PUBLIC HEALTH ASSESSMENT
AIR FORCE PLANT PJKS
WATERTON, JEFFERSON COUNTY, COLORADO
- How a chemical enters a person's blood after the chemical has been swallowed, has come into contact with the skin, or has been breathed in.
- Acute Exposure:
- Contact with a chemical that happens once or only for a limited period of time. ATSDR defines acute exposures as those that might last up to 14 days.
- Additive Effect:
- A response to a chemical mixture, or combination of substances, that might be expected if the known effects of individual chemicals, seen at specific doses, were added together.
- Adverse Health Effect:
- A change in body function or the structures of cells that can lead to disease or health problems.
- Antagonistic Effect:
- A response to a mixture of chemicals or combination of substances that is less than might be expected if the known effects of individual chemicals, seen at specific doses, were added together.
- 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.
- Used in public health, things that humans would eat - including animals, fish and plants.
- See Community Assistance Panel.
- A group of diseases which occur when cells in the body become abnormal and grow, or multiply, out of control
- Any substance shown to cause tumors or cancer in experimental studies.
- See Comprehensive Environmental Response, Compensation, and Liability Act.
- Small, partially underground septic tanks used for separating solids and agitating volatile organic compounds from sewage and wastewater before water is directed to a leach field.
- 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.
- Community Assistance Panel (CAP):
- A group of people from the community and health and environmental agencies who work together on issues and problems at hazardous waste sites.
- Comparison Value (CVs):
- Concentrations or the amount of substances in air, water, food, and soil that are unlikely, upon exposure, to cause adverse health effects. Comparison values are used by health assessors to select which substances and environmental media (air, water, food and soil) need additional evaluation while health concerns or effects are investigated.
- Comprehensive Environmental Response, Compensation, and Liability Act (CERCLA):
- CERCLA was put into place in 1980. It is also known as Superfund. This act concerns releases of hazardous substances into the environment, and the cleanup of these substances and hazardous waste sites. ATSDR was created by this act and is responsible for looking into the health issues related to hazardous waste sites.
- A belief or worry that chemicals in the environment might cause harm to people.
- How much or the amount of a substance present in a certain amount of soil, water, air, or food.
- See Environmental Contaminant.
- Delayed Health Effect:
- A disease or injury that happens as a result of exposures that may have occurred far in the past.
- Dermal Contact:
- A chemical getting onto your skin. (see Route of Exposure).
- The amount of a substance to which a person may be exposed, usually on a daily basis. Dose is often explained as "amount of substance(s) per body weight per day".
- Dose / Response:
- The relationship between the amount of exposure (dose) and the change in body function or health that result.
- The amount of time (days, months, years) that a person is exposed to a chemical.
- Environmental Contaminant:
- A substance (chemical) that gets into a system (person, animal, or the environment) in amounts higher than that found in Background Level, or what would be expected.
- Environmental Media:
- Usually refers to the air, water, and soil in which chemical of interest are found. Sometimes refers to the plants and animals that are eaten by humans. Environmental Media is the second part of an Exposure Pathway.
- U.S. Environmental Protection Agency (EPA):
- The federal agency that develops and enforces environmental laws to protect the environment and the public's health.
- The study of the different factors that determine how often, in how many people, and in which people will disease occur.
- Coming into contact with a chemical substance.(For the three ways people can come in contact with substances, see Route of Exposure.)
- Exposure Assessment:
- The process of finding the ways people come in contact with chemicals, how often and how long they come in contact with chemicals, and the amounts of chemicals with which they come in contact.
- Exposure Pathway:
- A description of the way that a chemical moves from its source (where it began) to where and how people can come into contact with (or get exposed to) the chemical.
ATSDR defines an exposure pathway as having 5 parts:
- Source of Contamination,
- Environmental Media and Transport Mechanism,
- Point of Exposure,
- Route of Exposure; and,
- Receptor Population.
- How often a person is exposed to a chemical over time; for example, every day, once a week, twice a month.
- Hazardous Waste:
- Substances that have been released or thrown away into the environment and, under certain conditions, could be harmful to people who come into contact with them.
- Health Effect:
- ATSDR deals only with Adverse Health Effects (see definition in this Glossary).
- Indeterminate Public Health Hazard:
- The category is used in Public Health Assessment documents for sites where important information is lacking (missing or has not yet been gathered) about site-related chemical exposures.
- Swallowing something, as in eating or drinking. It is a way a chemical can enter your body (See Route of Exposure).
- Breathing. It is a way a chemical can enter your body (See Route of Exposure).
- Lowest Observed Adverse Effect Level. The lowest dose of a chemical in a study, or group of studies, that has caused harmful health effects in people or animals.
- See Cancer.
- Minimal Risk Level. An estimate of daily human exposure - by a specified route and length of time -- to a dose of chemical that is likely to be without a measurable risk of adverse, noncancerous effects. An MRL should not be used as a predictor of adverse health effects.
- The National Priorities List. (Which is part of Superfund.) A list kept by the U.S. Environmental Protection Agency (EPA) of the most serious, uncontrolled or abandoned hazardous waste sites in the country. An NPL site needs to be cleaned up or is being looked at to see if people can be exposed to chemicals from the site.
- No Observed Adverse Effect Level. The highest dose of a chemical in a study, or group of studies, that did not cause harmful health effects in people or animals.
- No Apparent Public Health Hazard:
- The category is used in ATSDR's Public Health Assessment documents for sites where exposure to site-related chemicals may have occurred in the past or is still occurring but the exposures are not at levels expected to cause adverse health effects.
- No Public Health Hazard:
- The category is used in ATSDR's Public Health Assessment documents for sites where there is evidence of an absence of exposure to site-related chemicals.
- Public Health Assessment. A report or document that looks at chemicals at a hazardous waste site and tells if people could be harmed from coming into contact with those chemicals. The PHA also tells if possible further public health actions are needed.
- 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.
- A group of people living in a certain area; or the number of people in a certain area.
- Geologic time prior to 600 million years ago.
- Potentially Responsible Party. A company, government or person that is responsible for causing the pollution at a hazardous waste site. PRP's are expected to help pay for the clean up of a site.
- Public Health Assessment(s):
- See PHA.
- Public Health Hazard:
- The category is used in PHAs for sites that have certain physical features or evidence of chronic, site-related chemical exposure that could result in adverse health effects.
- Public Health Hazard Criteria:
- PHA categories given to a site which tell whether people could be harmed by conditions present at the site. Each are defined in the Glossary. The categories are:
- Urgent Public Health Hazard
- Public Health Hazard
- Indeterminate Public Health Hazard
- No Apparent Public Health Hazard
- No Public Health Hazard
- Receptor Population:
- People who live or work in the path of one or more chemicals, and who could come into contact with them (See Exposure Pathway).
- Reference Dose (RfD):
- An estimate, with safety factors (see safety factor) built in, of the daily, life-time exposure of human populations to a possible hazard that is not likely to cause harm to the person.
- Route of Exposure:
- The way a chemical can get into a person's body. There are three exposure routes:
- breathing (also called inhalation),
- eating or drinking (also called ingestion), and
- or getting something on the skin (also called dermal contact).
- Safety Factor:
- Also called Uncertainty Factor. When scientists don't have enough information to decide if an exposure will cause harm to people, they use "safety factors" and formulas in place of the information that is not known. These factors and formulas can help determine the amount of a chemical that is not likely to cause harm to people.
- The Superfund Amendments and Reauthorization Act in 1986 amended CERCLA and expanded the health-related responsibilities of ATSDR. CERCLA and SARA direct ATSDR to look into the health effects from chemical exposures at hazardous waste sites.
- Sample Size:
- The number of people that are needed for a health study.
- A small number of people chosen from a larger population (See Population).
- Source (of Contamination):
- The place where a chemical comes from, such as a landfill, pond, creek, incinerator, tank, or drum. Contaminant source is the first part of an Exposure Pathway.
- Special Populations:
- People who may be more sensitive to chemical exposures because of certain factors such as age, a disease they already have, occupation, sex, or certain behaviors (like cigarette smoking). Children, pregnant women, and older people are often considered special populations.
- A branch of the math process of collecting, looking at, and summarizing data or information.
- Superfund Site:
- See NPL.
- A way to collect information or data from a group of people (population). Surveys can be done by phone, mail, or in person. ATSDR cannot do surveys of more than nine people without approval from the U.S. Department of Health and Human Services.
- Synergistic effect:
- A health effect from an exposure to more than one chemical, where one of the chemicals worsens the effect of another chemical. The combined effect of the chemicals acting together are greater than the effects of the chemicals acting by themselves.
- Harmful. Any substance or chemical can be toxic at a certain dose (amount). The dose is what determines the potential harm of a chemical and whether it would cause someone to get sick.
- The study of the harmful effects of chemicals on humans or animals.
- Abnormal growth of tissue or cells that have formed a lump or mass.
- Uncertainty Factor:
- See Safety Factor.
- Urgent Public Health Hazard:
- This category is used in ATSDR's Public Health Assessment documents for sites that have certain physical features or evidence of short-term (less than 1 year), site-related chemical exposure that could result in adverse health effects and require quick intervention to stop people from being exposed.
Comparison values represent media-specific contaminant concentrations that are used to selectcontaminants for further evaluation to determine the possibility of adverse public health effects. Theconclusion that a contaminant exceeds the comparison value does not mean that it will cause adversehealth effects.
Cancer Risk Evaluation Guides (CREGs)
CREGs are estimated contaminant concentrations that would be expected to cause no more than oneexcess cancer in a million (10-6) persons exposed over their lifetime. ATSDR's CREGs arecalculated from EPA's cancer potency factors.
Environmental Media Evaluation Guides (EMEGs)
EMEGs are based on ATSDR minimal risk levels (MRLs). An EMEG is an estimate of dailyhuman exposure to a chemical (in mg/kg/day) that is likely to be without noncarcinogenic healtheffects over a specified duration of exposure.
Maximum Contaminant Level (MCL)
The MCL is the drinking water standard established by EPA. It is the maximum permissible level ofa contaminant in water that is delivered to the free-flowing outlet. MCLs are considered protective ofpublic health over a lifetime (70 years) for people consuming 2 liters of water per day.
Reference Media Evaluation Guides (RMEGs)
ATSDR derives RMEGs from EPA's oral reference doses. The RMEG represents the concentration in water or soil at which daily human exposure is unlikely to result in adverse noncarcinogenic effects.
Estimates of Human Exposure Doses and Determination of Health Effects
Deriving Exposure Doses
ATSDR estimated the human exposure doses/concentrations for past ingestion of Denver municipalwater originating from the Kassler Water Treatment Plant. Deriving exposure doses requiresevaluating the concentrations of the contaminants to which people may have been exposed and thefrequency and duration of those exposures. Health effects are also related to individualcharacteristics--such as age, gender, and nutritional status--that influence how a chemical might beabsorbed, metabolized, and eliminated by the body. Together, these factors help influence theindividual's physiological response to chemical contaminant exposure and potential noncancer(noncarcinogenic) or cancer (carcinogenic) outcomes. In the absence of site-specific exposureinformation, ATSDR applied several conservative exposure assumptions to define site-specificexposures as accurately as possible for residents near the AFP PJKS site.
Evaluating Potential Health Hazards
The estimated exposure doses are used to evaluate potential noncancer and cancer effects associatedwith chemicals of concern. When evaluating noncancer effects, ATSDR uses standard healthguidelines, including ATSDR's Minimal Risk Levels (MRLs) and EPA's Reference Doses (RfDs),to determine whether adverse effects will occur. The chronic MRLs and RfDs are estimates of dailyhuman exposures to a substance that are unlikely to result in adverse noncancer effects over aspecified duration. ATSDR compared estimated exposure doses associated with AFP PJKS exposurescenarios to conservative health guidelines such as MRLs or RfDs for each contaminant. If theexposure dose is greater than the MRL or RfD, then a possibility exists that noncancer effects couldoccur.
To evaluate cancer effects, ATSDR uses Cancer Potency Factors (CPFs) that define the relationshipbetween oral exposure doses and the increased likelihood of developing cancer over a lifetime. TheCPFs are developed using data from animal or human studies and often require extrapolation fromhigh exposure doses administered in animal studies to the lower exposure levels typical of humanexposure to environmental contaminants. CPFs represent the upper-bound estimate of the probabilityof developing cancer at a defined level of exposure; therefore, they tend to be very conservative (i.e.,overestimate the actual risk) in order to account for a number of uncertainties in the data used in theextrapolation.
ATSDR estimated the potential for cancer to occur using the following equation. (The estimatedexposure doses and CPF values for the contaminants of concern are incorporated into the equation):
Lifetime Cancer Risk = Estimated exposure dose (mg/kg/day) x CPF (mg/kg/day)-1
Although no risk of cancer is considered acceptable, it is impossible to achieve a zero cancer risk. Consequently, ATSDR often uses a range of 10-4 to 10-6 estimated lifetime cancer risk (or 1 newcase in 10,000 to 1,000,000 exposed persons), based on conservative assumptions about exposure,to determine whether a concern regarding cancer effects is valid. This range is consistent with valuesadopted by EPA for evaluating the need for cleanup at hazardous waste sites.
In addition to estimating the likelihood of noncancer and cancer effects, ATSDR reviewed theliterature to evaluate possible health effects associated with exposure at the doses/concentrationsestimated for the pathway described above.
Evaluation of Potential Exposure Pathways
Estimated Exposure From Ingestion of Municipal Water From the Kassler Water Treatment Plant
The following equation and assumptions were used to estimate exposure to contaminants in drinking water:
|Conc.:||Maximum concentration in the Kassler infiltration gallery water ( 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: 7 days/week x 52 weeks/year|
|ED:||Exposure duration, or the duration over which exposure occurs: adult=27 years; child=10 years|
|BW:||Body weight: adult=70 kg; child=16 kg|
|AT:||Averaging time, or the period over which cumulative exposures are averaged (10 years or 27 years x 365 days/year for noncancer effects; 70 years x 365 days/year for cancer)|
Assumptions for Estimating Exposure Doses
-- ATSDR assumed that an adult drinks 2 liters and a child drinks 1 liter of water a day and that all drinking water came from the affected source.
-- The exposure frequency (EF), or number of exposure events per year, was assumed to be 365 days per year, based on a 7-day-a-week exposure over 52 weeks per year.
-- The duration of exposure (ED) is assumed to have been a 27-year period for an adult. Thisvalue is the length of time that AFP PJKS had been in operation before the infiltrationgalleries at the Kassler Water Treatment Plant were closed. This 27-year figure most likelyoverestimates the actual duration of exposure, which was likely a small fraction of the 27 year maximum potential exposure period.
-- The averaging time (AT) was assumed to be 365 days/year for either 10 or 27 years for noncancer effects, and 70 years for 365 days/years for cancer effects.
Likelihood of Health Effects From Ingestion of Municipal Water From the Kassler Water Treatment Plant
The highest TCE, 1,1,1-TCA, and hexavalent chromium levels detected in the infiltration galleriesof the Kassler Water Treatment Plant before its closure in 1985 were below the MCLs. Nonetheless,community members are concerned about harmful effects from drinking water from the KasslerWater Treatment Plant. In response to the concern, ATSDR evaluated exposure to drinking watercontaining the maximum detected levels of TCE (3.1 ppb), 1,1,1-TCA (0.54 ppb), and hexavalentchromium (30 ppb) to determine whether a public health hazard existed.
Noncancer: Using the equation to calculate exposure dose, ATSDR estimated exposure doses from ingestion of municipal water with TCE (adult: 0.00009 mg/kg/day; child: 0.0002 mg/kg/day), 1,1,1-TCA (adult: 0.00002 mg/kg/day; child: 0.00003 mg/kg/day), and hexavalent chromium (adult: 0.0009 mg/kg/day; child: 0.002 mg/kg/day (see Table C-1). The resulting exposure doses for TCE and hexavalent chromium are lower than their respective health guidelines (MRLs) of 0.002 mg/kg/day and 0.003 mg/kg/day.(3) No chronic oral MRL is currently available for 1,1,1-TCA. For comparison, ATSDR reviewed the available toxicological literature to determine possible adverse effects associated with exposure at doses estimated for this pathway. On the basis of this review, the exposure doses estimated for 1,1,1-TCA by ATSDR are several orders of magnitude lower than the lowest doses reported in the toxicological literature capable of producing noncancer effects in experimental animals administered oral doses of 1,1,1-TCA (ATSDR, 1995a). Therefore, drinking water containing the highest detected levels of TCE 1,1,1-TCA, and hexavalent chromium reported in the Kassler Water Treatment Plant before its closure is not likely to result in adverse noncancer effect.
To account for dermal and inhalation exposures that might occur during domestic use of the water, ATSDR assumed that these exposures each equal the exposure from drinking the water. In applying this assumption, ATSDR multiplied the estimated oral dose by three (to account for all three routes: ingestion, inhalation, and dermal exposure) (see Table C-1). The resulting overall estimated doses are less than the MRLs for an adult and child exposed to TCE and for an adult exposed to hexavalent chromium. The estimated exposure dose for a child exposed to hexavalent chromium is slightly higher than the MRL. The slight difference does not indicate a public health hazard, however. It should be noted that the very conservative assumptions (e.g., exposure to the maximum concentration) used in the evaluation allowed ATSDR to estimate the highest possible exposure dose, even though ATSDR does not expect that children ever drank the most contaminated water for the 10-year potential exposure duration evaluated. Therefore, use of water for bathing, washing, and/or drinking would not have resulted in adverse health effects.
Cancer: TCE has been shown to cause cancer in laboratory animals given large doses. The link between TCE and cancer in humans drinking water is controversial, however. Available studies for TCE are inconclusive and the data are inadequate to establish a link. EPA is currently reviewing the scientific literature pertaining to the carcinogenicity of TCE to determine its cancer classification. As a conservative measure, ATSDR used the current CPF for TCE to estimate the excess lifetime cancer cases resulting from exposure to water containing the maximum concentration of TCE (3.1 ppb). ATSDR estimated 1 new cancer case per 1,000,000 persons could be expected if people are exposed over an extended period of time (see Table C-2). On the basis of these results, ATSDR concludes that ingestion of TCE at the levels detected in the infiltration gallery water, or even dermal contact or inhalation of its vapors, is not expected to result in an increased likelihood of developing cancer.
Maximum Contaminant Concentration (ppm)
|Estimated Exposure Dose (mg/kg/day)a||Total Estimated Exposure Dose (mg/kg/day)b||Health Guideline Oral (mg/kg/day)||Basis for Health Guideline|
Conc. = Maximum contaminant concentration measured in the Kassler Water Treatment Plant infiltration galleries, before closure (ppm)
IR = Ingestion rate: adult = 2 liters per day, child = 1 liter per day
EF = Exposure frequency, or the number of exposure events (1 event x 7 days x 52 weeks or 365 days per year)
ED = Exposure duration, or the duration over which exposure occurs: adult = 27 years; child = 10 years
BW = Body weight (kg): adult = 70 kg (154 pounds); child = 16 kg (35.2 pounds)
AT = Averaging time, or the period over which cumulative exposures are averaged (10 years or 27 years x 365 days)
b Total Estimated Exposure Dose = estimated exposure dose x 3 (to account for ingestion, dermal, and inhalation exposure routes)
c One detection of 0.07 ppm Cr VI was recorded during the evening of February 13, 1982. That detection represents an outlier in the available data set; the remainder of the detections falling in the range from 0.01 to 0.30 ppm Cr VI. For the purposes of this analysis, given the identified factors which mitigate any level used in these calculations, we selected 0.304 ppm as the representative maximum value represented in the data set.
Key: ppm = parts per million; mg/kg/day = milligrams contaminant per kilogram body weight per day; MRL = Minimal Risk Level ; RfD= Reference Dose
Maximum Contaminant Concentration (ppm)
|Estimated Exposure Dose-Cancer (mg/kg/day) a||Total Estimated Exposure Dose-Cancer (mg/kg/day) b||Cancer Potency Factor||Lifetime Cancer Risk c|
|Trichloroethylene||0.0031||0.00003||0.00009||0.011d||1 x 10-6|
Conc. = Maximum contaminant concentration in the Kassler Water Treatment Plant infiltration galleries, before closure (ppm)
IR = Ingestion rate: 2 liters per day
EF = Exposure frequency, or the number of exposure events (1 event x 7 days x 52 weeks or 350 days per year)
ED = Exposure duration, or the duration over which exposure occurs = 27 years
BW = Body weight (kg): 70 kg (154 pounds)
AT = Average time or the time over which cumulative exposures are averaged (70 years x 365 days)
b Total Estimated Exposure Dose = Estimated Exposure Dose x 3 (to account for ingestion, dermal, and inhalation exposure routes)
c Lifetime Cancer Risk = Total Estimated Exposure Dose (Cancer) x Cancer Potency Factor
d EPA is currently reviewing the CPF for TCE. ATSDR uses the previously derived CPF for screening purposes.
Key: ppm = parts per million; mg/kg/day = milligrams contaminant per kilogram body weight per day
At AFP PJKS, past operations and disposal practices have released contaminants to soil and surfacewater. Some of these contaminants have also migrated to groundwater. Contaminant fate andtransport discussions focus on the factors that influence how contaminants move and change afterthey have been released to the environment. Contaminants may migrate away from the point ofrelease in an unchanged form and/or may be changed (degraded) as they migrate. The followingprovides a brief overview of the physical and chemical properties that can affect how contaminantsmove through the environment, a description of several decrease contaminant concentrations in theenvironment, and a discussion of how several site-specific contaminants would be expected to moveand possibly degrade at AFP PJKS.
Physical and Chemical Properties
The most important factors that impact contaminant movement through the environment are thecontaminant's chemical and physical properties. Chemical and physical properties describe, forexample, how a contaminant interacts with water or how likely it is to enter the atmosphere. Eachcontaminant or group of contaminants have unique chemical and physical properties that influenceits movement. A description of several chemical and physical properties that strongly influencecontaminant migration is provided below. Table D-1 provides the chemical and physical propertiesfor the site-specific contaminants trichloroethylene (TCE), hydrazine, n-nitrosodimethylamine (NDMA), and hexavalent chromium.
- Water Solubility describes how easily a contaminant will dissolve in water. Solubility may beconsidered the most important chemical property when understanding contaminant movementin groundwater. Solubility measurements for most common organic compounds range frombelow 1 part per million (ppm) (low solubility) to 1,000,000 ppm (high solubility).
- Vapor Pressure describes how easily a contaminant in dry soil will volatilize to the atmosphere. A contaminant with a vapor pressure of less than 10-6 millimeters of mercury (mm Hg) will tend to remain in soil; above 10-6 mm Hg, the contaminant will tend to volatilize into the atmosphere.
- Henry's Law Constant combines water solubility with vapor pressure to describe how easilya contaminant in water or wet soil will volatilize to the atmosphere. Contaminants with aHenry's Law Constant higher than 10-3 atmospheres per cubic meter per mole (atm-m3/mole)are expected to easily volatilize; from 10-3 to 10-5 atm-m3/mole are expected to have moderatevolatilization; and below 10-5 atm-m3/mole are not expected to volatilize from water or wet soil.
- Specific Gravity measures the density of a contaminant in comparison to water. A contaminant that is not dissolved in water and has a specific gravity of greater than 1 is heavier than water and will tend to sink. A chemical that is not dissolved in water and has a specific gravity of less than 1 is lighter than water and will tend to float.
- Organic Carbon Partition Coefficient reflects the likelihood of a contaminant to remainadsorbed, or adhered, to soil. Normal ranges are from 1 to 107 milliliters per gram (mL/g).Lower values indicate a lower tendency to adhere to soil and higher values indicate a greatertendency to adhere to the soil. Contaminants with a low organic partition coefficient tend to be more mobile in the environment.
|Contaminant||Water Solubility (ppm)||Vapor Pressure (mm Hg)||Henry's Law Constant |
|Specific Gravity (unitless)||Organic Carbon Partition Coefficient (mL/g)|
|Hydrazine||miscible||10||no data||1.01||no data|
|NDMA||>100,000||0.1||no data||1.0||no data|
|Hexavalent Chromium||insoluble||negligible||not available||7.1||not available|
Migration and Degradation Processes
As contaminants move through the environment, contaminant concentrations decrease. Thisdecrease results from the physical process occurring during migration or chemical interactions andbiological processes that change or degrade the contaminant into new forms of chemicals. Physicalmigration and chemical degradation processes that may be occurring at AFP PJKS include:
Physical Migration Processes
- Molecular Diffusion is the random motion of chemical molecules from areas of highconcentration to areas of low concentration. An example of molecular diffusion is dripping redfood color into a still bowl of water. Initially, there is a small area with a deep red color, over time, however, all the water in the bowl becomes an even pink color.
- Turbulent Diffusion is the random motion of the air or water containing a chemical to move the chemical from areas of high concentration to low concentration. Turbulent diffusion occurs when red food color is dripped into a bowl of still water which is then stirred. All the water in the bowl quickly becomes an even pink color. Turbulent diffusion occurs in streams and rivers as water flows downstream and, to a lesser extent, in groundwater as water flows through pores and fractures.
- Dilution is the addition of uncontaminated water or air to an area of contamination. Dilution would occur when a bowl containing clear water is poured into a bowl containing pink water. The combination of water would become a paler pink. Another example is a stream with no surface water contamination flowing into a stream with surface water contamination. The resulting larger stream would have a lower surface water contaminant concentration.
Chemical Degradation Processes
- Hydrolysis is the interaction between a contaminant and water, either surface water or groundwater, to form new chemicals.
- Photolysis, or photodegradation, is the breaking of bonds that hold a contaminant together by the energy, or heat, in sunlight to form new chemicals.
- Biodegradation is the conversion of a contaminant by organisms, such as bacteria or fungi, toform new chemicals. Chlorinated compounds, such as TCE, are less likely to be biodegradedversus non-chlorinated compounds, such as hydrazine.
Fate and Transport of Site-Specific Contaminants
Understanding the chemical and physical properties for site-specific contaminants and potentialdegradation processes provides a basis for evaluating the overall fate and transport of contaminantsat AFP PJKS, as discussed below. Site-specific conditions, such as soil characteristics andgroundwater depth, will also impact contaminant fate and transport. The 1990 RemedialInvestigation and the 1999 Supplemental Remedial Investigation provide a more detailed evaluationof the fate and transport of contaminants at AFP PJKS.
TCE has been detected in on-site groundwater (to a maximum of 11,000 parts per billion [ppb]) andsurface water (to 22 ppb) at PJKS. Lower levels were measured off site. TCE is a colorless liquidwith a sweet odor and is mainly used as a solvent to remove grease from machinery parts. The watersolubility value of 1,000 ppm indicates that once released, TCE will dissolve readily in surfacewater or groundwater. Once in surface water or groundwater, two factors (Henry's Law Constantand the organic carbon partition coefficient) influence how TCE will migrate with surface water orgroundwater or migrate to other media, such as air or soil. The Henry's Law Constant is above 10-3,and indicates that TCE easily volatilizes to the air. TCE will volatilize to air from surface waterfaster than it will from groundwater because TCE in surface water is in direct contact with theatmosphere. Interactions between TCE and natural components of the atmosphere quickly degradeTCE into other chemicals. Studies have found that once in the atmosphere, approximately one halfof the TCE is degraded within one week. This degradation time, however, varies depending on theseason and temperature. TCE in groundwater will volatilize to the air found in soil and eventually tothe atmosphere. The organic carbon partition coefficient is low, indicating that TCE will only adhereto soil to a small degree. TCE, therefore, would be expected to be transported with water along thegroundwater or surface water flow pathways.
Chemical reactions in the air will quickly degrade TCE. Studies have found that hydrolysis andphotolysis do not substantially contribute to TCE degradation. Biodegradation does occur, but isminimal.
At PJKS, hydrazine (to 2,000 ppb on site) has been detected in the groundwater in the alluvium nearthe D-1 Test Stands. Hydrazine is a clear, colorless liquid with an ammonia-like odor and was oftenused as a component of rocket fuel or an additive to boiler water to reduce corrosion. Hydrazine'swater solubility is considered miscible, which means that an unlimited amount of hydrazine candissolve in water. As such, hydrazine released to either surface water or groundwater is expected tocompletely dissolve. Because hydrazine is very soluble in water, a high vapor pressure and Henry'sLaw Constant are needed for volatilization from water to occur. Hydrazine has a moderately highvapor pressure, indicating that volatilization from soil and water is likely. Although there are notenough data to determine the Henry's Law Constant, laboratory studies show that hydrazine inwater does readily volatilize. There are not enough data to determine the organic carbon partitioncoefficient for hydrazine, therefore, it is unknown how adherence to soil may influence hydrazinemovement in groundwater.
Once in air, hydrazine is completely degraded within a few minutes or hours by chemical reactionswith components of the atmosphere. In water and soil, chemical reactions with oxygen andbiodegradation will breakdown hydrazine. The primary chemical reaction in water producesnitrogen gas and water. In oxygen deficient waters, ammonia may also be produced. The rate atwhich the processes occur depend on site-specific conditions such as water quality and soilcharacteristics.
N-Nitrosodimethylamine (NDMA) (to 42 ppb) was detected in groundwater in the alluvium andbedrock along the East Fork area of AFP PJKS. NDMA, which is a breakdown product ofhydrazine, is a yellow, oily liquid with a faint odor. Similar to hydrazine, NDMA has a high watersolubility indicating that NDMA detected in groundwater is likely completely dissolved.Volatilization to air from water is expected because NDMA has a moderately high vapor pressure.Currently, there are not enough data to determine the Henry's Law Constant or organic carbonpartition coefficient. The tendency for NDMA to volatilize from water or adhere to soil, therefore, isunclear. NDMA, however, could be expected to move with groundwater flow based on its highwater solubility.
Hexavalent chromium has been detected in groundwater downgradient of the Inactive Site at theLockheed Martin Astronautics property surrounding AFP PJKS. Chromium, usually as trivalentchromium, is a naturally occurring element in the environment. Hexavalent chromium is generally produced by industrial processes. Hexavalent chromium is not found in the environment as anindividual molecule but as part of a compound, such as calcium chromate or potassium chromate.Hexavalent chromium is considered insoluble in water. If released to water, only very small amountsof the hexavalent chromium will dissolved; most will bind with soil, sediment, or other particles inthe water to form chromium compounds. As indicated by the vapor pressure and Henry's LawConstant, hexavalent chromium will not volatilize. When detected in water samples, hexavalentchromium is usually present adhered to suspended particles versus dissolved in the water. Based onhexavalent chromium's tendency to adhere to soil and its inability to volatilize, it is often consideredimmobile in the environment and most likely migrates with windblow dust or with particlessuspended in surface water or groundwater flow.
Chromium is a naturally occurring element in the environment, and therefore, will not degrade.Chromium, however, may be transformed from the hexavalent form to the trivalent form throughchemical reactions with organic matter in water.
ATSDR. 1997. Toxicological Profile for Hydrazines. Agency for Toxic Substances and DiseaseRegistry. U.S. Department of Health and Human Services. September 1997.
ATSDR. 1997. Toxicological Profile for Trichloroethylene (Update). Agency for Toxic Substancesand Disease Registry. U.S. Department of Health and Human Services. September 1997.
ATSDR. 1998. Toxicological Profile for Chromium (Draft). Agency for Toxic Substances andDisease Registry. U.S. Department of Health and Human Services. August 1998.
Hemond, H. and E. Fechner. 1994. Chemical Fate and Transport in the Environment. Academic Press. San Diego, California.
The Agency for Toxic Substances and Disease Registry (ATSDR) received the followingcomments/questions during the public comment period (April 9 to July 1, 1998) for the AFP PJKSPublic Health Assessment (PHA) (April 8, 1998). Comments were received from a total of sevenrespondents, including four from government or business entities and three from communitymembers or groups. Comments from the latter group were highly critical of the PHA and resulted inan extended fact-finding effort conducted by the ATSDR Ombudsman which concluded late in1999. Interested parties raised numerous issues during this fact-finding effort and were encouragedto supply or identify factual materials or information to ensure that the scope and content of thisassessment was accurate. In this section ATSDR documents our reply to the issue or question posedin the comment and indicates if changes or additions were made to the text.
For comments that questioned the validity of statements made in the PHA, ATSDR verified or corrected the statements. The list of comments does not include editorial comments concerning such things as word spelling or sentence syntax. ATSDR has not addressed requests for information to be included in the PHA, unless the party who filed the request provided the supporting documentation.
- Comment: Community members are concerned that trichloroethylene (TCE) reached DeerCreek Mesa wells located 1.5 to 2 miles north of the AFP PJKS property. Specify whetherinformation obtained since the 1987 sampling is available to suggest that contamination from AFP PJKS is migrating toward these wells.
- Comment: The text should be modified to reflect that the actual sampling data, whichindicates that eight Deer Creek Mesa (8) private wells and two (2) surface water samplelocations, were sampled by EPA's contractors.
- Comment: Specify whether chemicals other than TCE have been detected in the samplescollected from Deer Creek Mesa wells and whether these chemicals are present at levels that could be harmful to human health.
- Comment: Due to the rapid growth in the residential area surrounding the plant, 1990 censusinformation does not accurately reflect the number of residents living in the area. More recent census data should be used.
- Comment: Specify whether AFP PJKS contamination has migrated via groundwater beyond the Lockheed Martin Astronautics property boundary.
- Comment: Indoor air samples were not taken on site, therefore it is unknown whether or notworkers were actually exposed to unacceptable levels of indoor air contaminants emanatingfrom the groundwater/soil contamination. ATSDR cited infrequently detected soil gas as therationale that a hazard does not exist from this pathway. It is the Colorado Department ofPublic Health and the Environment's (CDPHE) experience that indoor air concentrations donot always correlate with soil gas concentrations. CDPHE contends that indoor air sampling is needed to more fully evaluate this exposure pathway.
- Comment: The concentrations of TCE and 1,1,1-trichloroethane (1,1,1-TCA) used tocalculate past exposures were 3.1 and 0.5 parts per billion (ppb), respectively. Samplescollected from alluvial groundwater monitoring wells in the vicinity of the Kassler WaterTreatment Plant contain contaminant concentrations that exceed those detected in theinfiltration galleries. Please explain why the infiltration galleries contaminant concentrations were used in estimating exposure.
- Comment: ATSDR estimated total doses from ingestion, dermal contact, and inhalation forpeople using the Kassler Water Treatment Plant water by multiplying the ingested dose bythree. CDPHE concurs that this is an acceptable way of quickly estimating the total dose forall three pathways. For emphasis, the information should also be added Tables C-1 and C-2 in Appendix C.
- Comment: Specify what type of post thorium-drum-removal verification was conducted and whether any residual contamination might affect soils or groundwater.
- Comment: Specify why risk from fish ingestion, or water quality standards that account forfish health, were not considered when evaluating potential exposure to contaminants in Brush Creek.
- Comment: Specify whether ATSDR has had access to all site data. Because ATSDR has notdiscussed what appears to be obvious chemicals of concern in on-site soil, there is someconcern that ATSDR may not have considered all appropriate data.
- Comment: The hypothetical scenario used by ATSDR's risk scenario is unhelpful andmisleading. No one ever drank undiluted water straight from the galleries. The water wasdiluted, typically containing more than 80% river water from upstream sources. It is alsouncontested in the Renaud case that the plaintiffs could have only received Kassler waterintermittently during two discrete time periods and, during those times less than 10% of thewater they received came from Kassler and only a tiny percentage of that came from thegalleries. Accordingly, Lockheed Martin Astronautics recommends that ATSDR reevaluatesthe potential risk based on the known facts, including actual dilution factors, actual periods oftime where complete exposure pathways were possible, and the actual efforts of chlorination and volatilization.
- Comment: The discussion of the amount of Kassler water distributed to Friendly Hills shouldmore accurately indicate that the water could only have reached Friendly Hills on anintermittent basis during two windows of time: June 1997 through December 1980 and June1982 through February 1983.
- Comment: Could hydrazines from AFP PJKS have reached the Kassler area ?
- Comment: What are the potential impacts from the synergistic effects between hydrazines and chlorine ?
- Comment: Did ATSDR consider the evaluation of contaminant migration as cited in theMiller, Huber, and Motz 1989 report on groundwater contamination at the Martin MariettaWaterton Facility and the Kassler Water Treatment Plant?
Response: ATSDR's assessment of potential contamination of drinking water in Deer CreekMesa wells is based on information presented in the environmental investigation documentsand well monitoring results (Earth Tech, 1996; Engineering Science, 1988, 1989, 1990;Geraghty & Miller, Inc. 1990; Parsons Engineering, 1999). ATSDR recognizes that samplingof the Deer Creek Mesa wells occurred over 10 years ago. Results from off-post groundwatermonitoring located on the Lockheed Martin Astronautics (LMA) property surrounding theAFP PJKS site indicate that contamination has not migrated beyond the LMA property. Inaddition, the observed elevations of the watertable in areas of concern and the areahydrogeology strongly suggest that TCE could not migrate to the Deer Creek Mesa wells. Theextent of off-site migration is limited because the bedrock and alluvial groundwater dischargesto a tributary of the Lariat Gulch where the contaminants are rapidly volatilized. The tributaryis approximately 3,500 feet southwest (and upstream) of the point where Lariat Gulch exitsthe LMA property. Together, these findings provide compelling evidence that contaminationhas not reached the Deer Creek Mesa wells.
Response: Thank you. The text has been modified as suggested.
Response: Methylene chloride and acetone were detected in 1987 samples collected fromDeer Creek Mesa wells. These chemicals were also found at similar concentrations in bothfield and trip blanks for sampled wells. Field blanks are prepared to detect errors resultingfrom the sampling process; while trip blanks detect possible laboratory contamination. Giventhat methylene chloride and acetone were detected in the blanks at levels similar to those in thewell samples, it seems highly unlikely that the aquifer or private well water is actuallycontaminated with either of these two chemicals. A note has been added to the text indicatingthat methylene chloride and acetone were detected in the samples and that they are probably unrelated to the site.
Response: ATSDR reviewed the U.S. 1990 census data because it is the most recent censusdata available. The area surrounding AFP PJKS may be more populated than it was in 1990,but the public health assessment identified no off-site environmental hazards. For this reason,ATSDR believes that a more elaborate review of census data was not warranted. ATSDR willuse the year 2000 U.S. census data when it becomes available.
Response: To date, several rounds of monitoring of strategically-placed groundwater wellsindicate that none of the suspected contaminants associated with the AFP PJKS site pose athreat to off-site areas. AFP PJKS-related contaminated groundwater is either contained withinthe AFP PJKS property or within the surrounding LMA property. Some pathways for off-sitemigration of LMA contaminants detected in alluvial groundwater have been identified withinthe South Central Valley, including Filter Gulch and the west branch of Brush Creek. To date,the AFP PJKS plumes do not appear to have migrated near Filter Gulch or toward BrushCreek in significant quantities.
Response: Likewise, ATSDR prefers to evaluate indoor air monitoring data when assessingpotential environmental exposures. According to occupational safety personnel at the site, airmonitoring data are not available, but they indicate that site conditions have not promptedconcerns about indoor air quality. In the absence of these data, however, ATSDR took a two-step approach to evaluating the potential for harmful exposure to indoor air contaminants.First, ATSDR identified on-site buildings located in the path of the plumes. The only buildingsidentified in the path of a plume are the T-6 Block House and the Propulsion ResearchLaboratory in located in the northern section of the site. Second, ATSDR reviewed soil gasconcentrations (1.4 ppm) collected near these buildings and estimated indoor airconcentrations values based on a conservative or "safe" screening approach. Using thisscreening approach, it appears that the estimated indoor air concentration is safely below levelsassociated with public health hazards. Furthermore, on the basis of this screening evaluation, indoor air monitoring is not deemed necessary.
Response: Whenever possible, ATSDR uses data collected directly from drinking water wellsor groundwater collections system, rather than data from monitoring wells. There are manyfactors that can result in differences in contaminant levels measured in monitoring wells andthose actually detected in the private or municipal water well or infiltration system. ATSDRbelieves that the contaminant levels detected in the water in the Kassler galleries or the Five-Sided Well more accurately represent the raw-groundwater component supplied as acomponent of the water processed by the Kassler Water Treatment Plant. For this reason,ATSDR used contaminant concentrations detected in the infiltration gallery system in ourexposure dose assessment. It should be noted that contaminant concentrations in the gallerieswould have been greatly diluted within the treatment and distribution system before reaching any residential taps.
Response: Magnesium-thorium alloy was used by the Air Force in the production of missiles.In 1971, 25 kilograms (or 55 pounds) of magnesium-thorium alloy shavings were disposed ofin the D-1 Landfill. This waste contained a total of 55.5 microcuries of radioactivity. In 1986,the drums containing the waste were removed from the landfill and transported to an approvedoff-site radioactive material handling facility. At the time of removal, the drums were intactand rust-free. Monitoring also confirmed that the drums emitted only background levels ofradiation. Based on this information, radioactive waste from the drums could not have enteredthe surrounding soil or groundwater at levels above background.
Response: TCE was the only site-related contaminant detected in the creek (surface water orsediment) at elevated levels. Together, TCE's experimentally measured bioconcentrationfactor--a measure of a chemical's tendency to partition to the tissue of organisms--andscientific literature indicate that TCE does not readily accumulate in fish tissue. For this reason, ATSDR considers exposure to site-related contaminants from ingestion of Brush Creek fish to be minimal.
Response: ATSDR conducted its evaluation and made conclusions and recommendationsbased on environmental data and exposure information most pertinent to the site that havebeen provided by AFP PJKS; LMA; local, state, and federal agencies; and the public. Ifanyone has additional information on the pathways addressed in the PHA, or evidence of otherpotential exposures, ATSDR encourages that person to share the information with us so that we can determine whether a health hazard exists.
In regards to our evaluation of on-site chemicals, it must be remembered that this public healthassessment is an evaluation of human exposure to contamination. ATSDR considers thepotential for on-site exposure to be low, even though high concentrations of certaincontaminants have been measured on site. ATSDR suggests that the high on-site soilcontaminant concentrations present more of a remediation concern than a human healthconcern.
Response: The situation described herein by Lockheed Martin Astronautics is an accuratecharacterization of past conditions. ATSDR's exposure scenario, however, represents ahypothetical event (considering worst case conditions) using the hypothetical maximumconcentration--the actual concentrations at the taps would have been much lower than themaximum detected in the infiltration galleries. This hypothetical maximum exposure scenarioassessment is not intended to describe actual past exposures to specific contaminant levels,rather, it is designed to illustrate that, even if these past exposure levels and exposurescenarios existed, no adverse health effects would have resulted.
Response: ATSDR has reviewed the summary of the Renaud case in the Ferrara citations.Accordingly, we have modified the exposure discussion to more accurately reflect the twowidows of time during which Friendly Hills could have received water from the Kassler WaterTreatment Plant distribution lines. The information in the Ferrara citations indicates, however,that the upper bound on the second window of time is December 1984, not February 1983 assuggested. Based on this information, we have modified our discussion to reflect the timeperiods (June 1997 through December 1980 and June 1982 through December 1984) forwhen Kassler Water Treatment Plant water could possibly have reached Friendly Hills.
Response: No evidence exists to suggest that hydrazines has been detected in surface water orgroundwater beyond AFP PJKS/LMA site boundaries, or that they reached the Kassler area. ATSDR contacted scientists at Wright-Patterson AFB and Brooks AFB to gather moreinformation about the uses of hydrazines at the AFP PJKS site. Hydrazines (referringcollectively at this site to hydrazine, monomethylhydrazine, and unsymmetrical dimethylhydrazine [UDMH]) are clear, colorless liquids used for rocket fuels. Testing of rocket engineswith hydrazine fuels resulted in inadvertent releases of hydrazines on site and generation ofhydrazine-containing waste/rinse water, which was collected, treated, and recycled forsubsequent rocket engine testing. Any inadvertent release of those rinse waters to Lower BrushCreek from the T-8A pond (the downgradient component of the collection system) would havebeen treated rinse waters.
Any hydrazines that may have been released from PJKS are unlikely to have migrated to theKassler area for several reasons. First, hydrazines break down readily in the environment.Most of the hydrazines were released to the air, where they quickly dissipated. Smalleramounts of hydrazines entered surrounding soil or surface water. Hydrazines released to on-site soil or surface water either evaporated into the air, dissolved in surface water, or bound tosoil, but most eventually dissipated. Second, the waste/rinse water was treated in a two stepprocess using hydrogen peroxide and an acid base neutralizing tank. This treatment reducedthe concentrations or removed hydrazines from the waste/rinse water before it was released tothe T-8A pond. Third, a substantial amount of reduction-known as biodegradation-occurswhen hydrazines move through an environment rich in organic mater. The organic material inthe stream bed and in the muddy water of Brush Creek would have further adsorbed anddegraded any residual hydrazines that entered the creek. Fourth, and most importantly,monitoring conducted by the Air Force found no evidence of hydrazines in off-site surfacewater or groundwater, further supporting that hydrazines could not have reached the Kassler area.
It should be noted that monitoring sponsored by the National Toxics Campaign (NTC) reportsfindings of hydrazines in off-site surface water samples collected from Lower Brush Creek.The NTC data, however, have largely been discredited because of a number of suspectpractices and errors associated with sample collection, analysis, and handling. Critical reviewof the NTC sampling, analysis, and data discloses the following problems: use of a methodprone to false positive results (ASTM D 1385); use of inadequate analytical equipment; laxquality control and assurance practices (i.e., poor record keeping [no record or chain ofcommand for samples; no record of a sampling plan or a sampling procedure, no record ofsampling date]); and lax laboratory procedures (i.e., failure to calibrate the analyticalequipment for hydrazine, failure to perform a duplicate sample for hydrazine, failure todetermine a detection limit for hydrazine). Because of these problems, the data are ofquestionable quality and have little usefulness for evaluating the potential for human health hazards in our public health assessment.
Response: ATSDR also asked Wright-Patterson AFB and Brooks AFB scientists about hydrazines' "interactions" with chlorine. Chlorine interacts with hydrazine to initiate theoxidation process. As a result of the oxidation process, hydrazines are broken down, resultingin greatly reduced concentrations and the release of breakdown byproducts. One primarybreakdown product of UDMH is nitrosodimethylamine (NDMA), a compound shown to causecancer in laboratory animals but not in human. Site information does not suggest that AFPPJKS used chlorine in its treatment process. Rather, as noted in Response 14, AFP PJKStreated rinse water containing hydrazine with hydrogen peroxide and an acid-base neutralizingsolution. Through these treatment processes, hydrazines were reduced to nitrogen and water(by its interaction with hydrogen peroxide). The Air Force monitored for hydrazine andNDMA levels in surface water and groundwater, but they found no levels above detectionlevels beyond site boundaries.
Kassler Water Treatment Plant used chlorine at their facility. Water entering the KasslerWater Treatment Plant was chlorinated at the well head and then pumped into storage tanks,where it was blended with ammoniated water and chlorinated again. In the unlikely event thatwater containing hydrazines reached Kassler Water Treatment Plant, chlorination would havefurther reduced hydrazines in water.
Response: The report in question is the Miller et al. 1989 report that was prepared andsubmitted on behalf of the plaintiffs in the Friendly Hills Renaud litigation. The reportevaluated and attempted to support the assertion that water entering and leaving the Five-sidedwell at the Kassler Water Treatment Plant between 1975 and 1985 was contaminated withharmful levels of chemicals from the AFP PJKS and the Lockheed Martin Astronauticsfacilities. Based on an evaluation of contaminants originating at Tanks 6032 and 6034 andreleased from the T-8A pond (or Lockheed Martin Astronautics aeration ponds) into BrushCreek, the report concluded that 88 part per billion (ppb) total hydrazine and 7.6 ppbtrichloroethylene (TCE) could have entered the Five-sided well at the Kassler facility.
The report was critically evaluated by a neutral expert (a geochemist/chemical hydrogeologist)appointed by the court. The expert found that the conclusions drawn in the report could not bereasonably relied upon because of a number weaknesses in the evaluation, including the use ofquestionable assumptions, misrepresented facts, factual omissions, poor documentation, andflawed methodology.
Following the expert review of the report, as well as testimony by the report's lead author, thecourt ruled that the report was "inadmissable as a matter of law because the opinions werebased on fundamentally flawed methodologies and incorrect assumptions." Without credibleevidence of contamination in the Five-sided well at the Kassler Water Treatment Plant, therewas no basis for proceeding with the plaintiff's claim that contaminants originating at AFPPJKS or Lockheed Martin Astronautics had reached residential taps.
ATSDR also reviewed the report and the expert's evaluation. While the report used a standardapproach to evaluating contaminant transport, ATSDR found that the authors relied uponassumptions at various steps that oversimplified the analysis of contaminantconcentration/migration, ultimately leading to overestimates of the contaminant concentrationsentering Kassler's system. Because of the problems in the evaluation, ATSDR was unable torely upon the data presented in the report for its assessment of potential human health hazards.Summaries of a few of the inappropriate assumptions or misinterpretation of data are providedbelow:
Estimating source (contaminant) loading.The source loading concentration is the initialconcentration of hydrazine, UDMH, and NDMA (and TCE) present in rinse water from Tanks6032 and 6034. This concentration was assumed to have been released to Pond T-8A.
- The authors selected a maximum pretreated concentration of 2,000 milligrams per liter(mg/L) of hydrazine rinse water from Tanks 6032 and 6034. In selecting this concentration,the authors assumed that untreated rinse water entered Pond T-8A. The rinse water from thetanks, however, was treated with copper sulfate and hydrogen peroxide prior to discharge toPond T-8A. Treated rinse water discharged to Pond T-8A would have contained lowerconcentrations of hydrazine and other contaminants than pretreated rinse water.
- The authors used a concentration measured at a single location to describe the continuousrelease of a contaminant over an 11-year period. This approach is not a scientifically soundpractice for describing the continuous release of a contaminant over a long time.
Estimating discharge/flow from Pond T-8A/aeration pond into Brush Creek. This stepattempted to predict the amount of rinse water, and ultimately the amount of hydrazine andother contaminants, that was released from Pond T-8A and the Lockheed Martin Astronauticsaeration ponds into Brush Creek.
- The authors assumed that the contents from Tank 6032 always discharged to a full Pond T-8A, and that the contents of the full pond overflowed/were flushed to Brush Creek.Available information indicates the Pond T-8A was not always full. Rather, water from thepond was regularly pumped to tanks located at the top of an adjacent hill that were used for the deluge area and fire control.
- The authors assumed that hydrazine was continuously released with water from the aerationpond on the Lockheed Martin Property. Documentation indicates that the aeration pond wasclosed and bypassed at times, thereby suggesting that there may not have been continuousreleases of hydrazine from the aeration pond into the Brush Creek (West Branch).
- The authors estimated the steam flow in Brush Creek at a rate of 174 gallons per minute(gal/min). Hydrographs for surface water monitoring stations along the East Branch ofBrush Creek, however, suggest that the average flow in the vicinity of Pond T-8A wasmuch lower, approximately 14 gal/min.
Estimating concentrations entering and leaving Kassler system/Five-sided well . Throughthis step, the authors attempted to predict contaminant concentrations that would reach and beintercepted by the Kassler infiltration gallery and eventually enter the Five-sided well.
- The methodology used to derive an average travel time through surface water pathwaysconsidered a steady-state flow. The surface water flow data presented in the 1989 remedialinvestigation, however, indicate that there are several perennially gaining and losing streamreaches along Brush Creek. These nonuniform conditions and significant losses of surfacewater to the groundwater suggest that the use of the steady-state flow assumption is notappropriate.
- The authors assumed that 11.5% of the Lower Brush Creek stream flow is lost togroundwater in the Platte River area. Stream flow data for stations in the areas of the river indicates that the area is characterized by a net gain in stream flow, not a loss.
- The authors assumed that 90% of the surface water flow of Lower Brush Creek thatinfiltrates into the saturated alluvium was intercepted by the infiltration gallery and theFive-sided well. This assumption did not consider travel time in groundwater anddegradation processes from the creek to the gallery, thus leading to an overestimate of the predicted concentration that predicted to entering the well.
- The authors did not consider contaminant concentration reductions that would have resultedfrom the chlorination process. Groundwater flowing into the Five-sided well waschlorinated at the well head and then pumped into two storage tanks at the Kassler WaterTreatment Plant, where it was blended with ammoniated water and chlorinated again. Anyhydrazine entering the system would have been rapidly oxidized, and thus concentrations ofhydrazine, UDMH, and NDMA would have been greatly reduced. A pilot study conductedby Lockheed Martin Astronautics in 1989 indicated that concentration of hydrazine,UDMH, and NDMA are reduced by 67%, 69%, and 58% respectively, following 29minutes of chlorination.
For the reasons given above, and because hydrazine, UDMA, or NDMA was never detected inoff-site groundwater, surface water, or raw water in the Five-sided well, ATSDR cannot baseits findings of potential past human health hazards upon data presented in the Miller et al.1989 report.
Response: The commenter may have been referring to the results of a 1986 sampling in which1,1,1-TCA (1.5 to 1.6 ppb) and 1,2-dichloroethylene (1.6 ppb) were detected in one hot watertank in a home at Friendly Hills. The levels detected in the hot water tank were safely belowEPA's maximum contaminant levels (MCLs) for drinking water. No VOCs were detected inone occupied or two additional unoccupied homes tested at Friendly Hills. Although thesource of the low levels of VOCs in the one hot water tank is still unknown, it would bereasonable to assume that contamination occurred during manufacturing, operating, orinstallation of the individual tank rather than through the water supply that served all tested homes.
Response: ATSDR contacted Kirkland Air Force Base for information aboutradioactive/nuclear material uses at AFP PJKS. Kirkland AFB oversees and maintains allrecords on closure at former Atomic Energy Commission (AEC) munition sites that weretransferred to the Air Force in 1965. Based on records searches and discussion with staff noevidence exist suggesting that AFP PJKS conducted AEC operations. ATSDR also contactedLMA to gather more information about the use and occurrence of radioactive materials at theirWaterton facility. According to the LMA safety officer, LMA has never been involved withthe design and production of radioactive/nuclear materials or weapons. They acknowledge thattheir Waterton facility used small amounts of radioactive materials in finished products. Thematerial used by LMA either: 1) required a license and storage in a "sealed source" (designedand approved by state or federal regulatory agencies), or 2) required minimal control or wereexempt from licensing due to low hazard potential (e.g., smoke detectors, laboratory samplestandards). In either case, the material had only low radioactive emissions. Any unusedmaterial was either returned to the original suppliers or disposed of in a permitted low-levelradioactive waste site. Some small amounts of radioactive materials were disposed of incontainers in on-site landfills; these containers have been removed and shipped off site to apermitted disposal facility.
LMA representatives also state that LMA had never mined or processed radioactive materialsat their Waterton facility. During the mid-1970s, LMA was approached with a proposal toexplore approximately 80 acres of the southwest portion of the site (and beyond the siteboundaries) for geological radiologic materials. The exploration proposal did not, however,result in mining activities at the Waterton facility.
Response: Much attention has been given to the occurrence of cancer or other health problemsin areas of Denver that received water from Kassler Water Treatment Plant. Some communitymembers believe that materials from LMA/AFP PJKS entered the drinking water supply (atthe Kassler Water Treatment Plant). They also believe the suspected contaminants in theirdrinking water contributed to alleged high rates of childhood cancer and other healthproblems (low birth weight, birth defects) among residents of the Friendly Hills/HarrimanPark neighborhoods of Denver.
In 1983, a community group conducted an informal, self-reported investigation of healthproblems in these neighborhoods. Although the community-organized survey reported anelevated number of unexplained illnesses and childhood cancer, a subsequent review by theColorado Department of Public Health and Environment (CDPHE) found neither frequentreports of chronic health problems (the most common problems were headaches and diarrhea)nor a viable means of exposure to chemicals at LMA or AFP PJKS.
Continued public health concern prompted CDPHE to conduct an investigation into thereported childhood cancer cases. An analysis of all childhood malignancies (ages 0-14 years)reported during 1979-1982 in a selected census tract (120.17) in the neighborhood of concern(population of 4,000) showed there were five cases of childhood cancer; this rate wasstatistically significant and was approximately 2.5 times the expected rate of 2. An extensivefield investigation of ground, surface, and drinking water, basement sumps, soils, sediments,and air conducted by EPA in 1984 showed all detected substances to be within normalbackground ranges. In the fall of 1984, a second cancer incidence investigation was conductedin 1984 for the original census tract (120.17) and an adjoining tract (120.16 ;CDPHE, 1985).The childhood cancer rates from 1979 through 1983 were not found to be statisticallysignificantly different from the rest of Jefferson County. The data, methods, and results of thisstudy were submitted for review and confirmation to the Cancer Branch, Center forEnvironmental Health, Centers for Disease Control. In December, 1984, the consensusreported to the residents of Friendly Hills/Harriman Park were told that the cancer "cluster"was most likely due to chance. While the results of the EPA environmental investigation andthe CDPHE (1985) cancer rate investigation satisfied many of the Friendly Hills/HarrimanPark residents, concern remained high among others. At the request of those residents, inMarch, 1985 a summary of the CDPHE review the incidence of non-cancer outcomes in thepreviously studied census tracts was made available to residents and made an addendum to thefinal report (CDPHE, 1985). Rates of neonatal deaths, fetal loss, birth defects, and low birthweight were found to be within statistically expected ranges for Jefferson County. Again at therequest of area residents, CDPHE conducted a follow-up review of the health statistics for1984 to update the previously reported 1979-1983 findings. Those data continued to showthat the incidence of childhood cancer, birth defects, fetal loss, neonatal deaths, and lowbirthweights were within expected limits.
ATSDR's Division of Health Studies (DHS) evaluated the methodology and findings of theCDPHE (1985) "Investigation into alleged health problems in the Friendly Hills/HarrimanPark Area" and the John Hopkins Oncology Center study entitled "Statistical report to theDenver Water Board concerning childhood cancer incidence and neonatal deaths in theDenver metropolitan area, 1979-1987" (Piantodosi, 1990). Together, the weight of all thestudies conducted to date suggest that there is no evidence of high rates of childhood cancer orhealth problems affecting infants or children that might be attributed to living in theseneighborhoods or from drinking water from the Kassler Water Treatment Plant. A summary ofeach study and ATSDR's DHS's conclusions are described below.
- Investigation into Alleged Health Problems in the Friendly Hills/Harriman Park Area. (CDPHE, 1985)
- Statistical Report to the Denver Water Board Concerning Childhood Cancer Incidence and Neonatal Deaths in the Denver Metropolitan Area, 1979-1987 (Piantadosi, 1990)
In response to a 1984 Citizen's Advisory Committee request for a study on alleged healthproblems in the Friendly Hills/Harriman Park area, the CDPHE (at the time known as theColorado Department of Health) completed a descriptive epidemiologic study of childhoodcancer, birth defects, fetal loss, neonatal deaths, and low birth weight infants for the periodfrom 1979 through 1983. Jefferson County was divided into 11 census tracts groupedaccording to demographic similarity, population size, and if the tracts were contiguous. Alldata are reported as census tract aggregate incidence rates.
Information on cancer in children age 14 and under was obtained from the Colorado CentralCancer Registry. The Friendly Hills/Harriman Park census tract had the second highestcancer incidence rate; however, rates for all census tracts were within the 95% confidenceintervals calculated for the expected number of cases for those areas. Comparisons of age-specific cancer incidence rates for children aged 14 and under for the years 1979 through1983, showed that rates in Jefferson County were not significantly different than rates in thestate of Colorado and the United States as a whole. Scientists from the Cancer Branch at theCenters for Disease Control and Prevention reviewed the data and concluded that the ratesin the Friendly Hills/Harriman Park area were not significantly higher than expected. However, they note that the wide confidence interval for cancer cases in FriendlyHills/Harriman Park (8.29 to 59.58 cases per 100,00 person-years) "reflects theuncertainties of an estimate based on only 5 cases."
Information on birth defects, fetal loss (miscarriage at 20 or more weeks of gestation),neonatal deaths (deaths within the first 28 days of life), and low birth weight was obtainedfrom the Health Statistics Section of CDPHE. For birth defects, both the number of casesand rates per 1,000 live births in all 11 census tracts did not exceed what was expected forthe time period. For fetal loss and neonatal deaths, the number of cases and rates per 1,000live births plus fetal losses and 1,000 live births, respectively, did not exceed the expectednumbers for the time period; additionally, one census tract had a significantly lower numberof cases and rate. For low birth weight, nine census tracts (including FriendlyHills/Harriman Park) had case counts and rates within the expected numbers, one censustract was statistically significantly lower than expected, and one census tract wasstatistically significantly higher than expected.
The epidemiologic analyses concluded that there is no evidence of excess childhood cancer,birth defects, fetal loss, neonatal deaths, or low birth weight infants in the FriendlyHills/Harriman Park area during 1979-1984. The methods used in the analyses ofchildhood cancer cases and adverse reproductive health effects seem appropriate given theavailable resources. DHS agrees with CDPHE's interpretation of the results.
A study conducted by the Johns Hopkins Oncology Center investigated the incidence ofchildhood cancer and neonatal deaths in the Friendly Hills/Harriman Park area of Denver,Colorado during 1979-1987. The study proposed to determine (1) what factors explain therates of childhood cancer and neonatal deaths in the Denver area, and (2) if water source isassociated with these rates. Because individual data about environmental exposures,biological factors, and demographic characteristics were not available, data were analyzedusing census tract specific number of childhood cancers and neonatal deaths and aggregatecharacteristics of census tracts. Poisson regression was used to estimate the rate ratios.
Analysis of the total number of childhood cancer cases in each census tract as a function ofpotential explanatory factors showed that residence in Friendly Hills/Harriman Park was notsignificantly associated with high rate of childhood cancer relative to other areas (RR=1.5,p value p=0.39). Additionally, drinking water from Kassler Water Treatment Plant was notsignificantly associated with high rate of childhood cancer relative to other water treatmentplants (RR=0.73, p=0.28). Residence in Friendly Hills/Harriman Park was associated witha marginally higher risk of non-leukemic childhood cancers (RR=2.4, p=0.05); however,this association disappears when other factors are added to the model indicating thatresidence in Friendly Hills/Harriman Park by itself is not responsible for the increased riskof non-leukemic cancers.
Neither residence in Friendly Hills/Harriman Park nor drinking water from Kassler WaterTreatment Plant was associated with a significantly elevated risk of neonatal deaths(RR=1.0, p=0.93 and RR=0.83, p=0.26, respectively). However, other sociodemographicfactors such as non-white race, some occupations, and income were associated with elevatedneonatal death rates.
The methods used in the analyses of childhood cancer cases and neonatal deaths seemappropriate given the available resources. DHS agrees with the interpretation of the results given in the Piantadosi report.
In summary, ATSDR's DHS agrees with the CDPHE and Piantadosi interpretations of theavailable data. At this time, ATSDR's DHS does not recommend conducting a large scaleepidemiologic study, ATSDR's DHS would only recommend conducting a new large scaleepidemiologic study if a review of more recent data showed statistically significantly elevatedrates of childhood cancer or adverse reproductive health effects among FriendlyHills/Harriman Park residents and the environmental data showed a completed exposurepathway at a level that could cause health effects.
References used in responding to public comments:
Anderson, A. 1990. Affidavit of Adrienne Anderson, U.S. Dist. Court, Dist. of Colorado: CivilAction No. 87-Z-42, James Earl Renaud, et al. vs. Martin Marietta Corp., et al..May 31, 1990.
ATSDR. 1999. Agency for Toxic Substances and Disease Registry, Division of Health Studies,Review of health studies in the Friendly Hills/Harriman Park neighborhoods. December 1999.
CDPHE. 1985. Colorado Department of Public Health and Environment (formerly ColoradoDepartment of Health), Final report of investigations into alleged health problems in the FriendlyHills/Harriman Park area. May 20, 1985
French American Metals Corporation (FRAMCO). 1975. Personal communication between JamesHiatt, Landman, FRAMCO, and Morris McLain, Martin-Marietta Aerospace. RE: Colorado,Jefferson County, Bonzo area. May 20, 1975.
French American Metals Corporation (FRAMCO). 1975. Personal communication between JamesHiatt, Landman, FRAMCO, and Morris McLain, Martin-Marietta Aerospace. RE: Colorado,Jefferson County, Bonzo area. June 9, 1975
Hauser Laboratories. 1987. Personal communications between Hauser Laboratories and WalterGerash, Attorney. Gerash, Robinson,, Miller & Miranda, P.C. RE: Friendly Hills Water/TCE in awater tank. October 27, 1987.
Hauser. 1990. Affidavit of Ray L. Hauser filed by Denver Water Board, U.S. Dist. Court, Dist. ofColorado: Civil Action No. 87-Z-42, James Earl Renaud, et al. vs. Martin Marietta Corp., et al.May 30, 1990.
Kaltofen, Marco. 1990. Affidavit of Marco Kaltofen. U.S. Dist. Court, Dist. of Colorado: CivilAction No. 87-Z-42, James Earl Renaud, et al. vs. Martin Marietta Corp., et al.
LMA. 1988. Interoffice memo between W.R. Haas, Ph.D., Manager, Environmental Management,Martin Marietta, and Ms. Kelcey Yarbrough Land. RE: Information regarding radioactivity atMartin Marietta Astronautics. March 1988.
LMA. 1988. Interoffice memo between B.Bath and T. Mueller and D.A. Clark. RE: Radioactivematerial use at Waterton. March 10,1988.
LMA. 1999. Personal communication between ATSDR and William W. Bath, EnvironmentalManagement, LMA, RE: Review of the Miller report. October 28, 1999.
Miller, W.L. , Huber, W.C., 1989. Report of water contamination at the Martin Marietta WatertonFacility and the Kassler Water Treatment Plant. October 18, 1989.
Parson Engineering. 2000. Personal Communication between Tom Larson, Parsons Engineering,and ATSDR. February 2000.
Pavlik, H.F. 1990. Comments on reports and testimony provided in the case of Renaud, et. Al.Versus Martin Marietta Corporation, et al., Civil Action Number 87-Z-42. Prepared for the unitedStates District Court District of Colorado, United States Courthouse, Denver Colorado. Prepared byHannah F. Pavlik, Ph.D. EBASCO Services Incorporated, Lakewood Colorado. August 29, 1990.
Piantadosi, S. 1990. Statistical report to the Denver Water Board concerning childhood cancerincidence and neonatal deaths in the Denver Metropolitan area, 1979 - 1987. Prepared by StevenPiantadosi, M.D., Ph.D., Director, Pncology Biostatistics, John Hopkins Oncology Center. April 24,1990.
Weinshienk, J. 1990. Order of Dismissal .U.S. Dist. Court, Dist. of Colorado: Civil Action No. 87-2-42, James Earl Renaud, et al. vs. Martin Marietta Corp., et al..May 30, 1990.
3. ATSDR recently withdrew the intermediate MRL and no chronic MRL for TCE or RfD exists. The study on which the intermediate MRL was based has been questioned because it contains certain flaws and limitations (e.g., the exact amount of TCE-contaminated water consumed by laboratory animals in the study is uncertain). As a conservative screening measure, ATSDR will continue to use the previously derived intermediate MRL for TCE in this document.