Threshold models posit an exposure level below which no effect occurs, supported by evidence for many toxic effects. Linear no-threshold models assume risk at any exposure and are applied to some carcinogens for regulatory purposes.
Which model applies varies by substance and endpoint.
Alternative Names:
Threshold, No-Effect Level
Why it Matters?
The regulatory use of no-threshold assumptions is frequently conflated with scientific evidence in litigation, since agencies adopt conservative linear models for policy purposes without asserting that low-dose effects have been demonstrated. That distinction is a substantive defense point where a plaintiff expert cites a regulatory position as establishing causation at low exposure. For non-carcinogenic effects, threshold evidence is generally stronger.
Frequently Confused with
Frequently asked questions
Do regulatory limits establish a causation threshold?
Does threshold evidence differ by effect?
