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1. ATSDR > Public Health Assessments & Consultations

PUBLIC HEALTH ASSESSMENT

NORFOLK NAVAL SHIPYARD
PORTSMOUTH, VIRGINIA

APPENDIX A: EVALUATION OF POTENTIAL PUBLIC HEALTH HAZARDS AT SITES UNDER INVESTIGATION AT NORFOLK NAVAL SHIPYARD

Sources: Baker 1994, 1995, 1996, 1999; CH2MHILL1999, 2000a, 2000b, 2001a, 2001d, 2001e, 2002; LANTDIV 1994; NNSY 1999, 2000, 2001a; NNSY and LANTDIV 2002; OHM 2001, 2002; Nielsen 2002, J. Nielsen, personal communication, July 10, 2003).

Notes:

No remedial actions were conducted, and no further investigation is planned, at several other sites, originally identified as Sites 11 to 16 under the IRP. These areas include the sites of former steel pickling tanks (Sites 11, 12, 13, and 16) and the site of a PCB spill that was cleaned up.

Further investigations have been recommended at five additional sites. A Site Screening Process (SSP) has been initiated and data analysis is currently underway for Building 236 (see Site 17), the 1927 Landfill area (see Site 10), and Building 369, a drum storage area in the southeastern portion of the main shipyard. SSP work has also been recommended for a soot hopper at Building 174 and a caustic cleaning area at Building 202. Building 174 was removed in 1988. Building 202 has been re-done, tanks have been removed, and new concrete has been installed.

At 11 sites currently considered AOCs, a document evaluation and/or limited sampling is planned to evaluate whether further investigation or no further action is appropriate. The AOCs are: Site 8, the 1941 Landfill; Site 18, the 1914 Landfill; Site 19, the 1942-1954 Landfill; an old incinerator known as Site 21 during the RCRA Facility Assessment; a former abrasive blast recycling facility; a former PCB storage area; an underground oil/water separator tank near Site 17; the Southern Branch of the Elizabeth River; shipyard storm sewers; and industrial wastewater piping leading to the industrial wastewater treatment plant.

APPENDIX B: ATSDR HAZARD CATEGORIES

APPENDIX C: SOIL TERMS AND CODES USED ON FIGURE 6

Source: USDA National Resource Conservation Service Soil Survey of Tidewater Cities Area, Virginia 06/12/2002 available on the web at http://www.va.nrcs.usda.gov/soils/web_surveys.htm

Tidewater Cities (Hampton, Newport News, Norfolk, Poquoson, Portsmouth)
Soil Scientist and point of contact for soil survey is Gene Crabtree 757-547-7172 ext. 3.

APPENDIX D: WETLAND CLASSIFICATION TERMS AND CODES FOR FIGURE 8

Click here to view Appendix D in PDF format (44KB, PDF)

APPENDIX E: ATSDR GLOSSARY OF TERMS

The Agency for Toxic Substances and Disease Registry (ATSDR) is a federal public health agency with headquarters in Atlanta, Georgia, and 10 regional offices in the United States. ATSDR's mission is to serve the public by using the best science, taking responsive public health actions, and providing trusted health information to prevent harmful exposures and diseases related to toxic substances. ATSDR is not a regulatory agency, unlike the U.S. Environmental Protection Agency (EPA), which is the federal agency that develops and enforces environmental laws to protect the environment and human health. This glossary defines words used by ATSDR in communications with the public. It is not a complete dictionary of environmental health terms. If you have questions or comments, call ATSDR's toll-free telephone number, 1-888-42-ATSDR (1-888-422-8737).

General Terms

Absorption:

The process of taking in. For a person or an animal, absorption is the process of a substance getting into the body through the eyes, skin, stomach, intestines, or lungs.

Acute:

Occurring over a short time [compare with chronic].

Acute exposure:

Contact with a substance that occurs once or for only a short time (up to 14 days) [compare with intermediate duration exposure and chronic exposure].

Adverse health effect:

A change in body function or cell structure that might lead to disease or health problems

Ambient:

Surrounding (for example, ambient air).

Background level:

An average or expected amount of a substance or radioactive material in a specific environment, or typical amounts of substances that occur naturally in an environment.

Biodegradation:

Decomposition or breakdown of a substance through the action of microorganisms (such as bacteria or fungi) or other natural physical processes (such as sunlight).

Biologic monitoring:

Measuring hazardous substances in biologic materials (such as blood, hair, urine, or breath) to determine whether exposure has occurred. A blood test for lead is an example of biologic monitoring.

Biota:

Plants and animals in an environment. Some of these plants and animals might be sources of food, clothing, or medicines for people.

Chronic:

Occurring over a long time [compare with acute].

Chronic exposure:

Contact with a substance that occurs over a long time (more than 1 year) [compare with acute exposure and intermediate duration exposure]

Completed exposure pathway:

[see exposure pathway].

Comprehensive Environmental Response, Compensation, and Liability Act of 1980 (CERCLA):

CERCLA, also known as Superfund, is the federal law that concerns the removal or cleanup of hazardous substances in the environment and at hazardous waste sites. ATSDR, which was created by CERCLA, is responsible for assessing health issues and supporting public health activities related to hazardous waste sites or other environmental releases of hazardous substances. This law was later amended by the Superfund Amendments and Reauthorization Act (SARA).

Concentration:

The amount of a substance present in a certain amount of soil, water, air, food, blood, hair, urine, breath, or any other media.

Contaminant:

A substance that is either present in an environment where it does not belong or is present at levels that might cause harmful (adverse) health effects.

Dermal:

Referring to the skin. For example, dermal absorption means passing through the skin.

Dermal contact:

Contact with (touching) the skin [see route of exposure].

Dose (for chemicals that are not radioactive):

The amount of a substance to which a person is exposed over some time period. Dose is a measurement of exposure. Dose is often expressed as milligram (amount) per kilogram (a measure of body weight) per day (a measure of time) when people eat or drink contaminated water, food, or soil. In general, the greater the dose, the greater the likelihood of an effect. An "exposure dose" is how much of a substance is encountered in the environment. An "absorbed dose" is the amount of a substance that actually got into the body through the eyes, skin, stomach, intestines, or lungs.

Dose (for radioactive chemicals):

The radiation dose is the amount of energy from radiation that is actually absorbed by the body. This is not the same as measurements of the amount of radiation in the environment.

Environmental media:

Soil, water, air, biota (plants and animals), or any other parts of the environment that can contain contaminants.

Environmental media and transport mechanism:

Environmental media include water, air, soil, and biota (plants and animals). Transport mechanisms move contaminants from the source to points where human exposure can occur. The environmental media and transport mechanism is the second part of an exposure pathway.

Epidemiology:

The study of the distribution and determinants of disease or health status in a population; the study of the occurrence and causes of health effects in humans.

Exposure:

Contact with a substance by swallowing, breathing, or touching the skin or eyes. Exposure may be short-term [acute exposure], of intermediate duration, or long-term [chronic exposure].

Exposure assessment:

The process of finding out how people come into contact with a hazardous substance, how often and for how long they are in contact with the substance, and how much of the substance they are in contact with.

Exposure pathway:

The route a substance takes from its source (where it began) to its end point (where it ends), and how people can come into contact with (or get exposed to) it. An exposure pathway has five parts: a source of contamination (such as an abandoned business); an environmental media and transport mechanism (such as movement through groundwater); a point of exposure (such as a private well); a route of exposure (eating, drinking, breathing, or touching), and a receptor population (people potentially or actually exposed). When all five parts are present, the exposure pathway is termed a completed exposure pathway.

Feasibility study:

A study by EPA to determine the best way to clean up environmental contamination. A number of factors are considered, including health risk, costs, and what methods will work well.

Groundwater:

Water beneath the earth's surface in the spaces between soil particles and between rock surfaces [compare with surface water].

Hazard:

A source of potential harm from past, current, or future exposures.

Hazardous waste:

Potentially harmful substances that have been released or discarded into the environment.

Health consultation:

A review of available information or collection of new data to respond to a specific health question or request for information about a potential environmental hazard. Health consultations are focused on a specific exposure issue. Health consultations are therefore more limited than a public health assessment, which reviews the exposure potential of each pathway and chemical [compare with public health assessment].

Health education:

Programs designed with a community to help it know about health risks and how to reduce these risks.

Health investigation:

The collection and evaluation of information about the health of community residents. This information is used to describe or count the occurrence of a disease, symptom, or clinical measure and to evaluate the possible association between the occurrence and exposure to hazardous substances.

Health statistics review:

The analysis of existing health information (i.e., from death certificates, birth defects registries, and cancer registries) to determine if there is excess disease in a specific population, geographic area, and time period. A health statistics review is a descriptive epidemiologic study.

Indeterminate public health hazard:

The category used in ATSDR's public health assessment documents when a professional judgment about the level of health hazard cannot be made because information critical to such a decision is lacking.

Incidence:

The number of new cases of disease in a defined population over a specific time period [contrast with prevalence].

Ingestion:

The act of swallowing something through eating, drinking, or mouthing objects. A hazardous substance can enter the body this way [see route of exposure].

Inhalation:

The act of breathing. A hazardous substance can enter the body this way [see route of exposure].

Intermediate duration exposure:

Contact with a substance that occurs for more than 14 days and less than a year [compare with acute exposure and chronic exposure].

Migration:

Moving from one location to another.

National Priorities List for Uncontrolled Hazardous Waste Sites (National Priorities List or NPL):

EPA's list of the most serious uncontrolled or abandoned hazardous waste sites in the United States. The NPL is updated on a regular basis.

No apparent public health hazard:

A category used in ATSDR's public health assessments for sites where human exposure to contaminated media might be occurring, might have occurred in the past, or might occur in the future, but where the exposure is not expected to cause any harmful health effects.

No public health hazard:

A category used in ATSDR's public health assessment documents for sites where people have never and will never come into contact with harmful amounts of site-related substances.

NPL:

[see National Priorities List for Uncontrolled Hazardous Waste Sites]

Point of exposure:

The place where someone can come into contact with a substance present in the environment [see exposure pathway].

Population:

A group or number of people living within a specified area or sharing similar characteristics (such as occupation or age).

Potentially responsible party (PRP):

A company, government, or person legally responsible for cleaning up the pollution at a hazardous waste site under Superfund. There may be more than one PRP for a particular site.

ppb:

Parts per billion.

ppm:

Parts per million.

Prevalence:

The number of existing disease cases in a defined population during a specific time period [contrast with incidence].

Prevention:

Actions that reduce exposure or other risks, keep people from getting sick, or keep disease from getting worse.

Public availability session:

An informal, drop-by meeting at which community members can meet one-on-one with ATSDR staff members to discuss health and site-related concerns.

Public comment period:

An opportunity for the public to comment on agency findings or proposed activities contained in draft reports or documents. The public comment period is a limited time period during which comments will be accepted.

Public health action:

A list of steps to protect public health.

Public health assessment (PHA):

An ATSDR document that examines hazardous substances, health outcomes, and community concerns at a hazardous waste site to determine whether people could be harmed from coming into contact with those substances. The PHA also lists actions that need to be taken to protect public health [compare with health consultation].

Public health hazard:

A category used in ATSDR's public health assessments for sites that pose a public health hazard because of long-term exposures (greater than 1 year) to sufficiently high levels of hazardous substances or radionuclides that could result in harmful health effects.

Public health hazard categories:

Public health hazard categories are statements about whether people could be harmed by conditions present at the site in the past, present, or future. One or more hazard categories might be appropriate for each site. The five public health hazard categories are no public health hazard, no apparent public health hazard, indeterminate public health hazard, public health hazard, and urgent public health hazard.

Public meeting:

A public forum with community members for communication about a site.

RCRA:

[see Resource Conservation and Recovery Act (1976, 1984)]

Remedial investigation:

The CERCLA process of determining the type and extent of hazardous material contamination at a site.

Resource Conservation and Recovery Act (1976, 1984) (RCRA):

This Act regulates management and disposal of hazardous wastes currently generated, treated, stored, disposed of, or distributed.

Risk:

The probability that something will cause injury or harm.

Risk reduction:

Actions that can decrease the likelihood that individuals, groups, or communities will experience disease or other health conditions.

Risk communication:

The exchange of information to increase understanding of health risks.

Route of exposure:

The way people come into contact with a hazardous substance. Three routes of exposure are breathing [inhalation], eating or drinking [ingestion], or contact with the skin [dermal contact].

Sample:

A portion or piece of a whole. A selected subset of a population or subset of whatever is being studied. For example, in a study of people the sample is a number of people chosen from a larger population [see population]. An environmental sample (for example, a small amount of soil or water) might be collected to measure contamination in the environment at a specific location.

Sample size:

The number of units chosen from a population or an environment.

Solvent:

A liquid capable of dissolving or dispersing another substance (for example, acetone or mineral spirits).

Source of contamination:

The place where a hazardous substance comes from, such as a landfill, waste pond, incinerator, storage tank, or drum. A source of contamination is the first part of an exposure pathway.

Special populations:

People who might be more sensitive or susceptible to exposure to hazardous substances because of factors such as age, occupation, sex, or behaviors (for example, cigarette smoking). Children, pregnant women, and older people are often considered special populations.

Stakeholder:

A person, group, or community who has an interest in activities at a hazardous waste site.

Substance:

A chemical.

Superfund:

[see Comprehensive Environmental Response, Compensation, and Liability Act of 1980 (CERCLA) and Superfund Amendments and Reauthorization Act (SARA)

Superfund Amendments and Reauthorization Act (SARA):

In 1986, SARA amended the Comprehensive Environmental Response, Compensation, and Liability Act of 1980 (CERCLA) and expanded the health-related responsibilities of ATSDR. CERCLA and SARA direct ATSDR to look into the health effects from substance exposures at hazardous waste sites and to perform activities including health education, health studies, surveillance, health consultations, and toxicological profiles.

Surface water:

Water on the surface of the earth, such as in lakes, rivers, streams, ponds, and springs [compare with groundwater].

Toxic agent:

Chemical or physical (for example, radiation, heat, cold, microwaves) agents that, under certain circumstances of exposure, can cause harmful effects to living organisms.

Toxicological profile:

An ATSDR document that examines, summarizes, and interprets information about a hazardous substance to determine harmful levels of exposure and associated health effects. A toxicological profile also identifies significant gaps in knowledge on the substance and describes areas where further research is needed.

Toxicology:

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

Urgent public health hazard:

A category used in ATSDR's public health assessments for sites where short-term exposures (less than 1 year) to hazardous substances or conditions could result in harmful health effects that require rapid intervention.

Volatile organic compounds (VOCs):

Organic compounds that evaporate readily into the air. VOCs include substances such as benzene, toluene, methylene chloride, and methyl chloroform.

Some other glossaries and dictionaries:

Environmental Protection Agency (www.epa.gov/OCEPAterms/ )

National Center for Environmental Health (CDC) (www.cdc.gov/nceh/dls/report/glossary.htm )

National Library of Medicine (NIH) (www.nlm.nih.gov/medlineplus/mplusdictionary.html )

For more information on the work of ATSDR, please contact:

Office of Policy and External Affairs
Agency for Toxic Substances and Disease Registry
1600 Clifton Road, N.E. (MS E-60)
Atlanta, GA 30333
Telephone: (404) 498-0080

APPENDIX F: RESPONSES TO PUBLIC COMMENTS

Comment #1: Summary, second paragraph. Norfolk Naval Shipyard (NNSY) does not include the annexes listed. The landowner is Commander Navy Region Mid-Atlantic (CNRMA). NNSY and CNRMA have agreed that NAVFAC/LANTDIV and NNSY will retain lead command responsibility for its historical IR sites until CERCLA remedial actions are completed, after which CNRMA will assume responsibility for the long term maintenance and monitoring of these sites.

Response: The text has been changed accordingly.

Comment #2: Summary, second paragraph. Past NNSY activities did extend to New Gosport but CNRMA is the current property owner and the NNSY is no longer involved in activities at that site.

Response: The text has been changed accordingly.

Comment #3: Summary, "Exposure to Lead in the New Gosport Area" section. This paragraph is confusing to the reader. Specifically, the paragraph begins by discussing the abrasive blasting material disposed of on the Navy property, and then discusses lead based paint on housing outside of the gate and the effect of cumulative exposure. It appears that the disposal of the abrasive blasting material on the Navy property may have contributed to the cumulative exposure of the residents living in the private housing. We feel that the health issues associated with the disposal of the abrasive blasting material is a separate issue from the health issues associated with exposure to lead based paint from residential dwellings. The two issues should be discussed in separate paragraphs.

Response: ATSDR concurs that a discussion of lead exposures should clearly distinguish between lead exposures associated with Site 1 and those associated with other sources. In response to this comment, we clarified this discussion. We retained the reference to lead-based paint because the possibility of multiple sources and routes of exposure contributes to our conclusion that past exposures were indeterminate. As part of our effort to clarify this discussion, we present our conclusions about past exposure in a separate paragraph from our conclusions about current and future exposure.

Comment #4: "Exposure to Lead in Soil in and Near the New Gosport Area." While important issues are raised by the discussion of lead-based paint and blood lead testing for children living at private residences outside the former New Gosport Housing complex, they are regional issues not directly related to the former Navy housing complex at New Gosport. These issues should be discussed separately in a section titled "Regional Public Health Concerns."

Response: Navy personnel live and have lived in Navy and non-Navy housing within the local community and within the New Gosport area. ATSDR is not endeavoring to identify which parties are the sources of lead exposures. For these reasons, ATSDR has not drafted a distinct discussion of regional lead-related issues.

Comment #5: Summary, "Exposure to Lead at Other Navy Family Housing Areas" subsection, second paragraph. Quarters P-Z (horseshoe area) have been demolished completely, as described later in the document.

Response: The text has been changed accordingly.

Comment #6: "ATSDR Involvement," third paragraph. Site 9 was adjacent to a parking lot but was not "within" the parking area. The site was separated from the parking area by barriers and signs.

Response: The text has been changed accordingly to reflect the above conditions during ATSDR second site visit.

Comment #7: "Demographics," "NNSY" subsection. The report should note that due to the nature of Navy assignments, typically Navy families only resided in the Navy housing for one to three years at a time.

Response: The text has been changed to reflect this information, along with information that some employees may reside at NNSY for longer periods of time, because of the nature of their assignments at different Naval commands in the area.

Comment #8: "Land and Natural Resource Use," "Discharges to Surface Water" subsection, second paragraph. NNSY began treating bilge-water and drydock wastewater using a dissolved air flotation (DAF) process in 1994. The DAF bilge-water and drydock wastewater treatment system described as under construction in this paragraph has been operational since August 2003.

Response: The text has been changed accordingly.

Comment #9: Discussions of exposure to calcium hydroxide from Southgate Annex throughout the report. Remediation of all of the calcium hydroxide on both the Navy and the Atlantic Wood Industries property has been completed.

Response: The text has been changed accordingly.

Comment #10: "Community Health Concerns," first paragraph. NNSY has completed the revision to the Community Relations Plan. As part of our effort to update the plan we interviewed local residents, civic league and other citizen community representatives, local businesses, local officials and media representatives.

Response: The text has been changed accordingly.

Comment #11: Summary, "Exposure to Emissions from the Former Shipyard Foundry." Although information is not available documenting the quantity of work done at the foundry during WWII, the type of work and the configuration of the building would have been the same as the 1945 configuration.

Response: The manner in which the foundry operated and the levels of production and releases could have changed at any time during its history. In order to avoid making assumptions, and given that no documents or other records confirming this statement have been provided to ATSDR, we have not added it to our discussion.

Comment #12: Summary, "Exposure to Emissions from the Former Shipyard Foundry." This section indicates that ATSDR identified a community health concern associated with exposure to lead released into the community from foundry emissions. However, the body of the report indicates that this issue was identified by ATSDR during the site visit and review of site related data. The Summary should clarify that ATSDR identified the potential health concern and remove reference to being a "community health concern."

Response: The paragraph to which this comment refers indicated that ATSDR identified a community concern about lead. As part of our evaluation of that concern and review of potential sources of lead, we requested information about the former Shipyard foundry. The paragraph was revised to remove the reference to community concern about lead from the Shipyard; it retains a reference to community concern about lead.

Comment #13: "Community Health Concerns," Foundry discussion. All references to the foundry and any potential for lead emissions should be very objective, defining both interpretations of the available information . . . . The foundry melted lead ingots for casting into various ship components. The foundry did not have a stack for emissions, but rather upper level windows for ventilation. As lead will be in particulate form, it is likely that the vast majority of any lead emission from these "melt and pour" operations would remain inside the foundry building.

Response: ATSDR appreciates receiving this additional information about the foundry. We agree that all the information in the public health assessment, including facts relating to the foundry, should be presented objectively. For this reason, ATSDR does not speculate on how the building configuration might have affected emissions. We have, however, incorporated additional detail about the building configuration into our discussion. This new information provides additional perspective on past operations, but does not change our conclusions.

Comment #14: Foundry discussion. As part of the recent NNSY background investigation, the Navy found that level of lead across the NNSY is relatively low and does not exhibit a lead contamination gradient extending from the foundry as one would expect if the foundry were a significant source.

Response: We did not include statements regarding the background study in our analysis of issues associated with the foundry because soil sampling performed as part of the study was not statistically based, nor were the sampling locations specifically selected to discern concentration gradients from the former foundry.

Comment #15: Foundry discussion. The PHA should note that a separate urban health consultation to address lead (lead based paint, leaded gasoline, and other potential sources including the NNSY foundry and ABEX) is forthcoming.

Response: ATSDR is not endeavoring to identify which parties are the sources of lead exposures. At this time, ATSDR is not planning to prepare a separate health consultation. As indicated previously, ATSDR is providing information about cumulative lead exposures to local populations, not trying to identify particular sources of lead and the extent to which they contributed to these exposures.

Comment #16: "Community Health Concerns," second paragraph of response to question about redevelopment of the Paradise Creek Disposal Area. Replace "deed restrictions" with the terms "land use controls."

Response: The text has been changed accordingly.

Comment #17: Figures. Some of the figures inaccurately depict the boundaries of NNSY and the annexes. The correct boundaries are outlined on the attached map.

Response: The figures have been revised accordingly, where possible.

Comment #18: Appendix A. The Site screening process document for Sites 20 and 21 was issued as a final document in July of 2003.

Response: The text has been changed accordingly. At this time, the Navy has not been able to provide documentation associated with those investigations. U.S. Environmental Protection Agency (EPA) and Virginia Department of Environmental Quality (VDEQ) oversight of the Installation Restoration Program is expected to ensure that there is no future human exposure to any contaminants identified at levels of potential health concern.

Comment #19: Appendix B describes ATSDR health categories, but no grade is found within the report for NNSY.

Response: The reference to Appendix B, which provides definitions of ATSDR's hazard categories, appears in the Conclusions section of the public health assessment (PHA). That section applies the hazard category designations to the exposure pathways discussed in this document. The designations applied in the Conclusions section and elsewhere in the PHA are not intended as grades. Instead, they provide additional perspective on ATSDR's assessment of the potential for adverse effects to occur or to have occurred.

Comment #20: "Evaluation of Environmental Contamination, Exposure Pathways, and Public Health Implications," text box. The highlighted box contains a list of what contaminants have been detected in samples from Paradise Creek. The text does not state whether or not the chemicals were detected above health standards. This is an important community concern. As presented the reader does not know whether the contaminants are of health concern. Providing a statement following each chemical class as to whether the chemicals were detected above or below health standards would be very beneficial to the reader. Particularly since the section is highlighted by being placed in a box.

Response: An additional paragraph providing perspective on the potential for adverse health effects from the expected types of exposures to Paradise Creek was added to the text box. The detected levels of different contaminants and contaminants classes found at concentrations exceeding screening values in Paradise Creek are presented in the last row of the table in Appendix A. ATSDR does not have screening values for surface water and instead uses drinking water screening values; similarly, ATSDR uses soil screening values, as a first step, when presented with sediment data. Because readers may find it difficult to interpret data compared to these screening values, they are not presented in the PHA.

Comment #21: The sediments of the Southern Branch of the Elizabeth River and most likely Paradise Creek are devoid of macrobiotic life due to creosote. Oil streams to the surface in a visible film upon disturbance. How can such a poisoned environment, one sterile of macro biota, possibly be safe? The report flippantly passes this off as "low levels of other chemical contaminants commonly associated with industrial activities." There are no other estuarine areas in Virginia this contaminated!

Response: In response to this comment, ATSDR re-reviewed data reflecting contaminant concentrations in Paradise Creek. The Navy collected and analyzed surface water and sediment samples in 1986, 1987, 1988, 1992, 1997, and 2000⁽¹⁾. ATSDR did not identify any other surface water or sediment samples collected in Paradise Creek by any state or regional agencies or organizations.

ATSDR evaluated potential exposures to adults and children that might occur if community members swim, wade, or play in Paradise Creek two days per week, for three hours at a time, five months of the year (May to September). The water temperature is likely too cold for swimming and wading during other months of the year. We overestimated the frequency and duration that people might be in contact with the creek in order to be protective, even though no regular use of Paradise Creek has been reported. In many locations, it is hard to access because of reeds and mud present along its banks, and there is no public access to the water from NNSY.

ATSDR also made the conservative assumption that people are regularly exposed to the highest level of a given contaminant ever measured, even though in actuality contaminant levels fluctuate and lower levels were observed during different sampling events. Furthermore, the assumption that people are exposed to the highest detected levels may overestimate exposures because contaminant levels were higher in Lower Paradise Creek than in Upper Paradise Creek, but Lower Paradise Creek is hard to access from its northern shore and not an attractive area for swimming, given the adjacent industrial facilities. People are probably more likely to walk along the creek or play or sunbathe on its shores than to swim.

For sediment exposures, ATSDR assumed that the adults inadvertently ingest 100 milligrams of sediment each time they visit Paradise Creek, whereas children ingest 200 milligrams of sediment per day. Finally, ATSDR assumed that people accidentally ingest between half and three-fourths of a cup of water (0.15 liters) every time they visit Paradise Creek, for visits lasting three hours (EPA 1997). This overestimates the amount of water accidentally ingested if people visiting the creek are not swimming in it. Our estimates of resulting exposure doses provide perspective on worst-case scenarios. ATSDR does not expect people come in contact with that much sediment and surface water at the maximum detected contaminant concentrations as frequently as we estimate in our calculations.

Using these assumptions, the exposure doses calculated by ATSDR for adults and children coming into contact with Paradise Creek surface water and sediment were consistently below doses shown in the scientific literature to cause adverse health effects. It is for this reason that ATSDR concluded that infrequent and incidental exposures to contaminant levels detected in the creek would not be expected to cause adverse health effects. No data for years prior to 1986 exist, nor were data collected at any specific times when contaminant transport from the Shipyard or other industrial sites was expected to be elevated. Therefore, any exposures under those scenarios cannot be evaluated. As a precautionary measure, people should follow any swimming advisories issued by local agencies and organizations, such as the Elizabeth River Project, which is studying Paradise Creek quality.

Other Comments: A few editorial comments were received, and changes were made accordingly.

Reference

[EPA] US Environmental Protection Agency, National Center for Environmental Assessment. 1997. Exposure Factors Handbook. Washington: US Environmental Protection Agency. EPA/600/P-95/002Fa.

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