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TOXMAP Glossary of Terms

Acute toxicity FRS (Facility Registry System) Response
Aggregate Geographic region Risk
ATSDR GIS Risk Assessment
Base map HRS (Hazard Ranking System) SARA
CAS (Chemical Abstract Service) HSDB® SIS
CERCLA Latitude Spatial data
CERCLIS Layer Superfund
Chronic toxicity Longitude TEHIP
Contaminant Males to 100 Females Topography
Coordinates Map projection Topology
Data set Median age Toxicity
Demographic data Metadata Toxicology
DHHS NPL (National Priorities List) TOXLINE®
Dose On-site release TOXMAP®
Environment Pre-defined region TOXNET®
Environmental fate PubMed® (Toxicology Subset) TRI
EPA Reference data User-defined region
Form A Release medium

Other toxicology-related glossaries:

Glossary for Chemists of Terms Used in Toxicology (National Library of Medicine®)

Glossary of Terms (Agency for Toxic Substances and Disease Registry)

Terms and Acronyms (Environmental Protection Agency)

Acute toxicity

The capacity of a biologically active agent to cause serious harm, injury, or death to a living system following a single dose or a single brief exposure.



The grouping together of a selected set of like entities (usually adjacent) to form one entity.

All TRI release amounts are aggregates in pounds of chemicals released to all environmental media (e.g., air, water, land, underground injection). TOXMAP shows only on-site releases.



The ATSDR (Agency for Toxic Substances and Disease Registry) is a federal public health agency of the US Department of Health and Human Services (DHHS). The ATSDR provides health information related to prevention of harmful exposures and diseases related to toxic substances.


Base map

A map depicting background reference information such as landforms, roads, landmarks, and political boundaries, onto which other thematic information is placed.


CAS (Chemical Abstract Service)

Chemical Abstract Service (, a division of the American Chemical Society; an abstracting and indexing service for chemical scientific literature. This service assigns unique Registry Numbers (RN) to chemical substances, which are often known by more than one name.



The Comprehensive Environmental Response, Compensation, and Liability Act (CERCLA) (, commonly known as Superfund (, was enacted by Congress on December 11, 1980. This law created a tax on the chemical and petroleum industries and provided broad Federal authority to respond directly to releases or threatened releases of hazardous substances that may endanger public health or the environment. CERCLA was amended by the Superfund Amendments and Reauthorization Act (SARA) on October 17, 1986.



The Comprehensive Environmental Response, Compensation and Liability Information System (CERCLIS) is an EPA database containing information on hazardous waste sites, potentially hazardous waste sites, and associated remedial activities across the nation.


Chronic toxicity

The capacity of a biologically active agent to produce toxic effects following long-continued or numerous brief exposures, or to produce effects which persist whether they occur immediately upon exposure or are delayed.



A substance that is either present in an environment where it does not belong or is present at levels that might cause harmful (adverse) health effects; any physical, chemical, biological, or radiological substance or matter that has an adverse effect on air, water, or soil.



A set of numbers that locates the position of a point on a map, usually represented by (x,y) values.


Data set

A collection of related data records on a computer-readable medium. In TOXMAP, "dataset" refers to the Toxics Release Inventory (TRI), Superfund, or demographic data.


Demographic data

Factual information pertaining to the study of the characteristics of human populations, such as size, growth, density, distribution, and vital statistics. TOXMAP allows users to overlay demographic data (e.g., US census, cancer mortality, income) over environmental data.



The Department of Health and Human Services (DHHS) is the United States government's principal agency for protecting the health of all Americans and providing essential human services, especially for those who are least able to help themselves. The National Institutes of Health (NIH) is an agency of the DHHS. The National Library of Medicine® (NLM) is an Institute of the NIH.



The total amount of a chemical administered to, or taken by, an organism.



The surroundings, including water, air, soil, and their inter-relationships as well as relationships between them and any living organism.


Environmental fate

The result/outcome of the chemical or biological pollutant after it has been released into the natural environment. The fate depends upon the specific characteristics of the chemical and the physical and biological forces which may act upon that chemical, such as heat, water or soil microorganisms.



The EPA (Environmental Protection Agency) is the federal agency designed to protect human health and the environment. The EPA produces the TRI (Toxics Release Inventory) database, which contains information on toxic chemical releases.


Form A

EPA's TRI Form A provides certain facilities the option of submitting a substantially shorter reporting form. Not all facilities are eligible to submit Form A reports; this has varied over the years. Eligibility has been based on the annual reportable amount of the chemical, such as the sum of production-related releases and other waste management and the amount manufactured, processed, or otherwise used.

For more information on Form A, search the EPA TRI FAQ.


FRS (Facility Registry System)

The Facility Registry System (FRS) ( is a centrally managed database from the EPA that identifies facilities, sites or places subject to environmental regulations or of environmental interest. TOXMAP plots the location of most TRI facilities using addresses and coordinates from the FRS.


Geographic region

In TOXMAP, a geographic region is a named collection of US states and/or counties whose boundaries are highlighted in red on a map. When a region is chosen, all TOXMAP maps show TRI and Superfund results only inside the specified region. In maps that show on-site chemical releases, the color of the circle represents the amount of release relative only to other releases in that geographic region. Other map data (such as roads, political boundaries, and demographic data) are visually muted on the map.



GIS (Geographic Information System) is a means of storing, displaying, and analyzing data that can be referenced geographically.

See also "What is GIS?"


HRS (Hazard Ranking System)

The Hazard Ranking System (HRS) ( is a numerically based screening system that uses information to assess the relative potential of sites to pose a threat to human health or the environment. The HRS is used by the EPA ( to place uncontrolled waste sites on the National Priorities List (NPL) (



HSDB (Hazardous Substances Data Bank) ( is a database from the National Library of Medicine (NLM) with comprehensive, peer-reviewed toxicology data for about 5,000 chemicals. It contains a broad scope in human and animal toxicity, safety and handling, and environmental fate.

See also the HSDB Fact Sheet (



The angular distance in degrees north or south from the equator of a point on the Earth's surface.



Visual representation of a geographic dataset in any digital map environment. Roads, national parks, political boundaries and rivers are examples of layers.



The angular distance in degrees east or west from the Prime Meridian (Greenwich, England) of a point on the Earth's surface.


Males to 100 Females

A method used by demographers to measure the relative number of males and females in a population. The male-to-female sex ratio is calculated by dividing the number of males (of all ages) by the number of females (of all ages) and multiplying by 100. A value above 100 means there are more males than females in the population. A value below 100 indicates more females than males.


Map projection

A map projection is a way to represent the curved surface of the Earth on the flat surface of a map. TOXMAP uses a map projection (called "North American Albers Equal Area Conic") which makes the continental United States look most accurate and realistic. Areas farther away from the US will appear increasingly distorted.

You can learn more about map projections from the USGS at


Median age

The median divides the age distribution into two equal parts: one-half of the cases falling below the median age and one-half above the median.



Metadata is data that describes other data.

See also "What is Metadata?"


NPL (National Priorities List)

The National Priorities List (NPL) contains the most serious uncontrolled or abandoned hazardous waste sites throughout the United States and its territories.

The EPA designates several NPL statuses for Superfund sites: Proposed, Final, Deleted, Withdrawn, and Removed. Other Superfund sites are not on the NPL. TOXMAP contains data only on sites designated as Final (currently on the final NPL), Proposed (proposed for the NPL), and Deleted (deleted from the final NPL). These three statuses are collectively referred to by the EPA as the "NPL Dataset".


On-site release

In TRI, a toxic chemical release that is located on the generating site (such as via a smokestack). This is in contrast to off-site releases (e.g., transfer to a location other than the generating site) that are reported to the TRI program but not included in TOXMAP. To view off-site release data, see TOXNET/TRI.


Pre-defined region

TOXMAP provides a variety of pre-defined geographic regions. These regions include the ten EPA Regions, the 21 Hydrologic Regions defined by the US Geological Survey (USGS), and several general regions defined by or adapted from other authoritative sources. When a region is chosen, all TOXMAP maps show TRI and Superfund results only inside the specified region.


PubMed® (Toxicology Subset)

PubMed (, NLM's bibliographic database for biomedical literature, contains subsets in specific areas. This subset strategy was created by NLM's Specialized Information Services to facilitate searching for subjects in the area of toxicology. TOXMAP's "Chemical & Map Area" feature searches within this PubMed subset.


Reference data

Data drawn on a map that helps to identify the position of physical features in relation to other information. For example, cities, roads, and state boundaries.


Release medium

Means by which a substance is released into, or enters, the environment (e.g. air, land, water, underground injection). TOXMAP shows only on-site releases.



In toxicology, the effect-- if any-- that a chemical has on a living organism. The response is related to the chemical dose and to the resulting concentration of the chemical in the organism.



The probability that a hazard or effect will occur at a specific level of exposure to a substance.


Risk Assessment

How scientists determine the likelihood that a harmful effect will happen at a specific level of exposure to a substance.



The Superfund Amendments and Reauthorization Act (SARA) ( amended the CERCLA, also know as Superfund, on October 17, 1986. SARA reflected EPA's experience in administering the complex Superfund program during its first six years and made several important changes and additions to the program.



The Specialized Information Services (SIS) Division ( of the National Library of Medicine (NLM) ( creates information resources and services in toxicology, environmental health, chemistry, HIV/AIDS, and specialized topics in minority health. SIS produces databases such as TOXMAP, TOXNET, and HSDB (Hazardous Substances Data Bank).


Spatial data

Information about the location and shape of, and relationships among, geographic features. This includes remotely sensed data as well as map data. It is usually stored as coordinates and topology.



Superfund is the Federal government's program to clean up the nation's uncontrolled hazardous waste sites. It is operated under the legislative authority of CERCLA and SARA that funds and carries out EPA solid waste emergency and long-term removal and remedial activities.



The Toxicology and Environmental Health Information Program (TEHIP) ( of the National Library of Medicine (NLM) creates, organizes, and disseminates toxicology and environmental health information.

See the TEHIP Fact Sheet for more information.



Graphic representation of the surface features of a place or region on a map, indicating their relative positions and elevations.



The relative location of geographic phenomena independent of their exact position. In digital data, topological relationships such as connectivity, adjacency and relative position are usually expressed as relationships between nodes, links and polygons. Topology is useful in GIS because many spatial modeling operations require topological information rather than co-ordinates.



The degree to which a chemical substance (or physical agent) elicits an adverse effect on the biological system of an organism exposed to the substance over a designated time period. Acute toxicity stems from a single dose or single exposure, while chronic toxicity results from long-continued or numerous brief exposures.



The study of the adverse effects of chemical or physical agents on living organisms and biological systems.



TOXLINE ( is the National Library of Medicine's (NLM) bibliographic database for toxicology. It provides access to extensive references to the literature on biochemical, pharmacological, physiological, and toxicological effects of drugs and other chemicals. TOXLINE references are drawn from a variety of sources.

See the TOXLINE Fact Sheet for more information (



TOXMAP is a web site from the National Library of Medicine (NLM) that uses maps of the United States to show location of Superfund sites and the amount and location of the on-site release of certain toxic chemicals into the environment.

See also "What is TOXMAP?" and the TOXMAP Fact Sheet.



TOXNET (TOXicology Data NETwork) ( is a group of databases covering toxicology, hazardous chemicals, environmental health and related areas.

See also the TOXNET FAQ ( and the TOXNET Fact Sheet (



The TRI (Toxics Release Inventory) is a publicly available EPA database that contains information on toxic chemical releases and other waste management activities reported annually by certain covered industry groups as well as federal facilities.

See also "Learn about the Toxics Release Inventory" for more information.


User-defined region

In TOXMAP, a user-defined region is created by the user choosing any combination of US states and/or state counties. The resulting region can be named and given associated descriptive text. When a region is chosen, all TOXMAP maps show TRI and Superfund results only inside the specified region.