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PUBLIC HEALTH ASSESSMENT

PEASE AIR FORCE BASE
PORTSMOUTH, ROCKINGHAM COUNTY, NEW HAMPSHIRE


II. EVALUATION OF ENVIRONMENTAL CONTAMINATION AND HUMAN EXPOSURE

A. Introduction

The following section discusses how people might come into contact with contamination and potential health effects that may result.

For exposure to occur, all elements of an exposure pathway must be present. A completed pathway consists of five elements: source, environmental media/transport, point of exposure, route of exposure, and receptor population. If one of these five elements is missing, no exposure will occur, but the potential for exposure may still exist. The ATSDR exposure evaluation process is presented in Figure 5.

Pathways are evaluated to determine whether people have been exposed to site-related contaminants in the past, are currently being exposed, or might be exposed in the future. When an exposure pathway is considered to be complete, a determination is made whether the exposure may pose a health hazard. ATSDR uses comparison values in selecting contaminants for further evaluation within an exposure pathway. These values are derived for specific environmental media (air, water, soils, etc.), and reflect the concentration for a given chemical that is not likely to cause adverse health effects from long-term exposure, given standard assumptions about body weight, ingestion, and contact rates. Since comparison values do not represent thresholds for toxicity, exposure to concentrations above comparison values will not necessarily produce adverse health effects. Comparison values used in this Public Health Assessment include USEPA's Maximum Contaminant Levels (MCLs) and ATSDR's Environmental Media Evaluation Guides (EMEGs), Reference Dose Media Evaluation Guides (RMEGs), and Cancer Risk Evaluation Guides (CREGs). Additionally, NHDES's and USEPA's risk based concentration tables were used when no ATSDR comparison value was available (NHDES 1998a, USEPA 1998). MCLs are enforceable drinking water regulations developed to protect public health, but also consider economic and technological factors in setting the standard. CREGs, EMEGs, and RMEGs are strictly health-based values and are not enforceable.

Chemicals disposed or released into the environment have the potential to come into contact with people, resulting in exposures that may cause adverse health effects. However, chemical releases do not always result in exposures. People can only become exposed if they come into contact with the chemical by ingestion (eating or drinking a substance containing the chemical), inhalation (breathing air containing the chemical), or by dermal absorption (skin contact with a substance containing the chemical).

Many factors are involved that determine whether an exposure will result in health effects. The type and severity of health effects that occur in an individual from contact with a chemical depend on the exposure concentration (how much), the frequency and duration of exposure (how often and how long), the route that the chemical enters the body (such as breathing, eating, and skin contact), toxic properties of the chemical, and interactions between other chemicals in the body. Once exposure occurs, many characteristics such as age, genetics, health, and nutritional status influence how the chemical behaves in the body. Together these factors affect the type, severity, and likelihood of health effects that may occur from exposure to hazardous substances.

B. Exposure Situations With No Apparent Public Health Hazard

NHDHHS evaluated available information and site conditions at Pease AFB to determine whether people could be coming into contact with chemical contaminants. If exposure pathways were completed, levels of exposure were evaluated to determine the likelihood of adverse health effects. Two completed exposure pathways were identified: (1) past consumption of contaminated groundwater; and (2) past recreational use of Peverly and Bass ponds (Table 1a). However, these pathways are categorized as no apparent public health hazard because the levels of exposure are not expected to result in adverse health effects.

1. Consumption of Contaminated Groundwater

        (a) Hydrogeology and Groundwater Use

Groundwater typically occurs 5 to 25 feet below ground surface on Pease AFB. Water depth varies as a result of natural and human factors such as precipitation and pumping rates. Overburden (shallow) groundwater generally flows east to southeast, while bedrock (deep) predominantly moves southeast. The principal overburden aquifers on the base are the Upper Sand and Lower Sand deposits, which merge in the center of the base under the flight line to form a 40-60 foot thick section of saturated, permeable sand (USAF 1990). This aquifer is the principal base water supply. The aquifer is susceptible to water quality impacts from contamination originating on or near ground surface.

Water for Pease AFB was supplied by three major wells located on base: the Haven well, the Smith well, the Harrison well, and three smaller wells now located within an area operated by the U.S. Department of the Interior as a wildlife refuge (Figure 6). The Haven well is the primary production well with a pumping capacity of 740 gallons per minute. The Smith and Harrison wells have pumping capacities of 420 and 225 gallons per minute, respectively. Prior to 1981, the wells all fed into a common distribution system. After 1981, a treatment plant was constructed and the supply wells were piped into a common point for blending, treatment, and distribution (CDM 1994). Currently, only the Haven and Smith wells supply water to the base. Since 1996, the Smith well has also served the golf course. The Harrison well has been off-line since 1987 due to poor condition of the well casing (CDM 1996).

(b) Opportunities for Exposure to Trichloroethylene in Groundwater

(i) Nature and extent of groundwater contamination near the Haven well

In 1977, in response to complaints about fuel odors in the drinking water, water from the base wells was tested and found to contain trichloroethylene (TCE), a volatile organic solvent widely used for cleaning and degreasing operations on the base. When first discovered in the spring of 1977, the maximum concentration detected at the Haven wellhead was 391 micrograms per liter (mg/L), and 28.5 mg/L at the Harrison well (Bradley 1982; Weston 1990). No standards for TCE in drinking water existed at that time, but this exceeded the current drinking water standard of 5 mg/L. By 1978, further sampling did not detect TCE in the Harrison or Smith wells (Bradley 1982).

Samples were only collected at the wellheads, not at the taps that supplied drinking water. Since the three wells fed into a common distribution system, blending of water from the three wells likely would reduce the actual levels at the tap.

There are many uncertainties about well operations that might have affected contamination levels at the tap. Since the wells fed into the distribution system at different locations, it is feasible that water in areas of the distribution system closest to the Haven well may have contained higher concentrations of TCE than other areas of the system closer to the Smith and Harrison wells. Another area of uncertainty is the operational schedules for individual wells. Past pumping schedules are unknown, and it is not clear whether the wells pumped in combination or were cycled one at a time. In the absence of more information about the well operational schedules, it is assumed that the wells were all on line and pumping into the distribution system simultaneously.

According to the water supply engineer for the City of Portsmouth, following discovery of the contamination, the wells were shut off and clean water was supplied to the base by the City of Portsmouth during the period of 1977-1978 (Craven 1998). During that time, the U.S. Geological Survey (USGS) investigated the contamination and identified a likely source to the north of the well (Bradley 1982).

During the investigation, the Haven well was heavily pumped, thus reducing the contaminant levels as clean groundwater entered the Haven well area. In Fall 1978, the wells went back on line. At the time, the Surgeon General established a TCE concentration limit of 280 mg/L in drinking water (USAF 1990). The concentrations of TCE in the Haven well had dropped below this level, but there was still concern regarding the safety of the drinking water. In 1981, the Air Force agreed to construct a water treatment plant. The treatment plant was finished in 1984 but never went on-line due to operational problems. Since January 1986, Haven well water samples indicate that TCE levels remain consistently below the current drinking water standard of 5 mg/L (Weston 1990).

The Air Force later determined that the likely source of TCE contamination was a leaking storm sewer line that passed in the vicinity of the Haven well (Weston 1995). This line carried TCE-contaminated wastewater that discharged into the storm sewer system from floor drains in building 227. TCE leaked from joints in the storm sewer line into groundwater in the well vicinity, where it was drawn into the well as groundwater was pumped into the water distribution system. A conceptual model of the Haven well contamination is in Figure 7. Remedial actions controlled the contamination source, and during 1985, TCE concentrations had dropped below the drinking water standard. Figure 8 and Table 2 show the contamination trends from 1977 until 1993. The declining trend in TCE concentrations indicates that the contamination has been lessened by natural breakdown, cessation of contributing sources of contamination, and infiltration of clean water into the Haven well area. Also, it is thought that reduced water usage following discovery of the contamination allowed the water table to rise above the storm sewer system. This impeded leaks of TCE contaminated wastewater from the pipes (Weston 1993). Currently, TCE concentrations are below the drinking water standard and remain stable at low levels. The pumping rate of the Haven well is limited to 300 gallons per minute so that clean-up operations in nearby Zone 3 are not affected (CDM 1994).

Groundwater contaminant plumes exceeding drinking water standards are located in several areas around the base (Figure 9). No exposure is occurring to these contaminant plumes, and the sources and plumes are under remediation, institutional controls, and long-term monitoring.

Although a plume of contaminated groundwater from site 8 has moved off-base into Newington, the plume underlies the Newington Town Forest, and no drinking wells are located in the area. An off-base well inventory indicated that no drinking water wells were located in areas of groundwater contamination (Weston 1992).

(ii) Current Exposure

Currently, plumes of groundwater contamination at Pease AFB are not impacting any drinking water wells. All public drinking water on base meets state and federal regulations and is routinely tested according to Safe Drinking Water Act requirements.

(iii) Past Exposure

It is not known when exposure to TCE in the Haven well began. No well sampling data were available prior to 1977. Upon discovery of the contamination in 1977, the supply wells were shut off and the City of Portsmouth provided water to the base. This action stopped exposure to TCE at concentrations as high as 391 mg/L. When the Haven well was placed back on line in the fall of 1978, the TCE levels had dropped to below 115 mg/L(Figure 8). After 1985, levels of TCE in the Haven well had dropped below the drinking water standard of 5 mg/L. Therefore, exposures to TCE above current drinking water standards were possible from 1978 until 1985. Table 2 and Figure 8 show the trend of TCE contamination in the Haven well over time.

Since there are no data on TCE concentrations in the base water supply before 1977, exposures to TCE earlier than this date are unknown. To account for this uncertainty, NHDHHS used very conservative assumptions about TCE concentrations and duration in its evaluation of past exposures to TCE in the base water supply:

  • Base residents were assumed to have been exposed to TCE at 122 mg/L between 1978 and 1985, even though the average concentration of TCE in the Haven well from 1977 through 1985 was 58 mg/L. This average includes data from a period in 1977-1978 when base residents were being supplied water from the City of Portsmouth and the TCE concentrations in the Haven well were near their maximum.
  • The actual concentrations of TCE in water consumed by base residents was likely to be lower than the well head concentrations used in the exposure assessment because water from Haven well was diluted with water from the Smith and Harrison wells before being distributed to residential taps.
  • In the 1970s and 1980s, the population on Pease Air Force Base was primarily composed of military personnel and their dependents who were stationed on base. NHDHHS assumed that base residents lived there for nine years (the median time in one residence for U.S. citizens from USEPA 1997), which is longer than the duration of time that exposures to TCE above the current drinking water standard were known to be possible (1978-1985).

While there are uncertainties about exposures before 1977, NHDHHS chose to be protective of public health by making conservative assumptions about the ways people may have been exposed in the past that likely overestimated actual exposures to TCE from using base drinking water.

NHDHHS compared the estimated exposure levels with available health guidelines, comparison values and information from the scientific literature regarding the health effects from exposure to TCE to assess the likelihood of adverse health effects.

NHDHHS methodology is consistent with the approach used by other public health agencies in its estimation of exposures to hazardous substances. To be more concise for the general public, a detailed explanation of the assumptions and calculations used to estimate exposures and determine the likelihood of adverse health effects is not presented in this document, but is available upon request.

(iv) Public Health Implications from Past Exposure

Based upon an evaluation of exposures to TCE and information about the toxicity of this chemical from the scientific literature, adverse health effects to adults, children, and unborn infants are unlikely.

Our evaluation of exposure levels in comparison to health guidelines and information on the toxicity of TCE, showed that no adverse health effects are likely in adult and child residents and adult workers from exposure to TCE-contaminated groundwater. For children, exposure levels slightly exceeded a provisional oral reference dose (RfD) for TCE. The RfD is an estimate of the daily exposure to a substance that is likely to be without risk of adverse non-cancer health effects for a lifetime. Exposure levels for TCE in Haven well water above the RfD will not necessarily produce adverse health effects. The RfD does not represent a threshold for toxicity, but rather establishes a dose that, if exceeded, increases the possibility that adverse health effects may occur as exposure levels and duration increase. Furthermore, based on review of the toxicological literature for TCE, the levels present in the Haven well have not been shown to cause adverse health effects.

Additional information on the toxicity of TCE that was considered in our evaluation is presented in the following three subsections: (1) cancer effects from exposure; (2) systemic (non-cancer) effects from exposure; and (3) child health considerations.

Cancer Effects from Exposure

Liver and lung tumors were seen in rats and mice following high doses of TCE administered in experimental studies. The significance to humans of the results seen in animal studies is unclear, as the mechanisms of toxicity may differ between rodents and humans (ATSDR 1997). The exposure doses of TCE causing cancer in animal studies were 4 million times higher than the estimated doses from consuming Haven well water.

The link between exposure to TCE and cancer in humans is controversial, and insufficient evidence exists to define TCE as a human carcinogen. Studies of human populations exposed to TCE in well water are contradictory. A study in New Jersey showed an association between TCE exposure and development of leukemia and non-Hodgkin's lymphoma, but a Finnish study demonstrated no association (ATSDR 1997). Both studies had several limitations, including simultaneous exposures to other chemicals and difficulties in classifying exposure levels.

In 1997, the Massachusetts Department of Public Health (MDPH) completed an epidemiologic study of childhood leukemia in Woburn, Massachusetts (MDPH 1997). In this study, MDPH observed an association between exposure to water drawn from Woburn's water supply wells G&H and the development of childhood leukemia. This association was strongest for exposures to the water that occurred in utero.

The water from wells G&H in Woburn was tested once for toxic substances before the wells were shut down. Contaminants detected in this sample were: trichloroethylene (TCE), tetrachloroethylene, chloroform, methyl chloroform, trichlorotrifluoroethane, 1,2-dichloroethylene, and arsenic. Other chemicals (i.e., trans-1-dichloroethyene, lead, chlordane, 1,1,1-trichloroethylene, and vinyl chloride) were also detected in the groundwater on properties presumed responsible for contaminating the wells G&H water. Since the wells were contaminated by multiple chemicals whose relative concentrations over time were unknown, MDPH could not conclude that exposure to TCE or any other specific chemical in particular was the cause of the elevated childhood leukemia incidence. Exposures to one, some, or all of the chemicals in the wells G&H water could have played a role.

As part of this Public Health Assessment for Pease AFB, NHDHHS reviewed available information on cancer incidence for the surrounding towns of Newington, Portsmouth, and New Castle (see Appendix D for details). Cancer incidence within Portsmouth and New Castle for the period between 1987 and 1991 (all the data that were available) were not statistically different from the number of cases seen in the State of New Hampshire as a whole during this same period. However, there were two cancer types that were elevated in Portsmouth: non-Hodgkin's lymphoma among males and cervical cancer among females. Environmental exposures are not thought to be the primary risk factors for the development of these cancer types. There were very few cases observed in Newington during this period which prevented further analysis.

Systemic (Non-Cancer) Effects from Exposure

Much of what is known about non-cancer effects from TCE exposure comes from animal studies and studies in humans who breathed or drank high levels of TCE. Dizziness, headache and a feeling of facial numbness have occurred in workers breathing TCE or people who have used TCE in unventilated areas. In the past, TCE was used as an anesthetic because of its effects on the central nervous system. More severe effects on the central nervous system, such as unconsciousness and death, were found to occur at high levels of exposure (ATSDR 1997).

Some health effects may occur from long-term exposure to TCE. This information is primarily from animal studies, which have shown that exposure to TCE can produce liver and kidney damage; effects on the blood; and tumors of the liver, kidney, and possibly tissues responsible for forming white blood cells (leukemia). Drinking alcohol can make people more susceptible to liver and kidney injury from exposure to TCE (ATSDR 1997). The lowest dose of TCE at which no adverse systemic health effects were seen in long-term animal studies was at least 5,000 times greater than the estimated doses from consumption of contaminated water from the Haven well (Maltoni 1986). Therefore, adverse health effects from exposures to TCE in the drinking water at Pease AFB are unlikely.

Child Health Considerations

Infants, older children, and developing fetuses require special attention when evaluating the likelihood of adverse health effects from exposure to hazardous substances. These populations differ in their sensitivity and response to chemical exposures in relation to adults, and are often the most sensitive populations of concern for chemical injury.

This is due to many reasons, including behaviors that can lead to increased contact with substances containing chemical contaminants, smaller body weights that result in increased exposure levels, sensitivity of developing organ systems, and differences in the way children's bodies respond to chemical exposures, such as how the body breaks down and eliminates chemicals (ATSDR 1998a).

The developing fetus can experience adverse health and developmental effects at levels below those of concern for health effects in the mother. The mother's body protects the developing fetus to some extent, but chemical injuries during critical periods in fetal development can increase the risk of birth defects, low birth weight, or miscarriage (Guzelian 1992).

Trichloroethylene rapidly crosses the placenta, with subsequent exposure to the fetus. In three out of ten pregnancies, concentrations of TCE in umbilical venous blood (indicative of fetal blood concentrations) exceeded concentrations in maternal blood after 10-15 minutes of exposure to TCE (Trilene ®) and nitrous oxide anesthesia (Laham 1970).

Important reproductive and developmental effects due to TCE exposure have not been clearly identified in humans. A few human studies have demonstrated an association with TCE exposure and developmental effects (Bove 1995, Goldberg 1990, Lagakos 1986, Schendel 1996, Sonnenfeld 1997), but methodological problems and other limitations in the studies make it difficult to clarify a causal link between exposure to TCE and adverse reproductive and birth outcomes.

Animal studies indicate that TCE can act as a developmental toxicant, though often at doses that cause maternal toxicity as well. In a study involving pregnant rats exposed to TCE in drinking water, the lowest maternal exposure dose at which developmental toxicity was seen was more than 42 times higher than the estimated exposure levels to mothers consuming TCE-contaminated water from the Haven well (Dawson 1993).

(c) Opportunities for Exposure to Nitrate in Groundwater

(i) Nature and Extent of Contamination

From 1994 through early 1996, nitrate levels in the Haven and Smith wells were near or exceeded the drinking water standard of 10 milligrams/liter (mg/L) (as nitrogen in nitrate), reaching peak concentrations of 11.4 mg/L in water from the Smith well. Monitoring data from prior to 1994 showed that the nitrate concentrations had increased from low levels (less than 1 mg/L) in 1990 to near 10 mg/L in 1994 (CDM 1994, CDM 1996). The likely source of the nitrate was the use of urea-based deicing agents on the runway, the application of which presumably increased during this time.

In 1995, the use of urea-based deicing agents was discontinued, and a groundwater monitoring program began (CDM 1996). A water management strategy was also adopted whereby water from the Haven and Smith wells were mixed, in proportions determined by their nitrate levels, to ensure that nitrate concentrations in the base water supply stayed below the drinking water standard (Hilton 1999). Nitrate levels in the base drinking water are currently monitored on a continuous basis via an in-line nitrate analyzer and meet all state and federal standards for drinking water. Also, the Pease Development Authority is participating in the City of Portsmouth's Wellhead Protection Program to protect the aquifer beneath the former base.

(ii) Current Exposure

Actions taken to reduce nitrate levels have been effective, and drinking water meets current state and federal drinking water standards for nitrate contamination.

(iii) Public Health Implications from Past Exposure

It is unlikely that adverse health effects would have resulted from consumption of Haven well water contaminated with nitrates slightly exceeding the drinking water standard.

The concern for ingestion of nitrate-contaminated water is primarily due to effects on infants younger than 4 months of age who are fed formula diluted with water containing excess nitrate contamination. Nitrate consumption can result in methemoglobinemia ("blue baby syndrome"), which is a disease caused by nitrate interference with the oxygen-carrying capacity of the red blood cells. There is little evidence that breast-fed infants develop methemoglobinemia from exposure to nitrates ingested by nursing mothers (ATSDR 1991). Consuming water containing nitrates above the drinking water standard does not imply that methemoglobinemia will result, rather it indicates that with increasing concentrations the possibility of adverse health effects may also increase.

Consumption of nitrate-contaminated water has resulted in spontaneous abortion in laboratory animals and livestock (Kross 1992, Sund 1957). A report in the July 1996 issue of the Centers for Disease Control and Prevention's "Morbidity and Mortality Weekly Report" cited a case in 1993, in which the LaGrange County Health Department in Indiana identified three women who reported a total of six spontaneous abortions between 1991 and 1993 and lived near each other. All of these women obtained water from nitrate-contaminated wells (Grant 1996). The nitrate levels identified in this report were on the order of 19-26 mg/L, higher than levels found in the base water supply in 1994 (approximately 10 mg/L at maximum levels).

In human populations, spontaneous abortions occur commonly and are directly associated with increasing maternal age (Grant 1996). Cases of spontaneous abortion may cluster by chance. The LaGrange County investigation did not establish a causal link, but demonstrated a possible association between elevated nitrate levels in water and spontaneous abortion in humans.

Therefore, based on comparisons with the LaGrange County study, it is unlikely that the nitrate levels in the Haven well were high enough to pose a risk to the developing fetus of a pregnant woman consuming the water on Pease AFB. This determination is based on the fact that the nitrate levels in the Haven well were much lower than those found in the LaGrange County wells. Furthermore, the LaGrange County wells were the primary source of drinking water for the women in the study, while Haven well water would likely have been consumed in lesser amounts during a normal work day by workers and visitors on the base.

2. Recreational use of Peverly and Bass Ponds

Peverly and Bass Ponds have been used in the past for recreational activities. When people swim or wade, they may come into contact with contaminants in water and sediments. Contamination can build up in the bodies of fish to levels that can pose a health hazard to the people and animals that eat them.

(a) Nature and Extent of Contamination

Peverly and Bass Ponds were studied extensively during the Zone 2 remedial investigation. Past use of pesticides for mosquito control has resulted in detectable levels of the pesticides lindane and DDT. Products of natural DDT breakdown in the environment, DDD and DDE, were also detected. An organic form of the metal mercury, called methyl mercury, was detected in fish tissues. Other contaminants, such as PCBs, were detected in fish, sediments, and surface waters that likely were introduced into the ponds as a result of drainage via nearby Peverly Brook, which collects surface water runoff from Zone 2 IRP sites and a section of the flight line parking apron.

The origin of the contaminants is not clear, but is likely a result of past activities on the base with the exception of mercury, which is a contaminant of concern in freshwater fish throughout New Hampshire. Sediments, fish, and surface waters in Peverly and Bass ponds are under a long-term sampling program to monitor contamination levels (Bechtel 1997a). Fish tissue concentrations detected in 1996 are presented in Table 3. Contaminants in sediments and surface water that were evaluated for human health risks are presented in Tables 4 and 5.

(b) Current Exposure

No exposure is currently occurring because the ponds are within the Great Bay National Wildlife Refuge under the U.S. Fish and Wildlife Service and are off limits to swimming and fishing.

(c) Public Health Implications from Past Exposure

Based upon exposure estimates and information about the toxicity of PCBs and mercury, exposure to contaminants in surface waters, sediments, and fish of Peverly and Bass Ponds is unlikely to result in adverse health effects.

In order to reach this determination, NHDHHS developed realistic, but conservative, assumptions about exposures for recreational users (e.g., monthly-to-bimonthly visits to the ponds to swim and wade during the warm half of the year). Exposure levels were then evaluated in light of available toxicological information for the compounds of concern. Special consideration was made for the unique vulnerabilities of small children to chemical exposures as described below.

Child Health Considerations

As stated previously in this document, children are usually more sensitive to chemical exposures than adults, and health risk evaluations involving children and developing fetuses require special emphasis due to this unique vulnerability. In animal studies, exposures to high levels of PCBs and mercury have been shown to result in adverse health effects in developing fetuses. Studies in humans have also demonstrated an association between exposure and effects in children and developing fetuses (ATSDR 1998b, ATSDR 1999). The exposure levels at which effects have been seen are higher than the exposure levels estimated from use of the ponds.

Currently in New Hampshire, a fish consumption advisory is in effect for finfish caught in all inland fresh water bodies. This is based on mercury levels that have been detected in the tissues of freshwater fish throughout the state. The advisory is designed to prevent adverse health effects from long-term exposure. The advice from NHDHHS is that adults should limit consumption to four 8-ounce meals per month. Pregnant women and children should limit consumption to one 8-ounce meal per month. It is good practice to skin and remove fatty tissues from the fish before cooking and to discard cooking juices and drippings.

C. Exposure Situations with No Public Health Hazard

The 49 IRP sites, underground storage tank sites and the flight line did not, and currently do not, present public health hazards because: (1) access to site contaminants is restricted or limited (thereby limiting exposure); and/or (2) migration of contaminants to areas where exposure might occur is not expected; and/or (3) contamination has been cleaned up. Ongoing remediation and long-term sampling is designed to prevent any future exposures. A summary of the IRP sites and an evaluation of health hazards is in Appendix C.

D. Potential Exposure Situations

After reviewing available environmental data, NHDHHS determined that some exposure pathways are not currently complete, but may be completed in the future (Table 1b). Therefore, these exposure situations do not pose a public health hazard at present, but should be monitored to guard against potential future hazards.

1. Potential Building Indoor Air Contamination

Because groundwater in some areas beneath Pease AFB is heavily-contaminated with volatile organic compounds (Pease 1999), there is the potential for indoor air contamination in some nearby buildings. The only data that are relevant to this issue are the results of a soil gas survey at site 49, where contaminated groundwater underlies an occupied building (TN&A 1998). These results do not indicate appreciable migration of contaminants from the groundwater to the soil gas at this location. First, the compounds detected in the soil gas (e.g., chloroform, tetrachloroethylene, benzene) did not match the compounds in the underlying groundwater plume (i.e., primarily TCE) (TN&A 1998, Bechtel 1997b). Second, the concentrations of chemicals in the soil gas were within either reported background ranges for indoor air or health-based screening levels for ambient air. Typically, concentrations of chemicals in the soil gas are tens to hundreds of times higher than corresponding indoor air concentrations (Fitzpatrick and Fitzgerald 1996). Therefore, based on the limited available data on soil gas, there is no evidence for current indoor air quality problems on the base.

The soil gas results from site 49 provide useful information but should be interpreted with caution. First, the analytical results have not been validated. Second, the potential exists for indoor air exposures at other locations in the future as the former base continues to be redeveloped. Developers should be cognizant of the potential for indoor air contamination when choosing sites for new buildings. A comprehensive review of groundwater data to identify potential problem locations in advance would likely prove a helpful and proactive measure. To assist in evaluating the potential for indoor air quality impacts from contaminated groundwater, guidance for evaluating potential indoor air quality issues has been developed by NHDES (NHDES 1998a, 1998b).

If new data for soil gas or indoor air quality are generated, NHDHHS remains willing to provide technical assistance on a case-by-case basis.


III. COMMUNITY HEALTH CONCERNS

ATSDR solicits and responds to health concerns expressed by members of the community. This section addresses health concerns that have come to NHDHHS's and ATSDR's attention during the health assessment process. Pease AFB has an existing community relations plan developed by the Air Force. In addition, an information repository has been established at the Air Force Base Conversion Agency offices in the New Hampshire Air National Guard area at Pease International Tradeport (Building 151). Site fact sheets and newsletters have been developed to describe and explain the clean-up process and status of remedial actions. Copies of these and other documents related to remedial activities at Pease AFB can be found at the repository. A Restoration Advisory Board (RAB) was established to serve as a liaison between the community and the Air Force. The RAB is composed of community members and representatives from the Air Force, USEPA and NHDES. RAB meetings are generally called on a quarterly basis and are open to the public.

The following is a summary of concerns that have been expressed:

Was drinking water safe in the past? How about currently and in the future?

Use of contaminated drinking water poses no apparent health hazard. Past use of solvents and deicing agents has resulted in TCE and nitrate contamination in groundwater that has been detected in water from wells serving the base water supply. Actions have been taken to reduce the contamination, and currently base water meets all drinking water standards. The wells are regularly monitored to ensure that future drinking water will be safe to use. A discussion of the contamination in the base drinking water can be found in the Environmental Pathways and Human Exposure section.

Will contamination under the flight line impact the Haven well?

Areas of contaminated soil and groundwater under the flight line have been thoroughly studied. Based upon the distance from the contamination to the Haven well, the rate of groundwater movement, and the rate of naturally occurring degradation, it is unlikely that TCE contamination will reach the Haven well at levels that pose a health risk. Flight line contamination is under a regular monitoring program that will detect any contamination approaching the well, and enable the Air Force, USEPA, and NHDES to take action to prevent Haven well water contamination.

I heard a rumor that there was an increase in stillbirths and miscarriages in the base hospital in early 1980s. Could it be attributed to contaminated drinking water?

In the early 1980s, base drinking water contained levels of TCE above current drinking water standards. The nature and extent of contamination and possibility of adverse health effects from use of this water are discussed in the Evaluation of Environmental Contamination and Human Exposure section of this document. This evaluation of estimated exposures to past residents and workers indicated that adverse health effects from drinking and bathing in this water are unlikely.

Studies have shown that there may be an association between TCE contamination in drinking water and low birth weight babies (Sonnenfeld 1997, Schendel 1996). Other studies suggest that there may also be an increase in birth defects (e.g., cleft lip, cleft palate, and heart defects) for babies whose mothers consumed TCE-contaminated drinking water during pregnancy (Bove 1995, Goldberg 1990, Schendel 1996). Although these studies indicate possible associations, it is difficult to say for certain that TCE contamination in the water caused the observed defects because of limitations in the studies. The evidence is not sufficient to prove causality, and further research is needed. For comparison, the maximum concentrations of TCE in drinking water identified in the study at Camp Lejeune, North Carolina (1400 mg/L) were higher than the concentrations at Pease AFB in the early 1980s (82 mg/L).

The period of potential exposure to nitrates above the drinking water standard was in 1994 and 1995, which was after the anecdotal reports of miscarriages and stillbirths on the base in the 1980s.

Data on adverse pregnancy outcomes at Pease AFB are not available, because the State of New Hampshire does not have a birth defects registry.

Smoke from the fire department training areas went over the base fence into Newington. Are there any health risks from the smoke?

According to the National Climactic Data Center, the wind rarely blows from the base toward Newington (approximately 5-10% of the time) (NCDC 1978). Furthermore, the burns were of short duration, lasting only 10-15 minutes. Therefore, it is unlikely that sustained exposures to contaminants in smoke occurred.

Because no air samples were taken during training burns, the concentrations of contaminants in smoke are unknown. Computer models have been used to estimate the worst-case concentration levels of volatile organic compounds, using benzene as a surrogate for the chemical mixture in the smoke because it is a potent human carcinogen. Smoke can contain other contaminants such as polyaromatic hydrocarbons (PAHs) that have shown to be carcinogenic in animal studies (USEPA 1993, ATSDR 1995, Benner 1990). The estimated concentrations of benzene were below levels likely to cause adverse health effects even under worst-case conditions, such as regular exposure over many years to conditions at the fence line of the base.

A review of disease statistics for the town of Newington, did not identify any elevated cancer rates for this town in the period between 1987 and 1991. A discussion of this evaluation is presented in the Health Outcome Data Review section and Appendix D.

Are there any risks from swimming and fishing in Peverly and Bass ponds?

Low levels of pesticides and some metals were detected in fish, surface water, and sediments. The contamination levels are unlikely to result in adverse health effects from swimming and fishing. More details on this exposure pathway are presented in the Environmental Pathways and Human Exposure section.

Asbestos was removed from the Bracket School in the mid 1980s. Was there any risk to students and staff?

The most significant health threat that asbestos poses is through the inhalation of airborne asbestos fibers. Toxicity of asbestos is primarily dependent on exposure intensity and duration, along with other factors including the physical and chemical properties of the fibers. Asbestos-related lung diseases have been primarily reported after long-term exposures to asbestos in occupational settings. Exposures of such magnitude and duration are not usually experienced by the general public.

When asbestos is firmly bound up in products such as insulation, ceiling and floor tiles, roof shingles, pipe wrapping and cement that are in good condition ("non-friable asbestos"), there is little likelihood that exposure will occur. However, when asbestos containing materials (ACM) are in a crumbling or deteriorated condition ("friable asbestos"), asbestos fibers can be released and pose the greatest risk for causing harm.

Since the mid-1980s, federal law has required that public school buildings be periodically inspected and monitored for asbestos. Precautions must be taken when friable asbestos is removed from schools to insure that there is no airborne release of fibers that would pose a risk to students, staff, or other people who may subsequently access the building. Asbestos abatement projects in schools that are done in a responsible and appropriate manner should not present an increased risk to users of these facilities.

Asbestos is still present in exterior and interior portions of the Bracket School building. The risk that this material poses to the community should be minimal as long as exterior ACM is intact and access to the building interior continues to be restricted.

There is asbestos in former base housing. The housing is in close proximity to a day care center. Is there a threat of release and exposure to children?

Since 1994, the Pease Development Authority has been involved with removing ACM and demolishing old housing units in the former base housing area. These activities will continue until all ACM that poses a potential health hazard is safely removed from these units and properly disposed. The likelihood that occupants of the nearby day care center will be exposed to ACM within the remaining units is not significant. Due to the presence of physical hazards, individuals should be cautioned to stay out of these buildings until they are demolished.

A fire occurred in February 1998 in one former base housing unit located across from the day care center. At the time of the fire, only a small quantity of ACM was estimated to be within floor tiles, insulation in hot water pipes, flashing in the garage roof, and some window caulking within this unit, and it was not likely to have become airborne as a result of this event. ACM that was present in this burnt housing unit has been removed and should no longer present a health risk to the community. There is evidence of vandalism and trespassing in the base housing area. Access to the area is unrestricted. Concern remains regarding physical hazards and the possibility of additional fires occurring in the former base housing area.

Is there an increased incidence of either breast or brain cancer among former base personnel, residents, and civilian staff?

No statistically significant increases in breast or brain cancers were found. Health statistics were evaluated and presented in the Health Outcome Data Review section of this document.

Is there an increased incidence of cancers among Newington residents?

No statistically significant increases in cancers were found in Newington residents. Health statistics were evaluated and presented in the Health Outcome Data Review section of this document.

Was any radiation released from the ordnance storage areas? Can I come into contact with it?

Pease AFB, being a Strategic Air Command base, had the potential for storing and maintaining nuclear weapons. Operations at the base did not involve any maintenance on unsealed sources of radioactive material. The potential for release and contamination was very unlikely. In 1990, the Air Force conducted a radiological survey of weapons storage areas and did not detect any radioactivity above background levels (Thurlow 1990).

Can I get sick from eating game hunted on base?

It is unlikely that hunters were at any health risk associated with the consumption of game taken from these areas. Considerable effort has been made at the former Pease AFB to identify and characterize the extent of chemical contamination and pathways by which humans could have been at risk from potential exposure to chemical contaminants at the base. No sampling data are available which would allow NHDHHS to directly evaluate the health risk associated with the consumption of game taken on the base. Even without sampling data, however, it can be stated that the possibility for exposure to chemical contaminants is probably low given that game species did not range in contaminated areas. Furthermore, hunting was infrequent and did not occur in areas of the base where chemical contamination was identified.

Are there any impacts to the wildlife refuge from base contamination?

For the purpose of this Public Health Assessment, NHDHHS and ATSDR focused on human health issues. Ecological impacts to the wildlife refuge are not addressed in this document. During the remedial process, ecological risks were considered in determining where and what remediation occurred. Documents evaluating ecological risks are located in the repository at the Air Force Base Conversion Agency offices.

How do emissions from aircraft, cars, and buses currently operating on the base affect the air quality at nearby homes? Is there a plan to monitor the impact of these emissions on the residents in the local area?

There are very little data on the concentrations of hazardous substances in the air near active airports nationwide. Jet engines are regulated by emission standards, not by ambient air monitoring near the runway. Therefore, NHDHHS cannot accurately evaluate the potential health impacts from aircraft or buses operating at Pease Air Force Base at this time because measurements of toxic substances in the air are not available.

The New Hampshire Department of Environmental Services Air Resources Division (NHDES-ARD) exercises regulatory control over individual sources of ambient air pollution and is responsible for operating an ambient air monitoring network. NHDHHS has reviewed the concerns raised in this comment with NHDES-ARD, who provided the following relevant information. The ambient air quality is continuously monitored in nearby Portsmouth and Rye. Air monitoring is resource intensive, and most of what is done in the State is funded by USEPA. NHDES-ARD said that ambient air pollution concentrations do not vary a great deal over broad regions, and there are not any plans at present to conduct additional monitoring in the area around the airport. The fuel that most aircraft and bus traffic use is similar to that used in on-highway heavy duty vehicles, andemissions from aircraft and on-road engines are regulated at the federal level. The contribution of aircraft activity to the regional air pollution inventory is small, and it is not expected that increased activity at the airport such as that proposed will create exceedances of any of the National Ambient Air Quality Standards. Residents who have further questions regarding ambient air quality and monitoring should write to:

Kenneth A. Colburn, Director
NHDES - Air Resources Division
PO Box 95 - 6 Hazen Drive
Concord, NH 03301

NHDHHS and ATSDR completed and distributed the Public Comment Release of the Public Health Assessment for Pease Air Force Base on July 28, 1999. Following this, NHDHHS and ATSDR held a public meeting on August 11, 1999, to present the findings of the draft public health assessment. Comments on the document were accepted until September 10, 1999. All the written comments received by this date with responses from NHDHHS are listed in Appendix F.


IV. HEALTH OUTCOME DATA REVIEW

In this section, health statistics from communities surrounding Pease AFB were evaluated to identify any elevated rates of cancer. As part of the health assessment process, ATSDR routinely conducts a review of available health data (e.g., birth and death certificates, cancer and birth defects registries) if exposures to site contaminants have occurred, or if there are community concerns regarding specific health outcomes (e.g., cancer, birth defects). This evaluation provides an overview of the general health status of a community, or it may confirm the presence of excess disease or illness in a community.

As part of this Public Health Assessment for Pease AFB, NHDHHS reviewed available information on cancer incidence for the surrounding towns of Newington, Portsmouth, and New Castle. Cancer incidence within Portsmouth and New Castle for the period between 1987 and 1991 (all the data that were available) were not statistically different from the number of cases seen in the State of New Hampshire as a whole during this same period. However, there were two cancer types that were elevated in Portsmouth: non-Hodgkin's lymphoma among males and cervical cancer among females. Environmental exposures are not thought to be the primary risk factors for the development of these cancer types. There were very few cases observed in Newington during this period which prevented further analysis.

It is important to note that elevated rates of a particular illness in a community may not necessarily be attributed to site contamination, nor does it establish a link or imply causality with environmental contamination identified at a site. Many factors influence the development of disease, including personal lifestyle, occupation, and socioeconomic status. Previously in this document, pathways of exposure to contaminants at Pease Air Force Base were evaluated. Completed exposure pathways were found exclusively for people on the base grounds. Therefore, it is unlikely that the elevated rates of non-Hodgkin's lymphoma and cervical cancer among males and females in Portsmouth, respectively, were due to chemical contamination on the base. Chemical contamination will not result in adverse health effects without there first being an opportunity for exposure.

Our current understanding of the etiology of cancer is that there can be a delay or latency period of up to decades between exposure to a carcinogen and the onset of the disease. For this public health assessment, NHDHHS reviewed cancer incidence data from the New Hampshire State Cancer Registry for 1987 to 1991, all the data that were available at the time of the evaluation. This period was nearly 15 years after the late 1970s when the highest exposures to TCE in the base water supply likely occurred and, hence, appropriate for evaluating these past exposures. Therefore, while data from the years following 1991 were not reviewed because they were not available at the time, NHDHHS considered the typical latency period of cancer in its evaluation of the available data.

The results and methodology used to evaluate health data for Portsmouth, Newington, and New Castle, New Hampshire, are presented in Appendix D.



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