The OECD publishes guidelines for Preclinical Safety Assessments, in order to help scientists discover the NOAEL.
[1] Some adverse effects in the exposed population when compared to its appropriate control might include alteration of morphology, functional capacity, growth, development or life span.
[citation needed] The NOAEL could be defined as "the highest experimental point that is without adverse effect," meaning that under laboratory conditions, it is the level where there are no side-effects.
[2] In toxicology it is specifically the highest tested dose or concentration of a substance (i.e. a drug or chemical) or agent (e.g. radiation), at which no such adverse effect is found in exposed test organisms where higher doses or concentrations resulted in an adverse effect.
[3][4][5] The NOAEL level may be used in the process of establishing a dose-response relationship,[6] a fundamental step in most risk assessment methodologies.