Science, Policy & Risk Perspectives: TSCA: Accelerating Risk-Based Chemical Safety Evaluations by Advancing Scientific Confidence in New Approach Methods
Traditionally, chemical product safety evaluation processes have relied heavily on tests conducted using laboratory animals because other options were limited. As a result of scientific advances in biology and toxicology, particularly those made over the last two decades, this is no longer true. Advanced methods (e.g., computational models, in vitro test systems and tiered integrated testing and assessment approaches) can now provide alternatives to laboratory animal testing in many cases. And, at the pace at which science is progressing, it’s certain that safety assessments can (or soon will be) conducted with these advanced methods as well as or better than animal testing, and with greater speed and efficiency.
A major accomplishment of TSCA reform in 2016 was recognizing this critical juncture and actively embracing the future of human safety assessment. Amendments were included to accelerate the development and application of new methods to reduce or replace vertebrate animals in lab tests on chemicals while still providing information of equivalent or better scientific quality and relevance. ACC fully supported those amendments, but we haven’t stopped there. ACC has continued working to realize this vision through the ACC Long-Range Research Initiative (LRI). ACC LRI funds research that contributes to development of these “new approach methods (NAMs),” as well as research to establish scientific confidence in NAMs for regulatory uses such as prioritization, screening, and in-depth safety determinations.
The regulatory scientific community includes government researchers (in EPA and other agencies), private sector scientists and institutions, animal welfare organizations, and academics. Together, this community has made large strides in the first 5 years of TSCA implementation on NAMs. EPA defines NAMs as “any technology, methodology, approach, or combination thereof that can be used to provide information on chemical hazard and risk assessment that avoids the use of intact animals.” And EPA’s New Approach Methods Work Plan provides tangible goals and specific activities that will certainly contribute to reducing the use of lab animals for toxicity testing and expand regulatory acceptance of NAMs.
The power of NAMs to accelerate risk-based decision making and reduce animal testing is illustrated by the results of the recent collaboration of EPA ORD scientists with chemical industry scientists. This research showed that risk-based priority screening can be carried out efficiently for approximately six thousand chemicals at once by integrating a computational NAM method for toxicity with EPA ORD’s advanced method for human exposure modeling. The only remaining scientific barrier for applying this efficient method to tens of thousands of chemicals on the TSCA active inventory is some additional effort to scientifically qualify it.
As impressive as that is, it is only a small portion of what the regulatory scientific community can achieve if it continues to work together to meet its shared responsibility to produce the data and analyses that fulfill the mandates of TSCA to look first to employing NAMs that provide equivalent or better scientifically relevant information prior to testing using vertebrate lab animals.
Replacing animals with ‘a la carte’ NAMs that must be integrated in a framework of evidence that supports understanding of the causal chain of events that can lead to adverse health effects is indeed a challenge. Yet, we believe it is already possible to use NAMs with adequate scientific confidence for defined applications to support regulatory and product stewardship decisions, and we have several ideas for how this can be done, starting now:
- Adopt a Framework for Science Confidence in NAMs - EPA (and OECD) should adopt and use a uniform, yet flexible framework to develop, document, and communicate the scientific confidence in specific NAMs for distinct uses. Such a scientific confidence framework is needed before using them to meet the statutory requirements of TSCA that NAMs must “... provide information of equivalent or better scientific quality and relevance for assessing risks of injury to health or the environment.”
- Evaluate and Deploy Fit for Purpose Approaches - EPA’s current pace identifying a dozen or so low priority substances and a dozen or so high priority substances every few years is inadequate to address the 30,000 to 40,000 chemicals on the TSCA Active Inventory. For the thousands of chemicals in commerce, the only way to accelerate the pace for conducting risk-based screening to differentiate low concern substances from substances that are candidates for prioritization for in depth TSCA risk evaluations is to develop and use NAMs that are qualified as scientifically fit-for-purpose for such risk-based screening. For example, the agency should evaluate the threshold of toxicological concern (TTC) approach, and as warranted, accept it for immediate use in TSCA by adding it to the agency’s list of alternative test methods or strategies that do not require new vertebrate animal testing.
- Enhance Processes for Evaluating External Nominations for NAMs - EPA should develop and implement a process to receive and evaluate external nominations for NAMs for specific uses in TSCA. This will enable industry, academia, research institutes, etc., to submit nominations and ensure that the nomination and review processes are sufficiently robust so that NAMs are fit-for-purpose and provide information of equivalent or better scientific reliability and quality to that which would be obtained from vertebrate animal testing.
- Foster Public/Private Research Collaboration - EPA’s New Chemicals Program has long employed predictive models and tools for assessing chemicals under TSCA. We are encouraged by EPA’s recent decision to create a collaborative research program to improve and modernize the methods used to review and evaluate new chemicals. We recommend EPA create opportunities for broad collaborations with scientific experts across the breadth of the regulatory science community. Contributions from academia, industry and other scientific experts should not be excluded, but rather welcomed as part of the collective responsibility of the regulatory science community to harness the power of NAMs to improve the scientific basis and efficiency of new chemical reviews.
The bottom line: NAMs that reduce or replace animal test systems continue to offer the best hope for testing and evaluating chemicals more efficiently and less expensively, while providing information about chemicals that is scientifically relevant, and of equivalent or better scientific quality than traditional animal tests. Building scientific confidence in NAMs and accelerating their use in risk-based screening and tiered testing is good for animal welfare, chemical regulation, and protection of human health and the environment.