Photobiology is broadly defined to include all biological phenomena involving non-ionizing radiation. It is recognized that photobiological responses are the result of chemical and/or physical changes induced in biological systems by non-ionizing radiation.
Photobiology concerns itself with biological processes that interact with electromagnetic radiation over a frequency range that does not ionize biological molecules — from the higher-energy ultraviolet, through the intermediate-energy visible, to the lower-energy infrared range of electromagnetic radiation. As sub-disciplines of physics, chemistry, engineering, biology, and medicine, photobiology has emerged as an interdisciplinary endeavor related to and interacting with theoretical scientists; academicians working in research, teaching and training, and application development; instrument makers; commercial groups seeking practical and useful applications; and hobbyists.
Topics in photobiology include interaction of light with molecules, cells, and tissues, the responses of those biological entities, photosynthesis, bioluminescence. In medicine, therapists employ various types of non-ionizing photon radiation protocols to treat diseases.
In part exemplifying the type and range of photobiology, a sample issue of the official journal of the American Society for Photobiology, viz., "Photochemistry and Photobiology", offers articles with these titles:
- Challenges in Applying Photoemission Electron Microscopy to Biological Systems
- Application of Nonlinear Optical Microscopy for Imaging Skin
- The Ability of Low Level Laser Therapy to Prevent Muscle Tissue Damage Induced by Snake Venom
- UV Radiation: Balancing Risks and Benefits
- Crayfish Procambarus clarkii Retina and Nervous System Exhibit Antioxidant Circadian Rhythms Coupled with Metabolic and Luminous Daily Cycles
- In Vitro Photodynamic Eradication of Pseudomonas aeruginosa in Planktonic and Biofilm Culture
- Solar Ultraviolet Protection Provided by Human Head Hair
- The Photoreactions of Recombinant Phytochrome CphA from the Cyanobacterium Calothrix PCC7601: A Low-Temperature UV–Vis and FTIR Study
- New Results on the Photochemistry of Biopterin and Neopterin in Aqueous Solution
- Quenching of Singlet Oxygen by a Carotenoid–Cyclodextrin Complex: The Importance of Aggregate Formation
- Ionizing & Non-Ionizing Radiation. United States Environmental Protection Agency.
- Radiation that has enough energy to move atoms in a molecule around or cause them to vibrate, but not enough to remove electrons, is referred to as "non-ionizing radiation." Examples of this kind of radiation are sound waves, visible light, and microwaves….Radiation that falls within the ionizing radiation" range has enough energy to remove tightly bound electrons from atoms, thus creating ions. This is the type of radiation that people usually think of as 'radiation.' We take advantage of its properties to generate electric power, to kill cancer cells, and in many manufacturing processes.