Appendix F: Written Comments on the Public Comment Release
NHDIIBS 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 the following section.
Comment 1: 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?
Response:
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 NJIDES-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, and emissions 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 monitoring should write to:
Kenneth A. Colburn, Director
NHDES – Air Resources Division
PO Box 95 – 6 Hazen Drive
Concord, NH 03301
Comment 2: TCE was first used on the base in 1956, but measurements of TCE in the Haven well only began in 1977. It is possible that contamination of the Haven well water with TCE started earlier than 1977, perhaps as early as 1956. Moreover, the trend of TCE concentrations in the Haven well shown in Figure 8 indicates that the TCE levels in the drinking water could have been higher than those detected in 1977 or at least at levels of health concern before monitoring began in 1977. Therefore, the exposures evaluated in the public health assessment may have underestimated both the duration and levels of the actual exposures to TCE in the base water supply.
Response:
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.
- First, base residents were assumed to have been exposed to TCE at 122 µg/L between 1978 and 1985, even though the average concentration of TCE in the Haven well from 1977 through 1985 was 58 µg/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.
- Second, the actual concentrations of TCE in water consumed by base residents was likely to be lower still because water from Haven well was diluted with water from the Smith and Harrison wells before being distributed to residential taps.
- Third, in the 1970s and 1980s, the population on Pease Air Force Base was primarily military personnel and dependents who were stationed there for a few years at a time. Nevertheless, 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).
Therefore, while there are uncertainties about exposures before 1977, NHDHHS is confident that its evaluation took these uncertainties into account and erred, where necessary, on the side of overestimating exposures to TCE in its evaluation of public health implications.
This enhanced discussion of uncertainties regarding past exposures and the conservative assumptions used in the NHDHHS evaluation to compensate for them has been added to the public health assessment.
*USEPA (1997) Exposure Factors Handbook, EPA/600/C-99/001, U.S. Environmental Protection Agency, Office of Research and Development, Washington, DC, August 1997.
Comment 3: The estimate by Bradley (1982) that TCE first arrived at the Haven well in the late 1970s relied on an assumed rate of groundwater flow and the distance from likely sources of TCE. However, it was later determined that the source TCE to the Haven well was a leaking storm sewer in the vicinity of the Haven well (Weston 1995). Therefore, TCE could have arrived at the Haven well earlier than the end of the 1970s.
Response:
As discussed in the response to Comment 2, it is not known when contamination of the Haven well began because there are no data from before 1977. See the response to Comment 2 for information on how NHDHHS dealt with this uncertainty in its evaluation of exposures.
The estimates of how long it would have taken for TCE to move through the groundwater from potential source areas in nearby buildings to the Haven well (Bradley 1982) were included for completeness. However, they are obviously inconsistent with the theory that the source of TCE to the Haven well in the 1970s was a leak from a storm drain near the well.
The sentence describing the travel time estimates in Bradley (1982) has been removed from the public health assessment to avoid confusion.
Comment 4: It is possible that the TCE concentrations in the Haven well were at some point similar to the levels of TCE found in the water supply system for Woburn, Massachusetts, where an association between TCE exposure and the development of leukemia and non-Hodgkin’s lymphoma was observed. This is especially important because the incidence of non-Hodgkin’s lymphoma among males in Portsmouth between 1987-1991 was found to be elevated relative to the state-wide averages.
The statement that the highest TCE level found in the Woburn water supply was “more than two times higher” than the levels used to estimate Pease exposures is inappropriate given that the highest TCE concentrations measured in Pease were almost 50% higher than the highest Woburn level.
Response
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.
The findings of the Woburn study are important, but must be interpreted with caution. In the draft public health assessment, NHDHHS compared central tendency TCE concentrations in the base water supply with the single test result for water from wells G&H in Woburn to provide the reader with a perspective on the findings from the Woburn study. However, in response to comments received, NHDHHS agrees that this comparison is not appropriate given that water from wells G&H in Woburn was only tested once and the fact that MDPH did not find an association between leukemia and ICE in particular. The sentence comparing the TCE levels in Wells G&H and the Haven well has been removed and replaced with a more detailed discussion of the findings from the Woburn study.
Statistically significant elevations of non-Hodgkin’s lymphoma were not reported for Woburn residents between 1987 and 1994, the latest data available from the Massachusetts Cancer Registry**. NHDHHS reported in the draft public health assessment that this cancer type had been found to be elevated in the Woburn study. The reference has been corrected to show that this association was observed by a study in New Jersey (Cohn et al. 1994***, as cited in ATSDR 1997). Please see the response to Comment 11 for more information on NHDHHS’ evaluation of the incidence of non-Hodgkin’s lymphoma among males in Portsmouth.
*MDPH (1997) Woburn Childhood Leukemia Follow-Up Study, Final Report, Massachusetts Department of Public Health, Bureau of Environmental Health Assessment, Boston, MA, July 1997.
**Cancer Incidence in Massachusetts, 1987-1994: City/Town Supplement, Massachusetts Department of Public Health, Bureau of Health Statistics, Research, and Evaluation, Boston, MA, November I 997.
***Cohn, P., Klotz, J., Bove, F., et al. (1994) Drinking water contamination and the incidence of leukemia and non-Hodgkin’s lymphoma, Environ. Health Perspect., 102: 556-561.
Comment 5: No discussion was presented on what is considered the latency period for these types of cancers. What is the probability of future cancers as a result of past exposure to TCE from say 1956 to 1985?
Response:
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.
It is important to remember that the conclusions of the public health assessment were not exclusively based on the review of cancer incidence data. An evaluation of chemical exposures and toxicology also concluded that adverse health effects from past exposures would not be expected. Therefore, NHDHHS is confident in the conclusions of the public health assessment. For clarity, this language about the typical latency period of cancer has been added to the public health assessment.
Comment 6: When were urea-based products first used to de-ice planes at Pease Air Force Base? Is it possible that nitrate concentrations in the base water supply could have been higher than the drinking water standard before 1994? The assumption that nitrate exposures were not high enough to pose a risk for the developing fetus is not appropriate without better information on the levels of nitrates in the drinking water before 1994.
Response:
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/Lin 1994 (COM 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 (COM 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.
This more detailed discussion regarding the nature and extent of nitrate contamination of the base water supply has been added to the public health assessment.
*Hilton, S. (1999) NHDES, Waste Management Division. Concord, NH. Personal communication.
Comment 7: The response to a community concern about miscarriages and stillbirths on the base in the early 1980s should discuss exposures to nitrates in the base drinking water supply, not just exposures to TCE.
Response:
As discussed in the response to Comment 6, 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.
This information has been added to the Community Health Concerns section of the public health assessment.
Comment 8: Would the death registry provide insight into the number of stillbirths on the base?
Response:
The NHDHHS’ Bureau of Vital Records maintains information on all births, deaths, marriages, and divorces that have occurred in the state. Stillbirths or spontaneous abortions that occur after a gestation period of 20 weeks or when the fetus weighs more than 350 grams are reported to the Bureau as fetal deaths*. However, there is evidence that many fetal deaths are not reported, especially ones that occur earlier in the gestational period**. In 1997, 51 fetal deaths were reported for the entire State of New Hampshire. In contrast, 14,520 live births and 5,100 new cases of cancer were reported for the state in this same year. Therefore, because of the low rate of reported fetal deaths, this registry could not be used for meaningful evaluations of small geographic areas such as the communities on or around Pease Air Force Base.
*New Hampshire Vital Statistics Report: 1992 -1997, New Hampshire Department of Health and Human Services, Office of Community and Public Health, Concord, NH, January 1999.
**Wilcox, L.S., and Marks, J.S., eds. (1994) From Data To Action: Public Health Surveillance for Women, Infants, and Children, U.S. Department of Health and Human Services, Public Health Service, Centers for Disease Control and Prevention, Atlanta, GA, 1994.
Comment 9: Why were reproductive and birth outcome data from the base hospital and Portsmouth Hospital not gathered and evaluated for this public health assessment? Would not such data be more extensive and more accessible than that for cancer rates in the area?
Response:
According to state law (RSA141-B:7), all facilities in New Hampshire must report cases of cancer diagnosed or being treated. New Hampshire does not have a similar birth defects or reproductive outcomes registry. Information on adverse birth or reproductive outcomes could not be obtained from local hospitals without the consent of the patients themselves. While data on birth weights are available, they are of limited value because this outcome is not known to be a major developmental concern relative to TCE exposures (ATSDR 1997).
Comment 10: It is clearly regrettable that health data on the predominant population exposed to these contaminants (the base personnel and dependents) appears to be unavailable, both due to the transient nature of military personnel and the fact that they were dispersed when the base closed in 1991. Yet, given the military’ s propensity for regimentation and paperwork, it seems conceivable that more such data could be retrieved. At the very least, this major gap in the health effects analysis would appear to preclude any definitive statements about the results of past toxics exposure on the base.
Response:
One of the objectives of a public health assessment is to identify additional evaluations or health studies that could resolve uncertainties or data gaps in the readily-available environmental and health outcome data. Before recommending additional studies, however, the value of the additional information that might be gained must be weighed against the feasibility of the project.
Since the population with greatest exposures to contamination at Pease Air Force Base was the base personnel and dependents, NHDHHS considered a health study for this group. Two factors led to the conclusion that such a study was not warranted. First, a conservative evaluation of exposure to TCE in the base water supply and available toxicological information for the chemical concluded that adverse health effects would not be expected. Second, between 1987 and 1991, four people living on the base were diagnosed with cancer, each one with a different cancer type. Hence, the available evidence was relatively strong and did not indicate that a health study would lead to appreciably different conclusions.
Comment 11: The conclusion that there is no association between the contamination on Pease Air Force Base and the elevated incidence of non-Hodgkin’s lymphoma in Portsmouth is too definitive given the considerable uncertainties about the causes of this type of cancer. The risk factors for nonHodgkin’s lymphoma are relatively unknown. Some possible risk factors for this type of cancer include occupational exposures to herbicides and chemicals such as volatile organic compounds (e.g., TCE). Given all this, it seems a stretch to logically conclude that such exposures are not a primary risk factor and that there is “no public health hazard” from past exposures, rather, all we can say is that the “jury is out”, that we do not have enough information to make a definitive conclusion.
Response:
In this public health assessment, 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 among males in Portsmouth were due to chemical contamination on the base. Uncertainty in the risk factors for this cancer type does not undermine the basic premise that chemical contamination will not result in adverse health effects without there first being an opportunity for exposure.
Comment 12: Was there any attempt to compare the health outcome review data with Primary Care Access Data from Portsmouth Hospital?
Response:
NHDHHS periodically publishes an analysis of primary care access data (PCAD) for the State of New Hampshire as a whole and for Hospital Service Areas (HSAs) within the state*. These analyses examine data pertaining to births, deaths, economic status, cancer incidence, and hospital discharge data.
In order to construct HSAs, hospital discharge data from all New Hampshire hospitals were examined by the town of the patient’s residence. A town is considered part of an RSA when the modal number of town residents who were discharged from hospitals were discharged from one hospital in particular (usually the hospital is located within close proximity to the town). For example, the towns of Greenland, New Castle, Newington, Portsmouth, and Rye are considered the HSA labeled Portsmouth since Portsmouth Regional Hospital is the hospital of choice for people in these towns. Therefore, it is important to remember that an HSA is a geographic area, and the data pertaining to the RSA does not necessarily reflect characteristics of the hospital, or hospitals in the area.
For this public health assessment, it was necessary to review cancer incidence data at a smaller geographic scale than the five-town Portsmouth RSA Therefore, NHDHHS exclusively used the more area-specific data from the New Hampshire State Cancer Registry.
*Primary Care Access Data, Accessing New Hampshire’s Communities, Third Edition 1990-1994, Office of Health Management, New Hampshire Department of Health and Human Services, Concord, NH (on the internet at www.dartmouth.edu/~ahechome/PCADTOC.htmlexternal icon)
Comment 13: Page 24, Lines 742-743, “…including maintaining compliance with the City of Portsmouth’s Wellhead Protection Program.”: Modify to read “…including formal adoption and promulgation of a written Wellhead Protection Program Plan jointly by the City of Portsmouth and Pease Development Authority.”
Response:
The formal aspects of the wellhead protection program are beyond the scope this public health assessment. NHDHHS will forward this comment to the parties responsible for this program.
Comment 14: Appendix D (Health Outcome Data Review) does not include tables behind the summary and relies on outdated data; statistics through 1994 are available
Response:
State law (RSA 141-B:9) precludes public disclosure of information on individual cancer cases reported to the New Hampshire State Cancer Registry. In order to comply with this law, NHDHHS only reports cancer data as aggregate summaries for towns or other geographic areas that do not disclose the identity of an individual and cannot be used to surmise an identity.
The health outcome data review considered cancer cases diagnosed between 1987 and 1991, all the years that were available from the New Hampshire State Cancer Registry at the time NHDHHS conducted its evaluation.
Comment 15: Data on health effects only summarized, not presented.
Response:
Detailed descriptions of the toxicological properties of chemicals are available in ATSDR’s toxicological profiles. These documents were used to complete the public health assessment and are cited in the References section. Toxicological profiles can be obtained from ATSDR’s Division of Toxicology (404-639-6300, www.atsdr.cdc.gov) or the National Technical Information Service (800-553-6847 or 703-605-6000, www.ntis.govexternal icon).
Comment 16: Geographic area too restricted. Region surrounding Great Bay should be studied.
Response:
In this public health assessment, pathways of exposure to contaminants at Pease Air Force Base were evaluated. Completed exposure pathways were found exclusively for people on the base grounds. Furthermore, in response to community concerns about cancer, NHDHHS reviewed cancer incidence data for some communities near the base, Portsmouth, Newington, and New Castle, for the years between 1987 and 1991. This evaluation did not discover elevated rates of cancer that were thought to be related to contamination on the base. These two findings argue against expanding the scope of the public health assessment to the entire Great Bay region. Concerned residents in the area around the Great Bay should contact NHDHHS if they would like more information.