ATSDR - PHA - Andrews Air Force Base, Camp Springs, Prince George's County, Maryland

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ATSDR > Public Health Assessments & Consultations

PUBLIC HEALTH ASSESSMENT

ANDREWS AIR FORCE BASE
CAMP SPRINGS, PRINCE GEORGE'S COUNTY, MARYLAND

APPENDICES

APPENDIX A: GLOSSARY OF TERMS

ATSDR Plain Language Glossary of Environmental Health Terms

Adverse Health Effect:

A change in body function or the structures of cells that can lead to disease or health problems.

ATSDR:

The Agency for Toxic Substances and Disease Registry. ATSDR is a federal health agency in Atlanta, Georgia that deals with hazardous substance and waste site issues. ATSDR gives people information about harmful chemicals in their environment and tells people how to protect themselves from coming into contact with chemicals.

Background Level:

An average or expected amount of a chemical in a specific environment. Or, amounts of chemicals that occur naturally in a specific-environment.

Cancer:

A group of diseases which occur when cells in the body become abnormal and grow, or multiply, out of control

Carcinogen:

Any substance shown to cause tumors or cancer in experimental studies.

CDC:

Centers for Disease Control and Prevention

CERCLA:

See Comprehensive Environmental Response, Compensation, and Liability Act.

Chronic Exposure:

A contact with a substance or chemical that happens over a long period of time. ATSDR considers exposures of more than one year to be chronic.

Completed Exposure Pathway:

See Exposure Pathway.

Comprehensive Environmental Response, Compensation, and Liability Act (CERCLA):

CERCLA was put into place in 1980. It is also known as Superfund. This act concerns releases of hazardous substances into the environment, and the cleanup of these substances and hazardous waste sites. ATSDR was created by this act and is responsible for looking into the health issues related to hazardous waste sites.

Concern:

A belief or worry that chemicals in the environment might cause harm to people.

Concentration:

How much or the amount of a substance present in a certain amount of soil, water, air, or food.

Contaminant:

See Environmental Contaminant.

Dermal Contact:

A chemical getting onto your skin. (see Route of Exposure).

Dose:

The amount of a substance to which a person may be exposed, usually on a daily basis. Dose is often explained as "amount of substance(s) per body weight per day".

Dose / Response:

The relationship between the amount of exposure (dose) and the change in body function or health that result.

Duration:

The amount of time (days, months, years) that a person is exposed to a chemical.

Environmental Contaminant:

A substance (chemical) that gets into a system (person, animal, or the environment) in amounts higher than that found in Background Level, or what would be expected.

Environmental Media:

Usually refers to the air, water, and soil in which chemicals of interest are found. Sometimes refers to the plants and animals that are eaten by humans. Environmental Media is the second part of an Exposure Pathway.

U.S. Environmental Protection Agency (EPA):

The federal agency that develops and enforces environmental laws to protect the environment and the public's health.

Epidemiology:

The study of the different factors that determine how often, in how many people, and in which people will disease occur.

Exposure:

Coming into contact with a chemical substance.(For the three ways people can come in contact with substances, see Route of Exposure.)

Exposure Assessment:

The process of finding the ways people come in contact with chemicals, how often and how long they come in contact with chemicals, and the amounts of chemicals with which they come in contact.

Exposure Pathway:

A description of the way that a chemical moves from its source (where it began) to where and how people can come into contact with (or get exposed to) the chemical.

ATSDR defines an exposure pathway as having five parts:

Source of Contamination,
Environmental Media and Transport Mechanism,
Point of Exposure,
Route of Exposure, and
Receptor Population.

When all 5 parts of an exposure pathway are present, it is called a Completed Exposure Pathway. Each of these 5 terms is defined in this Glossary.

Frequency:

How often a person is exposed to a chemical over time; for example, every day, once a week, twice a month.

Hazardous Waste:

Substances that have been released or thrown away into the environment and, under certain conditions, could be harmful to people who come into contact with them.

Health Effect:

ATSDR deals only with Adverse Health Effects (see definition in this Glossary).

Indeterminate Public Health Hazard:

The category is used in Public Health Assessment documents for sites where important information is lacking (missing or has not yet been gathered) about site-related chemical exposures.

Ingestion:

Swallowing something, as in eating or drinking. It is a way a chemical can enter your body (See Route of Exposure).

Inhalation:

Breathing. It is a way a chemical can enter your body (See Route of Exposure).

MRL:

Minimal Risk Level. An estimate of daily human exposure - by a specified route and length of time -- to a dose of chemical that is likely to be without a measurable risk of adverse, noncancerous effects. An MRL should not be used as a predictor of adverse health effects.

NPL:

The National Priorities List. (Which is part of Superfund.) A list kept by the U.S. Environmental Protection Agency (EPA) of the most serious, uncontrolled or abandoned hazardous waste sites in the country. An NPL site needs to be cleaned up or is being looked at to see if people can be exposed to chemicals from the site.

No Apparent Public Health Hazard:

The category is used in ATSDR's Public Health Assessment documents for sites where exposure to site-related chemicals may have occurred in the past or is still occurring but the exposures are not at levels expected to cause adverse health effects.

No Public Health Hazard:

The category is used in ATSDR's Public Health Assessment documents for sites where there is evidence of an absence of exposure to site-related chemicals.

Plume:

A line or column of air or water containing chemicals moving from the source to areas further away. A plume can be a column or clouds of smoke from a chimney or contaminated underground water sources or contaminated surface water (such as lakes, ponds and streams).

Point of Exposure:

The place where someone can come into contact with a contaminated environmental medium (air, water, food or soil). For examples:
the area of a playground that has contaminated dirt, a contaminated spring used for drinking water, the location where fruits or vegetables are grown in contaminated soil, or the backyard area where someone might breathe contaminated air.

Population:

A group of people living in a certain area; or the number of people in a certain area.

Public Health Assessment(s):

A report or document that looks at chemicals at a hazardous waste site and tells if people could be harmed from coming into contact with those chemicals. The PHA also tells if possible further public health actions are needed. Abbreviation: PHA.

Public Health Hazard:

The category is used in PHAs for sites that have certain physical features or evidence of chronic, site-related chemical exposure that could result in adverse health effects.

Public Health Hazard Criteria:

PHA categories given to a site which tell whether people could be harmed by conditions present at the site. Each are defined in the Glossary. The categories are:

Receptor Population:

People who live or work in the path of one or more chemicals, and who could come into contact with them (See Exposure Pathway).

Reference Dose (RfD):

An estimate, with safety factors (see safety factor) built in, of the daily, life-time exposure of human populations to a possible hazard that is not likely to cause harm to the person.

Route of Exposure:

The way a chemical can get into a person's body. There are three exposure routes:

Safety Factor:

When scientists don't have enough information to decide if an exposure will cause harm to people, they use "safety factors" and formulas in place of the information that is not known. These factors and formulas can help determine the amount of a chemical that is not likely to cause harm to people. Also called Uncertainty Factor.

Source (of Contamination):

The place where a chemical comes from, such as a landfill, pond, creek, incinerator, tank, or drum. Contaminant source is the first part of an Exposure Pathway.

Survey:

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

Toxic:

Harmful. Any substance or chemical can be toxic at a certain dose (amount). The dose is what determines the potential harm of a chemical and whether it would cause someone to get sick.

Toxicology:

The study of the harmful effects of chemicals on humans or animals.

Tumor::

Abnormal growth of tissue or cells that have formed a lump or mass.

Urgent Public Health Hazard:

This category is used in ATSDR's Public Health Assessment documents for sites that have certain physical features or evidence of short-term (less than 1 year), site-related chemical exposure that could result in adverse health effects and require quick intervention to stop people from being exposed.

APPENDIX B: ESTIMATED EXPOSURE AND HEALTH EFFECTS

Estimates of Human Exposure Doses and Determination of Health Effects

Overview of ATSDR's Methodology for Evaluating Potential Public Health Hazards

The Agency for Toxic Substances and Disease Registry (ATSDR) evaluated exposures to surface soil, surface water and sediment, biota, and groundwater at Andrews Air Force Base (AFB). To do so, ATSDR evaluated available data to determine whether contaminants were above ATSDR's comparison values (CVs). For those that were, ATSDR derived exposure doses and compared them against health-based guidelines. ATSDR also reviewed relevant toxicological data to obtain information about the toxicity of contaminants of interest.

Comparing Data to ATSDR's CVs

CVs are derived using conservative exposure assumptions. CVs reflect concentrations that are much lower than those that have been observed to cause adverse health effects. Thus, CVs are protective of public health in essentially all exposure situations. As a result, concentrations detected at or below ATSDR's CVs are not considered to warrant health concern. While concentrations at or below the relevant CV may reasonably be considered safe, it does not automatically follow that any environmental concentration that exceeds a CV would be expected to produce adverse health effects. It cannot be emphasized strongly enough that CVs are not thresholds of toxicity. The likelihood that adverse health outcomes will actually occur depends on site-specific conditions and individual lifestyle and genetic factors that affect the route, magnitude, and duration of actual exposure, and not an environmental concentration alone.

For this public health assessment, ATSDR evaluated data that were collected from surface soil, surface water and sediment, biota, and groundwater to determine whether people were exposed to contaminant concentrations that exceeded ATSDR's CVs. The majority of detected contaminants fell at or below CVs and were not evaluated further (see Table 3 through Table 13). Contaminants that were above CVs were deemed worthy of further evaluation, prompting ATSDR to estimate exposure doses (i.e., the amount of chemical a person is exposed to over time) using site-specific exposure assumptions.

Deriving Exposure Doses

ATSDR derived exposure doses for those contaminants that were detected above ATSDR's CVs or did not have CVs. When estimating exposure doses, health assessors evaluate (1) contaminant concentrations to which people may have been exposed and (2) length of time and the frequency of exposure. Together, these factors influence an individual's physiological response to chemical contaminant exposure and potential outcomes. Where possible, ATSDR used site-specific information about the frequency and duration of exposures. In cases where site-specific information was not available, ATSDR applied several conservative exposure assumptions to estimate exposures for on-base and off-base residents and recreational users.

The following equation was used to estimate exposure to contaminants in surface soil:

where:

Conc.: Maximum concentration in parts per million (ppm)

IR: Ingestion rate: adult = 100 milligrams (mg) per day; child = 200 mg per day

EF: Exposure frequency, or number of exposure events per year of exposure: 365 days/year

ED: Exposure duration, or the duration over which exposure occurs: adult = 30 years; child = 6 years

BW: Body weight: adult = 70 kg; child = 10 kg

AT: Averaging time, or the period over which cumulative exposures are averaged (6 years or 30 years x 365 days/year for noncancer effects; 70 years x 365 days/year for cancer effects)

The following equation was used to estimate recreational exposure to contaminants in surface water:

where:

Conc.: Maximum concentration in parts per billion (ppb)

IR: Ingestion rate: 0.15 liters per day^�

EF: Exposure frequency, or number of exposure events per year of exposure: 130 days/year for recreational and 260 days/year for occupational

ED: Exposure duration, or the duration over which exposure occurs: adult = 30 years; child = 8 years*

BW: Body weight: adult = 70 kg; child = 28.1 kg*

AT: Averaging time, or the period over which cumulative exposures are averaged (8 years or 30 years x 365 days/year for noncancer effects; 70 years x 365 days/year for cancer effects)

^� The ingestion rate is based on swimming for 3 hours per event (EPA 1997).
* The child's body weight is increased because ATSDR assumes that older children would be more likely to play in the streams than infants.

The following equation was used to estimate recreational exposure to contaminants in sediments:

where:

Conc.: Maximum concentration in parts per million (ppm)

IR: Ingestion rate: adult = 50 mg per day; child = 100 mg per day

EF: Exposure frequency, or number of exposure events per year of exposure: 130 days/year for recreational and 260 days/year for occupational

ED: Exposure duration, or the duration over which exposure occurs: adult = 30 years; child = 8 years*

BW: Body weight: adult = 70 kg; child = 28.1 kg*

AT: Averaging time, or the period over which cumulative exposures are averaged (6 years or 30 years x 365 days/year for noncancer effects; 70 years x 365 days/year for cancer effects)

* The child's body weight is increased because ATSDR assumes that older children would be more likely to play in the streams than infants.

The following equation was used to estimate exposure to contaminants in fish:

where:

Conc.: Maximum concentration in parts per million (ppm)

IR: Ingestion rate: adult = 54 grams per day^�; child = 27 grams per day^�

EF: Exposure frequency, or number of exposure events per year of exposure: 365 days/year

ED: Exposure duration, or the duration over which exposure occurs: adult = 30 years; child = 6 years

BW: Body weight: adult = 70 kg; child = 10 kg

AT: Averaging time, or the period over which cumulative exposures are averaged (6 years or 30 years x 365 days/year for noncancer effects; 70 years x 365 days/year for cancer effects)

^� The ingestion rate represents daily intake averaged over a year for a person eating seven meals of fish a month.

The following equation was used to estimate exposure to contaminants in strawberries:

where:

Conc.: Maximum concentration in parts per million (ppm)

IR: Ingestion rate: adult = 2.73 grams per day; child = 0.39 grams per day

EF: Exposure frequency, or number of exposure events per year of exposure: 365 days/year

ED: Exposure duration, or the duration over which exposure occurs: adult = 30 years; child = 6 years

BW: Body weight: adult = 70 kg; child = 10 kg

AT: Averaging time, or the period over which cumulative exposures are averaged (6 years or 30 years x 365 days/year for noncancer effects; 70 years x 365 days/year for cancer effects)

The following equation was used to estimate exposure to contaminants in groundwater:

where:

Conc.: Maximum concentration in parts per million (ppm)

IR: Ingestion rate: adult = 2 liters per day; child = 1 liter per day

EF: Exposure frequency, or number of exposure events per year of exposure: 365 days/year

ED: Exposure duration, or the duration over which exposure occurs: adult = 30 years; child = 6 years

BW: Body weight: adult = 70 kg; child = 10 kg

AT: Averaging time, or the period over which cumulative exposures are averaged (6 years or 30 years x 365 days/year for noncancer effects; 70 years x 365 days/year for cancer effects)

Using Exposure Doses to Evaluate Potential Health Hazards

ATSDR performs weight of evidence analyses to determine whether exposures might be associated with adverse health effects (noncancer and cancer). As part of this process, ATSDR examines relevant toxicologic, medical, and epidemiologic data to determine whether estimated doses are likely to result in adverse health effects. As a first step in evaluating noncancer effects, ATSDR compares estimated exposure doses to standard health guideline values, including ATSDR's minimal risk levels (MRLs) and the U.S. Environmental Protection Agency's (EPA's) reference doses (RfDs). The MRLs and RfDs are estimates of daily human exposure to substances that are unlikely to result in noncancer effects over a specified duration. Estimated exposure doses that are less than these values are not considered to be of health concern. To be very protective of human health, MRLs and RfDs have built in "uncertainty" or "safety" factors that make them much lower than levels at which health effects have been observed. Therefore, if an exposure dose is much higher than the MRL or RfD, it does not necessarily follow that adverse health effects will occur.

If health guideline values are exceeded, ATSDR examines the effect levels seen in the literature and more fully reviews exposure potential to help predict the likelihood of adverse health outcomes. ATSDR looks at human studies, when available, as well as experimental animal studies. This information is used to describe the disease-causing potential of a particular contaminant and compare site-specific dose estimates with doses shown to result in illness in applicable studies (known as the margin of exposure). For cancer effects, ATSDR also reviews genotoxicity studies to further understand the extent to which a contaminant might be associated with cancer outcomes. This process enables ATSDR to weigh the available evidence, in light of uncertainties, and offer perspective on the plausibility of adverse health outcomes under site-specific conditions.

Using Other Methods to Evaluate Potential Health Hazards

When dealing with exposure to lead, ATSDR calculates what the cumulative blood lead level might be as a result of exposure to the level of contamination present. This is done by multiplying the detected concentration by a media-specific slope factor (soil: 0.0068, water: 0.26, and biota: 0.24) [ATSDR 1999]. Then ATSDR compares this expected blood lead level to the level that according to the Centers for Disease Control and Prevention has an observed increase in childhood health effects,10 micrograms per deciliter.

Because essential nutrients (e.g., calcium, magnesium, potassium, and sodium) are important minerals that maintain basic life functions, certain doses are recommended on a daily basis and MRLs and RfDs do not exist for these chemicals. Additionally, health-based values do not exist for a few other compounds (e.g, endrin ketone, silicon, p-isopropyltoluene, and isopropylbenzene), leaving ATSDR with no basis for evaluating their toxicity at Andrews AFB. Total petroleum hydrocarbon is assessed by examining its components for toxicity.

Evaluation of Health Hazards Associated with Andrews AFB

ATSDR identified several pathways that had the potential to lead to exposures to either the residents of Andrews AFB or people living at or visiting areas off base (please refer to Table 2). For each of these completed and potential pathways, contaminant concentrations were compared to CVs when the data were available. Many of the contaminants were detected below their corresponding CVs. For each pathway in which chemicals were detected above CVs or did not have CVs, exposure doses were calculated. For most of the chemicals, the calculated exposure doses were less than their respective MRLs and RfDs and were not expected to cause an increase in cancer outcomes. After evaluating the available toxicologic data for those chemicals where the exposure doses exceeded health guidelines, ATSDR concludes that none of the chemicals were detected at levels of health concern in any of the evaluated pathways (with the exception of manganese in an off-site monitoring well at LF-05). More detail about each of the exposure pathways follows.

Surface Soil

Surface soil near water towers Nos. 3589 and 4614 was sampled for lead, cadmium, and chromium in April 2001. None of the cadmium and chromium detections were above CVs. Only the highest lead detection at water tower No. 3589 (1,330 ppm) and two lead detections at water tower No. 4614 (606 ppm and 1,260 ppm) exceeded EPA's soil screening level (SSL) of 400 ppm. The highest detection at water tower No. 3589 and second highest detection at water tower No. 4614 were found within the fence surrounding the water towers and are; therefore, inaccessible to people and cannot be causing adverse health effects because of the lack of exposure. The highest detection at water tower No. 4614 was found about 150 feet south of the water tower in the playground area. Additional soil sampling in this area to further define the extent of the lead contamination was performed in May 2001. The results are not yet available, however, preliminary data suggest that the extent is limited. ATSDR will make a determination concerning public health from exposure to soils at water tower No. 4614 after reviewing this data.

Surface soil sampling was conducted in the front and back yards of the Family Housing Units at 2131 Richmond Drive. Bis(2-ethylhexyl)phthalate and pyrene were detected above CVs (Table 3). Exposure doses were calculated using the formulas described above. Doses for adults were below the RfDs and are too low to be of health concern. Doses for children for both chemicals [bis(2-ethylhexyl)phthalate: 0.03 milligrams per kilogram per day (mg/kg/day) and pyrene: 0.054 mg/kg/day] were slightly above EPA's chronic RfDs [bis(2-ethylhexyl)phthalate: 0.02 mg/kg/day and pyrene: 0.03 mg/kg/day]. Therefore, ATSDR further examined the effects levels seen in the literature and more fully reviewed exposure potential to help predict the likelihood of adverse health outcomes.

Bis(2-ethylhexyl)phthalate is a synthetic compound that is commonly added to plastics to make them flexible. Some of the products it is found in are wall coverings, tablecloths, floor tiles, shower curtains, garden hoses, dolls, shoes, and rainwear. There is no conclusive evidence that bis(2-ethylhexyl)phthalate causes adverse health effects in humans. According to animal studies, the lowest dose needed for serious health effects to result in rats is 3.3 mg/kg/day. The dose resulting from exposure to the surface soil at the Family Housing Units (0.03 mg/kg/day) is much lower. Therefore, the levels detected are too low to be of health concern for both children and adults. In addition, because of its presence in plastics, bis(2-ethylhexyl)phthalate is a common laboratory contaminant and may not be present in the environment at the detected levels.

Pyrene is one of the many polycyclic aromatic hydrocarbons (PAHs) that result from the incomplete burning of coal, oil, gas, wood, garbage, or other organic matter. PAHs can occur naturally or be synthetically created and some are used in medicines, dyes, or asphalt. PAHs can cause adverse health effects from both short- and long-term exposures. The lowest dose seen in the literature to cause less serious health effects in mice is 125 mg/kg/day. This dose is orders of magnitude higher than the calculated dose resulting from exposure to surface soil at the Family Housing Units for both adults ( 0.004 mg/kg/day) and children (0.054 mg/kg/day). Therefore, the levels in the soil are too low to be of health concern.

Surface soil samples were taken at the former landfill prior to the construction of the golf course. These sampling results provided a worst case scenario in which a golfer would be exposed to soils in out of bounds areas. The chemicals that were detected were compared to CVs. Several semi-volatile organic compounds (SVOCs) [acenaphthylene, benz(a)anthracene, benzo(a)pyrene, benzo(b)fluoranthene, benzo(g,h,i)perylene, dibenz(a,h)anthracene, indeno(1,2,3-cd)pyrene, and phenanthrene], one polychlorinated biphenyl (PCB) [aroclor-1254], two pesticides (dieldrin and endrin ketone), and three metals (arsenic, iron, and mercury) were detected above soil CVs or did not have CVs (Table 4). Exposure doses were calculated for these chemicals using the equation and assumptions previously described. None of the chemicals were detected at a level of health concern (i.e., all the calculated exposure doses were less than the MRLs or RfDs).

Three off-site soil samples were taken from south of Andrews AFB, near Piscataway Creek. Of the chemicals detected, only arsenic was detected above a CV (Table 5). Benzo(g,h,i)perylene and phenanthrene did not have CVs to make a comparison. Therefore, ATSDR calculated conservative exposure doses for these three chemicals using the equation for surface soil described above. None of the chemicals were detected above EPA's chronic RfDs. Naphthalene's RfD was used as a conservative substitute for comparison to the calculated exposure doses from benzo(g,h,i)perylene and phenanthrene because MRLs and RfDs do not exist for these noncancerous chemicals.

Surface Water and Sediment

Surface water and sediment was sampled in the unnamed tributary to Paynes Branch, Cabin Creek, Base Lake, Piscataway Creek, and Charles Branch. Six SVOCs [benz(a)anthracene, benzo(a)pyrene, benzo(b)fluoranthene, benzo(g,h,i)perylene, naphthalene, and phenanthrene] were detected in the surface water and sediment of the unnamed tributary to Paynes Branch above CVs or did not have CVs (Table 6). Four VOCs (benzene, 1,2-dicloroethane, 1,1-dichloroethene, and tricloroethene), eight SVOCs [bis(2-ethylhexyl)phthalate, benz(a)anthracene, benzo(a)pyrene, benzo(b)fluoranthene, benzo(g,h,i)perylene, dibenz(a,h)anthracene, indeno(1,2,3-cd)pyrene, and phenanthrene], and four metals (arsenic, cadmium, iron, mercury, and thallium) were detected in the surface water, sediment, and seep of Cabin Branch above CVs or did not have CVs (Table 7). Antimony, arsenic, and cadmium were detected above CVs in the Base Lake (Table 8). Nine SVOCs [acenaphthylene, benz(a)anthracene, benzo(a)pyrene, benzo(b)fluoranthene, benzo(g,h,i)perylene, bis(2-ethylhexyl)phthalate, dibenz(a,h)anthracene, indeno(1,2,3-c,d)pyrene, and phenanthrene], three pesticides (dieldrin, endrin ketone, and heptachlor epoxide), and 12 inorganics (aluminum, antimony, arsenic, barium, cadmium, chromium, iron, lead, manganese, mercury, nickel, and vanadium) were detected in the surface water and sediment of Piscataway Creek above CVs or had no CVs (Table 9). Eight organic compounds [acenaphthylene, benz(a)anthracene, benzo(a)pyrene, benzo(g,h,i)perylene, chloroform, dibenz(a,h)anthracene, indeno(1,2,3-c,d)pyrene, and phenanthrene] and arsenic were detected in Charles Branch above CVs or did not have CVs (Table 10).

Recreational exposure doses were calculated for each of the listed chemicals using the formulas and assumptions described previously. All but one (iron in surface water of Piscataway Creek) of the exposure doses were below their respective MRLs and RfDs and; therefore, were not at a level of health concern. Iron in surface water of Piscataway Creek was evaluated further:

Iron is an important mineral that helps to maintain basic life functions. Exposure doses were calculated to be 0.65 mg/kg/day for adults and 1.6 mg/kg/day for children who incidentally ingest 0.15 liters of surface water during a 3 hour swim for 130 days a year. Based on exposures from ingesting the maximum detected concentration each time, these doses are slightly above EPA's RfD (0.3 mg/kg/day). However, it is highly unlikely that children or adults recreating in Piscataway Creek would incidentally ingest the highest concentration each time. Especially since all but three of the 28 detected concentrations are well below the comparison value. Because it is more realistic to base an exposure scenario on the average, ATSDR calculated the average iron concentration found in Piscataway Creek and calculated doses upon that concentration. The exposure doses based on the average iron concentration (0.031 mg/kg/day for adults and 0.076 mg/kg/day for children) are well below EPA's RfD and are not at a level of health concern.

In addition, to address Prince George's County Health Department's concern about children and construction workers contacting contaminated groundwater seeping from Foxley Road, ATSDR compared the levels of the three VOCs (chlorobenzene, 2-butanone, and acetone), one SVOC (1,4-dichlorobenzene), and six metals (arsenic, barium, cadmium, chromium, lead, and vanadium) detected in the seep and sediment to their appropriate CVs. All of the chemicals detected in the sediment samples as well as vanadium and chromium from the seep samples were below CVs. ATSDR then calculated occupational and recreational exposure doses to the chemicals in the seep that were above comparison values (chlorobenzene: 0.00051 mg/kg/day for workers and 0.0018 mg/kg/day for children; 1,4-dichlorobenzene: 0.00013 mg/kg/day for workers and 0.00044 mg/kg/day for children; arsenic: 0.0002 mg/kg/day for workers and 0.00069 mg/kg/day for children; barium: 0.0011 mg/kg/day for workers and 0.0039 mg/kg/day for children; and cadmium: 0.00024 mg/kg/day for workers and 0.00086 mg/kg/day for children). With the exception of children being exposed to the maximum arsenic concentration detected, the exposure doses likely to result from the incidental exposures to the water and/or sediment were well below their respective MRLs and RfDs (chlorobenzene: 0.02 mg/kg/day; 1,4-dichlorobenzene: 0.4 mg/kg/day; arsenic: 0.0003 mg/kg/day; barium: 0.07 mg/kg/day; and cadmium: 0.0002 mg/kg/day) [i.e., too low to be of health concern]. ATSDR further examined the effects levels seen in the literature for arsenic and more fully reviewed exposure potential to help predict the likelihood of adverse health outcomes.

Arsenic is a naturally occurring element, widely distributed in the Earth's crust. It is usually found in the environment combined with other elements such as oxygen, chlorine, and sulfur. Long-term oral exposure to inorganic arsenic may cause cancer, stomach and intestine irritation, or decreased production of red and white blood cells. According to human studies, the lowest dose needed for cancerous effects to result is exposure to 0.0011 mg/kg/day and the lowest dose needed for noncancerous effects is exposure to 0.002 mg/kg/day. The doses resulting from exposure to the seep at Foxley Road (0.0002 mg/kg/day for workers and 0.00069 mg/kg/day for children) are much lower. Therefore, the levels detected in the seep are too low to be of health concern for both children and workers. In addition, the exposure doses were calculated based on incidentally ingesting 0.15 liters of water a day, which is based on actually swimming in the water for three hours. Workers constructing roads and children playing are expected to ingest a much lower amount of water than what was used to calculate these exposures.

Biota

Fish from the Base Lake were sampled. Biota are evaluated slightly different than the other pathways because ATSDR does not have CVs to compare to contaminant levels. Instead of initially comparing the chemical concentrations to CVs, exposure doses were calculated for all detected chemicals (Table 8) using the assumption that a person ate seven meals of fish from the Base Lake a month. Of all the chemicals detected in fish from the Base Lake only aroclor-1254, aroclor-1260, antimony, and mercury were above MRLs and RfDs. Therefore, ATSDR further examined the effects levels seen in the literature for these chemicals and more fully reviewed exposure potential to help predict the likelihood of adverse health outcomes.

Aroclor-1254 and aroclor-1260 are two of 209 synthetic organic compounds known as PCBs. They are manmade compounds that are found as a colorless to light yellow oily liquid or solid. Health effects vary depending on which compound the person is exposed. Exposure doses for aroclor-1254 were calculated to be 0.00002 mg/kg/day for adults and 0.00007 mg/kg/day for children and exposure doses for aroclor-1260 were 0.000021 mg/kg/day for adults and 0.00008 mg/kg/day children. These doses are slightly above ATSDR's chronic MRL and EPA's chronic RfD of 0.00002 mg/kg/day for aroclor-1254. However, the lowest dose of PCBs (0.005 mg/kg/day) known to cause any kind of health effect (inflammation of tarsal glands and toenail deformities in monkeys) was much higher than the calculated exposure doses. Therefore, PCBs in fish from the Base Lake were not detected at a level of health concern.

Antimony is a silvery white metal that is naturally found in the environment. Antimony can enter the body by eating foods contaminated with it. After which a small amount can enter the blood stream. Consuming large doses (19,000 ppb) may induce vomiting. The exposure dose for adults (0.0001 mg/kg/day) was below EPA's chronic RfD (0.0004 mg/kg/day), but the exposure dose for children was slightly elevated (0.0005 mg/kg/day). However, this dose is well below effects levels seen in the literature for less serious health effects in animals (0.0748 mg/kg/day) and humans (0.529 mg/kg/day) and does not pose a health concern.

Mercury can be found in the environment as three naturally-occurring forms: metallic mercury, inorganic mercury, or organic mercury. Most of the mercury found in the environment is metallic or inorganic mercury. One common source of exposure to metallic mercury is from dental fillings. Both metallic and inorganic mercury are not readily absorbed if ingested, however, methylmercury is about 95% absorbed. The nervous system is the most sensitive system to mercury exposure. Even though the exposure doses for adults (0.00046 mg/kg/day) and children (0.0016 mg/kg/day) were slightly above ATSDR's chronic MRL (0.0003 mg/kg/day), they were well below doses seen in the literature for serious developmental health effects in animals (0.04 mg/kg/day). Therefore, exposure to mercury from eating fish out of the Base Lake is not a health concern.

Fish from Piscataway Creek were sampled. Exposure doses were calculated for all detected chemicals (Table 9) using the assumption that a person ate seven fish meals a month from Piscataway Creek. Exposure doses for aroclor-1254, aroclor-1260, antimony, mercury, dieldrin, and cadmium were above MRLs and RfDs. As with eating fish from the Base Lake, exposure from eating fish from Piscataway Creek is not of health concern.

As stated above, PCBs are synthetic compounds with varying health effects. The exposure doses to aroclor-1254 (0.000077 mg/kg/day for adults and 0.00027 mg/kg/day for children) and aroclor-1260 (0.000062 mg/kg/day for adults and 0.00021 mg/kg/day children) were slightly above ATSDR's chronic MRL and EPA's chronic RfD of 0.00002 mg/kg/day. However, the lowest dose of PCBs (0.005 mg/kg/day) known to cause health effects (inflammation of tarsal glands and toenail deformities in monkeys) was much higher than the calculated exposure doses. Therefore, consuming PCBs in fish from Piscataway Creek is not at a level of health concern.

As stated above, antimony is a naturally occurring element. The exposure dose for adults was below EPA's chronic RfD (0.0004 mg/kg/day), but the exposure dose for children was slightly higher (0.0009 mg/kg/day). However, this dose is well below effects levels seen in the literature for less serious health effects in animals (0.0748 mg/kg/day) and humans (0.529 mg/kg/day) and does not pose a health concern.

As stated above, mercury can be found in the environment as three naturally-occurring forms with metallic or inorganic mercury as the most common forms. The exposure dose for adults was below ATSDR's chronic MRL (0.0003 mg/kg/day), but the exposure dose for children was slightly elevated (0.00056 mg/kg/day). Even so, the dose was still well below levels seen in the literature for serious developmental health effects in animals (0.04 mg/kg/day). Therefore, exposure to mercury from eating fish from Piscataway Creek is not of health concern.

Dieldrin is a compound that was once used as an insecticide. It is not naturally found in the environment. From the 1950s to 1970 it was extensively used on crops such as corn and cotton to control insects. From 1972 to 1987 dieldrin was used to control termites. Since 1987 all uses have been canceled. Most exposure to dieldrin occurs from eating foods contaminated with it. Even exposure to small amounts can cause adverse health effects because dieldrin builds up in the body over time. The calculated exposure dose for adults was below ATSDR's chronic MRL and EPA's chronic RfD of 0.00005 mg/kg/day. Even though child doses (0.00008 mg/kg/day) were slightly above the MRL and RfD, the levels were well below doses seen in the literature for less serious health effects in animals (0.0335 mg/kg/day) and do not pose a health concern.

Cadmium is a naturally occurring element. Encountering cadmium in its pure form as a metal is rare because it usually combines with other elements (e.g., oxygen, chlorine or sulfur). Cigarette smoke is a large source of cadmium exposure for the general population. The calculated exposure dose for adults was below ATSDR's chronic MRL of 0.0002 mg/kg/day. Even though child doses (0.0003 mg/kg/day) were slightly elevated, the levels were well below doses seen in the literature for serious systemic health effects in animals (0.01 mg/kg/day). Therefore, exposure from ingesting fish with cadmium concentrations found in Piscataway Creek does not pose a health concern.

Exposure from consuming fish from Piscataway Creek seven times a month was too low to be of health concern. If people were to subsist on fish from the upper reaches of Piscataway Creek, then exposure doses may be elevated above health concern for specific contaminants (e.g., arsenic, antimony, chromium, cadmium, mercury, fluoranthene, dieldrin, aroclor-1254, and aroclor-1260). However, the current sampling is not adequate enough to base a health decision concerning subsistence fishing. In addition, composite sampling may not accurately represent the parts of the fish that are eaten.

Strawberries from the berry farm were also sampled. Exposure doses were calculated for all detected chemicals (Table 9) using the assumptions described above. All of the exposure doses for strawberries from the berry farm were less than the MRLs and RfDs and are not considered to be of health concern.

Groundwater

The well at Hexagon Developers property was sampled twice by Prince George's County Health Department (PGCHD) and once by Andrews AFB. As a result of these sampling periods, only methylene chloride and thallium were detected above ATSDR's drinking water CVs (Table 12). Exposure doses were calculated for these chemicals. Exposures from methylene chloride were below EPA's chronic RfD. Thallium's exposure doses [0.000154 mg/kg/day for adults and 0.00054 mg/kg/day for children] were detected above EPA's RfD (0.00007 mg/kg/day), therefore, ATSDR further examined the effect levels seen in the literature and more fully reviewed exposure potential to help predict the likelihood of adverse health outcomes to thallium.

Thallium is a metal found naturally in the environment as ore deposits. It is odorless and tasteless in its pure form and exists in two chemical states, thallous and thallic. Thallous is the more common and more stable form. Thallium can enter the body by drinking water contaminated with it. Most of the dose is rapidly absorbed to various parts of the body. About half the amount ingested will leave the body via urine or feces within 3 days. It may take up to 2 months for the body to completely excrete the entire dose ingested. Thallium can affect the nervous system, lungs, heart, liver, and kidneys if large amounts are ingested over a period of time. The amount of thallium detected in the well at Hexagon Developers property was too low to cause adverse health effects. The lowest dose of thallium (0.08 mg/kg/day) known to cause any kind of health effect (performance deficit in rats) was much higher than the calculated exposure doses for groundwater (0.00015 mg/kg/day for adults and 0.00054 mg/kg/day for children). Moreover, thallium was also detected in the blank sample, indicating that it may be a laboratory contaminant rather than a true detection.

Because of the potential for unidentified shallow groundwater wells to exist in the area downgradient from LF-05, the seep and off-site monitoring well detections were also compared to CVs. Exposure doses were calculated for those contaminants detected above CVs or did not have CVs in the seep and off-site monitoring wells (arsenic, benzene, cadmium, chlorobenzene, iron, and manganese; Table 13). The exposure doses for chlorobenzene, cadmium, iron, and manganese were detected above their respective MRLs and RfDs, therefore, ATSDR further examined the effect levels seen in the literature to help predict the likelihood of adverse health outcomes if people were to use the groundwater downgradient from LF-05 as their primary source of drinking water.

Chlorobenzene is a colorless organic liquid that has a faint almond-like odor. The presence of chlorobenzene in the groundwater is a direct result of past landfill activities (e.g., disposal of liquid solvents, paints, and hydrocarbon-based liquids) [EA Engineering 1996]. In 1992, it was reported that the chlorobenzene plume had migrated about 350 to 500 feet off site. None of the off-site monitoring wells detected chlorobenzene at a level of health concern. However, the exposure dose for children (0.033 mg/kg/day) based on the concentration detected by PGCHD from a seep on Foxley Road was slightly above EPA's chronic RfD (0.02 mg/kg/day).Studies have reported that workers exposed to high levels of chlorobenzene experienced headaches, numbness, sleepiness, nausea, and vomiting. Liver and kidney damage has resulted in animals exposed to doses of 60 mg/kg/day and greater. The resulting dose from drinking off-site groundwater from LF-05 (0.009 mg/kg/day for adults and 0.033 mg/kg/day for children) is much lower than levels reported to cause adverse health effects in animal studies. Therefore, chlorobenzene was not detected at a level of health concern.

Cadmium is an element found in natural ore deposits. Drinking water with very high levels of cadmium can irritate the stomach. Ingesting cadmium in lower doses over a long period of time can lead to kidney damage. Exposure doses for adults (0.00009 mg/kg/day) and children (0.00032 mg/kg/day) were calculated using a concentration detected in an off-site monitoring well. These levels of exposure are well below the doses documented in the literature that resulted in serious health effects in humans from long-term exposure (0.0078 mg/kg/day) and short-term exposure (25 mg/kg/day).

As stated above, iron is an important mineral that helps to maintain basic life functions. EPA has guidelines for iron in drinking water because water with high levels may have an unpleasant taste to some people and stain material that is washed in water with high concentrations. The iron concentrations detected in off-site monitoring wells were much higher than those levels set by EPA to minimize objectionable taste and color. These high concentrations would give the groundwater a distinct reddish-brown coloration. Most people would be adverse to drinking or using water with such high iron concentrations. Exposure doses were calculated to be 2.2 mg/kg/day for adults and 7.75 mg/kg/day for children who drink 2 liters and 1 liter, respectively, of groundwater a day. These doses are an order of magnitude above EPA's RfD (0.3 mg/kg/day), therefore, ATSDR further evaluated the documented health effects from iron.

According to the U.S. Food and Drug Administration (FDA), doses greater than 200 mg per event may poison and/or kill a child (FDA 1997). Doses of this magnitude are generally the result of children ingesting iron pills and not from drinking contaminated groundwater. Daily doses of iron average to be 155 mg/day for adults and 77.5 mg/day for children when consuming 2 liters and 1 liter of water, respectively. Moreover, because of the adverse taste associated with high iron-containing groundwater, it is highly unlikely that people are actually using the groundwater as their primary source of drinking water. Regardless, the doses are below levels likely to cause adverse health effects.

Manganese is a metal that helps produce energy for the body. However, too much manganese can cause harmful effects such as mental and emotional disturbances and may impair body movements. The combination of these symptoms is called manganism and is the result of months and years of exposure to high levels of manganese. The only human study reported that people who drank water with high concentrations of manganese (i.e., doses of 0.059 mg/kg/day) over a 50 year period exhibited mild neurological signs. The calculated exposure dose of manganese for children (0.22 mg/kg/day) and adults (0.06 mg/kg/day) are slightly higher than this dose.

The exposure doses are based on a concentration detected in an off-site monitoring well, not in a drinking water well. Therefore, adverse health effects are not assumed to be occurring. However, the potential exists for adverse exposure to manganese to ensue if people are found to be using groundwater wells downgradient from LF-05. ATSDR has recommended that PGCHD survey the area off base from LF-05 for drinking water wells and Andrews AFB sample the water if wells are found.

Cancer

Not all contaminants in the environment have the potential to cause cancer. The known carcinogens detected are the Andrews AFB sites that ATSDR evaluated are: aldrin, arsenic, BHC, benz(a)anthracene, benzene, benzo(a)pyrene, benzo(b)fluoranthene, benzo(k)fluoranthene, bis(2-ethylhexyl)phthalate, chlordane, chloroform, chloroethane, chloromethane, chrysene, 4,4-DDD, 4,4-DDE, 4.4-DDT, dibenz(a,h)anthracene, 1,2-dichloroethane, dieldrin, heptachlor, heptachlor epoxide, indeno(1,2,3-c,d)pyrene, and methylene chloride. Carcinogenicity for a few other chemicals (e.g., tetrachloroethylene and trichloroethylene) is currently under review. ATSDR evaluated long-term exposures to the carcinogens detected in surface soil, surface water and sediment, biota, and groundwater at Andrews AFB. Using conservative exposure assumptions, ATSDR found that the levels of the carcinogens found in the various media do not pose a risk for excess cancer cases in the community at and surrounding Andrews AFB. ATSDR conservatively assumed that people were exposed to the maximum detected contaminant concentrations daily over the entire exposure period, even though samples collected at other times contained lower contaminant levels. Therefore, ATSDR does not expect any increase in cancer risk from exposures to surface soil, surface water and sediment, biota, and groundwater at and surrounding Andrews AFB.

APPENDIX C: RESPONSE TO PUBLIC COMMENTS

The Agency for Toxic Substances and Disease Registry (ATSDR) received the following comments during the public comment period (July 6 to August 20, 2001) for the Andrews Air Force Base (AFB) Public Health Assessment (July 2001). For comments that questioned the validity of statements made in the public health assessment, ATSDR verified or corrected the statements. The list of comments does not include editorial comments concerning such things as word spelling or sentence syntax.

Comment: A community member requested information about who would conduct the use survey of Piscataway Creek to find out if people are fishing on a subsistence level.

Response: Because fish in Piscataway Creek might be contaminated with chemicals from other plants located along the creek and not just Andrews AFB, ATSDR suggests that either government regulatory agencies or Andrews AFB undertake the survey. The text has been modified to reflect this change.

Comment: It is premature to issue a public health assessment for Andrews AFB prior to the completion of the investigatory work at SS-01, LF-05, ST-14, and FT-04. Historic data used by ATSDR may be incomplete or invalid at this point in time. It is requested that the issuance of the public health assessment be withheld until the additional investigatory data can be incorporated into the analysis.

Response: At present it does not appear that hazards are associated with these sites based on the following:

SS-01 (Brandywine Defense Reutilization and Marketing Office) was evaluated by ATSDR in a separate public health assessment (April 2001). No conclusions were made about this site in this public health assessment; therefore, new data are not relevant to this public health assessment.
There are no human exposures associated with FT-04 (Fire Training Area 4) because no drinking water wells are located downgradient from the plume originating at FT-04 and there is no public access to the site soil.
ATSDR has determined that an indeterminate health hazard exists for LF-05 (Leroy's Lane Landfill) until it can be confirmed that no downgradient shallow groundwater wells are being used to supply drinking water. It should be noted that public water is supplied to residents located downgradient from the site and the currently identified wells are not being used to supply drinking water.
ATSDR received and evaluated data in this public health assessment from the environmental investigation that was conducted last year at ST-14 (East Side Service Station; IT Corporation 2000b).

When new data become available, and if requested, ATSDR can re-evaluate potential public health impacts.

Comment: Prince George's County Health Department (PGCHD) agrees to perform another well survey on Foxley Road although a non-regulatory agency may be more productive. A previous attempt to survey the area in question met with resistance from the property owners. Often the Health Department is prevented from evaluating undocumented or shallow water supplies on occupied sites due to the concern that this office will condemn the well. The Health Department requested several times in the past that Andrews AFB contact the adjacent property owners on Foxley Road to determine the presence of wells. This was never done.

Response: It is ATSDR's understanding that during the remedial investigation at LF-05, Andrews AFB, with the help of PGCHD, will identify any downgradient private wells to ensure that no exposures to contaminated groundwater are occurring. Perhaps this partnered investigation will elicit better response from the property owners. ATSDR suggests that previous experiences with well owners be taken into account when conducting the current investigations at LF-05.

Comment: Although at one time Prince George's County was highly agricultural, that has changed rapidly in the past 10 years.

Response: The text was modified accordingly to include current land uses.

Comment: Please provide a map in the document that indicates the locations of the water towers.

Response: The locations of the water towers are now indicated on Figure 3.

Comment: Please incorporate the section in Appendix B that addresses PGCHD's concern about children and construction workers contacting contaminated groundwater from the LF-05 chlorobenzene seep in the main body of the text where groundwater contamination from LF-05 is discussed.

Response: PGCHD's concern is first addressed in the Community Health Concern section of the public health assessment, with a reference to Appendix B for more details. Appendix B was created to explain in more detail how ATSDR calculated exposures and determined health effects. These detailed evaluations are discussed in Appendix B, so as not to inundate the body of the document with overwhelming details. Keeping the supporting exposure evaluation text for PGCHD's concern about children and workers contacting the LF-05 seep in Appendix B is consistent with how all the supporting evaluation text is handled throughout the public health assessment.

Table of Contents

Agency for Toxic Substances and Disease Registry, 1825 Century Blvd, Atlanta, GA 30345
Contact CDC: 800-232-4636 / TTY: 888-232-6348

Department of Health and Human Services

Conc.:	Maximum concentration in parts per million (ppm)
IR:	Ingestion rate: adult = 100 milligrams (mg) per day; child = 200 mg per day
EF:	Exposure frequency, or number of exposure events per year of exposure: 365 days/year
ED:	Exposure duration, or the duration over which exposure occurs: adult = 30 years; child = 6 years
BW:	Body weight: adult = 70 kg; child = 10 kg
AT:	Averaging time, or the period over which cumulative exposures are averaged (6 years or 30 years x 365 days/year for noncancer effects; 70 years x 365 days/year for cancer effects)

Conc.:	Maximum concentration in parts per billion (ppb)
IR:	Ingestion rate: 0.15 liters per day^�
EF:	Exposure frequency, or number of exposure events per year of exposure: 130 days/year for recreational and 260 days/year for occupational
ED:	Exposure duration, or the duration over which exposure occurs: adult = 30 years; child = 8 years*
BW:	Body weight: adult = 70 kg; child = 28.1 kg*
AT:	Averaging time, or the period over which cumulative exposures are averaged (8 years or 30 years x 365 days/year for noncancer effects; 70 years x 365 days/year for cancer effects)

Conc.:	Maximum concentration in parts per million (ppm)
IR:	Ingestion rate: adult = 50 mg per day; child = 100 mg per day
EF:	Exposure frequency, or number of exposure events per year of exposure: 130 days/year for recreational and 260 days/year for occupational
ED:	Exposure duration, or the duration over which exposure occurs: adult = 30 years; child = 8 years*
BW:	Body weight: adult = 70 kg; child = 28.1 kg*
AT:	Averaging time, or the period over which cumulative exposures are averaged (6 years or 30 years x 365 days/year for noncancer effects; 70 years x 365 days/year for cancer effects)

Conc.:	Maximum concentration in parts per million (ppm)
IR:	Ingestion rate: adult = 54 grams per day^�; child = 27 grams per day^�
EF:	Exposure frequency, or number of exposure events per year of exposure: 365 days/year
ED:	Exposure duration, or the duration over which exposure occurs: adult = 30 years; child = 6 years
BW:	Body weight: adult = 70 kg; child = 10 kg
AT:	Averaging time, or the period over which cumulative exposures are averaged (6 years or 30 years x 365 days/year for noncancer effects; 70 years x 365 days/year for cancer effects)

Conc.:	Maximum concentration in parts per million (ppm)
IR:	Ingestion rate: adult = 2.73 grams per day; child = 0.39 grams per day
EF:	Exposure frequency, or number of exposure events per year of exposure: 365 days/year
ED:	Exposure duration, or the duration over which exposure occurs: adult = 30 years; child = 6 years
BW:	Body weight: adult = 70 kg; child = 10 kg
AT:	Averaging time, or the period over which cumulative exposures are averaged (6 years or 30 years x 365 days/year for noncancer effects; 70 years x 365 days/year for cancer effects)

Conc.:	Maximum concentration in parts per million (ppm)
IR:	Ingestion rate: adult = 2 liters per day; child = 1 liter per day
EF:	Exposure frequency, or number of exposure events per year of exposure: 365 days/year
ED:	Exposure duration, or the duration over which exposure occurs: adult = 30 years; child = 6 years
BW:	Body weight: adult = 70 kg; child = 10 kg
AT:	Averaging time, or the period over which cumulative exposures are averaged (6 years or 30 years x 365 days/year for noncancer effects; 70 years x 365 days/year for cancer effects)