Sunlight: Irradiation directly from the sun.Ultraviolet Rays: That portion of the electromagnetic spectrum immediately below the visible range and extending into the x-ray frequencies. The longer wavelengths (near-UV or biotic or vital rays) are necessary for the endogenous synthesis of vitamin D and are also called antirachitic rays; the shorter, ionizing wavelengths (far-UV or abiotic or extravital rays) are viricidal, bactericidal, mutagenic, and carcinogenic and are used as disinfectants.Solar Energy: Energy transmitted from the sun in the form of electromagnetic radiation.Sunscreening Agents: Chemical or physical agents that protect the skin from sunburn and erythema by absorbing or blocking ultraviolet radiation.Vitamin D Deficiency: A nutritional condition produced by a deficiency of VITAMIN D in the diet, insufficient production of vitamin D in the skin, inadequate absorption of vitamin D from the diet, or abnormal conversion of vitamin D to its bioactive metabolites. It is manifested clinically as RICKETS in children and OSTEOMALACIA in adults. (From Cecil Textbook of Medicine, 19th ed, p1406)Vitamin D: A vitamin that includes both CHOLECALCIFEROLS and ERGOCALCIFEROLS, which have the common effect of preventing or curing RICKETS in animals. It can also be viewed as a hormone since it can be formed in SKIN by action of ULTRAVIOLET RAYS upon the precursors, 7-dehydrocholesterol and ERGOSTEROL, and acts on VITAMIN D RECEPTORS to regulate CALCIUM in opposition to PARATHYROID HORMONE.Skin Neoplasms: Tumors or cancer of the SKIN.Ligustrum: A plant genus of the family OLEACEAE. Oleuropein, a phenolic secoiridoid glycoside, is found in the leaves.Sunburn: An injury to the skin causing erythema, tenderness, and sometimes blistering and resulting from excessive exposure to the sun. The reaction is produced by the ultraviolet radiation in sunlight.Rickets: Disorders caused by interruption of BONE MINERALIZATION manifesting as OSTEOMALACIA in adults and characteristic deformities in infancy and childhood due to disturbances in normal BONE FORMATION. The mineralization process may be interrupted by disruption of VITAMIN D; PHOSPHORUS; or CALCIUM homeostasis, resulting from dietary deficiencies, or acquired, or inherited metabolic, or hormonal disturbances.Skin Pigmentation: Coloration of the skin.Geography, Medical: The area of medicine concerned with the effects on health and disease due to geographic factors such as CLIMATE, environmental conditions, and geographic location.Moon: The natural satellite of the planet Earth. It includes the lunar cycles or phases, the lunar month, lunar landscapes, geography, and soil.Photosensitivity Disorders: Abnormal responses to sunlight or artificial light due to extreme reactivity of light-absorbing molecules in tissues. It refers almost exclusively to skin photosensitivity, including sunburn, reactions due to repeated prolonged exposure in the absence of photosensitizing factors, and reactions requiring photosensitizing factors such as photosensitizing agents and certain diseases. With restricted reference to skin tissue, it does not include photosensitivity of the eye to light, as in photophobia or photosensitive epilepsy.Dermatitis, Phototoxic: A nonimmunologic, chemically induced type of photosensitivity producing a sometimes vesiculating dermatitis. It results in hyperpigmentation and desquamation of the light-exposed areas of the skin.Neoplasms, Radiation-Induced: Tumors, cancer or other neoplasms produced by exposure to ionizing or non-ionizing radiation.Seasons: Divisions of the year according to some regularly recurrent phenomena usually astronomical or climatic. (From McGraw-Hill Dictionary of Scientific and Technical Terms, 6th ed)Carcinoma, Basal Cell: A malignant skin neoplasm that seldom metastasizes but has potentialities for local invasion and destruction. Clinically it is divided into types: nodular, cicatricial, morphaic, and erythematoid (pagetoid). They develop on hair-bearing skin, most commonly on sun-exposed areas. Approximately 85% are found on the head and neck area and the remaining 15% on the trunk and limbs. (From DeVita Jr et al., Cancer: Principles & Practice of Oncology, 3d ed, p1471)Dolichos: A plant genus of the family FABACEAE that contains LECTINS. Many members have been reclassified into other genera of the FABACEAE family.Skin: The outer covering of the body that protects it from the environment. It is composed of the DERMIS and the EPIDERMIS.Sun Protection Factor: A measure of relative protection provided by SUNSCREENING AGENTS against burns due to ultraviolet (UV) radiation from a light source.Dose-Response Relationship, Radiation: The relationship between the dose of administered radiation and the response of the organism or tissue to the radiation.Light: That portion of the electromagnetic spectrum in the visible, ultraviolet, and infrared range.Skin Cream: A water-soluble medicinal preparation applied to the skin.Pyrimidine Dimers: Dimers found in DNA chains damaged by ULTRAVIOLET RAYS. They consist of two adjacent PYRIMIDINE NUCLEOTIDES, usually THYMINE nucleotides, in which the pyrimidine residues are covalently joined by a cyclobutane ring. These dimers block DNA REPLICATION.Heterotrophic Processes: The processes by which organisms utilize organic substances as their nutrient sources. Contrasts with AUTOTROPHIC PROCESSES which make use of simple inorganic substances as the nutrient supply source. Heterotrophs can be either chemoheterotrophs (or chemoorganotrophs) which also require organic substances such as glucose for their primary metabolic energy requirements, or photoheterotrophs (or photoorganotrophs) which derive their primary energy requirements from light. Depending on environmental conditions some organisms can switch between different nutritional modes (AUTOTROPHY; heterotrophy; chemotrophy; or PHOTOTROPHY) to utilize different sources to meet their nutrients and energy requirements.Solar System: The group of celestial bodies, including the EARTH, orbiting around and gravitationally bound by the sun. It includes eight planets, one minor planet, and 34 natural satellites, more than 1,000 observed comets, and thousands of lesser bodies known as MINOR PLANETS (asteroids) and METEOROIDS. (From Academic American Encyclopedia, 1983)Photosynthesis: The synthesis by organisms of organic chemical compounds, especially carbohydrates, from carbon dioxide using energy obtained from light rather than from the oxidation of chemical compounds. Photosynthesis comprises two separate processes: the light reactions and the dark reactions. In higher plants; GREEN ALGAE; and CYANOBACTERIA; NADPH and ATP formed by the light reactions drive the dark reactions which result in the fixation of carbon dioxide. (from Oxford Dictionary of Biochemistry and Molecular Biology, 2001)Sulfonium Compounds: Sulfur compounds in which the sulfur atom is attached to three organic radicals and an electronegative element or radical.Environmental Exposure: The exposure to potentially harmful chemical, physical, or biological agents in the environment or to environmental factors that may include ionizing radiation, pathogenic organisms, or toxic chemicals.Photochemical Processes: Chemical reactions effected by light.Sunbathing: Exposing oneself to SUNLIGHT or ULTRAVIOLET RAYS.Erythema: Redness of the skin produced by congestion of the capillaries. This condition may result from a variety of causes.PhotochemistrySeawater: The salinated water of OCEANS AND SEAS that provides habitat for marine organisms.Hydroxycholecalciferols: Hydroxy analogs of vitamin D 3; (CHOLECALCIFEROL); including CALCIFEDIOL; CALCITRIOL; and 24,25-DIHYDROXYVITAMIN D 3.Phthiraptera: An order of small, wingless parasitic insects, commonly known as lice. The suborders include ANOPLURA (sucking lice); AMBLYCERA; ISCHNOCERA; and Rhynchophthirina (elephant and warthog lice).Skin Aging: The process of aging due to changes in the structure and elasticity of the skin over time. It may be a part of physiological aging or it may be due to the effects of ultraviolet radiation, usually through exposure to sunlight.Prochlorococcus: A genus of marine planktonic CYANOBACTERIA in the order PROCHLOROPHYTES. They lack PHYCOBILISOMES and contain divinyl CHLOROPHYLL, a and b.Hemerocallis: A plant genus of the family LILIACEAE. Members contain steroidal saponins.Eye Protective Devices: Personal devices for protection of the eyes from impact, flying objects, glare, liquids, or injurious radiation.Rutin: A flavonol glycoside found in many plants, including BUCKWHEAT; TOBACCO; FORSYTHIA; HYDRANGEA; VIOLA, etc. It has been used therapeutically to decrease capillary fragility.Calcifediol: The major circulating metabolite of VITAMIN D3. It is produced in the LIVER and is the best indicator of the body's vitamin D stores. It is effective in the treatment of RICKETS and OSTEOMALACIA, both in azotemic and non-azotemic patients. Calcifediol also has mineralizing properties.Color: The visually perceived property of objects created by absorption or reflection of specific wavelengths of light.Acanthaceae: A plant family of the order Lamiales. It is characterized by simple leaves in opposite pairs, cystoliths (enlarged cells containing crystals of calcium carbonate), and bilaterally symmetrical and bisexual flowers that are usually crowded together. The common name for Ruellia of wild petunia is easily confused with PETUNIA.Disinfection: Rendering pathogens harmless through the use of heat, antiseptics, antibacterial agents, etc.Dehydrocholesterols: Cholesterol derivatives having an additional double bond in any position. 24-Dehydrocholesterol is DESMOSTEROL. The other most prevalent dehydrocholesterol is the 7-isomer. This compound is a precursor of cholesterol and of vitamin D3.Film Dosimetry: Use of a device (film badge) for measuring exposure of individuals to radiation. It is usually made of metal, plastic, or paper and loaded with one or more pieces of x-ray film.Photobiology: The branch of biology dealing with the effect of light on organisms.Water Microbiology: The presence of bacteria, viruses, and fungi in water. This term is not restricted to pathogenic organisms.25-Hydroxyvitamin D 2: 9,10-Secoergosta-5,7,10(19),22-tetraene-3,25-diol. Biologically active metabolite of vitamin D2 which is more active in curing rickets than its parent. The compound is believed to attach to the same receptor as vitamin D2 and 25-hydroxyvitamin D3.Photolysis: Chemical bond cleavage reactions resulting from absorption of radiant energy.Fresh Water: Water containing no significant amounts of salts, such as water from RIVERS and LAKES.