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PUBLIC HEALTH ASSESSMENT

NAVAL AIR WARFARE CENTER
[a/k/a NAVAL AIR DEVELOPMENT CENTER (8 WASTE AREAS)]
WARMINSTER TOWNSHIP, BUCKS COUNTY, PENNSYLVANIA


APPENDIX D: ESTIMATED EXPOSURES AND HEALTH EFFECTS FOR THE CASEY VILLAGE NEIGHBORHOOD

In the Casey Village neighborhood, sampling found carbon tetrachloride (to 8.7 parts per billion [ppb]), 1,1-dichloroethene (1,1-DCE) (to 19 ppb), cis-1,2-dichloroethene (cis-1,2-DCE) (to 530 ppb), tetrachloroethylene (PCE) (to 480 ppb), and trichloroethylene (TCE) (to 1,200 ppb). These volatile organic compounds (VOCs) were found in a TCE plume and PCE plume suspected to originate in the Casey Village neighborhood, rather than from site sources. These maximum detected concentrations were an order of magnitude higher than VOC concentrations found in other neighborhood private wells or public water supplies. As such, the Agency for Toxic Substances and Disease Registry (ATSDR) evaluated exposures to VOCs in drinking water supplies in Casey Village separately. ATSDR evaluated exposures to VOCs in drinking water during household use (ingestion, inhalation, and dermal contact) as described in Appendix C. In addition, ATSDR specifically evaluated inhalation exposures to TCE while showering because the maximum TCE concentration (1,200 ppb) found in one home was three orders of magnitude greater than its Maximum Contaminant Level (MCL) of 5 ppb.

When the Navy detected VOC contamination in private wells in Casey Village in 1993, bottled water was immediately provided to the homes where elevated VOC concentrations were detected. By 1995, the Navy and the U.S. Environmental Protection Agency (EPA) connected all homes in Casey Village to the municipal water supply. As a result of these actions, exposure to VOCs in private well water in Casey Village ceased. As such, ATSDR's evaluations focused on past exposures. Evaluation of past exposures and doses found that use of drinking water supplies is not expected to result in noncancer or cancer health effects.

Estimated Exposure Doses for Groundwater Use

As described in Appendix C, ATSDR estimated exposure doses for people using contaminated well water to determine whether exposures to contaminants in drinking water supplies may be related to adverse health effects. In estimating to what extent people might be exposed to contaminants, ATSDR used a number of "conservative" assumptions about contaminant concentrations in well water, as well as how much and how often people drink well water, to ensure that a worst-case exposure scenario was evaluated. ATSDR expects that few residents were actually exposed to the highest contaminant concentrations for the duration and frequency assumed.

ATSDR used the to following equation and exposure assumptions to estimate an exposure dose for drinking water:

Estimated exposure dose equals C times IR times EF times ED divided by BW times AT

where:

C Maximum concentration (parts per million [ppm])
IR Intake rate (accounts for ingestion, inhalation, and dermal contact): adult=4 liters per day; child=3 liters per day
EF Exposure frequency: residents=365 days/year
ED Exposure duration or the duration over which exposure occurs: residents (adults)=43 years, (children)=6 years (Exposure durations represent the time from when on-base disposal commenced and most homes in Casey Village were built in 1950 until private well users were provided with alternate water supplies in 1993 [43 years].)
BW Body weight: adult=70 kg (154 pounds); child=10 kg (22 pounds)
AT Averaging time or the period over which cumulative exposures are averaged (6 or 43 years x 365 days/year for noncancer effects and 70 year [considered a lifetime] x 365 days/year for cancer effects)

These assumptions are conservative because:

Noncancer

Table E-1 lists the noncancer doses for adults and children, the minimal risk levels (MRLs), and the no-observable-adverse-effects-level (NOAEL) or lowest-observable-adverse-effects-level (LOAEL) that served as the basis for the MRL. The doses for carbon tetrachloride, 1,1-DCE, and cis-1,2-DCE were below their MRLs. The child dose for TCE was above its MRL. The adult and child doses for PCE exceeded the MRLs. However, the estimated doses for exposure to each of these contaminants was well below the NOAEL or LOAEL used to develop the MRLs. Because of the toxicity data and the conservative assumptions described previously, ATSDR expects that actual exposure doses were below the estimated doses and that noncancer effects are not expected to occur.

Table E-1: Estimated Exposure Doses at Casey Village - Noncancer

Contaminant

Maximum Detected Concentration (ppb)

Estimated Exposure Dose (mg/kg/day)

NOAEL or LOAEL (mg/kg/day)

Health Guideline (mg/kg/day)

Basis for Health Guideline

Adult

Child

Carbon tetrachloride

8.7

0.0005

0.003

1

0.007

MRLintermediate

1,1-DCE

19

0.001

0.006

9

0.009

MRLchronic

cis-1,2-DCE

530

0.03

0.2

97

0.3

MRLintermediate

PCE

480

0.03

0.2

5

0.05

MRLacute

TCE

1,200

0.08

0.4

50

0.2

MRLacute 1

1 A chronic MRL is not available for TCE, therefore, the acute MRL is presented.

Bolded text indicates doses that exceeded health guidelines.

DCE dichloroethene
LOAEL lowest-observable-adverse-effects-level
mg/kg/day milligrams contaminant per kilogram body weight per day
MRL minimal risk level
NOAEL no-observable-adverse-effects-level
PCE tetrachloroethylene
ppb parts per billion
TCE trichloroethylene

Cancer

The cancer doses, cancer effects levels from the scientific literature, and lifetime cancer risks are provided in Table E-2. Although EPA is currently reviewing literature regarding the carcinogenicity of TCE and PCE, ATSDR evaluated exposures to these contaminants using the previously derived cancer potency factors (CPFs). This approach provides a conservative evaluation of the likely effects from exposures to PCE and TCE in drinking water supplies. ATSDR derived lifetime cancer risks for 1,1-DCE, PCE, and TCE slightly above the regulatory range of 10-4 to 10-6. However, these are overestimates of the actual risk. In addition to using extremely conservative assumptions about the intake rates, exposure frequency, and exposure duration as described previously, the cancer effect level for 1,1-DCE (0.6 mg/kg/day) is about 800 times higher than the cancer dose (0.0007 mg/kg/day); the cancer effect level for PCE (386 mg/kg/day) is about 20,000 times higher than the cancer dose (0.02 mg/kg/day); and the cancer effect level for TCE (1,000 mg/kg/day) is about 20,000 times higher than the cancer dose (0.05 mg/kg/day) (ATSDR 1997b, 1997c). The cancer effect level is the lowest level associated with the onset of cancer, as seen in experimental studies. Because of the toxicity data and the conservative assumptions about exposures, ATSDR expects that actual exposure doses were below the estimated doses and cancer effects are not expected to occur.

Table E-2: Estimated Exposure Doses at Casey Village - Cancer

Contaminant

Maximum Detected Concentration (ppb)

Estimated Exposure Dose (mg/kg/day)

CEL (mg/kg/day)

CPF (mg/kg/day)-1

Lifetime Cancer Risk1

Carbon tetrachloride

8.7

0.0003

20

0.1

4 x 10-5

1,1-DCE

19

0.0007

N/A

0.6

4 x 10-4

cis-1,2-DCE

530

0.02

N/A

unknown

N/A

PCE

480

0.02

386

0.05

1x 10-3

TCE

1,200

0.05

1,000

0.01

5 x 10-4

1lifetime cancer risk = dose x CPF

CPF cancer potency factor
CEL cancer effects level
DCE dichloroethene
mg/kg/day milligrams contaminant per kilogram body weight per day
N/A not available
PCE tetrachloroethylene
ppb parts per billion
TCE trichloroethylene

Estimated Exposures to TCE During Showering

ATSDR specifically evaluated inhalation exposures to TCE while showering because the maximum TCE concentration (1,200 ppb) found in one home was three orders of magnitude greater than its MCL of 5 ppb. TCE exposure during showering is a concern because it is a VOC, which means it can easily move from the water to the air. Exposure to TCE from drinking or contact with the skin, as evaluated previously in this appendix, was found to be below levels of health concern.

ATSDR used the to following equation and assumptions to estimate TCE concentrations in air during showering.

C sub a equals C sub w times MT times FR times T divided by V

where:

Ca Concentration of TCE in air (micrograms per cubic meter [ug/m3])
Cw Concentration of TCE in water: 1,200 micrograms per liter (ug/L)
MT Mass transfer: 1 (represents 100% transfer of TCE from water to the air)
FR Flow rate (rate of water flowing from the shower head): 12 liters per minute (L/min). Based on EPA's Exposure Factors Handbook for average flow from a high flow shower head.
T Time in shower: 10 minutes. Based on EPA's Exposure Factors Handbook for average shower length.
V Volume of bathroom: 10 cubic meters (m3). Based on a small bathroom with the dimensions of 7 feet by 7 feet by 8 feet.

These assumptions are conservative because:

As a result of ATSDR's evaluation, showering with water containing 1,200 ug/L of TCE would result in an air concentration of 14,400 ug/m3. MRLs for exposures to contaminants in air are expressed as concentrations (i.e., ug/m3) so that air concentrations can be directly compared to the MRLs without needing to estimate doses. The calculated concentration of TCE in the bathroom air during showering (14,400 ug/m3), therefore, is slightly above ATSDR's acute MRL for TCE in air (10,700 ug/m3). The acute MRL is based on a study of people exposed to TCE at a concentration of approximately 1,070,000 ug/m3. At this concentration, identified as the LOAEL for acute exposures to TCE in air, people experienced fatigue and drowsiness. The lowest NOAEL found in a review of the toxicologic literature was approximately 510,000 ug/m3 of TCE in air, which is 35 higher than the estimated TCE concentration in air from showering with water containing the maximum detected concentration of TCE found in Casey Village (1,200 ug/L) (ATSDR 1997c). As such, no acute health effects are expected from showering with water from private wells in Casey Village.

To evaluate intermediate and chronic exposures, the calculated acute exposure concentration (14,400 ug/m3) is expressed as a time weighted average (TWA). A TWA is the concentration of TCE a person would have to be exposed to constantly over a 24 hour day to match the amount that person was exposed to in only a 10 minute shower, as assumed in ATSDR's calculations. The time waited average was calculated as follows:

TWA equals 14,400 ug/m cubed divided by 144 equals 100 ug/mcubed

Where:

14,400 ug/m3 The TCE concentration estimated in the bathroom air during a 10 minute shower
144 The number of 10 minute intervals in a day.
(1,440 minutes per day/10 minutes)

The time weighted average of TCE in air (100 ug/m3), therefore, is below ATSDR's intermediate MRL for TCE in air (500 ug/m3). As such, no long term health effects are expected from using water from private wells in Casey Village.


APPENDIX E: ATSDR PLAIN LANGUAGE GLOSSARY OF ENVIRONMENTAL HEALTH TERMS (Revised December 1999)

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.


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.


CERCLA:
See Comprehensive Environmental Response, Compensation, and Liability Act.


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 (CVs):
Concentrations or the amount of substances in air, water, food, and soil that are not expected, 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 chemicals 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).


LOAEL:
Lowest Observed Adverse Effect Level. The lowest dose of a chemical in a study, or group of studies, that has caused harmful health effects in people or animals.


Media:
Soil, water, air, plants, animals, or any other parts of the environment that can contain contaminants.


Metabolize:
The chemical process of digesting or breaking down food or contaminants.


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 example:
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).


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:

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.


SARA:
The Superfund Amendments and Reauthorization Act in 1986 amended CERCLA and expanded the health-related responsibilities of ATSDR. CERCLA and SARA direct ATSDR to look into the health effects from chemical exposures at hazardous waste sites.


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.


Special Populations:
People who may be more sensitive to chemical exposures because of certain factors such as age, a disease they already have, occupation, sex, or certain behaviors (like cigarette smoking). Children, pregnant women, and older people are often considered special populations.


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


Superfund Site:
See NPL.


Survey:
A way to collect information or data from a group of people (population). Surveys can be done by phone, mail, or in person. ATSDR cannot do surveys of more than nine people without approval from the U.S. Department of Health and Human Services.


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.

APPENDIX F: RESPONSE TO PUBLIC COMMENTS

The Agency for Toxic Substances and Disease Registry (ATSDR) received the following comments/questions during the public comment period (September 28 to November 16, 2001) for the Naval Air Warfare Center (NAWC) Public Health Assessment (PHA) (September 28, 2001). In addition to receiving written comments, ATSDR also contacted people included on the mailing list for receipt of the PHA to confirm that their comments were received, if submitted, and to ensure that these concerns were addressed in the PHA. For comments that questioned the validity of statements made in the PHA, ATSDR verified or corrected the statements. The list of comments presented below does not include editorial comments concerning such things as word spelling or sentence syntax.

General

  1. Comment: The report concludes that soil, groundwater, and stream concentrations of contamination are not expected to cause illness or other adverse health effects. However, remediation efforts and regular monitoring were undertaken to address impacts to the environment. Groundwater remediation is still needed to restore the aquifer and ongoing stream monitoring is needed to protect human health and ecological systems. The report's conclusions should not be interpreted to mean that these measures are not required.

    2. Response: ATSDR evaluated possible current and future public health effects considering that proposed or ongoing remediation efforts and monitoring would be implemented as planned. ATSDR agrees that this PHA should not be misinterpreted to imply that no remediation is necessary.

  2. Comment: Remedial and Regulatory History: Warminster Municipal Water Authority (WMWA) has been an active participant in the Restoration Advisory Board (RAB) and the RAB Technical Subcommittee. It is WMWA's understanding that the U. S. Environmental Protection Agency's (EPA) and the Pennsylvania Department of the Environment Protection's (PADEP) investigations into additional sources of chlorinated solvents in groundwater north of NAWC are ongoing and to date, no definitive determinations have been made.

    3. Response: The "Remedial and Regulatory History" section of the PHA states that EPA identified an industrial area north of NAWC as a potential source of chlorinated solvents. EPA has confirmed that their investigations are ongoing and that no definitive determinations regarding additional sources of chlorinated solvents in groundwater north of NAWC have been made to date (Creamer 2002). The Navy's investigations identified off-base sources of groundwater contamination during the course of their RI investigations, but did not identify a specific off-base source.

  3. Comment: Remedial and Regulatory History: The report states that during the remedial investigation (RI) studies, the Navy evaluated several municipal and private water supplies that were later found to be affected by sources other than NAWC. The Navy's conclusions in this regard are not supported by the full Technical Subcommittee. Also, to be accurate, originally, it was the Navy's position that WMWA Well 26 had not been adversely impacted by activities at NAWC. It is now understood that WMWA Well 26 has been adversely impacted by activities at NAWC. The PHA should be revised to include this conclusion.

    4. Response: When groundwater contamination was found in several locations in the Warminster area, NAWC was identified as a potential source. In response, the Navy conducted investigations to characterize the nature and extent of groundwater contamination originating at the base. To provide a complete history of past events and address community concerns about groundwater contamination, ATSDR included information about water supplies that were impacted by NAWC sources, as well as water supplies included in Navy investigations, but found to be impacted by non-NAWC sources.

    As a result of these investigations, NAWC was implicated as the source of contamination found in WMWA Well 26. On-base wells and private wells were also identified as being impacted by NAWC sources. ATSDR organized the "Evaluation of Groundwater Exposure Pathway" section of this PHA to first discuss those water supplies impacted by NAWC sources, and then to discuss those water supplies impacted by non-NAWC sources. ATSDR modified the text to clearly indicate which water supplies were considered impacted by NAWC, including WMWA Well 26.

  4. Comment: Quality Assurance and Quality Control: This section should be revised to include the statement that RAB members have not yet reached a consensus regarding the potential for contamination from on-base sources and potential sources located beyond base boundaries to adversely impact municipal wells.

    5. Response: The "Quality Assurance and Quality Control" section of this PHA does note that several technical documents regarding NAWC are undergoing review and concerned parties, including the RAB, EPA, and PADEP, have not reached a consensus regarding conclusions provided in these documents because a concern about the source of groundwater contaminant in neighborhoods adjacent to NAWC remains. ATSDR added text stating that concerns about sources of groundwater contamination in municipal wells also remain.

  5. Comment: Evaluation of Groundwater Exposure Pathway: The trichloroethylene (TCE) concentration that exceeded the comparison value for the Off-Site Private Wells, Area 1, South (Speedway) had a detection frequency of 1/37. The Aroclor-1248 concentration exceeding the comparison value in Table 9 had a detection frequency of 1/21. For risk assessment purposes we do not recommend including sample concentrations that are detected in 5 percent or less of all of the samples collected. Remove chemicals from the health assessment that are detected in 5 percent or less than the total number of samples collected.

    6. Response: In the PHA process, ATSDR identifies possible exposures and potentially exposed populations before evaluating whether these exposures could lead to adverse health effects. As a result, ATSDR may identify exposures that occur infrequently or only at an individual household, which is the case with the single Aroclor-1248 detection in sediment and the TCE detection in a single well in the Speedway neighborhood. Evaluations of possible public health effects from these exposures are then conducted considering how often a person may contact a chemical (frequency), as well as other factors such as for how long exposures may occur (duration) and what chemical concentrations people may contact. Following this process, ATSDR uses conservative assumptions to purposely overestimate exposures during evaluations and ensure protection of public health. Removing chemicals detected in 5 percent or less than the total number of samples collected would preclude ATSDR from conducting a thorough evaluation of all public health impacts.

Water Supplies

  1. Comment: Hydrogeology: The PHA states that investigators have identified three underground layers of water or aquifers: overburden, shallow bedrock and deep bedrock. ATSDR should make it clear that this is the Navy's interpretation. Other investigators, including hydrogeologists representing various stakeholders on the RAB Technical Subcommittee have developed alternative hydrogeologic interpretations based upon independent review and analysis of the hydrogeologic data.

    2. Response: In comments on RIs submitted to the Navy, stakeholders have provided additional information and interpretations of groundwater conditions. These comments can be summarized as follows:

    (Earth Data 1996; Tetra Tech 1998; Pennoni 2000)

    The text provided in the "Hydrogeology" section of this PHA has been modified to reflect these comments. This information, however, does not change the conclusions drawn in the PHA. Possible past, current, and future exposures to contaminants through use of groundwater as a drinking water supply are too low to cause illness or adverse health effects. In addition, the Navy and municipal water suppliers are conducting activities, such as remediation and monitoring, to ensure the safety of the water supply.

  2. Comment: Off Base Supply Wells: What is the technical basis to support the statement that past, current and future residents may be exposed to arsenic in their drinking water supplied from WMWA Well 26.

    3. Response: During the Phase II RI of Operable Unit 1 completed in 1993, the Navy sampled several off-base wells, including WMWA Well 26. Analysis of the sample collected from WMWA Well 26 detected arsenic at 3.7 parts per billion [ppb]. This concentration is below EPA's maximum contaminant level, but above ATSDR's comparison value. Although water from this well is treated using an air stripper, this treatment method is not designed to remove arsenic from the water. As such, ATSDR considers that exposures to arsenic were possible and evaluated the potential for adverse health effects from these exposures. ATSDR found that the detected arsenic concentration was below levels that would cause health effects in potentially exposed populations.

Lead Paint

  1. Comment: Summary: The Summary states "Lead in paint, dust, and /or soil was found in eight homes located in the officer housing area, Quarters A, and Quarters B. To prevent current and future exposures, the Navy completed removal and abatement actions at these homes." The ATSDR conclusion includes the statement "ATSDR concluded that past exposure to lead was not expected to result in adverse health effects in all homes except one. In one home, lead exposures could have resulted in increased blood lead levels; however, possible adverse health effects are indeterminate because it is unknown if children and pregnant women lived in this home when lead was accessible." We agree that adverse health effects were possible, however, we do not feel that this should necessarily be categorized as "indeterminate" due to the conservatism incorporated into the health assessment. We believe the information provided in the report supports this opinion. We would appreciate your consideration of changing the category to "no apparent public health hazard."

    2. Response: As requested, ATDSR reviewed the information used to draw the conclusion that lead exposures in one home (Quarters A) posed an indeterminant health hazard. Because the elevated concentration of lead in soil (a maximum of 8,734 parts per million [ppm]) is consistent with scientific literature reporting elevated blood lead levels and past exposures by children and pregnant women is unknown, ATSDR retained the classification of indeterminate public health hazard for exposures to lead at Quarters A. The following provides additional information.

    Five surface soil samples were collected from the foundation, driveway, and 40 feet from the foundation of Quarters A. Detected concentrations ranged from 54 ppm, found 40 feet from the foundation, to 8,734 ppm, found at the foundation. The average detected concentration was approximately 1,980 ppm. A number of studies have been conducted to evaluate the relationship between elevated soil lead concentrations and elevated blood lead levels. ATSDR's Toxicological Profile reviews these studies and reports a 1 to 7 microgram per deciliter (ug/dL) increase in blood lead levels for every 1,000 ppm increase in soil lead concentrations. Based on these findings, an increase of 8.7 to 61 ug/dL in blood lead levels may result from exposure to the maximum lead concentration in soil (8,734 ppm) and an increase of 2 to 14 ug/dL in blood lead levels may result from exposure to the average lead concentration in soil (1,980 ppm). These increases exceed the Center for Disease Control's (CDC) level of concern of 10 ug/dL blood lead in children (ATSDR 1999).

    ATSDR also reviewed EPA's risk analysis conducted to support the development of EPA lead standards in paint, dust, and soil. One of the studies considered in this analysis was a 1996 EPA study of lead exposures to children in the Baltimore, Maryland, area. In this study, lead was found in soil at a maximum concentration of 3,450 ppm and an average concentration of 1,260 ppm at homes slated for lead abatement. The corresponding blood lead levels found in children living in these homes was a maximum of 65 ug/dL and an average of 10 ug/L. These levels meet or exceed CDC's level of concern (10 ug/dL). Children in this study were also exposed to lead in dust and paint in homes, nonetheless, soil lead concentrations in this study were similar to, if not lower than, concentrations found at Quarters A (EPA 1998).

    Based on this information, ATSDR believes that lead levels found at Quarters A have the potential to results in adverse health effects in exposed populations of children. Because lead exposures to pregnant woman can adversely affect the unborn child, ATSDR also considers pregnant woman as a susceptible population. However, no information is available to determine if a receptor population—children and/or pregnant women—lived in Quarters A when lead exposures were possible. Nor is information available to determine if the receptor population's activities would have resulted in frequent contact with elevated soil lead concentrations (e.g., gardening or playing in areas of elevated lead concentrations). Because this information is lacking, ATSDR categorized past exposures to lead at Quarters A as indeterminate. The Navy has completed lead abatement at Quarters A and other housing areas, therefore, ATSDR categorized current and future exposures as posing no public health hazard.

  2. Comment: The PHA discusses the potential public health risks related to exposures that may have resulted in the past from contact with lead concentrations in the soil at Quarters A. The highest lead concentrations in soil were detected at the building foundation (884 ppm and 8,734 ppm). Three of the five soil samples collected at Quarters A were below 400 ppm and only one floor dust sample and one window sill dust sample exceeded their respective HUD Guideline. Given the location of the samples collected and the frequency of samples exceeding the screening values, consider removing "pregnant women" from the conclusion.

    3. Response: A review of the scientific literature indicates that lead ingested or inhaled during pregnancy or lead released from the mother's bones can be sources of lead exposure to an unborn child. Lead exposure may continue during breast feeding. Unborn children exposed to lead may experience the following health effects: impaired neurological development, neurobehavioral deficits, growth retardation, low birth weights, and low gestational age. As discussed in the response to comment 8, information regarding a possible receptor population and possible activities (e.g. gardening) in areas of high lead concentrations is unavailable. As such, ATSDR considered pregnant woman as a possible susceptible population to past lead exposures at Quarters A and categorized past lead exposures as posing an indeterminate public health hazard.

  3. Comment: The "Evaluation of Lead Paint Exposure Pathway" section concludes with "Based on this assessment, ATSDR concluded that exposure to the maximum detected lead levels in soil could result in increased blood levels." Given that Quarters A was where the commanding officer lived we are certain that the grounds surrounding the house were landscaped, further reducing the potential contact with contaminated surface soil.

    4. Response: ATSDR agrees that landscaping and a vegetative cover would reduce potential contact with soil lead concentrations. The Navy's 1997 "Lead Management Plan, Senior Enlisted Quarters" report, which provided the information about lead sampling conducted at Quarters A, Quarters B, and the officer housing area used in this PHA, contains information about the vegetative cover at areas of soil sampling. At the location where the highest lead concentration (8,734 ppm) was detected, a vegetative cover of 95% was reported. However, at the location of the second highest lead concentration (884 ppm), a vegetative cover of only 20% was reported (Department of the Navy 1997). This information indicates that at least some areas surrounding Quarters A included bare soil.

References

Agency for Toxic Substances and Disease Registry (ATSDR). 1999. Toxicological profile for lead. Atlanta, GA: Agency for Toxic Substances and Disease Registry. July 1999.

Creamer, Charlene. 2002. Personal Communication with Charlene Creamer, EPA Region 3 Representative. February 27, 2002.

Department of the Navy. 1997. Lead Management Plan, Senior Enlisted Quarters, Naval Air Station Joint Reserve Base Willow Grove. January 1997.

Earth Data Incorporated and Pennoni Associates, Inc. (Earth Data). 1996. Correspondence from W. David Fennimore, J. Anthony Sauder, and Anthony S. Bartolomeo to Orlando Monaco regarding NAWC Warminster. October 9, 1996.

Pennoni Associates, Inc. (Pennoni). 2000. Correspondence from J. Anthony Sauder and Kevin J. Davis to Lonnie Monaco regarding RI/FS for Area D Groundwater, Former NAWC Warminster, Pennsylvania. May 30, 2002.

Tetra Tech NUS, Inc. (Tetra Tech). 1998. Correspondence from Neil Teamerson to Lonnie Monaco regarding Responses to Comments for Groundwater Monitoring Reports, Former Naval Air Warfare Center (NAWC) Warminster, Pennsylvania. December 31, 1998.

U.S. Environmental Protection Agency (EPA). 1998. TSCA Section 403, Risk Analysis to Support Standards for Lead in Paint, Dust, and Soil. Office of Pollution Prevention and Toxics. Publication No.: EPA 747-R97-006. June 1998.

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