PUBLIC HEALTH ASSESSMENT

PADUCAH GASEOUS DIFFUSION PLANT (U.S. DOE)
PADUCAH, MCCRACKEN COUNTY, KENTUCKY

APPENDIX K: ATSDR GLOSSARY OF TERMS

Absorption:

The process of taking in, as when a sponge takes up water. Chemicals can be absorbedthrough the skin into the bloodstream and then transported to other organs. Chemicals can also beabsorbed into the bloodstream after being breathed in or swallowed.

Activity (Radioactivity):

The number of nuclear transformations occurring in a given quantity ofmaterial per unit of time.

Acute:

Occurring over a short time, usually a few minutes or hours. An acute exposure can result inshort-term or long-term health effects. An acute effect happens a short time (up to 1 year) afterexposure.

Adverse Health Effect:

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

Ambient:

Surrounding. For example, ambient air is usually outdoor air (as opposed to indoor air).

Analyte:

A chemical component of a sample to be determined or measured. For example, if theanalyte is mercury, the laboratory test will determine the amount of mercury in the sample.

Aquifer:

A permeable rock stratum below the earth's surface through which groundwater moves;generally capable of producing water for a well.

Background Level:

A typical or average level of a chemical in the environment. Background leveloften refers to naturally occurring or uncontaminated levels.

Background Radiation:

Radiation resulting from cosmic rays and naturally occurring radioactivematerial. Background radiation is always present, and its level can change with altitude and theamount of radioactive material present in soil and building materials.

Becquerel (Bq):

The international unit of measure for the quantity of radioactive material; onebecquerel is that quantity of radioactive material in which one atom decays in 1 second. Onebecquerel is equivalent to 27 picocuries.

Biological Uptake:

The transfer of hazardous substances from the environment to plants, animals,and humans. This can be evaluated through environmental measurements (for example, bymeasuring the amount of the substance in an organ known to be susceptible to that substance). Morecommonly, biological dose measurements are used to determine whether exposure has occurred. Thepresence of a contaminant, or its metabolite, in human biological specimens, such as blood, hair, orurine, is used to confirm exposure and can be an independent variable in evaluating the relationshipbetween the exposure and any observed adverse health effects.

Biota:

The animal and plant life of a particular region. As used in ATSDR's public healthassessments, biota means animals, fish, and plants that humans would eat.

Body Burden:

The total amount of a chemical in the body. Some chemicals build up in the bodybecause they are stored in tissues (e.g., fat, bone) or are eliminated very slowly.

Cancer:

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

Carcinogen:

Any substance that can cause cancer.

Carcinoma:

A malignant neoplasm composed of epithelial cells, regardless of their derivation.

Case Study:

The medical or epidemiologic evaluation of a single person or a small number ofindividuals to determine descriptive information about their health status or potential for exposurethrough interview or biomedical testing.

Central Nervous System:

The part of the nervous system that includes the brain and the spinalcord.

CERCLA:

The Comprehensive Environmental Response, Compensation, and Liability Act of1980, also known as Superfund. CERCLA's major provisions are designed to comprehensivelyaddress the problems associated with hazardous waste sites. This is the federal legislation thatcreated ATSDR.

Chronic:

Occurring over a long period of time (1 year or more).

Committed Equivalent Dose:

(previously "Committed Dose Equivalent") The InternationalCommission of Radiological Protection's term (starting with ICRP Publication 60) for theequivalent dose to organs and tissues of reference that will be received from an intake of radioactivematerial by an individual over a 50-year period following the intake for adults and from age of theintake to 70 years for children.

Committed Effective Dose:

(previously "Committed Effective Dose Equivalent") The InternationalCommission for Radiological Protection's term for the sum of the products of (1) the weightingfactors applicable to each body organ or tissue that is irradiated and (2) the committed equivalentdose to the appropriate organ or tissue integrated over time (in years) following the intake. Theintegrated time is 50 years for an adult and from the time of intake to 70 years for children. Thecommitted effective dose is used in radiation safety because it implicitly includes the relativecarcinogenic sensitivity of the various tissues.

Comparison Value:

The estimated contaminant concentration in a specific medium that is notlikely to cause adverse health effects, given a standard daily ingestion rate and standard bodyweight. Comparison values are calculated from the scientific literature available on exposure andhealth effects.

Concentration:

The amount of one substance dissolved or contained in a given amount of another.For example, sea water contains a higher concentration of salt than fresh water.

Contaminant:

Any substance or material unintentionally introduced into a medium (air, water, soil,sediment, food) which has the effect of rendering them toxic or otherwise harmful.

Contaminant of Concern:

Any chemical or substance that has the potential to adversely affecthuman receptors due to its concentration, distribution, and mode of toxicity.

Curie (Ci):

The traditional unit of measure for the quantity of radioactive material; one curie is thatquantity of radioactive material in which 37 billion transformations occur per second, which isapproximately the activity of 1 gram of radium. One curie is equivalent to 37 gigabecquerels.

Decay Product (Daughter Product, Progeny):

A radioisotope formed by the radioactivetransformation of some other radioisotope.

Decay, Radioactive:

Transformation of the nucleus of an unstable nuclide by spontaneous emissionof charged particles and/or photons.

Depleted Uranium:

Uranium in which the proportion of uranium 235 to total uranium of allisotopes is decreased from 0.72% to a lower value.

Dermal:

Referring to the skin. Dermal absorption is absorption through the skin.

Detection Limit:

The minimum concentrations that can be accurately and precisely measured bythe laboratory and/or specified in a quality assurance plan.

Dose:

The amount of a substance that is absorbed or deposited in the body of an exposed organismfor an increment of time. For chemicals, dose often takes body weight into account. For radioactivematerials or radiation, dose denotes the quantity of radiation or energy absorbed and is a genericterm for absorbed dose, equivalent dose, effective dose, committed equivalent dose, or committedeffective dose.

Effective Dose:

(previously "Effective Dose Equivalent") The International Commission forRadiological Protection's term (starting with ICRP Publication 60) for the sum of the products of(1) the weighting factors applicable to each body organ or tissue that is irradiated and (2) the meanequivalent dose in the tissue or organ.

Enriched Uranium:

Uranium in which the proportion of uranium 235 to total uranium of allisotopes is increased from 0.72% to a higher value.

Environmental Contamination:

The presence of unnatural or unintentional substances in theenvironment. From the public health perspective, environmental contamination should beaddressed when it can affect the health and quality of life of people living and working near thecontamination.

Epidemiology:

The study of the occurrence and causes of health effects in human populations. Anepidemiological study often compares two groups of people who are alike except for one factor,such as exposure to a chemical or the presence of a health effect. The investigators try to determineif any factor is associated with the health effect.

Equivalent Dose:

(previously "Dose Equivalent") The International Commission for RadiologicalProtection's term (starting with ICRP Publication 60) for the product of the amount of energyabsorbed per mass of tissue (joules per kilogram) times the quality factor for the type of radiationimparting the energy. The unit used for equivalent dose is the sievert (Sv). The unit used previouslyfor dose equivalent was the rem. (1 rem = 0.01Sv)

Exposure:

Contact with a chemical by swallowing, breathing, or direct contact (such as through theskin or eyes). Exposure can be short-term (acute) or long-term (chronic).

Exposure Registry:

A system for collecting and maintaining, in a structured record, information onpersons with documented environmental exposure(s). The exposure registry evolved from the needfor fundamental information about the potential impact on human health of long-term exposure to low and moderate levels of hazardous substances.

Geographic Information System (GIS):

A computer hardware and software system designed tocollect, manipulate, analyze, and display spatially referenced data. One can use a GIS to solvecomplex resource, environmental, and social problems.

Gray (Gy) :

The international (SI) unit of absorbed radiation dose. One Gy equals the absorption ofone joule of energy per kilogram of absorber. One gray equals 100 rad.

Hazard:

A hazard is only a source of risk if an exposure pathway exists and if exposures can haveadverse consequences.

Health Outcome Data:

A major source of data for public health assessments. The identification,review, and evaluation of health outcome parameters are interactive processes involving healthassessors, data source generators, and the local community. Health outcome data are communityspecific and may be derived from databases at the local, state, and national levels, as well as fromdata collected by private health care organizations and professional institutions and associations.Databases to be considered include morbidity and mortality data, birth statistics, medical records,tumor and disease registries, surveillance data, and previously conducted health studies.

Indeterminate Public Health Hazard:

A category assigned to sites or pathways for which noconclusions about public health hazard can be made because data are lacking.

Ingestion:

Swallowing (such as eating or drinking). Chemicals can get in or on food, drink, utensils,cigarettes, or hands, where they can be ingested. After ingestion, chemicals can be absorbed into theblood and distributed throughout the body.

Inhalation:

Breathing. One can be exposed to contaminants through inhalation, because inhaledcontaminants can be deposited in the lungs, taken into the blood, or both.

Intermediate:

Occurring over a mid-length period of time. Intermediate exposure is exposurelasting 15 to 364 days.

Isotope:

Any nuclide of an element having the same number of protons in its nucleus (i.e., the sameatomic number) as the element, but a different number of neutrons (i.e., a different mass number oratomic weight).

Media:

Soil, sediment, water, air, plants, animals, or any other parts of the environment that cancontain contaminants.

Metabolism:

All the chemical reactions that enable the body to work. For example, food ismetabolized (chemically changed) to supply the body with energy. Chemicals can be metabolizedand made either more or less harmful by the body.

Metabolite:

Any product of metabolism.

Microcurie:

One-millionth of a curie, symbolized as µCi.

Millicurie:

One-thousandth of a curie, symbolized as mCi.

Minimal Risk Level (MRL):

An estimate of daily human exposure to a dose of radiation or achemical that is likely to be without an appreciable risk of adverse noncancerous effects over aspecified duration of exposure.

Morbidity:

Illness or disease. Morbidity rate is the number of illnesses or cases of disease in apopulation.

National Priorities List (NPL):

The U.S. Environmental Protection Agency's listing of sites thathave undergone preliminary assessment and site inspection to determine which locations poseimmediate threat to persons living or working near the release. These sites are most in need ofcleanup.

No Apparent Public Health Hazard:

A category assigned to sites or pathways where humanexposure to contaminated media is occurring or has occurred in the past, but is below a level ofhealth hazard.

No Public Health Hazard:

A category assigned to sites for which data indicate no current or pastexposure or no potential for exposure in the future and, therefore, no health hazard.

Picocurie:

One-trillionth of a curie, symbolized as pCi.

Plume:

An area of chemicals or radioactive materials in a particular medium, such as air orgroundwater, moving away from its source in a long band or column. A plume can be a column ofsmoke from a chimney or contaminants moving with groundwater.

Public Health Hazard:

A category assigned to a site or pathway that poses a public health hazardbecause of long-term exposures to hazardous substances could result in adverse health effects.

Radiation:

The emission and propagation of energy in the form of waves.The term, whenunqualified, usually refers to electromagnetic radiation, such as infrared, visible light, ultraviolet, X-ray, or gamma ray. It can also refer to corpuscular emissions, such as alpha and beta radiation.

Rad:

The traditional radiation unit for energy deposition per unit mass of matter. One rad is equal to0.01 Joules deposited per kilogram of matter (1 rad = 0.01 J/kg).

Radioactivity:

The property of certain nuclides to spontaneously transform into other elements byemitting alpha or beta particles.

Registry:

A system for collecting and maintaining, in a structured record, information on specificpersons from a defined population. Preliminary analyses and reviews are performed.

Rem:

The traditional unit of radiation equivalent dose and effective dose. The equivalent dose inrem is numerically equal to the absorbed dose in rad multiplied by a quality factor. One rem isequivalent to 0.01 sieverts (the international unit currently being used).

Risk:

In risk assessment, the probability that something will cause injury, combined with thepotential severity of that injury.

Route of Exposure:

The way in which a person comes in contact with a chemical or radioactivesubstance. For example, drinking (ingestion) and bathing (skin contact) are two different routes ofexposure to contaminants in water.

Sievert:

The international unit of radiation equivalent dose and effective dose. The equivalent dosein sieverts is numerically equal to the absorbed dose in gray multiplied by a quality factor. Onesievert is equivalent to 100 rems (the traditional unit).

Specific Activity:

The total radioactivity of a given nuclide per gram of an element. This is ameasure of the concentration of radioactivity. Specific activity can be expressed as µCi/gram, Bq/L,etc.

Superfund:

Another name for the Comprehensive Environmental Response, Compensation, and Liability Act of 1980 (CERCLA), which created ATSDR.

Superfund Amendments and Reauthorization Act (SARA):

The 1986 legislation thatextensively amended CERCLA and broadened ATSDR's responsibilities in the areas of publichealth assessment, establishment and maintenance of toxicologic databases, informationdissemination, and medical education.

Toxicological Profile:

A document (about a specific substance) in which ATSDR scientistsinterpret all known information on that substance and specify the levels at which people may beharmed if exposed to it. A toxicological profile also identifies significant data gaps in knowledge onsubstances and serves to initiate further research, when needed.

Urgent Public Health Hazard:

A category assigned to sites or pathways that pose a serious risk topublic health as the result of short-term exposures to hazardous substances.

Vapor:

The gaseous state of a substance that, under ordinary conditions, is liquid or solid.

Volatile Organic Compounds (VOCs):

Substances containing carbon and different proportions ofother elements such as hydrogen, oxygen, fluorine, chlorine, bromine, sulfur, or nitrogen. Thesesubstances easily become vapors or gases. A significant number of the VOCs are commonly used assolvents (paint thinners, lacquer thinners, degreasers, and dry cleaning fluids).

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