Written by the Fiveable Content Team • Last updated September 2025
Verified for the 2026 exam
Verified for the 2026 exam•Written by the Fiveable Content Team • Last updated September 2025
Definition
The NOEL is the highest tested dose or exposure level at which no effects, adverse or otherwise, are observed in any individuals during a study.
Related terms
LOEL (Lowest-Observed-Effect Level): The LOEL is the lowest tested dose or exposure level at which any effect, adverse or otherwise, is observed during a study.
Threshold Limit Value (TLV): TLV represents the maximum concentration of a substance to which workers can be exposed without experiencing adverse health effects over their working lifetime.
Reference Dose (RfD): RfD is an estimate of daily exposure to humans that is likely to be without appreciable risk of adverse effects during a lifetime.