The use of the “best-available science” underpins the EPA’s authority and mission to protect human health and the environment. It’s the basis for most regulatory authority EPA exercises, including Clean Air Act (CAA) regulations like vehicle emissions standards and National Ambient Air Quality Standards (NAAQS), as well as Clean Water Act (CWA) regulations like the Safe Drinking Water Act (SDWA) and the National Pollutant Discharge Elimination System (NPDES) permit program. Another requirement to use the best-available science falls under the Toxic Substances Control Act (TSCA).
Determining the meaning of the best-available science is important “as the Trump administration launches an effort to roll back clean air and water regulations at the same time it is preparing to replace all the members of two crucial EPA science advisory boards and considering eliminating the Office of Research and Development—the scientific research arm of the EPA,” according to nonprofit news organization The Conversation.
The definition for this term comes from Congress, court decisions, and EPA policies and procedures guidelines.
“The science must be reliable, unbiased, objective and value-neutral, meaning it is not influenced by personal views,” The Conversation continues. “Best available science is the result of the scientific process and hypothesis testing by scientists. And it is based on current knowledge from relevant technical expertise and must be credible.
“The EPA’s scientific integrity policy includes ‘processes and practices to ensure that the best available science is presented to agency decision-makers and informs the agency’s work.’ Those include processes to ensure data quality and information quality and procedures for independent reviews by scientific experts outside of government.”
The protection of scientific integrity and processes states that a “work environment that shields the conduct and products of science, their use in decision making, and their communication from political interference and inappropriate influence is necessary for science and public trust in science to thrive,” the EPA’s 2025 Scientific Integrity Policy says.
The creation of the EPA Science Advisory Board was congressionally mandated under the 1978 Environmental Research, Development, and Demonstration Act. This Act also resulted in the creation of the EPA Office of Research and Development (ORD).
This board “is tasked with reviewing the scientific and technological basis of EPA actions,” The Conversation notes. “During the first Trump administration, the EPA replaced several independent scientists on its advisory boards in a manner that deviated from established practice, according to the Government Accountability Office, and brought in scientists connected with the industries the EPA regulates.
“No matter who serves on the EPA’s advisory boards, the agency is required by law to follow the best available science. Failing to do so sets the stage for lawsuits.”
The ORD conducts research for the EPA that provides the foundation for credible decision-making to safeguard human health and ecosystems from environmental pollutants.
According to The Conversation, the ORD’s work informs:
- Regulatory decisions involving air, water, land, and chemicals;
- Enforcement actions;
- Cleanup actions; and
- Emergency response efforts.
Federal court decisions have recognized the validity of the EPA’s scientific processes.
“The DC Circuit’s August 13, 2024 decision in Huntsman Petrochemical provides a vivid illustration of courts’ continuing deference to agencies on factual issues,” law firm Morgan, Lewis & Brockius LLP says. “In Huntsman, a chemical manufacturer and two trade associations lost their bid challenging the [EPA’s] rule addressing exposure to ethylene oxide emissions at certain chemical manufacturing facilities. The heart of the case was whether EPA’s assessment of the cancer risk of ethylene oxide was arbitrary and capricious. The DC Circuit held that it was not, emphasizing that an agency’s evaluation of scientific data within its area of expertise is still accorded ‘an extreme degree of deference.’”
Why does this matter to industry?
On the surface, weaker environmental regulations may appear to be a good thing, meaning less money spent on compliance and reporting. However, a lack of regulations generally results in more pollution, which causes harm to human health and the environment. Polluters are held accountable both in legal courts and in the court of public opinion. Corporate reputations are at stake, and decision-makers must answer to shareholders and the public. Legal battles are costly and increase corporate risk.
Dismantling the EPA’s research arm that provides scientific evidence on which to base CWA and CAA regulations means losing valuable resources and expertise, and in some cases, closing long-term research projects may cause irreversible harm.
“Requiring the agency to use the best available science helps ensure that decisions are based on evidence, and that the reasoning behind them is the result of well-accepted scientific processes and free from biases, including stakeholder or political interference,” The Conversation adds. “The scientific challenges facing the EPA are increasing in complexity. Responding to them effectively for the health of the population and the environment requires expertise and robust scientific processes.”
Removing the best-available science foundation from EPA decision-making leaves the Agency vulnerable to arbitrary decisions.
“The only reason to get rid of all the scientists is if you plan to replace the best science with biased decisions driven by politics and favoritism,” said Jennifer Orme-Zavaleta, former principal deputy assistant administrator for the EPA’s ORD, in an Environmental Protection Network press release. “EPA’s mission is to protect human health and the environment. America’s bedrock environmental laws such as the [CAA and SDWA] require EPA to use the best available science.”