The Toxic Substances Control Act of 1976 (TSCA) stands as a foundational piece of legislation in the United States, designed to regulate chemicals and protect public health and the environment from hazardous substances. Signed into law by President Gerald Ford, TSCA aimed to provide the Environmental Protection Agency (EPA) with the authority to oversee the production, use, and disposal of chemicals. However, over the years, the effectiveness of TSCA in addressing
the evolving landscape of chemical risks has been a subject of considerable debate and has highlighted significant challenges in its implementation, particularly concerning the regulation of both existing and new chemical substances.
Regulating Existing Chemicals: The TSCA Inventory and its Limitations
At the heart of TSCA's approach to existing chemicals is the TSCA Chemical Substance Inventory, a comprehensive list that includes both confidential and non-confidential chemical substances. Chemicals that were already in commerce when TSCA was enacted were placed on this original inventory without prior assessment. While TSCA granted the EPA the authority to assess the risks of these existing chemicals, it did not initially mandate such assessments. This meant that many chemicals were "grandfathered" into the system without a thorough review of their potential hazards.
Prior to the passage of the Frank R. Lautenberg Chemical Safety for the 21st Century Act, the EPA faced considerable hurdles in regulating these existing chemicals. Manufacturers were required to generate and report data on risk, manufacturing and processing, adverse health effects, and both published and unpublished health and safety studies, as well as "substantial risks" to the EPA. However, the EPA's ability to compel testing was limited. Under Section 4, the EPA had the authority to require manufacturers to test existing chemicals, but this necessitated formal notice-and-comment rule-making, which was subject to judicial review under a "substantial evidence" standard. A significant challenge was the "Catch-22" situation: to determine that a chemical "may present an unreasonable risk" (a prerequisite for requiring testing), the EPA often needed the very data it couldn't access or generate without first making that determination. This regulatory burden was a key factor driving the push for TSCA reform.
The Process for New Chemicals: Premanufacture Notices and Data Gaps
TSCA also established a framework for regulating new chemicals, defined as those not yet listed on the TSCA Inventory. Companies intending to manufacture or import a new chemical for a non-exempt purpose are required to notify the EPA by submitting a Premanufacture Notice (PMN) at least 90 days before the first manufacture or import. However, Section 5 of TSCA did not mandate toxicity testing before submitting a PMN. Instead, submitters were required to include any existing data on the substance in their possession or control, such as physicochemical data, toxicity data, fate data, and exposure data.
If data on a substance were unavailable, the EPA relied on data from analogous chemicals or models to evaluate whether the substance "may present an unreasonable risk." To regulate new chemicals, the EPA had to demonstrate that the chemical "may present an unreasonable risk of injury to health or the environment" or that it "is or will be produced in substantial quantities, and such substance either enters or may reasonably be anticipated to enter the environment in substantial quantities or there is or may be significant or substantial human exposure to the substance." The EPA had only 90 days from receiving a PMN to act before a new chemical could be legally marketed. This tight timeframe often resulted in insufficient data. For instance, only about 40 percent of acute toxicity and mutagenicity testing was completed, and even less data was generated for long-term effects or specific endpoints like subchronic, neurotoxicological, developmental, reproductive, and chronic toxicity. Furthermore, less than 5 percent of data on toxicity to aquatic organisms was submitted with PMNs. EPA evaluations found that a significant portion of PMN data on health effects and environmental effects was deficient.
Addressing Data Deficiencies: The Role of SARs and the SAT
To compensate for these data deficiencies, Section 5 of TSCA led to the creation of the Structure Activity Team (SAT) and the development of structural-activity relations (SARs). The SAT comprises expert scientists and specialists who evaluate the potential environmental fate and health and environmental hazards of new chemicals. When data gaps existed for a PMN substance, hazard assessments heavily relied on models, SARs based on analogous chemicals, or data retrieved from public databases. However, critics argued that SARs and the SAT's review process did not adequately evaluate the risks associated with new chemicals, partly because there was no minimum data set beyond the information already in possession at the time of PMN submission. The EPA was left with the burden of proving the safety of existing chemicals and could only regulate chemicals entering the market under the specific standards of TSCA, which often proved challenging due to the lack of comprehensive data.
Historical Successes and Broader Criticisms
Despite these challenges, the EPA did achieve some successes in restricting chemicals under Section 6 of TSCA. In its 38-year history, the EPA successfully restricted five chemicals: PCBs, chlorofluorocarbons, dioxin, asbestos, and hexavalent chromium. A notable action was the 1989 final rule to ban the manufacturing, importing, and processing of nearly all asbestos-containing products in the USA, though this ban was partially overturned in 1991. However, many environmental groups, such as the Natural Resources Defense Council, contended that prior to the 2016 TSCA reform, the EPA was largely ineffective in taking regulatory action against dangerous chemicals, even those known to cause serious health effects like cancer. The High Production Volume (HPV) program, while leading to the generation or release of data on over 2,200 chemicals, also highlighted the concern about the lack of basic hazard information for many chemicals produced or imported in large quantities. The ongoing debates over the legal burden on the EPA to ban chemicals underscored the need for reform to strengthen the agency's ability to protect public health and the environment.
