Reject precautionary default assumptions in risk assessment
What the document says“Reject precautionary default models and uncertainty factors.”
The chapter says that in the face of uncertainty about links between pollutants and health effects, the agency's reliance on default assumptions such as the low-dose linear non-threshold model bakes orders of magnitude of risk into regulatory inputs. It asks that the agency instead default to less restrictive regulatory outcomes.
What the document actually says“Reject precautionary default models and uncertainty factors.”
Drop the safety-first models used when the facts are unclear.
Sometimes it is unclear how harmful a thing is. The EPA then assumes the worst. The book says that pushes rules too far. It wants a lighter starting point.
Restoring Gold Standard Science
2025-05-23 · 90 FR 22601
Executive Order 14303, signed May 23, 2025, directs agency heads and employees that highly unlikely and overly precautionary assumptions and scenarios should only be relied upon in agency decision making where required by law or otherwise pertinent to the action, requires them to document how uncertainty propagates through models, and requires a weight of scientific evidence approach. That is the shift in default assumptions the passage asks for, and it applies across the government rather than to the EPA alone. It falls short in three ways: the instruction on precautionary assumptions is worded as should rather than shall, the order names no particular model, so the low-dose linear non-threshold model and the uncertainty factors the chapter objects to are not addressed by name, and it does not tell agencies to default to less restrictive regulatory outcomes.
The order tells agencies to lean less on worst case guesses. They must show how doubt runs through their models. That is the shift the chapter asked for. But the wording is should, not must, and no model is named.
2 agency rules
- National Environmental Policy Act Implementing RegulationsInterior Department, Office of the Secretary · February 24, 2026
- Financial Assistance Regulations-Conflict of Interest and Conflict of Commitment Policy RequirementsEnergy Department · July 16, 2026
Each of these names the order above in its own summary, preamble or filing. That is a fact about the document, not a finding that it carries out this proposal: it is one step further away than the order is, and what it does about the proposal is a reading nobody has made here.