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Master Testing List - Introduction

Note: EPA no longer updates this information, but it may be useful as a reference or resource.


Under the Toxic Substances Control Act (TSCA), EPA is given broad authority to issue regulations designed to gather health/safety and exposure data on, require the testing of, and control exposure to chemical substances and mixtures. Drugs, cosmetics, foods and food additives, pesticides, and nuclear materials are exempt from TSCA and are subject to control under other Federal statutes (e.g., foods, food additives, drugs and cosmetics are under the purview of the Federal Food, Drug, and Cosmetic Act (FFDCA) which is administered by the U.S. Food and Drug Administration (FDA)).

It is important to note that TSCA has differing mandates regarding the regulations for "existing" chemicals (i.e., those already in U.S. commerce) and "new" chemicals (i.e., those not yet in U.S. commerce). Therefore, when TSCA became effective on January 1, 1977, it was imperative that EPA be able to distinguish between existing chemicals and new chemicals. This was accomplished by using TSCA Section 8(a) information reporting requirements to create the TSCA Chemical Substances Inventory. The TSCA Inventory is a compilation of the names of all existing chemical substances along with their respective Chemical Abstract Service (CAS) Registry numbers and certain other types of information (e.g., production/importation volume ranges, specific sites of production/importation). After 1977, a producer or importer of a "new" chemical (i.e., one that is not listed on the TSCA Inventory) is required to submit a TSCA Section 5 "Pre-Manufacture Notice" (PMN) to the New Chemicals Program in the Office of Pollution Prevention and Toxics (OPPT) in EPA's Office of Prevention, Pesticides and Toxic Substances (OPPTS). (For more information about the New Chemicals Program, the reader is directed to an article by Moss et al. which appeared in the January/February 1996 issue of Chemical Health and Safety published by the American Chemical Society.)    OPPT New Chemicals Home Page.

The Master Testing List (MTL) is an important component of EPA's Existing and New Chemicals Programs under TSCA. The Existing Chemicals Program is responsible for assessing and managing health and environmental risks that may be posed by existing chemical substances covered by TSCA. The "universe" of existing chemicals on EPA's TSCA Inventory that may present the greatest potential health and/or environmental concerns (including testing needs) have been and continue to be identified and refined through various screening activities within OPPT. This latest version of the MTL also includes priority testing and actions derived from the TSCA New Chemicals Program.

The TSCA Inventory currently contains over 70,000 existing chemicals, many of which are produced or imported at low or negligible volumes, while others are polymers which, because of their physical size (e.g., high molecular weight) and other characteristics, are unlikely to present significant risk concerns. By excluding low volume chemicals (~25,000 chemicals produced or imported in amounts less than 10,000 pounds per year) and polymers (which tend to be poorly absorbed by organisms and therefore typically exhibit low toxicity), the remaining TSCA Inventory is comprised of about 15,000 non-polymeric chemicals produced/imported at levels above 10,000 pounds per year.

Of these 15,000 non-polymeric chemicals, there are 3,000-4,000 chemicals that are produced/imported in amounts over 1 million pounds per year; these chemicals are considered by EPA to be U.S. High Production Volume (HPV) chemicals. EPA has identified this 15,000 chemical subset as being the broad focus "universe" of the TSCA Existing Chemicals and Chemical Testing Programs with the primary focus placed on the 3,000- 4,000 HPV chemicals.     TSCA Inventory Chart
This screening and testing approach is supported by an U.S. Office of Technology Assessment (OTA) report entitled "Screening and Testing Chemicals in Commerce" (OTA-BP-ENV-166; September, 1995). For more information with regard to the TSCA Existing Chemicals Program, the reader is directed to   Appendix I ("TSCA Existing Chemicals Program Overview")

Chemical Testing Under TSCA

Section 4 of TSCA gives EPA the authority to require chemical manufacturers and processors to test existing chemicals. Under Section 4, EPA can by rule require testing after finding that (1) a chemical may present an unreasonable risk of injury to human health or the environment, and/or the chemical is produced in substantial quantities that could result in significant or substantial human or environmental exposure, (2) the available data to evaluate the chemical are inadequate, and (3) testing is needed to develop the necessary data. The TSCA Chemical Testing Program also continues to work with members of the U.S. chemical industry to develop needed test data via TSCA Section 4 Enforceable Consent Agreements (ECAs) and Voluntary Testing Agreements (VTAs). ECAs and VTAs are usually much less resource intensive than formal TSCA rule-making and allow the Agency to consider agreed-upon pollution prevention and other product stewardship-related initiatives by the industry as a possible substitute for or adjunct to certain types of needed chemical testing.

Since 1979, approximately 540 of the 15,000 chemical sub-set of the TSCA Inventory have been the subject of testing actions within the OPPT Existing Chemicals Testing Program. Virtually all of the 540 chemicals are "HPV chemicals." The testing actions taken to date include a mix of formal TSCA Section 4 Test Rules and Section 4 Enforceable Consent Agreements, and Voluntary Testing Agreements. More than 50% of these testing actions have been taken in the last several years and have focussed on chemicals with clearly identified data "needs" (as opposed to simply data gaps). In addition, almost 250 formal TSCA Section 4 "Decisions Not To Test" (DNTs) have been issued by EPA to date. Screening efforts to identify priorities and determine testing needs for other chemicals are currently underway in OPPT.

Master Testing List

EPA has been using the Master Testing List (MTL) since 1990 to set OPPT's Chemical Testing Program agenda. The MTL presents a consolidated listing of OPPT's existing chemical testing priorities under TSCA and also includes the priority industrial chemical testing needs of OPPTS, other EPA Program Offices (e.g., Office of Air and Radiation, Office of Water), other Federal agencies (e.g., U.S. Occupational Safety and Health Administration, U.S. Consumer Product Safety Commission, U.S. Department of the Interior), and the TSCA Interagency Testing Committee (ITC).

The purposes of the MTL are to (1) identify chemical testing needs of the Federal Government (including EPA) and international programs of interest to the U.S., (2) focus limited EPA resources on the highest priority chemical testing needs, (3) identify and publicize EPA's testing priorities for industrial chemicals, (4) obtain broad public comment on EPA's Chemical Testing Program and its priorities, and (5) encourage voluntary initiatives by members of the U.S. chemical industry to provide EPA with the priority data identified via the MTL as being needed.

Companies with product stewardship programs will recognize the importance of promptly filling the data needs identified via the MTL because they know a database that is inadequate to support risk assessment deprives people who are exposed to a chemical substance of their right to know the hazards/risks that may be posed by that chemical. The identification of testing needs on the MTL provides an opportunity for responsible companies to initiate voluntary data development activities to develop the needed data for their own MTL-listed chemicals. Companies that are good product stewards will carefully evaluate and in many cases voluntarily meet the testing needs identified via the MTL. EPA believes that to the extent companies decline this opportunity, they are not living up to their own professed standards of corporate responsibility. In those instances in which voluntary testing is not undertaken, EPA is put in a position of having to initiate a formal, resource intensive, regulatory action such as promulgating a TSCA Section 4 Test Rule. EPA's issuance of such a rule can be viewed as "forcing" companies to adhere to their own product stewardship principles.

The MTL presents EPA's TSCA Chemical Testing Program priorities for 1996-1998 and includes over 500 individual existing chemicals and more than 10 existing chemical categories. Testing actions are currently being developed on more than 200 of the chemicals listed on the MTL while testing is currently underway on almost 300 other chemicals on the MTL. In addition, over 100 chemicals are being removed from the MTL at this time, more than 70 of those because of completion of their testing programs. It should be noted that a number of chemicals are found more than once on the MTL as the result of different testing actions that have been or are being developed on those chemicals.

This version of the MTL also includes information about EPA's TSCA New Chemicals Program (NCP). The TSCA NCP is responsible for reviewing new chemical substances prior to their entry into U.S. commerce. While testing of new chemicals can be required by way of an action under Section 5(e) of TSCA, the NCP has also had success in developing voluntary testing programs with the affected industry. Many of the new chemicals that have been or are being tested are members of the NCP's "Chemical Categories." Since 1979, EPA action under TSCA Section 5(e) has resulted in the generation of needed health and/or environmental effects data on over 1000 new chemicals. The required studies have been split evenly between health effects tests and environmental effects tests. Some environmental fate and physical/chemical properties testing has also been required. Additional information about the contributions of the TSCA NCP to the EPA's overall TSCA Chemical Testing Program are expected to appear in future iterations of the MTL.


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