NOAEL

level [lev´el]

relative position, rank, or concentration.

l's of care the six divisions of the health care system: preventive care, primary care, secondary or acute care, tertiary care, restorative care, and continuing care.

background level the usual intensity of a chemical or other stimulus in the environment.

confidence level the probability that a confidence interval does not contain the population parameter.

l's of consciousness see levels of consciousness.

lowest observed adverse effect level (LOAEL) (lowest observed effect level (LOEL)) in studies of the toxicity of chemicals, the lowest dosage level at which chronic exposure to the substance shows adverse effects; usually calculated for laboratory animals.

no observed adverse effect level (NOAEL) (no observed effect level (NOEL)) in studies of the toxicity of chemicals, the highest dosage level at which chronic exposure to the substance shows no adverse effects; usually calculated for laboratory animals.

level of significance a statistical measure that serves as the cutoff point used to determine whether a null hypothesis is retained or rejected; the probability of incorrectly rejecting the null hypothesis (see Type I error).

sterility assurance level (SAL) the probability that a process makes something sterile (see sterilization). An SAL of 10⁻⁶ is the recommended probability of survival for organisms on a sterilized device. This level means that there is less than or equal to one chance in a million that an item remains contaminated or nonsterile.

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NOAEL,

n ‘no-observed-adverse-effect-level,’ the maximum concentration of a substance that is found to have no adverse effects upon the test subject.