PUBLIC HEALTH ASSESSMENT
FAIRCHILD AIR FORCE BASE
SPOKANE, SPOKANE COUNTY, WASHINGTON
PATHWAYS ANALYSIS/PUBLIC HEALTH IMPLICATIONS
The following section discusses the various contaminants of
concern, how people might come into contact with these
contaminants and the potential health effects that may
result. In order for an exposure to these contaminants to
occur, all the elements of an exposure pathway must be in
place. Exposure pathways are divided into completed and
potential and can be current, past or future. A completed
exposure pathway consists of five elements: source,
environmental media/transport, point of exposure, route of
exposure and receptor population. A potential exposure
pathway exists when some but not all of these five elements
are present and the potential exists that the missing
element(s) have been present, are present or will be present.
The completed and potential 
exposure pathways for
Fairchild are given in Tables 2 and 3 below. Each pathway is then discussed in terms of the
contaminants of concern and the potential health hazard posed.
Evaluating Non-cancer Risk
In order to evaluate the potential for non-cancer adverse health effects to result from exposure to contaminated media (i.e., air, water, soil, and sediment), a dose is estimated for each contaminant of concern. These doses are calculated for situations (scenarios) in which nearby residents or on-base workers might come into contact with the contaminated media. The estimated dose for each contaminant under each scenario is then compared to ATSDR's minimal risk level (MRL) or EPA's oral reference dose (RfD). MRLs and RfDs are doses below which non-cancer adverse health effects are not expected to occur (so called "safe" doses). They are derived from toxic effect levels obtained from human population and laboratory animal studies. These toxic effect levels can be either the lowest observed adverse effect level (LOAEL) or a no-observed adverse effect level (NOAEL). In human or animal studies, the LOAEL is the lowest dose at which an adverse health effect is seen, while the NOAEL is the highest dose that did not result in any adverse health effects.
Because of the uncertainty in these data, the toxic effect level is divided by "safety factors" giving the lower and more protective MRL or RfD. If a dose exceeds the MRL or RfD, this indicates only the potential for adverse health effects. The magnitude of this potential can be inferred from the degree to which this value is exceeded. If the estimated exposure dose is only slightly above the MRL or RfD, then that dose will fall well below the toxic effect level. The higher the estimated dose is above the MRL or RfD, the closer it will be to the toxic effect level.
Evaluating Cancer Risk
Some chemicals have the ability to cause cancer. Cancer risk is estimated by calculating a dose similar to that described above and multiplying it by a cancer potency factor, also known as the cancer slope factor. Some cancer potency factors are derived from human population data. Others are derived from laboratory animal studies involving doses much higher than are encountered in the environment. Use of animal data require extrapolation of the cancer potency obtained from these high dose studies down to real-world exposures. This process involves much uncertainty. Current thinking suggests that there is no "safe dose" of a carcinogen and that a very small dose of a carcinogen will give a very small cancer risk. Cancer risk estimates are, therefore, not yes/no answers but measures of chance (probability). Such measures, however uncertain, are useful in determining the magnitude of a cancer threat since any level of a carcinogenic contaminant carries an associated risk. The validity of the "no safe dose" assumption for cancer-causing chemicals is not clear. Some evidence suggests that certain chemicals considered to be carcinogenic must exceed a threshold of tolerance before initiating cancer.
This document describes cancer risk qualitatively using terms like low, very low, slight and no significant increase in cancer risk. These terms can be better understood by considering the population size required for such an estimate to result in a single cancer case. For example, a low increase in cancer risk indicates an estimate in the range of one cancer case per ten thousand persons exposed over a lifetime. A very low estimate might result in one cancer case per several tens of thousands exposed over a lifetime and a slight estimate would require an exposed population of several hundreds of thousands to result in a single case. DOH considers cancer risk to be not significant when the estimate results in less than one cancer per one million exposed over a lifetime. The reader should note that these estimates are for excess cancers that might result in addition to those normally expected in an unexposed population.
Cancer is a common illness that increases with age. Depending on the type of cancer, an unexposed population could be expected to have a substantial number of cancer cases. There are many different forms of cancer that result from a variety of causes. About a quarter of the people in Washington State die of cancer. Approximately one quarter to one third of people living in the United States will develop cancer at some point in their lives.
Multiple Exposure and Toxicological Mixtures
A person can be exposed by more than one pathway and to more than one chemical. Exposure to multiple pathways occurs if a contaminant is present in more than one medium (i.e., air, soil, surface water, groundwater, and sediment). For example, the dose of a contaminant received from drinking water may be combined with the dose received from contact with that same contaminant in soil.
It is much more difficult, however, to assess exposure to multiple chemicals. In almost every situation of environmental exposure, there are multiple contaminants to consider. The potential exists for these chemicals to interact in the body and increase or decrease the potential for adverse health effects. The vast number of chemicals in the environment make it impossible to measure all of the possible interactions between these chemicals. Individual cancer risk estimates can be added since they are measures of probability. When estimating non-cancer risk, however, similarities must exist between the chemicals if the doses are to be added. Groups of chemicals that have similar toxic effects can be added such as volatile organic compounds (VOCs) which cause liver toxicity. Polycyclic aromatic hydrocarbons (PAHs) are another group of chemicals that can be assessed as one added dose based on similarities in chemical structure and metabolites. Although some chemicals can interact to cause a toxic effect that is greater than the added effect, there is little evidence demonstrating this at concentrations commonly found in the environment.
The following evaluations do not rely solely on whether the estimated dose of a contaminant
exceeds its health comparison value or acceptable cancer risk level. Factors such as background
exposure, a growing scientific data base and the inherent uncertainty in assessing health risk are
considered when formulating conclusions. These evaluations are based on current data and
subject to change should more data become available relative to the site and/or the toxic potential
of the contaminants.
| Table 2: COMPLETED EXPOSURE PATHWAYS FOR FAIRCHILD AIR FORCE BASE, WASHINGTON | ||||||||||||
| # | Pathway Name |
Contaminant | Source | Media | Point of Exposure |
Route of Exposure |
Exposed Population |
Persons Exposed b |
Time | Health Risk Non-cancer Cancer |
Comments | |
| 1a | Craig Road Landfill | TCE, Nitrate a | Craig Road
Landfill (SW-8) |
Groundwater | Vietzke Village water supply wells | Ingestion Skin contact Inhalation |
Vietzke Village residents | 1000 | Past | Low | Slight | Water supply wells abandoned. Past exposure of concern. |
| Airway Heights water supply wells | Ingestion Skin contact Inhalation |
Airway Heights residents | 4000 | Past | No | Not Significant | Low levels of TCE. Current monitoring. | |||||
| 2000 | Current | |||||||||||
| 4000 | Future | |||||||||||
| Scafco water supply wells | Ingestion | Scafco employees | 50 | Past | No | Not Significant | Water supply wells abandoned. | |||||
| 1b | Craig Road Landfill | VOC | Craig Road Landfill (SW-8) |
Air | Outdoor air near Vietzke Village | Inhalation | Vietzke Village residents | 1000 | Past | No | Not Significant | Low levels of VOCs. Current monitoring. |
| 200 | Current | |||||||||||
| 1000 | Future | |||||||||||
| 2 | Wastewater Lagoons | TCE | Wastewater
Lagoons (WW-1) |
Groundwater | West Thorpe Road residential wells | Ingestion Skin contact Inhalation |
West Thorpe Road residents | 100 | Past | No | Not Significant | Low levels of TCE. Current monitoring. |
| 50 | Current | |||||||||||
| 100 | Future | |||||||||||
| 3 | No-Name Ditch (Fairchild Easement) | TPH, Metals | Wastewater
lagoons (WW-1) |
Surface water Sediment |
No-Name Ditch (Fairchild Easement) | Ingestion Skin contact |
West Thorpe Road residents | 100 | Past | No | Not Significant | No comment. |
| 50 | Current | |||||||||||
| 100 | Future | |||||||||||
| 4 | Tordon Application | Tordon (Picloram) |
No-Name
Ditch, County Route 902 |
Groundwater | West Thorpe Road residential wells | Ingestion Skin contact |
West Thorpe Road residents | 100 | Past | No | Not Significant | No comment. |
| Surface water Soil |
No-Name Ditch County Route 902 |
Ingestion Skin contact |
West Thorpe Road residents | <100 | Past | No | Not Significant | No comment. | ||||
| 5 | On-base Activities | VOC, TPH, PCB, metals | P-1, P-2 and AOC sites |
Sediment/Soil | P-1, P-2 and AOC sites |
Ingestion Skin contact Dust inhalation |
On-base workers | 200 | Past | No | Not Significant | Areas of contamination infrequently accessed. |
| 100 | Current | |||||||||||
| 200 | Future | |||||||||||
| Lead | SW-11 | Soil | SW-11 | Ingestion Skin contact Dust inhalation |
On-base Recreators | 200 | Past | No | Not Significant | Low levels of lead in soil. | ||
| 100 | Current | |||||||||||
| 200 | Future | |||||||||||
a = Nitrate is discussed in this pathway relative to the Vietzke Village supply wells but is not thought to be related to the Craig Road Landfill.
b = The number of persons exposed is an estimate base on demographic data obtained from ATSDR and other sources.
| Table 3: POTENTIAL EXPOSURE PATHWAYS FOR FAIRCHILD AIR FORCE BASE, WASHINGTON | |||||||||
| # | Pathway Name |
Contaminant | Source | Environmental Media |
Point of Exposure |
Route of Exposure |
Exposed Population |
Time | Comments |
| 1 | Future Off-Base Development | VOC | SW-8, WW-1, FT-1 | Groundwater | NA | Ingestion Skin contact Inhalation |
Residents, workers | Future | Groundwater on abutting property is not suitable for domestic use. |
| 2 | Future On-Base Development | VOC, TPH | Priority-1, 2 and 3 sites | Groundwater | NA | Ingestion Skin contact Inhalation |
Workers Residents | Future | Groundwater in many areas of the base is not suitable for domestic use. |
| Soil | NA | Ingestion Skin contact |
Residents | Future | Some on-base areas are currently not suitable for high exposure activities (e.g., residential development). | ||||
| 3 | Base Supply Well #2 | VOC, TPH | NA | Groundwater | Base Residential and Building Taps | Ingestion Skin contact Inhalation |
Base workers and residents | Future | Site SW-13 (EOD range) represents a potential source of groundwater contamination. |
B. Completed Exposure Pathways
Completed exposure pathways are discussed below. A summary, background, health assessment,
conclusions, and recommendations are provided for each pathway. The health assessment is
separated into a discussion of non-cancer and cancer effects.
| Pathway 1a: Craig Road Landfill --> Groundwater --> Vietzke Village Residents/Airway Heights Residents/Scafco Employees |
The Craig Road Landfill is the source of TCE groundwater contamination that has been found in Vietzke Village public supply wells and the Scafco Corporation facility supply well. It is also a possible source of TCE contamination in the Airway Heights public supply wells.
Vietzke Village Residents
Past exposure to nitrate in Vietzke Village drinking water represents no apparent public health hazard to the general population. Levels of nitrate in the Vietzke wells could have caused methemoglobinemia in infants only if additional risk factors were present such as stomach infection, diarrhea or high dietary nitrate intake. An indeterminate health hazard exists for the children of women exposed while pregnant to nitrate in Vietzke Village drinking water. Inconclusive evidence suggests that levels of nitrates similar to those found in the Vietzke wells can cause adverse birth outcomes.
Airway Heights Residents
Scafco Employees
The Craig Road Landfill covers approximately 100 acres of base property along Craig Road approximately 0.7 miles south of U.S. Route 2 and 0.5 miles east of the main base. Operated as the main landfill for the base from the late 1950s through the late 1970s, it received various wastes including sanitary refuse, industrial waste, and construction debris. The Remedial Investigation/Feasibility Study completed for the Craig Road Landfill in September 1992 described two specific source areas within the landfill: the northeast area covering approximately 6 acres and the southwest area of about 13 acres. Both areas received waste via trench-and-fill at depths greater than 30 feet. A third area covering about 30 acres in the southeast corner is thought to have received only inert, solid materials (e.g., concrete). In addition to the fill areas, the landfill was also the site of the base sanitary wastewater treatment plant. This plant received sanitary wastewater from housing units and the base hospital as well as industrial waste from maintenance shops. Treated water was discharged to a surface evaporation/percolation pond and to underground trenches. Occasionally, treated wastewater was spread on the fill areas to help compact the waste. The treatment plant ceased operation in November 1993 (see Figure 5).
A substantial remedial effort has been undertaken
to address volatile organic compounds (VOCs) in
groundwater originating from the two identified
source areas of the landfill. A geo-textile liner
(cap) now covers the landfill to prevent rainwater
infiltration that could carry more contaminants into
the groundwater. Also, a groundwater pump-and-treat system was installed in September 1995 and
is currently operating at the site to remove
contaminants from groundwater and prevent
movement to off-base areas.
The Craig Road Landfill is the source of groundwater contamination that has affected Vietzke Village public water supply wells and Scafco Corporation water supply wells. The landfill is also a potential contributing source of the groundwater contamination currently affecting Airway Heights public supply wells. Groundwater flow is estimated to be moving east/northeast from the landfill in both the shallow (alluvial) and bedrock (basalt) aquifers. Bedrock groundwater in this area is part of the Wanapum Basalt aquifer and is divided into an upper flow region (Basalt A) and deeper flow region (Basalt B) by a layer of mostly impermeable sedimentary rock (Interbed A). Bedrock groundwater flow in the Craig Road Landfill area was measured at a range of 0.3-8.6 feet per day for Basalt A and 8 feet per day for Basalt B.
Most of the contamination detected in and around
the landfill has been found in the upper Basalt A
bedrock flow. Interbed A is not completely
impermeable, however, and can allow groundwater
and contaminants to move into the deeper Basalt B
flow. It is possible, therefore, for contaminants to
move from the ground surface of the landfill through
the shallow aquifer into the Basalt A flow and then
through fractures into the deeper Basalt B flow. The
Basalt B region of the Wanapum Basalt aquifer is
separated from the deeper Grande Ronde Basalt
aquifer by another layer of sedimentary rock
(Interbed B). No drinking water or monitoring wells in this area are located in the Grand Ronde aquifer.
Figure 6 shows the outline of a TCE plume moving from the two identified source areas in the landfill. In April 1991, a maximum of 2,800 ppb TCE was detected in monitoring well MW-85 located in the Basalt A bedrock flow just across the north perimeter of the landfill. The maximum contaminant level (MCL) for TCE is 5 ppb. Although several other VOCs were detected in soil gas samples, TCE is the only groundwater contaminant migrating off-base at levels of concern. TCE originating from the landfill has impacted drinking water wells at the Vietzke Village trailer park, Scafco supply wells and possibly the Airway Heights public supply wells. These three points of exposure are discussed below.
Vietzke Village Residents
Vietzke Village is a 55-60 unit trailer park located along the northeast border of the Craig Road
Landfill. The land originally contained only one residence until 1968 when the trailer park was
started. Drinking water for trailer park residents was formerly supplied by three blended, open
bore-hole wells (RW-9, RW-10 and RW-11) located on the park grounds as indicated in Figures 5
and 6. According to the owner, the wells were installed
between the late 1960s and early 1970's. RW-11 served
as the primary source of drinking water for Vietzke
Village. RW-10 and RW-9 were primarily used for
irrigation and laundry but also served as drinking water
supply wells during times of high use. Specifics on the
type and rates of water use from these wells are not
available.
Initial sampling and analysis for VOCs in July 1989
detected only TCE at a maximum level of 80 ppb in well RW-9. The most recent sampling in
June 1991 detected maximum levels of TCE at 59 ppb (RW-11) and tetrachloroethylene (PCE) at
0.6 ppb (RW-9). Fairchild provided bottled drinking water to residents of the park from July, 18
through early August 1989 when the park was connected to the Fairchild water supply. 14 All
three wells were officially abandoned between May and June 1993. The TCE sampling results for the Vietzke wells are given in Table 4 below.
Table 4. Vietzke Village Supply Well TCE Measurements
| Well | July 1989* |
June 1990 |
April 1991 |
June 1991 |
| RW-9 | 60/80 | 78 | 22 | 43 |
| RW-10 | 30/27 | 57 | NS | 47 |
| RW-11 | 40/51 | 79 | 52 | 59 |
* Two values represent duplicate samples.
NOTE: Wells no longer in use as of August 1989.
TCE is the only contaminant of concern related to the Craig Road Landfill that has been detected in the Vietzke wells. However, nitrate was also found at elevated levels in the Vietzke water supply. Samples taken between September 1982 and May 1988 showed elevated nitrates with a maximum of 10.5 ppm detected in January 1986. It is not know from what point in the Vietzke water distribution system these samples were taken. A maximum of 19.2 ppm nitrate was also detected in monitoring well MW-80 located in the Vietzke Village trailer park. Although the source of this nitrate contamination is unknown, the RI noted that MW-80 is located near the Vietzke septic field. Septic fields, landfills and agricultural runoff are common sources of nitrate contamination in drinking water wells. In general, only shallow wells are at risk for nitrate contamination. However, the improperly cased bedrock wells at the Vietzke Village were susceptible to contaminants moving from the shallow aquifer. Nitrate levels detected in monitoring wells located near the landfill indicate that the landfill is not a substantial source of nitrate.
There is currently no exposure of Vietzke Village residents to TCE or nitrate in drinking water since water is now supplied by the base. Past exposure occurred via ingestion, skin contact and inhalation of vapors (TCE only). Exposure via ingestion ceased when the base supplied residents with bottled drinking water. Inhalation of TCE vapor ceased when the village was supplied with base water.
Specific contributions of each well to the overall drinking water supply are not available. Tap water samples were reportedly taken from Vietzke Village residences but this data could not be located. In order to be protective of public health, it was assumed that Vietzke Village residents were exposed to the maximum level of TCE detected in the primary supply well (RW-11 at 79 ppb). Exposure to nitrates was estimated using the maximum level detected of 10.5 ppm. The period of concern for past exposure of Vietzke Village residents could have extended from 1968 when the trailer park first started through July 1989 when exposure ceased.
Additional exposure of Vietzke residents to TCE occurred as a result of landfill emissions from soil into air. The dose received from breathing TCE in air emitted directly from the landfill was calculated using estimated air levels derived from mathematical models. The contribution of this pathway to the overall exposure of Vietzke residents to TCE is very small and does not affect the dose comparisons made below. Current and past exposure of Vietzke residents to landfill gases is addressed separately as completed exposure pathway 1b (page 28).
Non-Cancer Effects
Trichloroethylene (TCE)
Past exposure to TCE in Vietzke Village drinking water is not expected to pose a non-cancer
risk for the general population. There is a concern that children born to women who drank
Vietzke Village water while pregnant prior to August 1989 could have been at some risk for
birth defects and other adverse birth outcomes. There is no clear evidence, however, to
indicate that the levels of exposure at Vietzke Village were high enough to cause these types
of health effects. There is no current exposure to TCE in drinking water at the Vietzke
Village.
The estimated dose from the maximum level of TCE
detected in primary supply well RW-11 (79 ppb) is
below ATSDR's acute oral minimal risk level (MRL)
for TCE. This means that short-term exposure (i.e.,
less than two weeks) is not of concern. EPA has not
provided a chronic oral reference dose (RfD) and no
intermediate or chronic oral MRLs are available with
which to evaluate longer-term exposure to TCE. A
previously available intermediate oral MRL for TCE
has been withdrawn as of November 1997. The
potential for non-cancer health effects from longer-term
exposure was based, therefore, on available data from
human and animal studies.
One animal study determined that rats exposed to high doses of TCE in drinking water while
pregnant gave birth to offspring with heart defects. Although this study has been criticized, it
represents the most sensitive toxic endpoint of TCE exposure and is supported by limited
evidence in humans. 15 The 
lowest-observed adverse effect level (LOAEL) from this study
was compared with the estimated dose received by a pregnant woman exposed to 79 ppb TCE
in drinking over a 9-month period. The estimated dose was approximately 35 times below
this LOAEL. This dose was based on an assumption of 2 liters of drinking water ingested per
day combined with an equivalent dose from skin absorption and inhalation of TCE as a result
of showering, bathing and other indoor water use. This comparison indicates that TCE in the
Vietzke wells would not have been of concern.
It is important to consider, however, that some human studies have associated TCE exposure with birth defects in children as a result of exposure prior to birth (i.e., in utero exposure). The birth defects identified included heart malformations, neural tube defects and oral clefts. Other adverse birth outcomes reported include decreased fetal weight and increased fetal death. The levels at which pregnant mothers were exposed in these studies are not well defined. Some exposures appear to have been substantially higher than the levels measured at Vietzke Village while others are similar. These studies are suggestive of an association between TCE exposure and developmental effects but are not sufficient to allow an accurate estimate of what the risk might have been for Vietzke Village residents. Further study may show no association between the levels of TCE in the Vietzke wells and developmental effects. More discussion of the non-cancer effects of TCE is given in the Toxicological Summaries section (page 51).
Also of concern is the potential that levels of TCE in the Vietzke wells may have been higher in the past. Although no data exists prior to July 1989 when these wells were first sampled, levels of TCE may have been higher in the past. Each of the three supply wells is located approximately 800 feet downgradient of monitoring well (MW-85) that showed considerable variation in TCE levels with no established trend. Such variation could also have occurred in the Vietzke wells. Since an exposure duration as short as the first trimester of pregnancy could be of concern, short-term increases in TCE levels could be important. Any fluctuations in the Vietzke wells, however, would not likely have reached levels found in MW-85 because of the expected dilution of TCE moving from Basalt A into uncontaminated water from the relatively clean Basalt B aquifer.
The suggestive nature of the humans studies associating TCE in drinking water with birth defects, along with the possibility that exposures may have been higher prior to initial sampling, is cause for concern. Babies born to women who drank Vietzke water while pregnant prior to August 1989 may have been at risk for birth defects and other adverse birth outcomes. The small and transient nature of the population at Vietzke Village make it an unlikely candidate for a study aimed at evaluating birth defects. Any residents living at Vietzke Village during the period of concern (1968 through July 1989) can contact Robert Duff (DOH) toll-free at 1-888-5TOXICS (1-888-586-9427) or ATSDR at 800-447-1544 for more information.
Nitrate
Nitrate in Vietzke Village drinking water is not expected to result in non-cancer health effects
to the general population. Exposure of infants to formula prepared with Vietzke Village
drinking water prior to August 1989 could have resulted in methemoglobinemia only if
exposure was accompanied by other risk factors such as stomach infection, diarrhea or high
dietary nitrate intake. An indeterminate health hazard exists for the children of women
exposed while pregnant to nitrate in Vietzke Village drinking water. Inconclusive evidence
suggests that levels of nitrates similar to those found in the Vietzke wells can cause adverse
birth outcomes.
The estimated dose for an infant ingesting 0.6 liters per day of formula prepared with 10.5 ppm nitrate contaminated water is equivalent to the RfD for nitrate. This RfD is based on a study that found no methemoglobinemia in infants at drinking water levels below 10 ppm while 2 % of the infants exposed at 11-20 ppm showed early clinical signs of this disorder. Most studies show that levels below 20 ppm will not result in symptoms or adverse health effects unless accompanied by a large dietary source or simultaneous exposure to bacteria that can enhance the conversion of nitrate to nitrite in the digestive tract. 16
Nitrate-induced methemoglobinemia is caused by decreased oxygen delivered to body tissue by the blood and is directly related to the conversion of nitrate to nitrite in the body. Infants are more susceptible to nitrates in drinking water because of a relatively high fluid intake and increased levels of fetal hemoglobin compared with older children and adults. Fetal hemoglobin is more easily converted to methemoglobin than is the adult form. At very high levels of exposure, the decreased oxygen availability to the tissues can cause a serious condition called "blue baby" syndrome. This syndrome is often difficult to diagnose but is indicated by a bluish color around the lips, hands and feet. Other symptoms can include lethargy, sweating, flushed skin, vomiting and diarrhea that are easily confused with other common ailments. "Blue baby" syndrome can be diagnosed directly by measuring the amount of methemoglobin in the blood. Death can result if severe cases are not recognized. 17
Some animal studies have shown a relationship between adverse birth outcomes and nitrate in drinking water but only at high doses. 18 A LOAEL was derived from a study that found impaired neurobehavoiral development in rats given relatively low doses of nitrate in utero and as pups. An estimated dose for a pregnant women drinking water from Vietzke Village at 10.5 ppm nitrate is approximately 20 fold lower than this LOAEL. This comparison suggests that the level of nitrate in Vietzke water would not have been a concern for developmental effects. Such a comparison assumes dietary intake and nitrate/nitrite metabolism are similar between the rat and human.
There is some human evidence that pregnant women who drink nitrate contaminated water are at risk for adverse birth outcomes. A recent study showed that nitrate levels above 20 ppm may be associated with increased spontaneous abortions. 19 Another study showed a significant increase in birth defects associated with nitrate in drinking water at 5-15 ppm. 20 The latter association could not be attributed solely to nitrate exposure since other chemicals including pesticides were likely present in the drinking water. These and other studies examining the relationship between nitrate in drinking water and birth defects remain inconclusive. 17,21,22
Although there is no conclusive evidence indicating that the level of nitrate in Vietzke Village drinking water would have been of concern for the developing fetus, the concurrent exposure to TCE should be considered. Inconclusive evidence suggests that both contaminants may adversely impact the developing fetus. More research is needed to establish or refute this potential health effect. Both of these contaminants are widespread in drinking water supplies across the country, indicating that more research is warranted.
Cancer Effects
Trichloroethylene (TCE)
Discussions with residents indicate that the population of the trailer park is quite transient with
many residents staying less than one year. No significant cancer risk is expected for Vietzke
Village residents exposed for only a few years to the maximum level of TCE detected in
primary supply well RW-11 (79 ppb). A slight increase in cancer risk is expected for those
residents exposed for many years at this level. This slight increase in cancer risk was
calculated for a 30-year period of a child growing to adulthood exposed TCE in drinking
water via ingestion, skin contact and inhalation. If levels of TCE in the Vietzke wells were
higher in the past, this cancer risk would increase.
TCE was previously classified by EPA as a Group B2 probable human carcinogen based on adequate animal data and insufficient human data. This classification has since been removed, however, and is pending further review. Quantitative cancer assessment was, therefore, performed based on animal data provided by EPA prior to the ongoing review. 23 Although EPA has withdrawn its former classification of TCE as a probable human carcinogen, evidence shows that high doses of TCE can cause lung, liver and kidney tumors in animals. Some human studies suggest a link between TCE in drinking water and leukemia. The International Agency for Research on Cancer (IARC) recently classified TCE as probably carcinogenic to humans (Group 2A). 24 The cancer effects of TCE are discussed further in the Toxicological Summaries section (page 51).
DOH also performed a crude comparison of cancer rates in the Vietzke Village zip code (i.e., 99022) with statewide rates. Cancers associated with exposure of animals and humans to TCE were examined including lung, liver, kidney/bladder and leukemia as wells as total cancers. A slight elevation in lung cancer was found (21 cases observed versus 14.2 expected). The reason for this increase is not known but is unlikely to be related to TCE exposure. There was no indication that any other types of cancer were elevated.
This type of comparison is limited in its ability to find small increases in cancer within the exposed population for two main reasons. First, the size of the population within the exposed zip code is too small to detect an increase in cancer at the very low rates estimated. Second, not everyone within the zip code was exposed which could mask an actual increase within the exposed population. The results and limitations of this analysis are discussed further in the Health Outcome Data section (page 55).
Nitrate
EPA has not classified the cancer potential of nitrates. There is evidence that the body can
convert nitrite into cancer-causing nitrosamines. It has been postulated, therefore, that nitrate
in drinking water could lead to increased cancer risk via conversion into nitrite and the
subsequent formation of nitrosamines. Exposure of rats to nitrite in drinking water along with
concurrent exposure to nitrosable amines has been shown to cause an increase in digestive
tract tumors attributed to the formation of nitrosamines in the body. However, this increase
was not seen in rats exposed to nitrate and nitrosable amines. In addition, no increase in
tumor formation was seen in rats exposed separately to these nitrosamine precursors. Several
human studies have failed to provide clear evidence to support a link between nitrate exposure
and cancer. 17
Cancer risk resulting from nitrate in drinking water would thus depend on several factors including the total amount of nitrate/nitrite ingested, the conversion of nitrate to nitrite, the conversion of nitrite to nitrosamine and the cancer potency of the resulting nitrosamine. The difficulty in assessing these variables currently prohibits a quantitative estimate of cancer risk from nitrate exposure. The average adult daily intake of nitrate from dietary sources is estimated at 73 mg/day. The amount of nitrate formed daily inside the body is estimated to be approximately equal to this amount. The additional daily intake estimated for an adult drinking the maximum level of nitrate detected in the Vietzke wells is 21 mg/day. 17 Considering the lack of clear evidence associating nitrate in drinking water with cancer and the relatively limited contribution from the Vietzke wells to the overall daily dose of nitrate (i.e., 13%), nitrate exposure from Vietzke drinking water is not expected to result in a significant increase in cancer risk.
Airway Heights Residents
As groundwater moves east from the Craig Road Landfill past Vietzke Village, it reaches an depression into which shallow and Basalt A bedrock groundwater flows from all directions. The deeper Basalt B bedrock flow also enters this channel before continuing east. This depressed shallow aquifer channel, therefore, serves as a barrier against contaminants reaching wells to the east that are in the shallow or Basalt A bedrock flow. It is likely that contaminants in the Basalt B flow are substantially diluted and not a threat to impact deep bedrock wells further east. Airway Heights public supply wells RW-1and RW-4 are located in this shallow aquifer depression (Figure 6). Currently, water from these wells is blended with that from a third supply well (Well #5) before being routed to a storage tank that serves the city's water needs. A fourth supply well (Well #7) was recently developed by the city at the corner of Russel and McFarlane. This well is connected to the water line supplying the storage tank but reportedly gives inconsistent yields. No VOCs were detected in a sample taken from Well #7 in March 1997. 25
TCE has been consistently detected in RW-1 and RW-4 at low levels. A blended sample from these two wells is taken four times per year as part of the base residential well sampling plan. The most recent sampling in June 1997 detected a maximum of 0.7 ppb TCE. The maximum TCE level ever found in these wells is 3.2 ppb detected in February 1995. Airway Heights residents and workers are currently being exposed to TCE in drinking water through ingestion, skin contact and inhalation of vapors. It is likely that the level of TCE exposure is less than the amount found in RW-1 and RW-4 samples since the output from these wells is mixed with that of Well #7 and Well #5 which have no history of TCE contamination.
Non-Cancer Effects
Non-cancer adverse health effects are not expected to result from current or past exposure to TCE in the Airway Heights public drinking water supply. The estimated dose resulting from exposure via ingestion, skin contact and inhalation to the maximum level ever detected in the Airway Heights public supply wells (3.2 ppb) is 900 times below the LOAEL. This dose was calculated assuming a 9-month exposure of a pregnant woman drinking 2 liters of water per day combined with an equivalent dose from skin absorption and inhalation as a result of showering, bathing and other indoor water use. This LOAEL is based on developmental heart defects in rats and represents the most sensitive health effect yet found in animal studies.
Some studies of people exposed to TCE in drinking water indicate a potential association with birth defects. The levels of TCE are much higher in these studies than those to which Airway Heights residents were exposed. Further discussion of the non-cancer effects of TCE is given in the Toxicological Summaries section.
No significant cancer risk is estimated to result from current or past exposure to TCE in the Airway Heights public drinking water supply. A dose was estimated using the maximum level of TCE (3.2 ppb) ever detected in Airway Heights public water supply. Exposure via ingestion, skin contact and inhalation was assumed to occur over a 30-year period of a child growing to adulthood. The estimated cancer risk calculated for this scenario was determined to be insignificant. The cancer effects of TCE are discussed in the Toxicological Summaries section.
Scafco Employees
The Scafco Corporation facility is located at the intersection of Craig Road and McFarlane Road directly east of the southern portion of the Craig Road Landfill. This facility is currently being leased to a tenant business. Residential well RW-7, installed in April 1974, supplied all water needs for this facility until August 1992 when RW-7A was drilled. RW-7A was used as the water supply well for the facility from sometime after installation on August 13, 1992, until June 1996, when the company connected to the Airway Heights public water supply. The base notified Scafco of TCE contamination in this well on October 26, 1992. Immediately following this notice, bottled drinking water was provided to workers at the Scafco facility and all taps were labeled as non-drinkable. 26, 27
Initial sampling of RW-7 in July 1989 detected TCE at 2 ppb and this level was not exceeded through the final sample round in March 1996 which detected no VOCs. RW-7A has consistently contained elevated levels of TCE with an initial detection of 15 ppb in September 1992. A maximum level of 63 ppb TCE was detected in November 1995. The most recent sampling of RW-7A in March 1996 detected TCE at 0.67 ppb. Exposure of workers to low levels of TCE at the Scafco facility occurred via ingestion of drinking water from RW-7 for a maximum duration of 18 years (1974-1992). Ingestion of higher levels of TCE from RW-7A drinking water may have occurred over a maximum period of 2 months. Inhalation and skin exposure via showering and bathing are not considered as routes of exposure for these workers.
Non-cancer adverse health effects are not expected to result from past exposure to TCE in the Scafco water supply wells. Workers were assumed to be exposed to 2 ppb TCE via ingestion of drinking water from RW-7 at a rate of 2 liters of water ingested per day. The estimated dose resulting from this exposure is 2,800 times below the LOAEL. This estimated dose assumed a worst-case scenario of a pregnant woman exposed over a 9-month period and so will be protective of all workers. This LOAEL is based on developmental heart defects in rats and represents the most sensitive health effect yet found in animal studies.
Some studies of people exposed to TCE in drinking water indicate a potential association with birth defects. The levels of TCE are much higher in these studies than those to which Scafco workers were exposed. Further discussion of the non-cancer effects of TCE is given in the Toxicological Summaries section.
The possibility exists that exposure of Scafco workers increased to 15 ppb TCE in drinking water for the period from August 13, 1992 to October 26, 1992. The estimated dose at this level of exposure would still be well below the LOAEL and is at the lower end of the exposure ranges estimated in the human studies described above. Also, lower exposures are expected in the workplace versus home setting because of increased use of water at home (e.g., showering, cooking). This increased period of exposure is, therefore, not expected to have resulted in adverse health effects for Scafco workers.
Cancer Effects
No significant cancer risk is estimated to result from past exposure to TCE in Scafco water supply wells. Workers were assumed to be exposed to 2.0 ppb TCE via ingestion of drinking water from RW-7 for 18 years at a rate of 2 liters of water ingested per day. The estimated cancer risk calculated for this scenario was determined to be insignificant. The possibility exists that exposure of Scafco workers increased to 15 ppb TCE in drinking water for the period from August 13, 1992 to October 1992. This potential short-term increase in exposure is expected to have no significant impact on cancer risk. The cancer effects of TCE are discussed in the Toxicological Summaries section.
Vietzke Village Residents
No current public health hazard exists for the residents of the Vietzke Village trailer park through
the use of drinking water. Use of the formerly contaminated water supply wells that served the
park was discontinued in August 1989 when the park was connected to the Fairchild water supply.
Past exposure to TCE and nitrate in Vietzke Village drinking water represents no apparent public health hazard to the general population. However, an indeterminate public health hazard exists for the children of women exposed while pregnant to TCE and nitrate in Vietzke Village drinking water prior to August 1989 when exposure ceased. Children born to women who drank Vietzke Village water while pregnant prior to August 1989 could have been at some risk for birth defects and other adverse birth outcomes. There is no clear evidence, however, to indicate that the levels of exposure at Vietzke Village were high enough to cause these types of health effects.
Airway Heights Residents
No apparent public health hazard exists for residents of Airway Heights using the public water
supply. Very low levels of TCE are currently being detected in the city water supply. Ingestion
and inhalation of TCE from drinking water at these levels is not expected to cause health
problems. The Airway Heights public water supply is monitored by the base four times per year.
Scafco Employees
No apparent public health hazard exists for employees exposed to TCE in drinking water while
working at the Scafco Corporation facility. Low-level exposure of workers to TCE via ingestion
of drinking water occurred for some period of time between April 1974 and August 1992 when
the facility was connected to the Airway Heights water supply.
ATSDR and DOH recommend continued quarterly monitoring of the Airway Heights public supply wells for VOCs until three quarterly samples have shown no detections for base-related contaminants. Testing of these wells for VOC contamination can then return to annual sampling as required for all public supply wells. Detection limits for VOCs should be at or below Method Detection Limits required under EPA Method 524.2.
The base investigated a previous DOH recommendation to sample residential wells RW-32 and
RW-49 for possible VOC contamination. These wells are either non-existent or not in-use.
Pathway 1b: Craig Road Landfill --> Air --> Vietzke Village Residents |
No outdoor (ambient) air sampling data are available for any areas of the base. The potential for VOCs to volatilize from Craig Road Landfill soil into outdoor air was assessed using a mathematical model. Results from this model indicate that levels of VOCs in outdoor air at the nearby Vietzke Village pose no apparent public health hazard. The Spokane County Air Pollution Control Authority (SCAPCA) currently requires periodic monitoring of emissions from the Craig Road Landfill. Annual averages of contaminant emissions are used to model ambient air levels at the perimeter of the landfill to insure that these emissions do not pose a public health hazard. SCAPCA is currently evaluating recent landfill emission data and will require further action if annual averages exceed a level of concern.
No outdoor (ambient) air sampling data are available for any areas of the base. Concentrations in air of some VOCs detected in soil gas at the Craig Road Landfill were estimated for locations at the perimeter of the landfill including the Vietzke Village trailer park. These estimates were made as part of the RI/FS for the Craig Road Landfill using EPA's SCREEN air dispersion model (Version 1.1) and maximum concentrations of benzene, TCE and methylene chloride detected in landfill soil gas. Point source air sampling data associated with the landfill's groundwater treatment facility and methane vents are available from the Spokane County Air Pollution Control Authority (SCAPCA).
Modeled air concentrations for the Vietzke Village trailer park indicate that past levels of some VOCs in air off-gassing from the Craig Road Landfill may have resulted in a very low increase in cancer risk for residents of the trailer park. This estimated risk was primarily due to TCE and benzene although some carcinogenic VOCs found in soil gas were not included in the model. It is likely that this model substantially overestimates past air concentrations at the trailer park since it uses maximum soil gas concentrations and worst-case 1-hour averages rather than annual averages. Annual averages are recommended for use in cancer risk assessment and are expected to be 10 times lower than 1-hour averages. The model also assumed worst-case weather conditions.
Non-Cancer Effects
Cancer Effects
Measurements of VOCs currently being emitted from the landfill are made on a regular basis in accordance with SCAPCA requirements. Samples are taken from four methane vents and the intake and output of the two air stripping towers. These towers work to "strip" VOCs from extracted groundwater into air that is then cleaned of the VOC contaminants prior to discharge into the atmosphere. Amounts of VOCs emitted from the landfill are monitored to ensure that yearly average concentrations estimated for off-site locations are below levels of concern as established by SCAPCA. SCAPCA uses EPA's SCREEN air dispersion model (Version 3.0) to predict annual average concentrations at locations outside of the landfill. If modeled air concentrations exceed acceptable annual averages, further investigation will be carried out by the Department of Ecology under the Controls for New Sources of Toxic Air Pollutants rule (WAC 173-460) as mandated by the Washington Clean Air Act (70.94 RCW).
No apparent public health hazard exists for the residents of Vietzke Village from inhalation of volatile contaminants off-gassing from the Craig Road Landfill. Air emissions are likely to decrease as contaminants degrade and are removed from the groundwater beneath the landfill.
No recommendations are necessary with respect to this pathway. Emissions from the landfill are
monitored on a regular basis.
|
Pathway 2: Wastewater Lagoons --> Groundwater --> West Thorpe Road Area Residents |
The base wastewater lagoons are the apparent source of TCE groundwater contamination that is currently impacting residential wells in the West Thorpe Road area. Exposure of West Thorpe Road area residents to current levels of TCE in drinking water represents no apparent public health hazard. Monitoring of residential wells should continue in this area.
Groundwater contamination has been identified in the area east of the wastewater lagoons (WW-1) located on the eastern border of the base along Rambo Road (Figure 7). Groundwater is estimated to be moving east/southeast in this area. WW-1 consists of two wastewater lagoons, a skimming pond, and a holding lagoon. The skimming pond receives runoff from the storm water drainage system that at one time included discharge from 54 oil/water separators. Many of these separators received industrial wastes from base maintenance shops. Historical observations have noted oil sheens in the lagoons and drainage ditches indicating that many of these separators were not operating properly. At some point, several separators were redirected to discharge to the sanitary sewer system. In 1991, a major upgrade of the remaining separators resulted in removal, replacement or cleaning of those separators still discharging to the storm water drainage system. A groundwater pump-and-treat system installed in February 1996 is currently operating in the WW-1 area with extraction wells extending southeast towards the anticipated edge of the plume.
TCE is the only contaminant of concern affecting residential wells in the West Thorpe Road area. A plume containing primarily TCE appears to be moving east/southeast from the WW-1 site and is currently impacting residential wells in the West Thorpe Road area. The exact source of this plume has not been determined but is estimated to be in the vicinity of monitoring well MW-102 (Figure 7).
The maximum level of TCE ever detected in the WW-1 area is 280 ppb found in on-base monitoring well MW-102 in February 1991. The maximum level of TCE ever detected off-base in the WW-1 vicinity is 69 ppb found at MW-120 in December 1995. The most recent sampling of monitoring wells at the WW-1 site in June 1997, detected an on-base maximum of 190 ppb in WP-03 and an off-base maximum of 45 ppb TCE in MW-120. MW-120 is an off-base shallow well located approximately 800 feet east of the WW-1 site that has shown increasing levels of TCE since initial sampling detected 18 ppb in April/May 1991. MW-122 is a Basalt A bedrock well adjacent to MW-120 that has shown only minimal TCE contamination suggesting that the plume remains in the shallow aquifer at this point (see Figure 7). Other contaminants, not currently impacting residential wells, are discussed under potential exposure pathway (page 44).
Residential wells in the West Thorpe Road area are currently being monitored for VOC contamination by the base. TCE is the only contaminant of concern detected in residential wells in this area with a maximum of 1.5 ppb found in RW-13. The most recent sampling of these wells in June 1997 detected a maximum TCE level of 1.1 ppb in RW-23. 28 Some West Thorpe Road area residents are currently being exposed to low levels of TCE in drinking water through ingestion, skin contact and inhalation of vapors.
Non-Cancer Effects
Some studies of people exposed to TCE in drinking water indicate a potential association with birth defects. The levels of TCE are much higher in these studies than those to which Airway Heights residents were exposed. Further discussion of the non-cancer effects of TCE is given in the Toxicological Summaries section (page 51).
Cancer Effects
No significant cancer risk is estimated to result from current or past exposure to TCE in the West Thorpe Road area drinking water wells. A dose was estimated using the maximum level of TCE (1.5 ppb) ever detected in West Thorpe Road residential wells. Exposure via ingestion, skin contact and inhalation was assumed to occur over the 30-year period of a child growing to adulthood. The estimated cancer risk calculated for this scenario was determined to be not significant. The cancer effects of TCE are discussed in the Toxicological Summaries section (page 55).
In addition to the estimated cancer risk, DOH performed a crude analysis of cancer incidence in the West Thorpe Road zip code (i.e., 99022). Cancers associated with exposure of animals and humans to TCE were examined including lung, liver, kidney/bladder, and leukemia as well as total cancers. No elevations in these types of cancers were detected when compared with statewide rates except for a slight elevation in lung cancer (21 cases observed versus 14.2 expected). The reason for this increase is not known but is unlikely to be related to TCE exposure.
This type of comparison is limited in its ability to find small increases in cancer within the exposed population for two main reasons. First, the size of the population within the exposed zip code is too small to detect an increase in cancer at the very low rates estimated. Second, not everyone within the zip code was exposed which could mask an actual increase within the exposed population. The results and limitations of this analysis are discussed further in the Health Outcome Data section (page 55).
No apparent public health hazard exists for West Thorpe Road area residents using private wells for drinking or any other purpose. Very low levels of TCE are currently being detected in West Thorpe Road area residential wells. Ingestion and inhalation of TCE from drinking water at these levels is not expected to cause health problems. Residential drinking water wells in the West Thorpe Road area are currently monitored by the base on a quarterly basis.
Current monitoring of residential wells in the West Thorpe Road area should continue until these
wells are no longer threatened by groundwater contaminants associated with the base. DOH will
consider a well to be safe after three quarterly samples have shown no detections for base-related
contaminants. Detection limits for VOCs should be at or below Method Detection Limits
required under EPA Method 524.2.
|
Pathway 3: No-Name Ditch (Fairchild Easement) --> Sediment/Surface Water --> West Thorpe Road Area Residents |
No-Name Ditch (also known as the Fairchild Easement) runs from the base wastewater lagoons (WW-1) across Rambo Road and through several residential properties. The wastewater lagoons currently receive surface water runoff from the base storm water discharge system. This system formerly delivered waste discharge from base maintenance shops to the lagoons. The ditch is an exposure point for children who might play in and around it during the summer months. No apparent public health hazard exists for children who currently play in and around No-Name Ditch. Although past levels of petroleum-related contaminants in ditch sediment and surface water could have been higher, exposure was probably infrequent and not of concern.
No-Name Ditch originates on-base at the wastewater lagoons (WW-1) located on Rambo Road. The wastewater lagoons consist of a skimming pond and a holding lagoon. The ditch carries effluent from the skimming pond east/southeast across Rambo Road through residential properties on West Thorpe Road before discharging to a field where the water infiltrates into the ground. The skimming pond receives input from the base storm water drainage system. Before discharge into the ditch, this effluent is skimmed with a surface boom that directs water to the holding lagoon. Discussions with residents in the West Thorpe Road area revealed that flooding of this ditch occurs frequently in the winter months and can be aggravated by obstructions such as excessive weed growth. Observations by base personnel indicate that water is present in the ditch throughout the year except in times of drought. A public comment received from a resident states that the ditch contains water year round even in times of drought. Residents living along the ditch have recalled visible contamination in the past including oil sheens. One resident claims that the ditch was once set on fire by local children.
Several rounds of surface water and sediment samples
were taken from the ditch between 
October 1986 and
December 1991. The contaminants of concern found in
off-base ditch surface water and sediment during this
period are listed in Table 3, Appendix C. Total petroleum
hydrocarbons (TPH) were detected at a maximum of 22
ppm in off-base ditch surface water and 860 ppm in
sediment. The final round of ditch sampling conducted
during the RI in November 1991 detected lower levels of
TPH with a maximum of 0.4 ppm in surface water and
120 ppm in sediment. No TPH were detected in two off-base ditch samples taken in October 1995. 29
Several metals are listed as contaminants of concern for this pathway. Maximum values of these metals exceeded either their respective screening value or estimated background levels in surface water or sediment. However, the mean values calculated for the last round of sediment sampling in the ditch (November 1991) indicate that none of metals listed was consistently detected at an elevated level.
Residents recreating in and around the ditch could be exposed to contaminants in surface water and sediment via accidental ingestion and skin contact. Children reportedly use the ditch for recreation in the summer as noted by base personnel. 21 A ponded area is located along the ditch near a residential property. Anecdotal evidence indicated that this small pond is stocked for recreational fishing. Further inquiry with the owner of the property revealed that small, non-recreational fish are occasional thrown into the pond but are never caught or eaten. There is no evidence to indicate that anyone uses the ditch for fishing. Exposure to ditch contaminants through the ingestion of fish is, therefore, not of concern.
Non-Cancer Effects
Metals
90th
percentile values of these two metals derived from the final round of sampling in the ditch in
November 1991 do not exceed the 90th percentile background levels published by Ecology. 30
Exposure to magnesium and aluminum in ditch sediment and surface water will not, therefore, result in substantial exposure.
Total Petroleum Hydrocarbons (TPH)
Past exposure of children or adults to contaminants in ditch surface water and sediments may have been higher. Discussions with residents indicate that in the past oil sheens could be seen on the surface water. One resident commented that the surface water in the ditch was ignited by area children. The operation of approximately 25 oil/water separators at the base prior to their upgrade in 1991 may well have been faulty. 6 Poor maintenance of these separators would have allowed the movement of jet fuel spills and leaks through the base drainage system into the wastewater lagoons and then to No-Name Ditch. The bulk of contamination in the ditch was likely jet fuel. Analysis of surface water and sediment for old fuel spill contamination is reported as TPH. TCE is another major on-base contaminant but would not have been expected to reach levels of concern at any time in the ditch because of rapid volatilization from surface water.
The potential for adverse health effects from past exposure is dependent on the amount of TPH present and the frequency and duration of exposure to ditch surface water and sediment. Areas of the ditch with petroleum contamination at levels of concern would likely have been visible and avoided. Occasional exposure of persons contacting TPH in ditch surface water and sediment in the past is not considered a health concern. TPH is discussed further in the Toxicological Summaries section.
Cancer Effects
In addition to the estimated cancer risk, DOH performed a crude analysis of cancer incidence in the West Thorpe Road zip code (i.e., 99022). Arsenic was the only cancer-causing contaminant of concern found in the ditch. The type of skin cancer associated with arsenic exposure is not malignant and not tracked by the state cancer registry. Therefore, only a comparison of total cancers was performed. No elevation in total cancers was detected when compared with statewide rates. The results and limitations of this analysis are given in the Health Outcome Data section (page 55).
No apparent public health hazard exists for children playing in No-Name Ditch (Fairchild Easement). Ingestion of and skin contact with contaminants in sediment and surface water are estimated to be below a level of concern.
No recommendations are necessary with respect to this pathway.
| Pathway 4: Tordon --> Groundwater/Soil --> West Thorpe Road Area Residents |
The herbicide Tordon was applied to roadways in the West Thorpe Road area and No-Name Ditch. In 1979, low levels of Tordon were detected in residential garden soil, drinking water wells, and No-Name Ditch surface water. No apparent public health hazard exists from past exposure of West Thorpe Road area residents to Tordon in drinking water, surface water or soil.
Tordon was applied repeatedly to No-Name Ditch from 1966 to 1978 in efforts by the base and the Spokane County Road Department to control weed growth in the ditch. The herbicide was also used on county roads and rights of way that may have included West Thorpe Road. Complaints by West Thorpe Road area residents about affected garden crops prompted the Washington Department of Agriculture to sample residential drinking water wells in January 1979. Use of Tordon was banned in the West Thorpe Road area in June 1979, following detection of Tordon in these wells. 32
In January 1979 the Washington Department of Agriculture sampled surface water, soil, groundwater and cow's milk in the West Thorpe Road area. Groundwater sampling revealed Tordon contamination in several residential wells (maximum at 13.2 ppb), Fairchild on-base supply well #2 (maximum at 0.33 ppb) and the Airway Heights water supply (maximum at 1.73 ppb). Tordon was also detected at a maximum of 0.16 ppb in No-Name Ditch surface water and in residential garden soil at a maximum of 15.0 ppb. A single sample of cow's milk from an animal grazing in the West Thorpe Road area revealed no Tordon. West Thorpe Road area residents were exposed in the past to Tordon in drinking water, soil, and surface water via ingestion and skin contact.
Non-Cancer Effects
Cancer Effects
A quantitative estimate of the cancer risk associated with the Tordon exposure of West Thorpe Road residents was not possible because a cancer potency factor for picloram has not been derived. DOH did, however, perform a crude comparison of cancer rates in the West Thorpe Road zip code (i.e., 99022) with statewide rates. The small amount of data available indicates that liver tumors were caused by high doses of picloram fed to rats. Therefore, liver cancer as well as total cancer incidence was examined. No elevations in these types of cancers were detected when compared with statewide rates. The results and limitations of this analysis are given in the Health Outcome Data section (page 55).
Multiple Exposures
No apparent public health hazard exists from past exposure of West Thorpe Road area residents to Tordon detected in drinking water, surface water, soil, and sediment in the West Thorpe Road area. Although the cancer-causing ability of Tordon is unclear, the low levels detected are not likely to pose a significant health hazard.
No apparent public health hazard exists from the combined exposure of West Thorpe Road area residents to contaminants detected in completed exposure pathways 2, 3 and 4.
No recommendations are necessary with respect to this pathway.
| Pathway 5: On-Base Activities --> Sediment/Soil --> Fairchild Personnel |
Thirty-nine contaminated sites have been identified on base. No apparent public health hazard exists for on-base workers exposed to contaminants in soil, surface water or sediment. No base personnel are exposed to contaminated groundwater.
No apparent public health hazard exists for children exposed to lead in surface soil at the former aircraft salvage yard site (SW-11). The site is currently a recreation area (Warrior Park) and was found to contain elevated levels of lead in surface soil with a maximum of 1,340 ppm. Based on a previous DOH recommendation, the base conducted further sampling to determine if this maximum level was representative of high use areas of the park. This extensive sampling found a maximum of 98 ppm lead in surface soil. Blood lead levels in children exposed to lead in Warrior Park soil are not expected to increase above a level of health concern. The park should be periodically inspected, however, to ensure that sub-surface debris left over from salvage operations does not become a physical hazard in the future.
To date, thirty-nine sites have been investigated for contamination of soil, sediment and groundwater at the base. Many of these sites contain elevated levels of metals, TPH, and VOCs. The contaminants of concern for this pathway are given in Appendix C, Table 5 along with the base-wide maximum levels detected. Some sites that are not listed in the table contain contaminants of concern at lower levels. On-base contamination is the result of fuel spills and leaks, discharge of wastes to the storm water drainage system and landfilling. Much of the contamination was detected below ground surface and represents an exposure pathway only for clean-up workers or those workers involved in projects requiring soil excavation. Other sites, such as the wastewater lagoons (WW-1) and the former fire training area (FT-1), are abandoned or infrequent work areas and do not present opportunities for repeated exposure.
Site IS-3 is the location of the former reciprocating engine test shop that was housed in Building 2150. The building operated as an engine test shop from 1942 to 1956 when it was converted to a multi-purpose facility. The main area of concern is in the basement where six transformers were installed and several others temporarily stored during a base-wide PCB removal. A 8.5-foot deep sump also located in the basement apparently received waste from basement floor drains. Sump sediments and surface water contained low levels of PCBs, SVOCs and metals. Building 2150 was demolished in June 1997. Soil sampling at the site following demolition did not detect PCBs.
Site SW-11 represents a potential exposure point for base personnel and their children to soil contaminants while using the recreation facilities located in this area (Warrior Park). This area includes a basketball court, a dirt baseball field, and some grass-covered lawn. The site was formerly used as an aircraft parts salvage and reclamation area from 1945 to 1958. A Limited Field Investigation (LFI) conducted in October 1991 uncovered a considerable amount of metallic debris in sub-surface soil. Soil sample analysis conducted during the LFI indicated elevated levels of lead and cadmium. The LFI also noted several hundred reciprocating engine test valves buried together under one foot of soil. Six valves were opened, two of which were found to contain elemental sodium. 34
In March 1992, a layer of soil and grass seed was placed over some portions of the SW-11 site to prevent contact with metallic debris and contaminants in soil. 35 This action was supported by ATSDR as a temporary measure pending further investigation provided the soil cover remained intact. 36 Later analysis of soil samples taken in March 1993 during the Remedial Investigation (RI) for Priority 2a sites revealed elevated levels of metals in both surface and subsurface soil. The RI also noted metallic debris in surface and sub-surface soil and that approximately 90% of the SW-11 area was unvegetated.
The Draft for Public Comment release of this health assessment in August 1997 concluded that an indeterminate public health hazard existed for children who played frequently at Warrior Park. A recommendation for further sampling was made in order to better characterize the potential exposure of children to lead in surface soil at the park. In response to this recommendation, the base collected 35 surface soil samples at Warrior Park in November 1997. Samples were taken in areas of potentially high exposure (i.e., sparsely covered or bare dirt areas, baseball field) and analyzed for lead.
Base-Wide Worker Exposure
Contaminants of concern in on-base soil were assessed using the maximum values detected base-wide given in Appendix C, Table 5. Workers could be exposed to contaminants through accidental ingestion of and skin contact with soil and inhalation of dust. Exposure to VOCs in soil could also occur via inhalation of vapors. Exposure via vapor and particulate inhalation was evaluated qualitatively.
Non-Cancer Effects
None of the estimated doses calculated for workers exposed to on-base contaminants exceeded their respective MRL or RfD. The combined doses also did not exceed a level of concern. Considering that the exposure scenario outlined above provides a high estimate of exposure, this estimate will likely be protective of any added exposure through inhalation of vapors or dust.
Some contaminants of concern found in on-base soil have no RfDs or MRLs with which to compare a dose estimate. Of all the inorganic contaminants (metals) of concern that do not have RfDs or an MRLs, only magnesium was detected consistently above background. A 90th percentile value calculated for magnesium in WW-1 lagoon sediments was 3 times higher than the 90th percentile value derived by Ecology. This elevation is probably due to past waste drainage from base maintenance shops that now discharge to a sanitary sewer. Because levels of magnesium will not likely increase and the area is not frequented, non-cancer adverse health effects are not anticipated from exposure to magnesium in on-base soil or sediment.
Alkylbenzenes, 2-methylnaphthalene and 2-hexanone are organic contaminants of concern that do not have an RfD or an MRL. Surrogate RfDs were adopted from chemicals with similar structure in order to compare with resulting doses of these contaminants. The calculated doses were all well below their respective surrogate RfDs and are not expected to contribute substantially to the overall estimate for non-cancer risk.
Cancer Effects
Cancer risks calculated for the maximum level of arsenic found in a drainage basin near the flight line (SD-38) and 1,1,2,2-tetrachloroethane in the area of the tank excavation at Building 2447 (SD-37) were slightly elevated using the above exposure scenario. This scenario probably overestimates the actual risk, however, as neither area requires repeated maintenance activity. A more realistic exposure would be that of an excavation worker exposed for 30 days during a one-time removal action. Exposure of workers during an on-base removal action is not expected to result in a significant cancer risk because of the shorter exposure duration and required implementation of a health and safety plan.
On-Base Recreators at Warrior Park (SW-11)
The SW-11 site is currently used as a recreation area (Warrior Park) with picnic benches, basketball court and baseball field. The only contaminant of concern at the site is lead in surface soil. A maximum of 1,340 ppm of lead was detected in surface soil at the SW-11 site during RI sampling in March 1993. Soil sampling conducted during the RI and previous investigations was limited, however, and did not include high use areas of the park (e.g., baseball field). In November 1997, the base conducted extensive surface soil sampling of high use areas at Warrior Park to better determine the potential exposure of children to lead in soil. A maximum of 98 ppm lead in surface soils was detected during this sampling. It was assumed that children could be exposed primarily through accidental ingestion of soil and inhalation of dust while playing in the park.
Also of concern is the presence of debris left over from past aircraft salvage operations that could pose a physical hazard. The debris was noted in soil borings taken in March 1993 indicating that the soil cover installed in March 1992 was compromised in this area. Further inspection of the park in November 1997 noted small amounts of debris in surface soil. Sodium metal contained in buried reciprocating engine valves will only be a hazard if excavated.
Non-Cancer Effects
indicates that blood lead levels in children
between 1 and 6 years of age would not exceed 3.9 ug/dl
at this level of exposure. This is well below EPA's action
level of 10 ug/dl.
Children between 1 and 2 years of age are most susceptible to increased blood lead levels resulting from exposure to lead in soil. 37 Evidence exists to indicate that health effects in young children may occur at blood lead levels as low as 6 ug/dl. The most sensitive toxic effect from lead exposure in children involves behavioral changes resulting from nervous system toxicity. Many of these behavioral changes involve impaired learning ability and include decreased performance on IQ tests. 38
Cancer Effects
No apparent public health hazard exists for workers exposed to contaminants in on-base soil or sediment.
No apparent public health hazard exists for children exposed to lead in surface soil while playing at Warrior Park (SW-11). Debris in surface soil from past salvage operations appears to be minimal and is not expected to pose a physical hazard for recreators in the park unless more debris is exposed through erosion or excavation. Sodium metal containing engine valves found in the park will not be a hazard provided they remain below the surface.
A previous recommendation made in the Draft for Public Comment release of this document for further soil sampling of Warrior Park was addressed by the base.
The Warrior Park area should be periodically inspected ensure that any debris found in surface soil poses no physical hazard. Excavation in the area should be monitored in order to prevent unintentional disturbance of the engine valves containing sodium metal.
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