Cod liver oil - a potentially toxic source of Vitamin A: Hypervitaminosis A can result from ingestion of too much vitamin A from diet, supplements, or prescription medications.
This visible light region consists of a spectrum of wavelengths that range from approximately 700 nanometers (abbreviated nm) to approximately 400 nm. Expressed in more familiar units, the range of wavelengths extends from 7 x 10 -7 meter to 4 x 10 -7 meter.
1 The amount of energy of a wave can be determined by measuring its wavelength, the distance between consecutive points of a wave.  Visible light is a type of radiant energy within the electromagnetic spectrum; other types of electromagnetic radiation include UV, infrared, gamma, and radio rays as well as X-rays.