activities at the LIA, ATSDR reviewed the surface soil data and determined that none of the SWMUs pose a public health hazard.

53. Comment: With the exception of 32 surface samples collected in August 1999 along the EMA's western boundary, none of the sample results cited in the PHA have been reviewed (by the commentator). Therefore, it is difficult to evaluate the PHA's conclusions.

54. Response: ATSDR evaluated the technical and scientific data in the referenced documents and summarized the essential information in the PHA for the general public. The full references are provided in the PHA for those wishing to evaluate the original studies themselves.

55. Comment: ATSDR misrepresented the extent of the data that is available for the EMA. The PHA claims that Hoffsommer and Glover only analyzed two areas in the EMA and four in the LIA, however, Hoffsommer and Glover actually found pollutants in fifteen areas in the EMA, eleven areas in western Vieques, and two drinking water samples. This discrepancy is indicative of a broader program (on the part of ATSDR) to deliberately misread its source materials.

56. Response: In May 1978, the Naval Surface Weapons Center obtained and analyzed soil samples for explosive compounds from two areas within the EMA (described as "soil near Bahia de la Chiva, Maneuver Area, Camp Garcia" and "soil near brackish water at Bahia Tapon") and four areas within the LIA (described as "soil sample between craters A and B," "soil from small lagoon," "soil from dry lagoon," and "soil from crater B Demolition Range #6") (Hoffsommer and Glover 1978). They also took water samples from 11 areas outside the LIA and from 15 areas within the LIA. These data were appropriately included in ATSDR's evaluation of the drinking water supplies and groundwater on Vieques (ATSDR 2001a). This PHA, the Soil Pathway Evaluation, evaluates only those pathways involving exposure to potentially contaminated soil on Vieques and; therefore, presented and analyzed all available soil data.

57. Comment: ATSDR's evaluation omits important independent work by experts such as Dr. Neftali Garcia and Jorge Fernández, whose findings contradict ATSDR's.

58. Response: Data collected by Neftalí Garcia was included in the PHA. The reference is:

    Servicios Científicos y Técnicos, Inc. (SCI). 2000. Environmental impact of Navy activities in Vieques. Dr. Neftalí Garcia, Ana M. López, Mariela Soto, Shereeza Rosado, and Brenda Berríos. July 11, 2000.

    At this time, ATSDR is not aware of any soil data collected by Dr. Jorge Fernández. ATSDR welcomes any additional information to support our ongoing efforts on Vieques. Please send additional information 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

59. Comment: The PHA should include a map showing the locations of the 420 samples evaluated in the assessment to help the reader independently verify that the data samples were of adequate quality.

60. Response: Figure 4, which shows all the sample locations, has been included in the final release of the PHA.

Other Exposure Pathways

52. Comment: There are potential health risks associated with consuming contaminated plants and animals around Vieques. Locally grown crops might be bioaccumulating metals. A study conducted by Dr. Massol in 2001, reported high concentrations of the following metals in local crops: lead, cadmium, manganese, cobalt, nickel, and copper. In addition, ATSDR should consider the effect of wastewater treatment plants on nearby marine life.

53. Response: Community concerns about heavy metal accumulation in plants and animals around Vieques have been included in the final release of this PHA (see Section V. Community Health Concerns). To address the concern about marine life, ATSDR contracted EPA to collect and analyze fish and shellfish in the coastal waters and near shore areas of Vieques in July 2001. ATSDR's fish and shellfish evaluation documents the results of the sampling and public health evaluation (see Sections I and VIII).

54. Comment: The PHA having to do with drinking water was an excellent overview of the island's water supply and hydrogeology, however here is some additional information. USMC Well #6 and Navy Well #14 at Camp Garcia were installed after 1967. Before 1967, an underground pipeline provided water to Camp Garcia. Camp Garcia's sanitary water system involved salt water pumped from the lagoon to a holding pond.

55. Response: Thank you for the information.