TOXMAP (http://toxmap.nlm.nih.gov) is a Geographic Information System (GIS) from the Division of Specialized Information Services (http://sis.nlm.nih.gov) of the US National Library of Medicine® (NLM) (http://www.nlm.nih.gov) that uses maps of the United States to help users visually explore data from the US Environmental Protection Agency (EPA)'s Toxics Release Inventory (TRI) and Superfund Program.

For more information, see the NLM TOXMAP Fact Sheet.

The TOXMAP Tour (http://toxmap.nlm.nih.gov/toxmap/tour/index.html) will walk you through TOXMAP's main features step-by-step. It is designed to take about 20 minutes.

The Toxics Release Inventory (TRI) is a publicly available 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. This inventory was established under a federal law called the Emergency Planning and Community Right to Know Act of 1986 (EPCRA) (http://www.epa.gov/regulations/laws/epcra.html) and was expanded by the Pollution Prevention Act of 1990 (http://www.epa.gov/oppt/p2home/pubs/p2policy/act1990.htm). It requires facilities in certain industries which manufacture, process, or use significant amounts of toxic chemicals, to report annually on their releases of these chemicals. The reports contain information about the types and amounts of toxic chemicals that are released each year to the air, water, land and by underground injection, as well as information on the quantities of toxic chemicals sent to other facilities for further waste management.

Facilities with ten or more full-time employees that process more than 25,000 pounds in aggregate, or use greater than 10,000 pounds of any one TRI chemical, are required to report releases annually. The US Environmental Protection Agency (EPA) (http://www.epa.gov) maintains this information in the Toxics Release Inventory (TRI) (http://www.epa.gov/tri/). The toxics release files on the National Library of Medicine's® (NLM) Toxicology Data Network (TOXNET®) (http://toxnet.nlm.nih.gov) come from TRI.

TOXMAP uses the most current, final TRI data available from the EPA. Data submission deadlines, data entry processes, and data quality control and review all influence the actual date of data release by both the EPA and by TOXMAP.

A complete list of the TRI chemicals currently listed in TOXMAP can be found at http://toxmap.nlm.nih.gov/toxmap/main/chemicals.jsp. A complete list of TRI chemicals required to be reported to the EPA can be found at http://www.epa.gov/tri/trichemicals/index.htm.

NOTE: At this time, TOXMAP uses reported on-site releases only. Some TRI chemicals have no reported releases, and so will not appear in the TRI release data or in TOXMAP. All release amounts are reported in pounds except dioxin which is reported in grams.

For more information, see the TRI Fact Sheet (http://www.nlm.nih.gov/pubs/factsheets/trifs.html).

The effect a chemical has on a living organism-- if any-- is called the organism's response. The response is related to the chemical dose and to the resulting concentration of the chemical in the organism. (The dose is the total amount of chemical administered to, or taken by, an organism.) The dose of a chemical often determines the extent of the effect it produces. Understanding the dose-response relationship is necessary for understanding the cause and effect relationship between chemical exposure and illness.

The toxicity of a substance depends on many factors: the form and chemical activity; the dosage, especially the dose-time relationship; exposure route; species; age; sex; ability of the chemical to be absorbed; metabolism; distribution within the body; excretion; and the presence of other chemicals.

The variety of responses among organisms that get the same dose of chemical is due to individual susceptibility. Dose and individual susceptibility play roles in all situations involving chemical exposure. Toxicologists study responses of living organisms to doses of chemicals.

Always keep in mind that the co-occurrence of a substance and a particular health problem does not by itself imply an effect on human health by that substance; the association of two or more variables (correlation) does not, by itself, imply a cause and effect relationship.

You can learn more about chemicals and toxicity with these Toxicology Tutorials (http://sis.nlm.nih.gov/enviro/toxtutor.html). These three short high school level tutorials about basic toxicology are organized by chapter and offer text, graphics, and quizzes/assessments.

TOXMAP maps the Toxics Release Inventory (TRI) chemicals reported to the Environmental Protection Agency (EPA), as required by the Emergency Planning and Community Right to Know Act (EPCRA).

TOXMAP uses the most current, final TRI data available from the EPA. Data submission deadlines, data entry processes, and data quality control and review all influence the actual date of data release both by the EPA and by TOXMAP.

Some TRI chemicals have no reported releases, and so will not appear in the TRI release data or in TOXMAP. A complete list of chemicals currently listed in TOXMAP can be found at (http://toxmap.nlm.nih.gov/toxmap/main/chemicals.jsp).

A complete list of TRI chemicals required to be reported to the EPA can be found at http://www.epa.gov/tri/trichemicals/index.htm.

The Superfund program (http://www.epa.gov/superfund/index.htm) is part of a federal government effort to clean up land in the United States that has been contaminated by hazardous waste and that has been identified by the Environmental Protection Agency (EPA) (http://www.epa.gov/) as a candidate for cleanup because it poses a risk to human health and/or to the environment.

The program was created in 1980 when Congress enacted the Comprehensive Environmental Response, Compensation, and Liability Act (CERCLA) (http://www.epa.gov/superfund/action/law/cercla.htm). The US Environmental Protection Agency (EPA) works with communities, "potentially responsible party" (PRPs), scientists, researchers, contractors, and state, local, tribal, and Federal authorities to identify hazardous waste sites, test the conditions of the sites, formulate cleanup plans, and to decontaminate the sites.

Sites where releases or potential releases have been reported are listed in a searchable EPA database called the Comprehensive Environmental Response Compensation and Liability Information System (CERCLIS) (http://www.epa.gov/superfund/sites/cursites/index.htm).

CERCLA was amended by the Superfund Amendments and Reauthorization Act (SARA) (http://www.epa.gov/superfund/action/law/sara.htm) in 1986.

It is difficult to answer this question simply because there is currently no standard approach to assess overall human health risk. People are exposed to chemicals in our environment via in the air we breathe, the water we drink, the houses we live in, and the food we eat. TRI releases and Superfund sites are just a few examples of sources of chemical exposure.

Some of these chemicals may affect our health. Understanding exposure and determining whether there is a health risk is a very complex process. There are many factors that affect health risk. A large release of one chemical might be less harmful to our health than a smaller release of another chemical; the impact of air releases can be affected by wind direction and other factors.

Learn more about chemicals and risk to human health with the links below:

• What is Relative Risk? (NLM - http://toxtown.nlm.nih.gov/text_version/disclaimer.php#relative_risk)
• Is my health at risk because of toxic chemicals in my community? (EPA - http://www.epa.gov/tri/stakeholders/communities/index.htm)
• Basic Risk Assessment (EPA - http://epa.gov/riskassessment/basicinformation.htm)
• Human Health Risk Assessment (EPA - http://epa.gov/riskassessment/health-risk.htm)
• Toxicology Research (EPA - http://epa.gov/ncct/index.html)
• The Habitable Planet: Risk, Exposure, and Health (Annenberg Learner - http://www.learner.org/courses/envsci/unit/text.php?unit=6&secNum=0)

TOXMAP can create several types of maps:

• TRI Facilities Maps
• TRI Chemical Releases Maps
• TRI Chemical Trends Maps
• Superfund Maps
• TOXNET® Search Maps
• Combination Maps

TRI Facilities Maps

TOXMAP's "TRI Facilities" maps show all facilities that have reported to the US Environmental Protection Agency (EPA)'s Toxics Release Inventory (TRI) (http://www.epa.gov/tri/) program.

Federal law requires certain industrial facilities which manufacture, process, or otherwise use particular toxic chemicals in amounts exceeding specific threshold values, to report annually on their releases of these chemicals to the environment or transferred off-site to be processed as waste. Information about source reduction and recycling is also reported. The label above the TOXMAP map notes the TRI year represented.

Each TOXMAP TRI facility location is represented with a small white square and is mapped using coordinates from the EPA's Facility Registry System (FRS).

The "TRI facility details" link to the right of the map provides additional information about each facility. If a TRI facility (identified by its TRI Facility ID) has a name change between TRI years, the most recent name is displayed in TOXMAP.

To create a facilities map, enter search terms (excluding chemical name) in the TOXMAP "Quick Search" box (to the left of the home page map) with the "TRI" checkbox checked. Alternatively, select the TOXMAP "TRI Facilities" tab and then move the map to the desired area.

TRI Chemical Releases Maps

TOXMAP's "TRI Releases" maps show color-coded maps for reported on-site TRI chemical releases. Each release is represented with a colored circle indicating the amount of total on-site release in a single calendar year. The location is mapped using coordinates from the EPA's Facility Registry System (FRS). The color of the circle represents the amount of on-site release relative to all other such releases nationwide (based on the search criteria). The releases map legend provides details.

To create a releases map, enter search terms (including chemical name) in the TOXMAP "Quick Search" box (to the left of the home page map) with the "TRI" checkbox checked. Alternatively, select the TOXMAP "TRI Releases" tab, select a chemical on the "Search" page, optionally choose the year, and move the map to the desired area.

Additional information about each facility and release can be found by clicking the "TRI on-site release details" link to the right of the map. If a single facility (identified by its TRI Facility ID) has a name change between TRI years, the most recent name is displayed in TOXMAP.

Maps can show on-site releases of a single chemical in a single year, or releases identified by a search in NLM's TOXNET Toxics Release Inventory (TRI). The criteria available in TOXNET TRI allow for customized TOXMAP chemical releases maps. For example, a map could show on-site TRI chemical releases for a particular Standard Industrial Classification (SIC) code in a particular ZIP code.

TRI Chemical Trends Maps

TOXMAP's "TRI Trends" maps show changes in reported on-site TRI release amounts for a chosen chemical.

At this time, TOXMAP's trend calculation does not account for changes to the TRI program's release or waste management data. Therefore, an apparent increase or decrease in on-site releases may actually reflect a change in TRI chemical reporting requirements. We intend to change TOXMAP to take some or all of these reporting requirement changes into account in an upcoming version of TOXMAP.

The "trend," or "chemical on-site release amount change" for a given facility and chemical, is calculated by comparing the total on-site release amount for the most recent year of TRI data in TOXMAP to the average of all previous years. The TOXMAP FAQ "How are TRI trends calculated?" provides additional details about this calculation.

Each trend is represented with a colored triangle indicating the degree of change in total on-site release amount and is mapped using coordinates from the EPA's Facility Registry System (FRS). Upward trends are represented with an upright triangle, downward trends with a triangle pointing downward. The color of the triangle represents the amount of change relative to all other changes nationwide of the same chemical. The trends map legend provides details.

Additional information about each facility and trend can be found by clicking the "TRI facility details" link. If a single facility (identified by its TRI Facility ID) has a name change between TRI years, the most recent name is displayed in TOXMAP.

To create a trends map, click the TOXMAP "TRI Trends" tab, and then select or enter a chemical name on the "Search" page, and move the map to the desired area.

TOXNET® TRI Search Results Maps

TOXMAP maps can also be created from TOXNET (http://toxnet.nlm.nih.gov/) TRI search results.

Select TRI (http://toxnet.nlm.nih.gov/cgi-bin/sis/htmlgen?TRI) from the TOXNET database menu, search chemical name, CAS Registry Number, TRI data year, and/or details about the releases or releasing facility. Your TRI search results can be mapped with TOXMAP by clicking on the "Map it with TOXMAP" icon located on the upper right of the results page/s.

NOTE: At this time, TOXMAP shows reported on-site releases only; it does not show transfers off-site or those managed via waste reduction. Also, TOXMAP Chemical Releases maps do not show Form A (short form) submissions (http://tri.supportportal.com/ics/support/KBAnswer.asp?questionID=22811), because Form A release amounts vary. Consequently, the number of results in TOXNET might not match the number of releases mapped in TOXMAP.

Superfund Maps

TOXMAP's "Superfund" maps show sites which have been identified by the US Environmental Protection Agency (EPA)'s Superfund Program (http://www.epa.gov/superfund/index.htm).

The EPA Superfund Program is part of a federal government effort to clean up land in the United States that has been contaminated by hazardous waste and that has been identified by the EPA (http://www.epa.gov/) as a candidate for cleanup because it poses a risk to human health and/or to the environment.

Each Superfund site location is represented with a small red square (indicating its Status on the National Priorities List (NPL) and is mapped using coordinates from the EPA's Facility Registry System (FRS).

The "Superfund site details" link provides additional information about each Superfund site.

To create a Superfund site map, enter search terms in the TOXMAP "Quick Search" box (to the left of the home page map) with the "Superfund NPL" checkbox checked. Alternatively, select the TOXMAP "Superfund" tab and then move the map to the desired area. Click the "Search" subtab or the "Search a chemical" link to show only those sites containing a specific chemical.

Combination Maps

TOXMAP allows users to create maps that combine both TRI and Superfund data. The "Combo" tab lets users select specific TOXMAP datasets to be mapped (e.g. TRI facilities, TRI on-site chemical releases, TRI chemical release trends, Superfund sites on the National Priorities List (NPL), and demographic data).

Examples of Combination maps include:

• A TRI facilities and Superfund sites map shows both all facilities that have reported to the US Environmental Protection Agency (EPA)'s Toxics Release Inventory (TRI) (http://www.epa.gov/tri/) program and all sites (of a given NPL Status) that have been identified by the EPA's Superfund Program (http://www.epa.gov/superfund/index.htm). The "TRI facility details" link provides additional information about each TRI facility. Likewise, the "Superfund site details" link provides additional information about each Superfund site.
  
  
• A Chemical releases map shows color-coded maps for reported on-site TRI releases of a specified chemical, and Superfund sites that contain that same chemical according to the US Environmental Protection Agency (EPA)'s CERCLIS database. A list of the TRI chemicals in TOXMAP can be found at http://toxmap.nlm.nih.gov/toxmap/main/chemicals.jsp. A list of the Superfund chemicals in TOXMAP can be found at http://toxmap.nlm.nih.gov/toxmap/main/sfChemicals.jsp).
  
  
• A Superfund sites and TRI chemical release trends map shows locations of Superfund sites and changes in reported on-site release amounts for a chosen TOXMAP TRI chemical.

Demographic Data

Many types of demographic data can be overlaid on any TOXMAP map. Available demographic layers include US population, age group, and race (US Census 2000, 1990); per capita personal income (1988-2003); cancer mortality (1970-1994); and mortality from various causes (1988-1992).

Geographic Region

Once a geographic region has been chosen, all TOXMAP maps show TRI and Superfund results only inside the specified region. Other map data (such as roads, political boundaries, and demographic data) are visually muted on the map. TOXMAP provides many pre-defined geographic regions, or users can create and name their own regions.

The EPA's Toxics Release Inventory (TRI) Program is a national database that identifies facilities, chemicals manufactured, processed and used at the identified facilities, annual amounts of chemicals released and otherwise managed (on and off site) in waste.

The following information is excerpted from the EPA's "The Toxics Release Inventory (TRI) and Factors to Consider When Using TRI Data" [Download Acrobat Reader]:

TRI data do not include release information from all sources or from other waste management activities, and all industry sectors and all chemicals are not covered. TRI data report releases and waste management of the chemicals, but do not reflect exposure information of the public to the chemicals. Only facilities meeting specific criteria are required to report.

All data in TRI (chemicals released, release amounts, etc.) is required by law to be self-reported annually, and is not validated by the EPA. In addition, some of the reporting facilities submit estimated data to TRI. (Since different estimation practices are used, the EPA has published estimation guidance for the user.)

TRI release estimates are one resource that can be used to evaluate exposure or calculate potential risks to human health and the environment. However, it is essential to understand that they do not, by themselves, represent risk. The determination of potential risk depends on many factors, including toxicity, chemical fate after release, release location, and population concentrations.

CERCLIS (Comprehensive Environmental Response, Compensation and Liability Information System) (http://www.epa.gov/superfund/sites/cursites/index.htm) is a database maintained by the US Environmental Protection Agency (EPA).

CERCLIS contains information such as the current status of cleanup efforts, cleanup milestones reached, and amounts of liquid and solid media treated at sites on the National Priorities List (NPL) or under consideration for the NPL.

Search the CERCLIS database at http://cfpub.epa.gov/supercpad/cursites/srchsites.cfm.

TRI or Superfund search results can be saved from any map page except Chemical Release Trends. Only the results within your current map area are saved; be sure to navigate to your area of interest before saving results. The saved data correspond to the information presented via the links in the Map Details area.

To save search results, click on the Download sub-tab. Make sure pop-up blockers are disabled in your browser for toxmap.nlm.nih.gov. Then click "Download TRI (or Superfund) search results." Then click "download now" to start the download process. Closing this window while the download is in progress will cancel the download.

While the results are downloading, you can continue to use TOXMAP in the main TOXMAP window.

When your results are ready, your browser will ask you whether to save or open the file. The file contains comma-delimited data which can be imported into a spreadsheet like Microsoft Excel, or into a resource such as Google Maps (http://support.google.com/maps/).

GIS stands for Geographic Information System, a means of storing, displaying, and analyzing data that can be referenced geographically. Maps are a common GIS product. A GIS consists of data, computer hardware and software, and of course, operating personnel.

A GIS takes data stored in traditional tabular format databases (i.e. rows and columns), and gives it geographic references so that it can be displayed graphically. A GIS can also organize data by subject matter or theme, via data sub-sets called layers. A GIS can combine many layers of information.

TOXMAP uses the most current, final TRI data available from the EPA. 1987 is the first reporting year of the TRI program, but by industry convention, 1988 is the first year that TRI data is used for analysis. Data submission deadlines, data entry processes, and data quality control and review all influence the actual date of data release.

Prior to the final release of a given TRI release year, EPA at times publishes a preliminary dataset of the upcoming release data. However, TOXMAP does not add a release year until it is final.

A complete list of chemicals currently listed in TOXMAP TRI can be found at http://toxmap.nlm.nih.gov/toxmap/main/chemicals.jsp. A complete list of TRI chemicals required to be reported to the EPA can be found at http://www.epa.gov/tri/trichemicals/index.htm.

NOTE: At this time, TOXMAP uses reported on-site releases only. Some TRI chemicals have no reported releases, and so will not appear in the TRI release data or in TOXMAP.

For more information, see the TRI Fact Sheet.

The substances found at Superfund sites have been designated by the Comprehensive Environmental Response, Compensation, and Liability Act (CERCLA) as 1) causing or contributing to an increase in mortality or in irreversible or incapacitating illness, or 2) posing a substantial present or potential hazard to human health or to the environment when improperly treated, stored, transported, disposed of, or otherwise managed.

More than 800 substances are currently designated as hazardous (http://www.epa.gov/oswer/riskassessment/glossary.htm#h), and many more as potentially hazardous. These substances do not include petroleum or natural gas.

A list of Superfund chemicals found in TOXMAP can be found at http://toxmap.nlm.nih.gov/toxmap/main/sfChemicals.jsp.

At this time, TOXMAP uses reported on-site releases only. Some TRI chemicals have no reported releases, and so will not appear in the TRI release data or in TOXMAP.

Certain industries in the United States which manufacture, process, use, or transport significant amounts of specific toxic chemicals (approximately 650 chemicals and chemical categories covering about 23,000 industrial and federal facilities) are required by law to report annually on the releases of these chemicals to the EPA (through its Toxics Release Inventory Program/TRI). TOXMAP maps on-site releases of these chemicals.

It should be noted that although facilities are required by federal law to use the best available data for their reporting, the accuracy of the reported data is unknown since it can be based on both actual measurements and on estimates. However, the Toxics Release Inventory is the best public information available on these chemicals.

The EPA Superfund Program is part of a federal government effort to decontaminate any land in the United States that has been contaminated by hazardous waste and that has been identified by the EPA as a candidate for cleanup because it poses a risk to human health and/or the environment. The program designates more than 800 substances as hazardous, and many more as potentially hazardous to human health or to the environment when improperly treated, stored, transported, disposed of, or otherwise managed. TOXMAP also maps Superfund chemicals and sites.

The toxic chemicals reported in this way make up only a small portion of the total amount manufactured, handled and used in the United States.

Industries are not the only entities responsible for toxic chemicals. Since the current reporting requirements apply only to industrial sources, sources of toxic chemicals from transportation, farming and households are not included. In addition, thousands of new chemicals are studied each year and thousands are manufactured. This number far exceeds the ability to test them all regarding possible toxic effects on people, plants or animals.

Overview

TOXMAP plots the location of all TRI facilities and Superfund sites using addresses and coordinates from the EPA Facility Registry System (FRS) (http://www.epa.gov/frs). The location of some of these may appear to be slightly inaccurate, because they are calculated by a geocoding estimation process. General information about the accuracy of locations in TOXMAP can be found in the TOXMAP FAQ "Why are the locations of some TOXMAP facilities slightly inaccurate?"

The following provides more detailed information about the problems with TRI location data, EPA's ongoing efforts to improve it, the limitations of FRS, and location accuracy in TOXMAP today.

Problems with TRI, Limitations of FRS

The EPA recommends use of addresses and coordinates from their Facility Registry System (FRS) (http://www.epa.gov/frs). TOXMAP only plots TRI facilities with defined FRS locations. Corrections to FRS are made year-round by EPA and are incorporated into TOXMAP annually with each year's publicly available data.

This approach avoids many errors in the TRI location data. However, there are also limitations to FRS data, such as in the case of a large facility (tens or hundreds of square miles in area) that reports to multiple EPA programs. Since FRS only uses the "best" of the reported coordinates, a more accurate location for a TRI release could be overlooked (e.g. the street address coordinate is used because it is easily identified as "best", but the TRI release actually takes place miles away).

Coordinate Accuracy Assessment

To get a better understanding of coordinate accuracy in EPA FRS data, TOXMAP annually conducts an assessment in which each facility's reported ZIP code is compared with the 5-digit ZIP code the coordinate lies within (plus a 5-mile buffer).

To translate coordinates into ZIP codes, TOXMAP uses a ZIP code file created by ESRI in 2006 (based on ZIP code boundaries from an earlier date).

The results place facilities into five categories based on the number of matching digits. Because ZIP codes follow a pattern across the US, these categories helped, to some degree, indicate accuracy. The latest results are as follows:

• Number of facilities evaluated: 54032
• TRI data for years: 1988-2011
• FRS data as of: November, 2012
• First 3 or More Digits Match: ~99.06%
• First 1 or 2 Digits Match: ~0.25%
• None of The Digits Match: ~0.004%
• Not Evaluated: ~0.68%

Look for the "Coordinate accuracy suspect" and "Coordinate not evaluated" notes when viewing TRI details. These notes indicate that the facility falls in one of the last four categories above.

Some facilities have correct coordinates but are categorized with partial ZIP code matches simply because their reported ZIP code was incorrect.

Facilities categorized with "No ZIP Code Was Found" have coordinates that fall outside of five-mile buffered ZIP code boundaries. Facilities in Puerto Rico and other US territories were not evaluated.

To Report a data error to EPA, please use the "Report an Error" (http://www.epa.gov/epahome/comments3.htm) web service and click the link on that page to report a data error.

The Superfund site cleanup process begins with the reporting of possible releases of hazardous substances by individual citizens, responsible parties or EPA regional offices. The EPA then registers the information in the Comprehensive Environmental Response, Compensation and Liability Information System (CERCLIS), an electronic record of sites affected by potentially hazardous substances.

The EPA examines possible release of hazardous substances from a site via several processes:

• Preliminary Assessment/Site Inspection (PA/SI)- reports the initial/current state of a site
• HRS Scoring- determines if the site should be on the National Priorities List (NPL)
• NPL Site Listing Process- prioritizes the most serious sites
• Remedial Investigation/Feasibility Study (RI/FS)- studies the degree of site contamination
• Record of Decision (ROD)- explains which cleanup alternatives will be used to clean up a Superfund site. The ROD for sites listed on the NPL is created from information generated during the Remedial Investigation/Feasibility Study (RI/FS)
• Remedial Design/Remedial Action (RD/RA)- discusses effective remediation options
• Construction Completion- signals the end of the site cleanup process
• Post Construction Completion - ensures long-term protection for the community and the environment.

The development of Superfund site cleanup plans includes several cleanup options. The EPA regularly invites public comment on the cleanup process in their community. The EPA also encourages citizens to participate in community advisory groups.

One of the most common reasons to use a GIS is its ability to create graphical images -- maps -- from database data. It is often easier to identify patterns in such images than in tables and rows.

Because a GIS can link data sets together, it can make data sharing and management easier. GIS can also assist with decision-making, because it helps users to analyze, query, and map the data. "Answers" can be displayed visually, allowing the user to compare different data more easily.

The data found in TOXMAP comes from several providers, including:

• Toxics Release Inventory (TRI)
  A federal law called the Emergency Planning and Community Right to Know Act (EPCRA) (http://www.epa.gov/regulations/laws/epcra.html) requires facilities in certain industries which manufacture, process, or use significant amounts of toxic chemicals, to report annually on their releases of these chemicals. The reports contain information about the types and amounts of toxic chemicals that are released each year to the air, water, land and by underground injection, as well as information on the quantities of toxic chemicals sent to other facilities for further waste management.
  
  Facilities with ten or more full-time employees that process more than 25,000 pounds in aggregate, or use greater than 10,000 pounds of any one TRI chemical, are required to report releases annually. The US Environmental Protection Agency (EPA) (http://www.epa.gov) maintains this information in a database called the Toxics Release Inventory (TRI) (http://www.epa.gov/tri/). The toxics release files on the National Library of Medicine's® (NLM) Toxicology Data Network (TOXNET®) (http://toxnet.nlm.nih.gov) come from TRI.
  
  TOXMAP uses the most current, final TRI data available from the EPA. Data submission deadlines, data entry processes, and data quality control and review all influence the actual date of data release by both the EPA and by TOXMAP.
  
  A complete list of chemicals currently listed in TOXMAP can be found at http://toxmap.nlm.nih.gov/toxmap/main/chemicals.jsp. A complete list of TRI chemicals required to be reported to the EPA can be found at http://www.epa.gov/tri/trichemicals/index.htm..
  
  NOTE: At this time, TOXMAP uses reported on-site releases only. Some TRI chemicals have no reported releases, and so will not appear in the TRI release data or in TOXMAP.
  
  For more information, see the TRI Fact Sheet (http://www.nlm.nih.gov/pubs/factsheets/trifs.html).
  
  
• EPA's CERCLIS
  CERCLIS (Comprehensive Environmental Response, Compensation and Liability Information System) (http://www.epa.gov/superfund/sites/cursites/index.htm) is a database maintained by the US Environmental Protection Agency (EPA).
  
  CERCLIS contains information about Superfund sites, such as the current status of cleanup efforts, cleanup milestones reached, and amounts of liquid and solid media treated at sites on the National Priorities List (NPL) or under consideration for the NPL. The CERCLIS database can be searched at http://cfpub.epa.gov/supercpad/cursites/srchsites.cfm.
  
  
• EPA's Facility Registry System (FRS)
  TOXMAP plots the location of TRI facilities using addresses and coordinates from the EPA's Facility Registry System (FRS) (http://www.epa.gov/frs/). The FRS is a centrally managed database that identifies facilities, sites or places subject to environmental regulations or of environmental interest.
  
  
• Hazardous Substances Databank® (HSDB)
  HSDB (http://toxnet.nlm.nih.gov/cgi-bin/sis/htmlgen?HSDB) contains comprehensive toxicological information on over 4,700 chemicals. Data in HSDB are peer-reviewed, and are derived and referenced from a core set of books, government documents, technical reports and selected primary journal literature. For more information, see the HSDB Fact Sheet (http://www.nlm.nih.gov/pubs/factsheets/hsdbfs.html).
  
  
• TOXLINE®
  TOXLINE® (http://toxnet.nlm.nih.gov/cgi-bin/sis/htmlgen?TOXLINE) is the National Library of Medicine's (NLM) bibliographic database on toxicology, containing over 3 million references to literature on biochemical, pharmacological, physiological, and toxicological effects of drugs and other chemicals. It is composed of articles from PubMed®/MEDLINE® and references from an assortment of specialized journals and other sources. For more information, see the TOXLINE® Fact Sheet.
  
  
• Agency for Toxic Substances and Disease Registry
  The Agency for Toxic Substances and Disease Registry (ATSDR) (http://www.atsdr.cdc.gov/atsdrhome.html) is an agency of the US Department of Health and Human Services. It strives to use the best science, to take responsive public health actions, and to provide trusted health information to prevent harmful exposures and disease related to toxic substances.
  
  
• National Atlas of the United States of America (USGS)
  TOXMAP uses the USGS's National Atlas (http://www.nationalatlas.gov/) for the following data:
  
  
  • 1990 and 2000 US Census population (http://www.nationalatlas.gov/mld/ce2000t.html): this includes selected county-level demographics (age, male/female ratio, population and race/ethnicity) and can be found in its original form on the US Census Bureau's website (http://www.census.gov/geo/www/index.html).
    
    
  • Personal Income (http://www.nationalatlas.gov/mld/bea001p.html): this data is originally collected by the US Bureau of Economic Analysis (BEA) (http://www.bea.gov/beahome.html), part of the US Department of Commerce (http://www.commerce.gov/).
    
    
  • US cities, states, counties, federal land, urban areas, and roads (http://www.nationalatlas.gov/maplayers.html).
  
  
• National Cancer Institute (NCI)
  TOXMAP uses the NCI's SEER*Stat Database (http://www.seer.cancer.gov/) for its cancer and disease mortality data. Underlying mortality data provided by the National Center for Health Statistics (NCHS) (http://www.cdc.gov/nchs/) of the Centers for Disease Control and Prevention (CDC) (http://www.cdc.gov).
  
  
• National Weather Service OST/SEC GIS Map Group
  Map data for US Territories such as Puerto Rico, US Virgin Islands, American Samoa, Guam, Marshall Islands, & Midway come from NOAA's (http://www.noaa.gov) National Weather Service OST/SEC GIS Map Group (http://www.nws.noaa.gov/geodata/catalog/national/html/us_state.htm).
  
  
• ESRI
  Data for hospitals, lakes, rivers, and other bodies of water, and for boundaries of Mexico come from ESRI (http://www.esri.com/). Hospital data was derived from the AHA FY2005 data release.
  
  
• GeoGratis
  Data for Canadian boundaries come from GeoGratis (Canadian government) (http://geogratis.cgdi.gc.ca/).

TOXMAP calculates the "trend," or "on-site release amount change," for a given facility and chemical by comparing the total on-site release amount for the most recent year of TRI data with the average of all previous years.

Specifically, subtract the average total on-site release amount (prior years) from the most recent total on-site release amount (current year). If the value is negative, the trend is downward; if the value is positive, the trend is upward.

TOXMAP's Trends Legend (directly below Trends maps) uses the greatest increase OR decrease of on-site chemical release as both the minimum and the maximum values (left and right sides) of the legend. For this reason, the Trends Legend will always display the same value on each side of the legend bar. The bar is divided into five equal intervals.

HANDLING SPECIAL CASES

1) What if there isn't data for one of the intermediate years?

TOXMAP ignores release values of "N/A". If no release data is provided by a facility, the EPA reports the release as "zero." In these cases, TOXMAP uses "zero" as the release value when calculating the trend.

2) What if there isn't data for the most recent year?

If there is no data for the most recent year, a trend is not calculated. Refer to the map legend for the special map icon that represents this situation ("insufficient data").

3) What if there is only data for the most recent year?

If the only available data is for the most recent year, it is treated as an increase, and the trend value is set to the total on-site release value for the most recent year.

4) What if there are multiple records for a year?

If there are multiple records for a year, the total on-site release values are added together and treated as a single value for that year.

5) What if there are changes to the TRI program that affect a trend calculation?

At this time, TOXMAP's trend calculation does not account for changes to the TRI program's release or waste management data. Therefore, an apparent increase or decrease in on-site releases may actually reflect a change in TRI chemical reporting requirements. We intend to change TOXMAP to take some or all of these reporting requirement changes into account in an upcoming version of TOXMAP.

See the EPA's Making Year-to-Year Comparisons of TRI Data (http://www.epa.gov/enviro/triexplorer/yearsum.htm) for more details.

• EPA EnviroMapper StoreFront
  EPA EnviroMapper StoreFront (http://www.epa.gov/enviro/html/em/) provides several GIS-based mapping tools. Window to My Environment (http://www.epa.gov/enviro/wme/) and EnviroMapper for Envirofacts (http://www.epa.gov/enviro/emef/) both display Superfund sites along with other locations that report to the EPA.

• US Geological Survey (USGS) National Atlas
  The US Geological Survey (USGS) National Atlas (http://www.nationalatlas.gov/) can map Superfund sites (http://www.nationalatlas.gov/natlas/Natlasstart.asp) and over 400 other kinds of data.

• HUD Enterprise Geographic Information System (EGIS)
  HUD Enterprise Geographic Information System (EGIS) (http://egis.hud.gov/egis/) can map Superfund locations with HUD (Department of Housing and Urban Development) community and housing data.
• Environmental Defense/"Scorecard"
  Environmental Defense, a US non-profit environmental organization (http://www.scorecard.org/), provides a resource for information about pollution problems and toxic chemicals; it includes maps of Superfund sites (http://www.scorecard.org/env-releases/land/community.tcl).

GIS and GPS are not the same thing, but they are related. GPS stands for Global Positioning System, a worldwide radio-navigation system of 24 satellites and their ground stations. GPS uses these satellites as reference points to calculate positions accurate to meters. These geographic position data are converted to a file that can be used by a GIS, which can map it to show the location of the actual coordinates.

There are many sources for geospatial information and data. The US federal government has created a portal known as the Geo.Data.gov (http://geo.data.gov/), part of Data.gov, to promote communication and sharing of geographic data by all levels of government and the public. GIS data are also available at the state and local government levels, from commercial vendors, and from other organizations.

Some sources of GIS data include:

United States Federal Government

• Geo.Data.gov - http://geo.data.gov/
• US Census Bureau - http://www.census.gov/geo/www/index.html
• US Census Bureau State & County QuickFacts- http://quickfacts.census.gov/qfd/index.html
• National Atlas of the United States - http://www.nationalatlas.gov/
• National Aeronautics and Space Administration (NASA) - http://www.nasa.gov/home/index.html
• EPA National Geospatial Program - http://www.epa.gov/geospatial/
• Federal Emergency Management Agency (FEMA) - http://gis.fema.gov/
• National Geodetic Survey - http://www.ngs.noaa.gov/
• National Cancer Institute - http://seer.cancer.gov/

Other

• The Geography Network - http://www.geographynetwork.com/
• GIS.com - http://www.gis.com/ (information and links)
• Center for Agricultural, Resource and Environmental Systems (CARES) (http://www.cares.missouri.edu/), University of Missouri at Columbia

TOXMAP facility locations are calculated by an estimation process that relies on "geocoding." Geocoding is a method that assigns a latitude and a longitude to an address. Even the most accurate latitude/longitude coordinate calculations, including those used by TOXMAP, are estimates; this can account for minor inaccuracies in site locations on a map.

Addresses are geocoded using software that accesses location information from a variety of sources which contain street segments; address ranges are attached to each side of the segment. TOXMAP's geocoding program estimates the location of each facility address based on this address range. Although very accurate, these locations are estimates, and they should not be used to definitively locate a particular facility.

More information about the accuracy of locations in TOXMAP can be found in the TOXMAP FAQ "How accurate are TRI locations in TOXMAP?"

TOXMAP offers several ways to create maps (listed below). Most of these maps can also be created via TOXMAP's Search page.

• Tabs and subtabs along the top of the page
• The "Quick Search" box to the left of the homepage map
• The "Combo/Define Map" tab
• The "Map Controls" area below the map

Tabs and subtabs

• Select the "TRI Facilities" tab for a map of all facilities that have reported to the Toxics Release Program (TRI) (http://www.epa.gov/tri/) for a specified geographical area since 1988.
• Select the "TRI Releases" tab for a map of on-site chemical releases of a specific TRI chemical. TRI data is available from 1988 to the year of the most current, final TRI data available from the EPA. Select subtabs above the map to change TRI chemical or to view a TRI year other than the most current.
• Select the "TRI Trends" tab for a map of on-site release trends for a specific TRI chemical. Select the Search subtab above the map to change chemical.
• Select the "Superfund" tab for a map of all Superfund Program sites. Select subtabs above the map to limit displayed sites to those containing a particular Superfund chemical or having a particular NPL status.
• Select the "Combo" (Combination) tab to create a map that combines TRI and Superfund data. You can specify what datasets to display and what demographic layer to overlay on top of this data. Click the TRI and/or Superfund checkbox, and optionally specify the type of TRI map to create, the TRI release year or NPL status(es) to view, and what demographic layer (e.g., US Census, Income, and Health data) to overlay. To limit the displayed Superfund sites to those that contain a particular chemical, select the "Search for a chemical at NPL sites" checkbox.
• Select the "Search" tab for a page to specify a variety of search options. See How can I specify more search options in TOXMAP? for details.

Quick Search

Use the "Quick Search" box to the left of the homepage map (http://toxmap.nlm.nih.gov/) to enter a TRI or Superfund chemical name, United States city, state, and/or ZIP code. Use the checkboxes to limit your search to only TRI or Superfund NPL datasets. All fields are optional; a map will be created based on the criteria you supply.

Next to the Quick Search area, click the individual maps of the continental United States, Alaska, Hawaii, American Samoa, Puerto Rico and the US Virgin Islands, Guam and the Marianas to create a TRI and Superfund map for the selected area.

Map Controls

The "MAP CONTROLS" appear below every map and provide short cuts for modifying your map. You can toggle amongst specific TRI map types, NPL Statuses, and whether or not to overlay demographic data. Additional links bring up pages to change the demographic layer, search for a chemical, define a combination map, or start over.

Getting details

After a map has been created, select either the "TRI facility details", "TRI on-site release details", or the "Superfund site details" link for a list and more detailed information about TRI facilities, releases, or Superfund sites on the map.

More information about creating TOXMAP maps can be found in the FAQ "What kinds of maps can TOXMAP create?"

(This list includes federal government sites only.)

• TOXMAP
  TOXMAP (http://toxmap.nlm.nih.gov) provides a "Download" option that allows users to download TRI facility, release, and trends data via the Facilities, Releases, Trends, Combo, and Search pages (located on the bar under the main menu). Data is saved locally as a compressed comma-separated text file (.zip). Moreover, users can save their search results via the Download pages, or with the "Save results" links in the map description and map controls. NOTE: At this time, TOXMAP includes reported on-site releases only.
  
  The user also has the option of downloading the ESRI shapefile, which can be read with ESRI's GIS software such as ArcView (http://www.esri.com/software/arcgis/arcview/index.html).

• TOXNET®
  TOXNET TRI (http://toxnet.nlm.nih.gov/cgi-bin/sis/htmlgen?TRI) allows users to search TRI chemical names, CAS Registry Numbers, TRI data years, and/or details about the releasing facility. The left menu of the "TRI Search Results" page provides a download option for the retrieved TRI data. TOXNET TRI search results can also be mapped with TOXMAP by clicking on the "Map it with TOXMAP" icon located on the upper right of results pages.
  
  
• EPA TRI Explorer
  EPA TRI Explorer (http://www.epa.gov/triexplorer/) offers custom reports on Releases, Waste Transfer, and Waste Quantity. Users can view and sort report data online or download it to a text file.
  
  
• EPA Envirofacts
  EPA Envirofacts (http://www.epa.gov/enviro/index.html) provides simple and advanced queries and reports for TRI data. Find them on the right under "Advanced Capabilities".
  
  
• EPA's TRI data site
  EPA's TRI data site (http://www.epa.gov/tri/tridata/) gives the user different ways to download TRI data:
  • "Annual TRI Public Data Release"-- includes a general overview of that year's TRI data and information on trends;
  • State Fact Sheets (http://www.epa.gov/triexplorer/statefactsheet.htm)-- provide a brief summary of the TRI data by state and downloadable data files containing TRI reports submitted for the reporting year;
  • TRI state data files (http://www.epa.gov/tri/tridata/index.htm#statefile)-- contain all data submitted to the Toxic Chemical Release Inventory by facilities located in a selected state for a specific year.

Potentially Responsible Parties (PRPs) of Superfund sites are current or former owners or operators of a facility, transporters of a hazardous substance who chose the site for disposal, or agents who coordinate treatment or disposal of hazardous substances at the site. Identifying the PRPs for clean up of a site is an EPA priority.

Sometimes the PRP is unwilling or unable to assume responsibility, or the PRP cannot be found. In these cases, the EPA, the state, or the tribe will clean the area with funding from the Superfund program. The EPA website on Compliance and Enforcement provides further information on legal responsibility for cleaning dangerous waste sites (http://www.epa.gov/compliance/).

The National Technical Information Service offers a list of PRPs at individual sites (http://www.ntis.gov).

Simply defined, metadata is data that describes other data. It provides additional information about the data that the GIS uses, which is not included in the data itself, such as date of origination, currency, accuracy, extent, format, custodianship, and collection methodology. Metadata is typically stored in data models, dictionaries, schemas and other representations. Spatial metadata supports easier data access and management. The adoption of metadata standards promotes consistency in the naming, defining, operating, and cataloging of data among different entities.

User feedback guides TOXMAP. Feedback received through focus groups and other evaluation methods has identified features to be considered for future versions of TOXMAP. These include the ability to view two or more chemicals on one map and more types of US map, health, and census data. You can learn more about some of these potential new features by visiting "TOXMAP Tomorrow "(http://toxmap.nlm.nih.gov/toxmap/tour/part2/index.html).

Other features that are being considered for future versions of TOXMAP include: the ability to combine TOXMAP data with data from other sources (such as another mapping system on the Internet); inclusion of spatial data from sources in addition to TRI and Superfund; information that assists users in using and "interpreting" created maps; and inclusion of other TRI data, such as off-site waste transfers.

Your priorities are ours. Please contact TOXMAP with your comments and feedback.

Effective sharing of data and services, both within and across organizations, depends on accepted standards. Industry standards organizations such as the International Organization for Standardization (ISO) (http://www.iso.org) develop, discuss, and publish requirements and specifications for implementation by software vendors and system integrators.

Like many areas of information technology, GIS is growing rapidly. Standards are crucial to share GIS spatial data accurately, and for GIS systems to be able to work together.

The Open Geospatial Consortium, Inc. (OGC) (http://www.opengeospatial.org/) is working on the development of geospatial interoperability standards that will facilitate access to and use of geographic information by a broad range of users.

• US EPA TRI Explorer Dynamic Maps
  EPA TRI Explorer Dynamic Maps (http://www.epa.gov/triexplorer/maps.htm) lets the user create reports and color-coded state and county maps of TRI data.

• US EPA EnviroMapper and MyEnvironment
  EPA EnviroMapper for Envirofacts (http://www.epa.gov/emefdata/em4ef.home) and MyEnvironment (http://www.epa.gov/myenvironment/) both display TRI facility locations along with other locations that report to the US EPA.

• US Geological Survey (USGS) National Atlas
  The US Geological Survey (USGS) National Atlas (http://www.nationalatlas.gov/) can map TRI facility locations and over 400 other kinds of data.

A Superfund site is any land in the United States that has been contaminated by hazardous waste and identified by the Environmental Protection Agency (EPA) as a candidate for cleanup because it poses a risk to human health and/or the environment. These sites are placed on the National Priorities List (NPL) .

The NPL is the list of national priorities among the known releases or threatened releases of hazardous substances, pollutants, or contaminants throughout the United States and its territories. The NPL is intended primarily to guide the EPA in determining which sites warrant further investigation. The site's NPL "status" can provide more information about the site in relationship to the NPL:

• Proposed: Site proposed (by the EPA, the state, or concerned citizens) for addition to the NPL due to contamination by hazardous waste and identified by the Environmental Protection Agency (EPA) as a candidate for cleanup because it poses a risk to human health and/or the environment
• Withdrawn: Site removed from the National Priorities List (NPL) because the EPA has determined that it poses no real or potential threat to human health and the environment
• Final: Site determined to pose a real or potential threat to human health and the environment after completion of Hazard Ranking System (HRS) screening and public solicitation of comments about the proposed site
• Deleted: Site deleted from the National Priorities List (NPL) by the EPA (with state concurrence) because site cleanup goals have been met and no further response is necessary at the site.

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 on-site release relative only to other such releases in that geographic region. Other map data (such as roads, political boundaries, and demographic data) are visually muted on the map.

TOXMAP provides a variety of pre-defined geographic regions, or users can create and name their own regions. To set a region, click the Set Region tab on any map. Entering a location in TOXMAP's Quick Search or Zoom to a Place will not set or change your geographic region, but will zoom the map to that location. You can select "Region" from the Zoom To dropdown menu on the map to zoom to the geographical extent of your region.

Sometimes data will appear outside your region. This can happen when address or location data is inaccurate for a given TRI facility or Superfund site. See the TOXMAP FAQ "How accurate are TRI locations in TOXMAP?"

To draw the Earth (or a portion of it) onto a map, map makers use different map projections that apply (or "project") the curved Earth surface onto a flat map. Although no projection will perfectly depict all areas of the Earth, different map projections make specific areas of the Earth look as accurate and realistic as possible. TOXMAP uses a map projection (called "North American Albers Equal Area Conic") which makes the continental United States look most realistic. Areas farther away from the US will appear increasingly distorted.

You can learn more about map projections from the USGS at http://www.nationalatlas.gov/articles/mapping/a_projections.html.

To display an accurate visual representation of a location, a GIS uses an absolute location reference system. Latitude and longitude, written in degrees (°), is one such system.

Latitude lines, known as parallels, run horizontally, and measure the distance north or south of the Equator. The Equator is the starting point of measuring latitude and is 0° latitude. Latitude is measured in degrees from 0° to 90° and is specified as North or South.

Longitude lines run vertical and are known as meridians. They indicate the distance east or west of the "prime meridian." The prime meridian runs through Greenwich, England and is 0°longitude.

TOXMAP can dynamically generate specific custom-made TRI and Superfund maps and facility or on-site release details via simple links.

How it works
Linking to TOXMAP works by adding a single HTML tag (called an HREF) that tells a web page to go to the TOXMAP web site. Information about the custom map requested is passed to TOXMAP through the URL (see examples below) by including specific information about the type of map desired.

Restrictions
There are no restrictions on and no limit to the number of custom maps that can be created; this service is free. The TOXMAP page linked to may be displayed in a frame set or in a new browser window.

Examples of dynamically generated custom-made maps

On-site releases of Toluene Diisocyanate by reporting TRI facilities in the United States and Superfund sites containing Toluene Diisocyanate:
http://toxmap.nlm.nih.gov/toxmap/main/mapIt.do?registryNumber=26471-62-5

TRI facilities and Superfund sites in area of Green Bay, WI:
http://toxmap.nlm.nih.gov/toxmap/main/mapIt.do?city=green+bay&state=WI

On-site releases of Mercury Compounds by reporting TRI facilities in the United States and Superfund sites containing Mercury Compounds in EPA Region 4:
http://toxmap.nlm.nih.gov/toxmap/main/mapIt.do?
chemicalName=mercury+compounds®ionID=EPARegion04

Note: for custom links to start TOXMAP with a pre-defined region selected, see the region's description on the Set Region page.

TRI releases with the specified submission numbers in the area of San Juan County, NM:
http://toxmap.nlm.nih.gov/toxmap/main/mapIt.do?
subnos=1302200254249,1302200776502&otherPlace=san+juan+county

TRI or Superfund only Maps

If your URL contains "/tri/" or "/superfund/" instead of "/main/" TOXMAP creates a map showing only the TRI or Superfund data sets. For example, http://toxmap.nlm.nih.gov/toxmap/tri/mapIt.do?chemicalName=mercury+compounds
creates a map of on-site TRI releases of Mercury Compounds by reporting TRI facilities in the United States; Superfund sites containing Mercury Compounds will not be mapped.

Required "Parameters" (CGI variables after the question mark in the URL)
None

Optional "Parameters"
> city
> state
> ZIP
> otherPlace - a county, body of water, or other place
> regionID - the region ID of a pre-defined or user-defined region
> chemicalName
> registryNumber - CAS registry number (preferred over chemicalName)
> subnos - A comma-delimited list of one or more TRI submission numbers (overrides "chemicalName" and "registryNumber")

Parameter combinations that can be used for specifying a place
> city and state
> state only
> city only
> ZIP code only
> otherPlace only
> regionID only

ZIP code is ignored if a city and state is provided; state is ignored if a ZIP code is provided; all place parameters are ignored if a regionID is provided.

Types of maps created
If your URL contains "chemicalName" or "registryNumber," then TOXMAP creates a custom map showing on-site TRI chemical releases in the most recent TRI year as well as all Superfund sites in the National Priorities List (NPL) dataset containing the specified chemical. If your URL contains "subnos", then TOXMAP creates a map showing the TRI chemical releases corresponding to the specified submission numbers. When none of these items is supplied, TOXMAP creates a combination map showing all TRI facilities and Superfund NPL sites, unless the URL has specified only the TRI or Superfund dataset (see above)

If your URL contains place information (city, state, or ZIP), TOXMAP creates a map of that area. If a region is specified, then the map will show results only inside the specified region. When none of these is supplied, TOXMAP creates a map of the entire United States. In all cases, you have full control to zoom or pan the map to see the entire nation and surrounding countries.

URL Rules
1. The URL must follow standard HTML rules
2. There can be no hard returns in the URL
3. There can be no spaces within the HREF. Replace spaces with the plus sign (+). Special characters within the URL must be replaced by their octal equivalent.

> Use %%25 to represent the % character
> Use %%26 to represent the & character
> Use %%30 to represent the + character

Links to facility or on-site release details
TOXMAP supports custom links to TRI facility details (including name, address, on-site chemical release data, etc.). Similar links are available for on-site chemical releases, release trends, or Superfund NPL sites. Contact us at tehip@teh.nlm.nih.gov for the format of the URLs of these links.

Get help setting up a TOXMAP link on your site
Contact us at tehip@teh.nlm.nih.gov.

For questions, suggestions or comments about TOXMAP or other resources from NLM's Division of Specialized Information Services contact:

National Library of Medicine
Division of Specialized Information Services
2 Democracy Plaza, Suite 510
6707 Democracy Blvd., MSC 5467
Bethesda, MD 20892-5467

Fax: (301) 480-3537
Telephone: (301) 496-1131
e-mail: tehip@teh.nlm.nih.gov
URL: http://sis.nlm.nih.gov/siscontact.html

Once a geographic region has been chosen, map headers will include a link to a "Regional TRI Summary" in the regional description. These summaries show cumulative on-site TRI release data over a period of years.

If your map shows TRI facilities, then the Regional TRI Summary will provide a regional on-site chemical releases table that lists the names and release amounts of chemicals released on-site by facilities in the region (with the greatest total on-site releases listed first).

For a TRI Releases map, the Regional TRI Summary will list on-site release totals of the selected chemical broken down by release medium.

Note that these are cumulative summary data and do not reflect specific search settings such as facility name and release amount threshold.

The National Priorities List (NPL) contains the most serious uncontrolled or abandoned hazardous waste sites throughout the United States and its territories. The NPL lists sites after 1) completing a Hazard Ranking System (HRS) screening and 2) soliciting and addressing public comments about the proposed site.

The NPL guides the federal government in determining which sites should be investigated. It is updated on a regular basis.

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".

For details on the NPL site listing process, see http://www.epa.gov/superfund/sites/npl/npl_hrs.htm.

TOXMAP's Quick Search on the home page allows you to search TRI and Superfund data by chemical and to zoom the resulting map to a specified city, state, or ZIP code.

More search options are available by clicking the "More Search Options..." link or by selecting the Search tab (http://toxmap.nlm.nih.gov/toxmap/search/setupSearch.do). The resulting search page allows you to search a chemical (in either TRI, Superfund, or both datasets) and specify more search options pertaining to TRI and Superfund. TRI-specific options include facility name, release medium, and on-site release amount. Superfund-specific options include site name and Hazard Ranking System (HRS) score.

TOXMAP can optionally zoom the map to the area of your search results. Note that in some cases this will zoom the map to an area larger than North America (e.g., to include Hawaii or the Mariana Islands). The "Zoom To" drop down box will zoom the map to a state or other pre-defined map area.

As with statistics, graphs, and other visual representations of data, it's important to examine the content of a map closely. Subtle details, generalizations, and personal perspectives all impact the viewer's interpretation of what the map portrays.

In his book, How to Lie With Maps [i], geographer Mark Monmonier provides users with guidelines to help them read maps critically. Some of these tips, along with others from TOXMAP, are listed below.

• Remember that not all maps are made by professional cartographers. Today's image and cartography software have made it possible for non-cartographers to create and design maps that may hide or obscure features that many users would expect to find.



• Keep in mind that when portraying a three-dimensional world via a map, the geographic region that the map represents may in some ways be changed or distorted. For example, map symbols are often "thicker" or larger than the elements they depict.



• Don't forget that not all maps are designed to inform the user about a location or geographic region. While some maps are symbols for geographic knowledge, others are created just for "looks," with less or little attention to accuracy.



• Pay close attention to the map legend and to the symbols used on the map. For maps that use color-coding to represent ranges of data values, note how the ranges are determined and how data are categorized within.



• Learn as much as possible about the data depicted on the map. When was it created? Was it summarized or simplified in some way before being used?



• Know that everything on a map can be considered "data" and deserves whatever attention is relevant to your work. For example, a map might use accurate data to represent large rivers and bodies of water, but have incomplete or out-of-date representations of streams, ponds, tributaries, and other small water features. While this map might be useful for the casual user, someone concerned with local flooding or wildlife would likely need better water resource data.



• Think as much about what isn't shown on the map as what is. Are there geographic features such as mountain ranges that, if shown, would improve your understanding of the map?


There are many things to keep in mind when reading and interpreting a map. Don't be intimidated by the map and the information it conveys--maps can help you discover things that no other medium can. However, be sure to keep the guidelines above in mind.



---

[i] Monmonier, Mark. How to Lie with Maps. 2nd edition. Chicago: University of Chicago Press, 1996.

Many US federal government organizations, as well as state and local governments, use GIS to display health-related information. Some US federal sites include:

• Cancer.gov (http://gis.cancer.gov/) from the National Cancer Institute (NCI) (http://www.cancer.gov/) is a central source of information about GIS and related resources for use by the public, cancer researchers, and the GIS Special Interest Group (http://gis.cancer.gov/overview/gissig.html).
  
  
• EnviroMapper StoreFront (http://www.epa.gov/enviro/html/em/) from the EPA (http://www.epa.gov/) helps you view federal, state, and local information about environmental conditions and features in an area of your choice.
  
  
• MyEnvironment (http://www.epa.gov/myenvironment/) is a powerful web-based tool from the EPA (http://www.epa.gov/) that provides a wide range of federal, state, and local information about environmental conditions and features in an area of your choice.
  
  
• GATHER, Geographic Analysis Tool for Health and Environmental Research, (http://gis.cdc.gov/) from the CDC (http://www.cdc.gov/) is an online spatial data access system that provides members of the public health community and general public access to spatial data that is pertinent to the analysis and exploration of public health issues.

Some of the organizations working on international and GIS standards include:

• American National Standards Institute (ANSI) - (http://www.ansi.org/)
• Digital Geographic Information Working Group (DGIWG) - (http://www.dgiwg.org/digest/About2.htm)
• European Committee for Standardization (CEN) - (http://www.cen.eu/cen/)
• Federal Geographic Data Committee (FGDC) - (http://www.fgdc.gov/)
• Global Spatial Data Infrastructure (GSDI) - (http://www.gsdi.org/)
• International Hydrographic Organization (IHO) - (http://www.iho.int/)
• International Organization for Standardization (ISO) - (http://www.iso.org/)
• Location Interoperability Forum (LIF) - (http://www.cellular.co.za/technologies/location/lif.htm)
• Open Geospatial Consortium (OGC) - (http://www.opengeospatial.org/)
• Web Services Interoperability Organization (WS-I) - (http://www.ws-i.org/)
• Wireless Location Industry Association (WLIA) - (http://www.wliaonline.com/)
• World Wide Web Consortium (W3C) - (http://www.w3.org/)