Ecological Structure Activity Relationships (ECOSAR)
NEW v. 1.11, June, 2012
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What is ECOSAR?
The Ecological Structure Activity Relationships (ECOSAR) Class Program is a computerized predictive system that estimates aquatic toxicity. The program estimates a chemical's acute (short-term) toxicity and chronic (long-term or delayed) toxicity to aquatic organisms such as fish, aquatic invertebrates, and aquatic plants by using computerized Structure Activity Relationships (SARs).
How Does ECOSAR Work?
ECOSAR uses structure-activity relationships (SARs) to predict the aquatic toxicity of untested chemicals based on their structural similarity to chemicals for which aquatic studies are available. Application of structure activity relationships is a technique routinely used by the U.S. EPA Office of Pollution Prevention and Toxics under the New Chemicals Program to estimate the toxicity of chemicals being reviewed in response to Pre-Manufacture Notices mandated under Section 5 of the Toxic Substances Control Act (TSCA). The toxicity data used to build the SARs are collected from publicly available experimental studies and confidential submissions provided to the U.S. EPA New Chemicals Program. The SARs in ECOSAR express correlations between a compound's physicochemical properties and its toxicity within specific chemical classes.
Through publication of the ECOSAR Model, the U.S. EPA provides public access to the same methods the EPA uses for evaluating aquatic toxicity. Many of the SARs have been validated through studies published in the open literature or through validation activities conducted by the U.S. EPA is conjunction with other regulatory agencies. For access to some of the ECOSAR validation activities and publications, ECOSAR References section within the ECOSAR model’s Help Menu, or visit the U.S. EPA’s SustainableFutures/Publications webpage.
Note Regarding EPISuite and ECOSAR
ECOSAR is maintained and developed as a stand-along program. However, for users’ convenience when screening chemicals, ECOSAR was included in the EPA EPISuite program many years ago so users could obtain a full environmental profile. Since that time, associated funding and maintenance schedules have become dramatically different between the two models and now the ECOSAR version in EPIsuite is now out of date. We are unsure when the new version might be added.
We encourage users to try ECOSAR as a standalone program since the tool contains many additional features in the stand alone program that are not included in the EPISuite version.
Enhancements to Version 1.11 of ECOSAR
- The flag below has been added to the ECOSAR program to better distinguish between chemicals that truly fall into a structurally defined ECOSAR chemical class versus those being estimated by default using the neutral organics/baseline toxicity equation.
- An update has been made to the Green Algae and Daphnid acute QSAR equations for neutral organics along with edits to the benzyl nitriles daphnid ChV QSAR and the haloalcohol Fish ChV
- Minor changes were made to some of the class definitions and supporting documents.
- Additional clarification was added to the ECOSAR Operation Manual regarding use of the molecular weight adjustment field (section 5.3.4) and corrections for chemicals containing acid moieties (section 6.3.1)
What Information Do I Need to Use ECOSAR?
Description of chemical structure:
- This can be entered into the system using:
- Simplified Molecular Input Line Entry System (SMILES) notation
- CAS registry number or name if available in the look-up data base
- The new drawing program within ECOSAR
- A .mol file for single chemical entry, or .sdf file or string files to perform batch runs
The Octanol/water Partitioning Coefficient (Kow)
- ECOSAR will estimate Kow using the EPISuite (WSKowwin) module or retrieve the measured Log Kow using the built-in experimental database. The user may also enter a Kow values using the data entry screen.
With this information, ECOSAR can perform a SAR analysis and automatically estimate standard toxicity values for a chemical of interest.
What type of Chemicals can be run in ECOSAR?
There are a number of chemical classes that should not be run in ECOSAR or are difficult to model. This is not an exhaustive discussion, but provides general limits of the tool.
ECOSAR was designed and developed for organic chemicals. Inorganic or organometallic chemicals should not be profiled. Polymers and chemicals with a molecular weight greater than 1,000 should not be profiled using this tool since the model was not extensively trained on these large substances. However, many polymers may be made up of dimers, trimers, and oligomers that have a molecular weight of less than 1,000. These smaller molecules can be run through the model. If the chemical to be profiled is a mixture, then each substance can be run through the model separately or a representative structure must be assigned; this method does not account for synergistic effects. ECOSAR does not have the ability to simultaneously assess multiple chemicals and requires input of a discrete structure. This system also does not account for the unique physical properties of nanomaterials which may contribute to novel mechanisms of toxicity for this class of chemicals.
How Are ECOSAR Estimates Used?
The U.S. EPA Office of Pollution Prevention and Toxics uses SARs to predict the aquatic toxicity of new industrial chemicals in the absence of test data. The use of SARs has been an accepted practice in the U.S. EPA New Chemicals Program for estimating the aquatic toxicity of industrial chemicals for over 25 years. Environmental assessors, chemical manufacturers, chemical suppliers, and other regulatory agencies have used ECOSAR to develop quantitative screening level toxicity profiles. For more information on the use of ECOSAR in assessing aquatic toxicity of industrial chemicals when measured data are not available, please visit the U.S. EPA’s Sustainable Futures webpage and review the training material developed by EPA.
The Sustainable Futures Initiative is a voluntary program that encourages chemical developers to use EPA's models and methods to screen new chemicals for potential risks early in the development process. The overall goal of the program is to provide public access to predictive tools that can assist in chemical management decisions and ultimately allow the production of safer chemicals. Sustainable Futures Partners and other interested stakeholders are free to use these materials. The Sustainable Futures site contains presentations, including an over view of ECOSAR with a discussion of what the method does, necessary model inputs, how to interpret results, and how the results are used in a U.S. EPA New Chemicals Program screening level assessment.
How can Community Groups use ECOSAR?
Community groups can use ECOSAR in ways similar to those listed above to estimate aquatic toxicity. However, technical assistance from specialists is advisable as the program was designed for use by individuals with experience and knowledge of organic chemistry, ecotoxicology, and SARs.
What Type of Computer System Do I Need?
Software Required: Microsoft Windows 95 or later (including 98, ME,
NT, XP, Vista, and Windows 7).
Hardware: IBM-compatible computer with an 80386, 80486 or more
recent processor; 2 MB RAM minimum; at least 30 MB available disk space.
What Do I Need to Know to Run the Program and Interpret Model Results?
The program requires an understanding of organic chemistry, ecotoxicology, and SARs. Interpretation of the model output requires an understanding of the model design and users are strongly encouraged to read the ECOSAR Methodology Document v1.11 contained within the ECOSAR Help Menu and also posted below.
How Can I Obtain ECOSAR?
ECOSAR is available for free from the EPA Office of Pollution Prevention and Toxics (OPPT). It is posted below as a downloadable software program and does not require a license for installation and use.
Download ECOSAR by selecting the following link EcoSarsetup.exe (33MB).
ECOSAR is a self-extracting file. Once it is copied to diskette or hard drive, execute (double-click) the file to install the program. The ECOSAR Help Menu contains all relevant information on the use and interpretation of the model including copies of the ECOSAR Operation Manual and the ECOSAR Methodology document for Version 1.11 describing program development. You may also download those documents separately from the links below:
Download the latest ECOSAR Operation Manual v1.11 (PDF) (60 pps, 653KB). This file also requires the Acrobat Reader which is available above.
Download the latest ECOSAR Methodology Document v1.11 (PDF) (46 pps, 593KB). This file also requires the Acrobat Reader which is available above.
ECOSAR Model Library – Version History
On occasion our users need to reference older version of the ECOSAR model to reconcile old reports or make comparisons among documents. We have set up the ECOSAR Model Archives for users to download previously released versions of ECOSAR.
How Can I Obtain Additional Information about ECOSAR and Structure Activity Relationships?
The U.S. EPA, in conjunction with various public partners and interested public sponsors, provides training on the use and application of models used within the New Chemicals Program including ECOSAR. For additional information about ECOSAR and other predictive tools used by the U.S. EPA Office of Pollution Preventions and Toxics, please visit the U.S. EPA’s Sustainable Futures webpage for training and information on models for assessing industrial chemicals.
U.S. EPA Technical Contact:
Kelly E. Mayo-Bean, U.S. EPA
Risk Assessment Division (7403M)
1200 Pennsylvania Ave., N.W.
Washington, DC 20460-0001
Sustainable Futures Website: http://www.epa.gov/oppt/sf/
Kendra E. Moran, U.S. EPA
Risk Assessment Division (7403M)
1200 Pennsylvania Ave., N.W.
Washington, DC 20460-0001
Model Development Contact:
Syracuse Research Corporation
Environmental Science Center
6225 Running Ridge Road
North Syracuse, NY 13212
phone: 315 452-8421
fax: 315 452-8440
SRC website: http://www.syrres.com/what-we-do/environment.aspx