PUBLIC HEALTH ASSESSMENT
NAVAL SURFACE WARFARE CENTER
INDIAN HEAD DIVISION (NSWC-IHDIV)
(a/k/a INDIAN HEAD NAVAL SURFACE WARFARE CENTER)
INDIAN HEAD, CHARLES COUNTY, MARYLAND
The following health concerns have been identified by ATSDR through meetings, correspondence, and telephone calls with the NSWC-IHDIV, the state environmental protection agency, and community members.
Several concerns were expressed in comments to the draft version of this report. The NSWC-IHDIV Public Health Assessment was released for public comment on October 3, 1997 and the
comment period ended on November 7, 1997. Written comments were received from the
base, a member of the Restoration Advisory Board, and a representative of the Friends of
Mattawoman Creek organization. Additionally, ATSDR attended a Restoration Advisory Board
meeting on October 16, 1997, and received oral comments on the draft report. These
comments are included in summarized form.
What actions are being taken, or should be taken, to ensure the safety of the remediation (clean-up) workers at NSWC-IHDIV?
During the site visit, ATSDR spoke with representatives from the base's Installation Restoration
Program (IRP) which is responsible for the clean-up of chemical contamination at the base,
and with the Safety and Emergency Response groups. We concluded that procedures to
protect worker safety are being followed at NSWC-IHDIV. Remediation workers are subject to
the requirements of the Occupational Safety and Health Administration for ensuring workplace
and worker safety. Specifically, plans for base clean-up work must include a Health and
Safety Plan. Standards for these plans require many components, including identification of
the physical and chemical hazards present, the potential health effects associated with
exposure to the hazards, and actions and protective clothing and gear to be used by workers
to ensure that exposures of health concern do not take place. These actions are
supplemented by monitoring of chemical hazards in the field during clean-up activities. All
workers are required to read and sign the health and safety plan, abide by the standards set
forth in the plan, and participate in a medical monitoring program. The Health and Safety Plan
is the responsibility of the contractor who drafts the plan based on site-specific information
provided by the IRP Program, Safety, and Emergency Response. An example of a Health and
Safety Plan for the NSWC-IHDIV is available in the site document repository at the La Plata
Public Library.
What actions are being taken, or should be taken, to ensure the safety of employees at NSWC-IHDIV who work in proximity to the contaminated sites?
A primary purpose of the site visit and the Public Health Assessment document is to evaluate
whether the environmental contamination at a site poses or has posed a health threat to
people located off-base, to on-base residents, and to employees who are likely to work in
proximity to the areas of environmental contamination. For the contamination to pose a public
health concern, there must be a mechanism (an exposure pathway) for people to come into
contact with the contamination. ATSDR staff reviewed the available chemical contamination
data and site information for, and personally visited, each of the IRP sites at NSWC-IHDIV.
We found that employees do not generally come into contact with the contamination at the IRP
sites; therefore, these sites do not pose a health hazard to employees working at the facility.
For example, the shallow contaminated groundwater which is present at several of the sites, is
not utilized as a drinking water or industrial water resource. The Town Gut Landfill/Site 8 pond
has received contaminants from several contaminated sites within its watershed; however,
because the pond is not used for swimming or recreational fishing, direct contact with, or
ingestion of, site contaminants is prevented. ATSDR observed that areas of soil
contamination, including the network of drainage ditches that ultimately discharges into
Mattawoman Creek and the Potomac River, are well vegetated and in some cases have been
paved over: this prevents direct contact with the soils or inhalation of contaminated dusts from
these areas. Finally, in some cases, portions of buildings or entire buildings are contaminated
(e.g., Buildings 101 and 102): in these cases, the contaminated areas are secured from entry.
Metals-contaminated soils from Removal Actions at IRP Sites 5 and 8 have been secured in on-site disposal areas at NSWC and the Stump Neck Annex. What actions have been taken, or should be taken, to ensure that future activities do not inadvertently disturb these disposal locations and release these contaminants?
Silver-contaminated soils from two drainage ditches at Site 5 have been secured in two locations. Soils from Swale (ditch) 1 were chemically stabilized and placed into the base of a newly constructed 30 foot high soil berm at Site 5. Soils from Swale (ditch) 2 were used to reclaim the old Rum Point soil borrow pit at the Stump Neck Annex. These soils were covered with one foot of low permeability (clay) material, one foot of common fill, six inches of topsoil, and then reseeded. Caution tape, stating "silver contaminated soil" was placed between the clay and common fill layers. Similarly, mercury contaminated soils from Site 8 were incorporated into the soil cover of an explosives storage magazine. The contaminated soils were covered with clay, caution tape labeled "mercury contaminated soils", common fill, top soil, and then reseeded. The presence of this tape at both disposal areas ensures that, should someone mistakenly dig at these locations, the presence of the contaminated soils will be immediately known.
Finally, the contractors prepared drawings documenting the exact placement locations for
these metals contaminated soils. These "as-built" drawings are available at NSWC-IHDIV and
at the Engineering Field Activity, Chesapeake, for reference by the Navy and contractors when
planning future earth-moving and construction activities.
Local deer graze on the base, potentially eating forage grown in contaminated soils and drinking from contaminated ponds on the base. Is there a health risk to people consuming meat from the local deer population?
People are not at risk for exposure to chemical contaminants from NSWC through the
consumption of deer meat from the local herd. Only a very small percentage of the NSWC
property has contaminated soils with the potential for growing grasses and other deer forage
with elevated levels of chemicals. In addition, the deer obtaining food and water at the base
are not confined to the main base and Stump Neck Annex properties. Because they are free
to range on and off the base, they are obtaining food and water from multiple sources: forage
and water from NSWC would represent only a small fraction of their total food intake.
Does shallow contaminated groundwater at the Stump Neck Annex pose a threat to off-base shallow residential wells?
Shallow groundwater contamination at the NSWC and the Stump Neck Annex does not pose a
threat to shallow residential wells located off-base. The movement of shallow groundwater
(and associated chemicals) will be primarily controlled by the three surface water bodies
surrounding the Cornwallis Neck and Stump Neck peninsulas: Mattawoman Creek,
Chicamuxen Creek and the Potomac River. Shallow groundwater flows toward, and
discharges to, these surface waters. Evaluations of the locations of waste areas at the base
indicate that they are generally downgradient of off-base residential areas. Additional text has been added to the groundwater discussion to clarify this issue.
The small sample sizes (5 fish per species sampled) and range of concentrations reported in the U.S. Fish and Wildlife Service data set for mercury in fish tissue from Mattawoman Creek may not be adequate for drawing public health conclusions.
The U.S. Fish and Wildlife Service analysis for mercury was conducted on whole fish tissue samples rather than the portion of the fish that is actually prepared and consumed. Edible fillets do not include bones and organs of the fish. Therefore, concentrations of mercury in the edible fillet portions of those same fish would have been even lower than the concentrations reported by U.S. Fish and Wildlife. When ATSDR compared the reported maximum whole fish tissue concentrations to EPA's Risk Based Concentrations (RBCs), we found that the concentrations of mercury in whole fish tissue collected from Mattawoman Creek were below levels of health concern for each fish species analyzed. The concentrations in edible fillets would also be below levels of health concern.
Although efforts such as increasing the sample size (and analyzing the edible fillet tissue) would improve the representativeness of the data set, the sample size of 5 fish per species does not compromise the usability of the data set for drawing public health conclusions for the purposes of this public health assessment. This is particularly true since the whole fish tissue values were below levels of health concern.
This same discussion applies to the other fish tissue analyses reported for Mattawoman Creek.
Additional clarifying text has been added to the public health assessment discussion of this
issue.
The role of potentially contaminated submersed aquatic vegetation as a food source to fish and waterfowl is not addressed in the public health assessment, for example, the relationship between contaminant uptake by wild celery and consumption by local hunters of the mallards which feed on the plants. Testing of the submersed aquatic vegetation (plants) would improve the thoroughness of the PHA.
The purpose of a public health assessment is to evaluate releases of contaminants into the
environment from a facility and the potential for people to be exposed to those contaminants at
levels that may cause health effects. This evaluation is most appropriately made at the point
of exposure, that is, where the person comes into direct contact with the chemical through
eating, breathing, or skin contact. Although testing of submersed plants would improve overall
understanding of differences in metals uptake by different species of plants and how the
Mattawoman Creek ecosystem functions, this type of analysis is not within the scope of a
public health assessment. No information was provided to ATSDR that indicated terrestrial
populations (deer, beaver) or waterfowl are contaminated and are being consumed by people
at frequencies to be of public health concern.
Do exposures to sediments in Mattawoman Creek pose a health risk to people participating in water-contact sports?
In the past, NSWC-IHDIV discharged chemicals from base operations to local surface waters,
including Mattawoman Creek. The base has taken steps to reduce or eliminate these
discharges. Limited sampling performed by the base indicates that the sediments near some
of the base discharge locations show elevated levels of metals. The full nature and extent of
the contamination is not yet known, but will be determined by the base as part of the on-going
Remedial Investigation studies. The shore areas of the base are posted "No Trespassing" and
water contact sports such as bathing are not likely to occur in these areas where the
concentrations are likely to be highest (near base discharge points). Infrequent, short-term,
exposures through accidental ingestion of, or skin contact with, metals bound to suspended
sediments during bathing, water- and jet-skiing, or drag net fish collection activities are not
likely to pose a health risk.
It would be helpful if ATSDR addressed the disposition of dredge materials from Mattawoman Creek.
The comment noted that the U.S. Fish and Wildlife Service reported metals concentrations in
the creek sediments below state thresholds triggering special handling of the dredge materials.
In addition, no pathway was identified for people to be exposed to these dredge materials.
Therefore, ATSDR did not perform a public health evaluation of this issue.
An assessment of the relevance of fish lesions to public health was not provided in the PHA. It would seem appropriate that additional studies be conducted to confirm these findings in light of the recent outbreak of Pfiesteria in tributaries of the Chesapeake.
The Fish and Wildlife study noted a significant elevation of the total number of lesions (wound or injury) and the number of non-parasitic lesions on fish collected around Marsh Island in Mattawoman Creek. However, no information was presented to ATSDR suggesting the cause of the fish lesions, therefore, it is not possible to evaluate whether the presence of these lesions on fish in the creek have implications for the health of people using the creek for recreational activities. In addition, no evidence was presented to suggest that the lesions were caused by exposures to chemicals in the environmental from NSWC-IHDIV.
No outbreaks of Pfiesteria have been reported in Mattawoman Creek. This small aquatic organism is neither a bacteria nor a virus and is not infectious or contagious. Pfiesteria does produce a chemical called a toxin: the presence of large populations of toxin-producing Pfiesteria have been correlated with specific patterns of lesions on fish and fish kills in the Chesapeake Bay and its tributaries. Early research suggests that people are not exposed to the toxin by eating fish.
Considerable research on the occurrence, causes, and effects of Pfiesteria is being conducted by a consortium of state, federal, and university researchers. Readers wanting additional information about Pfiesteria should contact the Maryland Department of Natural Resources either directly or by accessing the MDNR Internet page at: www.dnr.state.md.us/.
In general, it is good public health practice to avoid eating fish, from any source, that exhibit lesions or other evidence of disease.
ATSDR conducts a review of existing health outcome data (e.g., birth and death certificates, birth defects registries, cancer registries, etc.), when available, if people have been exposed to site contaminants or if the community has concerns related to specific health outcomes.
ATSDR did not evaluate health outcome databases in conjunction with our evaluation of metals in fish tissue, or chemicals in groundwater, because we determined that the people who live on and off the base were not exposed to site contaminants at levels that might cause public health hazards.
Although the potential for lead exposures of children at levels of health concern exists, the NSWC-IHDIV maintained no database of past blood lead testing results which could be made available for review by ATSDR. Thus exposed individuals could not be identified, nor could health outcome data, if such data exist, reviewed. NSWC provided blood lead data obtained in 1997 through their voluntary blood lead screening program. Data from five of the 65 children living in the Detached (one child) and Riverview (four children) housing demonstrate that these children are not being exposed to lead at levels of health concern.
ATSDR has requested from the NSWC-IHDIV, and will review, the physical examination and
biologic testing results for the Building 101 and 102 workers who participated in the mercury
medical monitoring program. Our evaluation of these health outcome data will be incorporated
into an addendum to the Final Public Health Assessment.
Julie L. Corkran, Ph.D.
Environmental Health Scientist
Federal Facilities Assessment Branch
Division of Health Assessment and Consultation
Agency for Toxic Substances and Disease Registry
Advisors:
Lynn Wilder, Certified Industrial Hygienist
Environmental Health Scientist
Exposure Investigation and Consultation Branch
Division of Health Assessment and Consultation
Agency for Toxic Substances and Disease Registry
Richard Canady, Ph.D.
Senior Toxicologist
Exposure Investigation and Consultation Branch
Division of Health Assessment and Consultation
Agency for Toxic Substances and Disease Registry
Reviewer:
Diane Jackson
Chief, Defense Facilities Assessment Section
Federal Facilities Assessment Branch
Division of Health Assessment and Consultation
Agency for Toxic Substances and Disease Registry
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