PUBLIC HEALTH ASSESSMENT
NAVAL AIR WARFARE CENTER
[a/k/a NAVAL AIR DEVELOPMENT CENTER (8 WASTE AREAS)]
WARMINSTER TOWNSHIP, BUCKS COUNTY, PENNSYLVANIA
In the Casey Village neighborhood, sampling foundcarbon 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), andtrichloroethylene (TCE) (to 1,200 ppb). Thesevolatile organic compounds (VOCs) were found ina TCE plume and PCE plume suspected to originatein the Casey Village neighborhood, rather than fromsite sources. These maximum detectedconcentrations were an order of magnitude higherthan VOC concentrations found in otherneighborhood private wells or public watersupplies. As such, the Agency for Toxic Substancesand Disease Registry (ATSDR) evaluatedexposures to VOCs in drinking water supplies inCasey Village separately. ATSDR evaluatedexposures to VOCs in drinking water duringhousehold use (ingestion, inhalation, and dermalcontact) as described in Appendix C. In addition,ATSDR specifically evaluated inhalation exposuresto TCE while showering because the maximumTCE concentration (1,200 ppb) found in one homewas three orders of magnitude greater than itsMaximum Contaminant Level (MCL) of 5 ppb.
When the Navy detected VOC contamination inprivate wells in Casey Village in 1993, bottledwater was immediately provided to the homeswhere elevated VOC concentrations were detected.By 1995, the Navy and the U.S. EnvironmentalProtection Agency (EPA) connected all homes inCasey Village to the municipal water supply. As aresult of these actions, exposure to VOCs in privatewell water in Casey Village ceased. As such,ATSDR's evaluations focused on past exposures.Evaluation of past exposures and doses found thatuse of drinking water supplies is not expected toresult in noncancer or cancer health effects.
Estimated Exposure Doses for GroundwaterUse
As described in Appendix C, ATSDR estimatedexposure doses for people using contaminated wellwater to determine whether exposures tocontaminants in drinking water supplies may berelated to adverse health effects. In estimating towhat extent people might be exposed tocontaminants, ATSDR used a number of "conservative" assumptions about contaminantconcentrations in well water, as well as how muchand how often people drink well water, to ensurethat a worst-case exposure scenario was evaluated.ATSDR expects that few residents were actuallyexposed to the highest contaminant concentrationsfor the duration and frequency assumed.
ATSDR used the to following equation andexposure assumptions to estimate an exposure dosefor drinking water:
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:
- ATSDR assumed a person was exposed tothe maximum detected concentration ofall the VOCs, however, the maximumdetected concentrations of thesecontaminants were found in differentwells. As such, no one person could havebeen exposed to the highest levels of allthe detected VOCs.
- The maximum detected TCE (1,200 ppb)and cis-1,2-DCE (530 ppb) concentrationswere found in a private well that was usedonly until 1987, when the home wasconnected to the public water supply. Thiswell served a home where a degreasingoperation was reportedly run in the 1960sand 1970s. This degreasing business is thesuspected source of the TCE plume inCasey Village. Wells serving neighboringhomes contained TCE and cis-1,2-DCEconcentrations to a maximum of 120 ppband 36 ppb, respectively.
- Exposures were assumed to occur dailyfrom 1950 until 1993, a 43 year period. Actual exposure duration is expected tobe much shorter because the degreasingoperation suspected of resulting in theTCE plume commenced in the 1960s.ATSDR expects that the PCE plume wasreleased after the neighborhood wasdeveloped and that private wells werefree of PCE contamination when theybegan use.
- ATSDR also conservatively assumed thatadults and children were exposed everyday for the entire exposure period. Theactual exposure frequency is expected tobe much lower because people woulddrink water from other sources (e.g.,work and school or pre-packaged drinks)and would travel away from their homesfor vacations or other purposes.
Table E-1 lists the noncancer doses for adults andchildren, the minimal risk levels (MRLs), and theno-observable-adverse-effects-level (NOAEL) orlowest-observable-adverse-effects-level (LOAEL)that served as the basis for the MRL. The doses forcarbon tetrachloride, 1,1-DCE, and cis-1,2-DCEwere below their MRLs. The child dose for TCEwas above its MRL. The adult and child doses forPCE exceeded the MRLs. However, the estimateddoses for exposure to each of these contaminantswas well below the NOAEL or LOAEL used todevelop the MRLs. Because of the toxicity data andthe conservative assumptions described previously,ATSDR expects that actual exposure doses werebelow the estimated doses and that noncancereffects are not expected to occur.
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
1 A chronic MRL is not available for TCE, therefore, the acute MRL is presented.
Bolded text indicates doses that exceeded health guidelines.
|mg/kg/day||milligrams contaminant per kilogram body weight per day|
|MRL||minimal risk level|
|ppb||parts per billion|
The cancer doses, cancer effects levels from the scientific literature, and lifetime cancer risks areprovided in Table E-2. Although EPA is currently reviewing literature regarding the carcinogenicityof TCE and PCE, ATSDR evaluated exposures to these contaminants using the previously derivedcancer potency factors (CPFs). This approach provides a conservative evaluation of the likely effectsfrom exposures to PCE and TCE in drinking water supplies. ATSDR derived lifetime cancer risksfor 1,1-DCE, PCE, and TCE slightly above the regulatory range of 10-4 to 10-6. However, these areoverestimates of the actual risk. In addition to using extremely conservative assumptions about theintake rates, exposure frequency, and exposure duration as described previously, the cancer effectlevel for 1,1-DCE (0.6 mg/kg/day) is about 800 times higher than the cancer dose (0.0007mg/kg/day); the cancer effect level for PCE (386 mg/kg/day) is about 20,000 times higher than thecancer dose (0.02 mg/kg/day); and the cancer effect level for TCE (1,000 mg/kg/day) is about20,000 times higher than the cancer dose (0.05 mg/kg/day) (ATSDR 1997b, 1997c). The cancereffect 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 thatactual exposure doses were below the estimated doses and cancer effects are not expected to occur.
4 x 10-5
4 x 10-4
5 x 10-4
1lifetime cancer risk = dose x CPF
|CPF||cancer potency factor|
|CEL||cancer effects level|
|mg/kg/day||milligrams contaminant per kilogram body weight per day|
|ppb||parts per billion|
Estimated Exposures to TCE During Showering
ATSDR specifically evaluated inhalation exposures to TCE while showering because the maximumTCE concentration (1,200 ppb) found in one home was three orders of magnitude greater than its MCLof 5 ppb. TCE exposure during showering is a concern because it is a VOC, which means it can easilymove from the water to the air. Exposure to TCE from drinking or contact with the skin, as evaluatedpreviously 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 duringshowering.
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:
- ATSDR assumed that all of the TCE in the water would move from the water to the air inthe bathroom. Based on the chemical properties of TCE, however, a portion of the TCEwould actually remain in the water and would not be available for inhalation exposures.
- The equation used to estimate air concentrations of TCE assumes that all the TCE thatmoves from the water to the air would remain in the bathroom used for showering. Becauseof bathroom fans or drafts at the door or windows, a portion of the TCE would move out ofthe bathroom during the showering, lessening the air concentration in the bathroom. A smallincrease in TCE concentrations in other portions of the house would occur, however, theseconcentrations would still be well below the concentration found in the bathroom.
- ATSDR evaluated exposure to the maximum detected TCE concentration (1,200 ug/L)found in well water. This was the highest concentration found in the home where adegreasing business was reportedly conducted from the 1960s to the 1970s. TCEconcentrations in private wells serving neighboring homes were reported at a maximum ofonly 120 ug/L. Therefore, exposure concentrations in these homes would be much lowerthan predicted by ATSDR in this appendix.
- Because the home where the highest TCE concentrations was found was also the homewhere TCE was expected to be used in a degreasing business operated in the 1960s and1970s, other sources of TCE exposures may have been present in this home. No informationis available to assess TCE exposures that may have occurred in this home during degreasingoperations.
As a result of ATSDR's evaluation, showering with water containing 1,200 ug/L of TCE would resultin an air concentration of 14,400 ug/m3. MRLs for exposures to contaminants in air are expressed asconcentrations (i.e., ug/m3) so that air concentrations can be directly compared to the MRLs withoutneeding 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). Theacute MRL is based on a study of people exposed to TCE at a concentration of approximately1,070,000 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 toxicologicliterature was approximately 510,000 ug/m3 of TCE in air, which is 35 higher than the estimated TCEconcentration in air from showering with water containing the maximum detected concentration of TCEfound in Casey Village (1,200 ug/L) (ATSDR 1997c). As such, no acute health effects are expectedfrom showering with water from private wells in Casey Village.
To evaluate intermediate and chronic exposures, the calculated acute exposure concentration (14,400ug/m3) is expressed as a time weighted average (TWA). A TWA is the concentration of TCE a personwould have to be exposed to constantly over a 24 hour day to match the amount that person wasexposed to in only a 10 minute shower, as assumed in ATSDR's calculations. The time waited average was calculated as follows:
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 MRLfor TCE in air (500 ug/m3). As such, no long term health effects are expected from using water fromprivate wells in Casey Village.
- 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.
- 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.
- A group of diseases which occur when cells in the body become abnormal and grow, or multiply, out of control.
- Any substance shown to cause tumors or cancer in experimental studies.
- 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.
- A belief or worry that chemicals in the environment might cause harm to people.
- How much or the amount of a substance present in a certain amount of soil, water, air, or food.
- See Environmental Contaminant.
- Dermal Contact:
- A chemical getting onto your skin. (see Route of Exposure).
- 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.
- 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.
- The study of the different factors that determine how often, in how many people, and in which people will disease occur.
- 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:
- Source of Contamination,
- Environmental Media and Transport Mechanism,
- Point of Exposure,
- Route of Exposure, and
- 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.
- 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.
- Swallowing something, as in eating or drinking. It is a way a chemical can enter your body (See Route of Exposure).
- Breathing. It is a way a chemical can enter your body (See Route of Exposure).
- 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.
- Soil, water, air, plants, animals, or any other parts of the environment that can contain contaminants.
- The chemical process of digesting or breaking down food or contaminants.
- 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.
- 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.
- 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.
- 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.
- 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:
- Urgent Public Health Hazard
- Public Health Hazard
- Indeterminate Public Health Hazard
- No Apparent Public Health Hazard
- 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:
- - 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.
- 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.
- A branch of the math process of collecting, looking at, and summarizing data or information.
- Superfund Site:
- See NPL.
- 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.
- 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.
- The study of the harmful effects of chemicals on humans or animals.
- 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.
The Agency for Toxic Substances and Disease Registry(ATSDR) received the following comments/questionsduring the public comment period (September 28 toNovember 16, 2001) for the Naval Air Warfare Center(NAWC) Public Health Assessment (PHA) (September28, 2001). In addition to receiving written comments,ATSDR also contacted people included on the mailinglist for receipt of the PHA to confirm that theircomments were received, if submitted, and to ensure thatthese concerns were addressed in the PHA. Forcomments that questioned the validity of statementsmade in the PHA, ATSDR verified or corrected thestatements. The list of comments presented below doesnot include editorial comments concerning such things asword spelling or sentence syntax.
- Comment: The report concludes that soil,groundwater, and stream concentrations ofcontamination are not expected to cause illnessor other adverse health effects. However,remediation efforts and regular monitoring wereundertaken to address impacts to theenvironment. Groundwater remediation is stillneeded to restore the aquifer and ongoingstream monitoring is needed to protect humanhealth and ecological systems. The report'sconclusions should not be interpreted to meanthat these measures are not required.
- Comment: Remedial and Regulatory History:Warminster Municipal Water Authority(WMWA) has been an active participant in theRestoration Advisory Board (RAB) and theRAB Technical Subcommittee. It is WMWA'sunderstanding that the U. S. EnvironmentalProtection Agency's (EPA) and thePennsylvania Department of the EnvironmentProtection's (PADEP) investigations intoadditional sources of chlorinated solvents ingroundwater north of NAWC are ongoing andto date, no definitive determinations have beenmade.
- Comment: Remedial and Regulatory History:The report states that during the remedialinvestigation (RI) studies, the Navy evaluatedseveral municipal and private water supplies thatwere later found to be affected by sources otherthan NAWC. The Navy's conclusions in thisregard are not supported by the full TechnicalSubcommittee. Also, to be accurate, originally,it was the Navy's position that WMWA Well 26had not been adversely impacted by activities atNAWC. It is now understood that WMWAWell 26 has been adversely impacted byactivities at NAWC. The PHA should berevised to include this conclusion.
- Comment: Quality Assurance and QualityControl: This section should be revised toinclude the statement that RAB members havenot yet reached a consensus regarding thepotential for contamination from on-basesources and potential sources located beyondbase boundaries to adversely impact municipalwells.
- Comment: Evaluation of GroundwaterExposure Pathway: The trichloroethylene(TCE) concentration that exceeded thecomparison value for the Off-Site Private Wells,Area 1, South (Speedway) had a detectionfrequency of 1/37. The Aroclor-1248concentration exceeding the comparison valuein Table 9 had a detection frequency of 1/21.For risk assessment purposes we do notrecommend including sample concentrationsthat are detected in 5 percent or less of all of thesamples collected. Remove chemicals from thehealth assessment that are detected in 5 percentor less than the total number of samplescollected.
Response: ATSDR evaluated possible currentand future public health effects considering thatproposed or ongoing remediation efforts andmonitoring would be implemented as planned.ATSDR agrees that this PHA should not bemisinterpreted to imply that no remediation isnecessary.
Response: The "Remedial and RegulatoryHistory" section of the PHA states that EPAidentified an industrial area north of NAWC asa potential source of chlorinated solvents. EPAhas confirmed that their investigations areongoing and that no definitive determinationsregarding additional sources of chlorinatedsolvents in groundwater north of NAWC havebeen made to date (Creamer 2002). The Navy'sinvestigations identified off-base sources ofgroundwater contamination during the course oftheir RI investigations, but did not identify aspecific off-base source.
Response: When groundwater contaminationwas found in several locations in theWarminster area, NAWC was identified as apotential source. In response, the Navyconducted investigations to characterize thenature and extent of groundwater contaminationoriginating at the base. To provide a completehistory of past events and address communityconcerns about groundwater contamination,ATSDR included information about watersupplies that were impacted by NAWC sources,as well as water supplies included in Navyinvestigations, but found to be impacted bynon-NAWC sources.
As a result of these investigations, NAWC wasimplicated as the source of contamination foundin WMWA Well 26. On-base wells and privatewells were also identified as being impacted byNAWC sources. ATSDR organized the "Evaluation of Groundwater ExposurePathway" section of this PHA to first discussthose water supplies impacted by NAWCsources, and then to discuss those watersupplies impacted by non-NAWC sources.ATSDR modified the text to clearly indicatewhich water supplies were considered impactedby NAWC, including WMWA Well 26.
Response: The "Quality Assurance and QualityControl" section of this PHA does note thatseveral technical documents regarding NAWCare undergoing review and concerned parties,including the RAB, EPA, and PADEP, havenot reached a consensus regarding conclusionsprovided in these documents because a concernabout the source of groundwater contaminant inneighborhoods adjacent to NAWC remains.ATSDR added text stating that concerns aboutsources of groundwater contamination inmunicipal wells also remain.
Response: In the PHA process, ATSDRidentifies possible exposures and potentiallyexposed populations before evaluating whetherthese exposures could lead to adverse healtheffects. As a result, ATSDR may identifyexposures that occur infrequently or only at anindividual household, which is the case with thesingle Aroclor-1248 detection in sediment andthe TCE detection in a single well in theSpeedway neighborhood. Evaluations ofpossible public health effects from theseexposures are then conducted considering howoften a person may contact a chemical(frequency), as well as other factors such as forhow long exposures may occur (duration) andwhat chemical concentrations people maycontact. Following this process, ATSDR usesconservative assumptions to purposelyoverestimate exposures during evaluations andensure protection of public health. Removingchemicals detected in 5 percent or less than thetotal number of samples collected wouldpreclude ATSDR from conducting a thoroughevaluation of all public health impacts.
- Comment: Hydrogeology: The PHA states thatinvestigators have identified three undergroundlayers of water or aquifers: overburden, shallowbedrock and deep bedrock. ATSDR shouldmake it clear that this is the Navy'sinterpretation. Other investigators, includinghydrogeologists representing variousstakeholders on the RAB TechnicalSubcommittee have developed alternativehydrogeologic interpretations based uponindependent review and analysis of thehydrogeologic data.
Response: In comments on RIs submitted tothe Navy, stakeholders have provided additionalinformation and interpretations of groundwaterconditions. These comments can besummarized as follows:
- The designation and description ofgroundwater occurring in shallow,intermediate, and deep aquifers is anoversimplification. The actualgroundwater conditions are morecomplex and do not fit thesedesignations across the entirety ofNAWC.
- Groundwater flow in the shallow andintermediate aquifers is not entirelybased on topography. Recharge areas,such as grassy areas or stormwatersystem leaks, may have an impact ongroundwater flow. Groundwater flowin the deep aquifer would be impactedby the bedrock fracture systems.
- The hydrogeologic data indicate thatgroundwater flows from the northwestportions of NAWC to the north.Groundwater in the shallow aquiferwould flow downward and rechargethe deeper aquifers north of the base.
(Earth Data 1996; Tetra Tech 1998; Pennoni2000)
The text provided in the "Hydrogeology" section of this PHA has been modified to reflectthese comments. This information, however,does not change the conclusions drawn in thePHA. Possible past, current, and futureexposures to contaminants through use ofgroundwater as a drinking water supply are toolow to cause illness or adverse health effects. Inaddition, the Navy and municipal watersuppliers are conducting activities, such asremediation and monitoring, to ensure thesafety of the water supply.
Response: During the Phase II RI of OperableUnit 1 completed in 1993, the Navy sampledseveral off-base wells, including WMWA Well26. Analysis of the sample collected fromWMWA Well 26 detected arsenic at 3.7 partsper billion [ppb]. This concentration is belowEPA's maximum contaminant level, but aboveATSDR's comparison value. Although waterfrom this well is treated using an air stripper,this treatment method is not designed to removearsenic from the water. As such, ATSDRconsiders that exposures to arsenic werepossible and evaluated the potential for adversehealth effects from these exposures. ATSDRfound that the detected arsenic concentrationwas below levels that would cause health effectsin potentially exposed populations.
- Comment: Summary: The Summary states "Lead in paint, dust, and /or soil was found ineight homes located in the officer housing area,Quarters A, and Quarters B. To prevent currentand future exposures, the Navy completedremoval and abatement actions at these homes."The ATSDR conclusion includes the statement"ATSDR concluded that past exposure to leadwas not expected to result in adverse healtheffects in all homes except one. In one home,lead exposures could have resulted in increasedblood lead levels; however, possible adversehealth effects are indeterminate because it isunknown if children and pregnant women livedin this home when lead was accessible." Weagree that adverse health effects were possible,however, we do not feel that this shouldnecessarily be categorized as "indeterminate" due to the conservatism incorporated into thehealth assessment. We believe the informationprovided in the report supports this opinion. Wewould appreciate your consideration ofchanging the category to "no apparent publichealth hazard."
- Comment: The PHA discusses the potentialpublic health risks related to exposures that mayhave resulted in the past from contact with leadconcentrations in the soil at Quarters A. Thehighest lead concentrations in soil were detectedat the building foundation (884 ppm and 8,734ppm). Three of the five soil samples collected atQuarters A were below 400 ppm and only onefloor dust sample and one window sill dustsample exceeded their respective HUDGuideline. Given the location of the samplescollected and the frequency of samplesexceeding the screening values, considerremoving "pregnant women" from theconclusion.
- Comment: The "Evaluation of Lead PaintExposure Pathway" section concludes with "Based on this assessment, ATSDR concludedthat exposure to the maximum detected leadlevels in soil could result in increased bloodlevels." Given that Quarters A was where thecommanding officer lived we are certain thatthe grounds surrounding the house werelandscaped, further reducing the potentialcontact with contaminated surface soil.
Response: As requested, ATDSR reviewed theinformation used to draw the conclusion thatlead exposures in one home (Quarters A) posedan indeterminant health hazard. Because theelevated concentration of lead in soil (amaximum of 8,734 parts per million [ppm]) isconsistent with scientific literature reportingelevated blood lead levels and past exposures bychildren and pregnant women is unknown,ATSDR retained the classification ofindeterminate public health hazard forexposures to lead at Quarters A. The followingprovides additional information.
Five surface soil samples were collected fromthe foundation, driveway, and 40 feet from thefoundation of Quarters A. Detectedconcentrations ranged from 54 ppm, found 40feet from the foundation, to 8,734 ppm, foundat the foundation. The average detectedconcentration was approximately 1,980 ppm. Anumber of studies have been conducted toevaluate the relationship between elevated soillead concentrations and elevated blood leadlevels. ATSDR's Toxicological Profile reviewsthese studies and reports a 1 to 7 microgram perdeciliter (ug/dL) increase in blood lead levels forevery 1,000 ppm increase in soil leadconcentrations. Based on these findings, anincrease of 8.7 to 61 ug/dL in blood lead levelsmay result from exposure to the maximum leadconcentration in soil (8,734 ppm) and anincrease of 2 to 14 ug/dL in blood lead levelsmay result from exposure to the average leadconcentration in soil (1,980 ppm). Theseincreases exceed the Center for DiseaseControl's (CDC) level of concern of 10 ug/dLblood lead in children (ATSDR 1999).
ATSDR also reviewed EPA's risk analysisconducted to support the development of EPAlead standards in paint, dust, and soil. One ofthe studies considered in this analysis was a1996 EPA study of lead exposures to childrenin the Baltimore, Maryland, area. In this study,lead was found in soil at a maximumconcentration of 3,450 ppm and an averageconcentration of 1,260 ppm at homes slated forlead abatement. The corresponding blood leadlevels found in children living in these homeswas a maximum of 65 ug/dL and an average of10 ug/L. These levels meet or exceed CDC'slevel of concern (10 ug/dL). Children in thisstudy were also exposed to lead in dust andpaint in homes, nonetheless, soil leadconcentrations in this study were similar to, ifnot lower than, concentrations found atQuarters A (EPA 1998).
Based on this information, ATSDR believesthat lead levels found at Quarters A have thepotential to results in adverse health effects inexposed populations of children. Because leadexposures to pregnant woman can adverselyaffect the unborn child, ATSDR also considerspregnant woman as a susceptible population.However, no information is available todetermine if a receptor populationchildrenand/or pregnant womenlived in Quarters Awhen lead exposures were possible. Nor isinformation available to determine if thereceptor population's activities would haveresulted in frequent contact with elevated soillead concentrations (e.g., gardening or playingin areas of elevated lead concentrations).Because this information is lacking, ATSDRcategorized past exposures to lead at Quarters Aas indeterminate. The Navy has completed leadabatement at Quarters A and other housingareas, therefore, ATSDR categorized currentand future exposures as posing no public healthhazard.
Response: A review of the scientific literatureindicates that lead ingested or inhaled duringpregnancy or lead released from the mother'sbones can be sources of lead exposure to anunborn child. Lead exposure may continueduring breast feeding. Unborn children exposedto lead may experience the following healtheffects: impaired neurological development,neurobehavioral deficits, growth retardation,low birth weights, and low gestational age. Asdiscussed in the response to comment 8,information regarding a possible receptorpopulation and possible activities (e.g.gardening) in areas of high lead concentrationsis unavailable. As such, ATSDR consideredpregnant woman as a possible susceptiblepopulation to past lead exposures at Quarters Aand categorized past lead exposures as posingan indeterminate public health hazard.
Response: ATSDR agrees that landscaping anda vegetative cover would reduce potentialcontact with soil lead concentrations. TheNavy's 1997 "Lead Management Plan, SeniorEnlisted Quarters" report, which provided theinformation about lead sampling conducted atQuarters A, Quarters B, and the officer housingarea used in this PHA, contains informationabout the vegetative cover at areas of soilsampling. At the location where the highest leadconcentration (8,734 ppm) was detected, avegetative cover of 95% was reported.However, at the location of the second highestlead concentration (884 ppm), a vegetativecover of only 20% was reported (Department ofthe Navy 1997). This information indicates thatat least some areas surrounding Quarters Aincluded bare soil.
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 withCharlene Creamer, EPA Region 3 Representative.February 27, 2002.
Department of the Navy. 1997. Lead Management Plan,Senior Enlisted Quarters, Naval Air Station JointReserve Base Willow Grove. January 1997.
Earth Data Incorporated and Pennoni Associates, Inc.(Earth Data). 1996. Correspondence from W. DavidFennimore, J. Anthony Sauder, and Anthony S.Bartolomeo to Orlando Monaco regarding NAWCWarminster. 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 DGroundwater, Former NAWC Warminster,Pennsylvania. May 30, 2002.
Tetra Tech NUS, Inc. (Tetra Tech). 1998.Correspondence from Neil Teamerson to LonnieMonaco regarding Responses to Comments forGroundwater Monitoring Reports, Former Naval AirWarfare Center (NAWC) Warminster, Pennsylvania.December 31, 1998.
U.S. Environmental Protection Agency (EPA). 1998.TSCA Section 403, Risk Analysis to Support Standardsfor Lead in Paint, Dust, and Soil. Office of PollutionPrevention and Toxics. Publication No.: EPA 747-R97-006. June 1998.