The highest non-zero dose at which no toxic effect is observed in a study on animals is called

The highest dose showing no harmful effect in animal testing is the No Observed Adverse Effect Level.

LD50 is instead the dose that kills half of the test animals.

LOAEL marks the lowest dose at which an adverse effect first appears.

NOEFF is not a standard toxicology term.

The gap between the no-effect and lowest-effect levels helps set safe exposure limits.

Regulators divide the no-effect level by safety factors to derive acceptable human intake.