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 absorbed
through the skin into the bloodstream and then transported to other organs. Chemicals can also be
absorbed into the bloodstream after being breathed in or swallowed.
Activity (Radioactivity):
The number of nuclear transformations occurring in a given quantity of
material per unit of time.
Acute:
Occurring over a short time, usually a few minutes or hours. An acute exposure can result in
short-term or long-term health effects. An acute effect happens a short time (up to 1 year) after
exposure.
Adverse Health Effect:
A change in body function or the structures of cells that can lead to disease
or 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 the
analyte 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 level
often refers to naturally occurring or uncontaminated levels.
Background Radiation:
Radiation resulting from cosmic rays and naturally occurring radioactive
material. Background radiation is always present, and its level can change with altitude and the
amount of radioactive material present in soil and building materials.
Becquerel (Bq):
The international unit of measure for the quantity of radioactive material; one
becquerel is that quantity of radioactive material in which one atom decays in 1 second. One
becquerel 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, by
measuring the amount of the substance in an organ known to be susceptible to that substance). More
commonly, biological dose measurements are used to determine whether exposure has occurred. The
presence of a contaminant, or its metabolite, in human biological specimens, such as blood, hair, or
urine, is used to confirm exposure and can be an independent variable in evaluating the relationship
between the exposure and any observed adverse health effects.
Biota:
The animal and plant life of a particular region. As used in ATSDR's public health
assessments, 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 body
because 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 of
individuals to determine descriptive information about their health status or potential for exposure
through interview or biomedical testing.
Central Nervous System:
The part of the nervous system that includes the brain and the spinal
cord.
CERCLA:
The Comprehensive Environmental Response, Compensation, and Liability Act of
1980, also known as Superfund. CERCLA's major provisions are designed to comprehensively
address the problems associated with hazardous waste sites. This is the federal legislation that
created ATSDR.
Chronic:
Occurring over a long period of time (1 year or more).
Committed Equivalent Dose:
(previously "Committed Dose Equivalent") The International
Commission of Radiological Protection's term (starting with ICRP Publication 60) for the
equivalent dose to organs and tissues of reference that will be received from an intake of radioactive
material by an individual over a 50-year period following the intake for adults and from age of the
intake to 70 years for children.
Committed Effective Dose:
(previously "Committed Effective Dose Equivalent") The International
Commission for Radiological Protection's term for the sum of the products of (1) the weighting
factors applicable to each body organ or tissue that is irradiated and (2) the committed equivalent
dose to the appropriate organ or tissue integrated over time (in years) following the intake. The
integrated time is 50 years for an adult and from the time of intake to 70 years for children. The
committed effective dose is used in radiation safety because it implicitly includes the relative
carcinogenic sensitivity of the various tissues.
Comparison Value:
The estimated contaminant concentration in a specific medium that is not
likely to cause adverse health effects, given a standard daily ingestion rate and standard body
weight. Comparison values are calculated from the scientific literature available on exposure and
health 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 affect
human 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 that
quantity of radioactive material in which 37 billion transformations occur per second, which is
approximately the activity of 1 gram of radium. One curie is equivalent to 37 gigabecquerels.
Decay Product (Daughter Product, Progeny):
A radioisotope formed by the radioactive
transformation of some other radioisotope.
Decay, Radioactive:
Transformation of the nucleus of an unstable nuclide by spontaneous emission
of charged particles and/or photons.
Depleted Uranium:
Uranium in which the proportion of uranium 235 to total uranium of all
isotopes 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 by
the 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 organism
for an increment of time. For chemicals, dose often takes body weight into account. For radioactive
materials or radiation, dose denotes the quantity of radiation or energy absorbed and is a generic
term for absorbed dose, equivalent dose, effective dose, committed equivalent dose, or committed
effective dose.
Effective Dose:
(previously "Effective Dose Equivalent") The International Commission for
Radiological 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 mean
equivalent dose in the tissue or organ.
Enriched Uranium:
Uranium in which the proportion of uranium 235 to total uranium of all
isotopes is increased from 0.72% to a higher value.
Environmental Contamination:
The presence of unnatural or unintentional substances in the
environment. From the public health perspective, environmental contamination should be
addressed when it can affect the health and quality of life of people living and working near the
contamination.
Epidemiology:
The study of the occurrence and causes of health effects in human populations. An
epidemiological 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 determine
if any factor is associated with the health effect.
Equivalent Dose:
(previously "Dose Equivalent") The International Commission for Radiological
Protection's term (starting with ICRP Publication 60) for the product of the amount of energy
absorbed per mass of tissue (joules per kilogram) times the quality factor for the type of radiation
imparting the energy. The unit used for equivalent dose is the sievert (Sv). The unit used previously
for dose equivalent was the rem. (1 rem = 0.01Sv)
Exposure:
Contact with a chemical by swallowing, breathing, or direct contact (such as through the
skin 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 on
persons with documented environmental exposure(s). The exposure registry evolved from the need
for 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 to
collect, manipulate, analyze, and display spatially referenced data. One can use a GIS to solve
complex resource, environmental, and social problems.
Gray (Gy) :
The international (SI) unit of absorbed radiation dose. One Gy equals the absorption of
one 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 have
adverse 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 health
assessors, data source generators, and the local community. Health outcome data are community
specific and may be derived from databases at the local, state, and national levels, as well as from
data 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 no
conclusions 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 the
blood and distributed throughout the body.
Inhalation:
Breathing. One can be exposed to contaminants through inhalation, because inhaled
contaminants can be deposited in the lungs, taken into the blood, or both.
Intermediate:
Occurring over a mid-length period of time. Intermediate exposure is exposure
lasting 15 to 364 days.
Isotope:
Any nuclide of an element having the same number of protons in its nucleus (i.e., the same
atomic number) as the element, but a different number of neutrons (i.e., a different mass number or
atomic weight).
Media:
Soil, sediment, water, air, plants, animals, or any other parts of the environment that can
contain contaminants.
Metabolism:
All the chemical reactions that enable the body to work. For example, food is
metabolized (chemically changed) to supply the body with energy. Chemicals can be metabolized
and 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 a
chemical that is likely to be without an appreciable risk of adverse noncancerous effects over a
specified duration of exposure.
Morbidity:
Illness or disease. Morbidity rate is the number of illnesses or cases of disease in a
population.
National Priorities List (NPL):
The U.S. Environmental Protection Agency's listing of sites that
have undergone preliminary assessment and site inspection to determine which locations pose
immediate threat to persons living or working near the release. These sites are most in need of
cleanup.
No Apparent Public Health Hazard:
A category assigned to sites or pathways where human
exposure to contaminated media is occurring or has occurred in the past, but is below a level of
health hazard.
No Public Health Hazard:
A category assigned to sites for which data indicate no current or past
exposure 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 or
groundwater, moving away from its source in a long band or column. A plume can be a column of
smoke from a chimney or contaminants moving with groundwater.
Public Health Hazard:
A category assigned to a site or pathway that poses a public health hazard
because 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, when
unqualified, 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 to
0.01 Joules deposited per kilogram of matter (1 rad = 0.01 J/kg).
Radioactivity:
The property of certain nuclides to spontaneously transform into other elements by
emitting alpha or beta particles.
Registry:
A system for collecting and maintaining, in a structured record, information on specific
persons from a defined population. Preliminary analyses and reviews are performed.
Rem:
The traditional unit of radiation equivalent dose and effective dose. The equivalent dose in
rem is numerically equal to the absorbed dose in rad multiplied by a quality factor. One rem is
equivalent to 0.01 sieverts (the international unit currently being used).
Risk:
In risk assessment, the probability that something will cause injury, combined with the
potential severity of that injury.
Route of Exposure:
The way in which a person comes in contact with a chemical or radioactive
substance. For example, drinking (ingestion) and bathing (skin contact) are two different routes of
exposure to contaminants in water.
Sievert:
The international unit of radiation equivalent dose and effective dose. The equivalent dose
in sieverts is numerically equal to the absorbed dose in gray multiplied by a quality factor. One
sievert is equivalent to 100 rems (the traditional unit).
Specific Activity:
The total radioactivity of a given nuclide per gram of an element. This is a
measure 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 that
extensively amended CERCLA and broadened ATSDR's responsibilities in the areas of public
health assessment, establishment and maintenance of toxicologic databases, information
dissemination, and medical education.
Toxicological Profile:
A document (about a specific substance) in which ATSDR scientists
interpret all known information on that substance and specify the levels at which people may be
harmed if exposed to it. A toxicological profile also identifies significant data gaps in knowledge on
substances and serves to initiate further research, when needed.
Urgent Public Health Hazard:
A category assigned to sites or pathways that pose a serious risk to
public 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 of
other elements such as hydrogen, oxygen, fluorine, chlorine, bromine, sulfur, or nitrogen. These
substances easily become vapors or gases. A significant number of the VOCs are commonly used as
solvents (paint thinners, lacquer thinners, degreasers, and dry cleaning fluids).
