1. applied to radiation: capable of producing a photochemical effect; exhibiting actinism
2. applied to other concepts or to devices: referring to actinism
NOTE 1 A natural actinic effect is a chemical change caused by natural radiation. Examples are: production of ozone in the atmosphere, photosynthesis, daylight vision.
NOTE 2 An artificially induced actinic effect is a photochemical change caused by artificially produced optical radiation under controlled conditions. Examples are: control of plant growth by time-programmed lighting, lighting of poultry to increase egg production, therapeutic treatment by means of special lamps.
NOTE 3 A direct actinic effect is one that occurs at the place where the radiant energy responsible for the effect is absorbed. An example of this is the conversion of 7-dehydrocholesterol to previtamin D3. An indirect actinic effect is one that occurs away from the place where the radiant energy responsible for the effect is absorbed. The distinction between a direct and an indirect actinic effect mainly applies to photobiological changes. The photostimulation of endocrine glands is an example of an indirect actinic effect, as is the conversion of previtamin D3 to vitamin D by a non-photochemical thermal reaction.