A dose is a quantity of something (chemical, physical, or biological) that may impact an organism biologically; the greater the quantity, the larger the dose. A chemical substance is a Material with a definite chemical composition. In nutrition, the term is usually applied to how much of a specific nutrient is in a person's diet or in a particular food, meal, or dietary supplement. Nutrition (also called nourishment or aliment) is the provision to cells and Organisms of the materials necessary (in the form of food to support A nutrient is food or chemicals that an organism needs to live and grow or a substance used in an organism's metabolism which must be taken in from its environment In medicine, the term is usually applied to the quantity of a drug or other agent administered for therapeutic purposes. Medicine is the art and science of healing It encompasses a range of Health care practices evolved to maintain and restore Human Health by the A drug, broadly speaking is any chemical substance that when absorbed into the body Therapy (in Greek: θεραπεία) or treatment, is the attempted Remediation of a health problem usually following a Diagnosis In toxicology dose may refer to the amount of a harmful agent (such as a poison, carcinogen, mutagen, or teratogen), to which an organism is exposed. Toxicology (from the Greek words toxicos and logos) is the study of the adverse effects of Chemicals on living organisms In the context of Biology, poisons are substances that can cause damage, Illness, or Death to Organisms usually by The term carcinogen refers to any substance Radionuclide or radiation that is an agent directly involved in the promotion of Cancer or in the fatation of its propagation In Biology, a mutagen ( Latin, literally origin of change) is a physical or chemical agent that changes the genetic information (usually DNA) Teratology stems from the Greek ( Genitive) meaning monster, or marvel and, meaning word, speech.

Chemicals are the most common things for which doses are measured, but there are others, such as radiation exposure. For humans, most doses of micronutrients and medications are measured in milligrams (mg. Dietary minerals are the Chemical elements required by living Organisms other than the four elements Carbon, Hydrogen, Nitrogen, and ), but some are measured in micrograms because of their potency. In the Metric system, a microgram is 1/1000000 of a Gram (1 × 10-6 or 1/1000 of a milligram is one of the smallest units of weight/mass commonly used Nonmedicinal poisons span the measurement scale; some poisons are so dangerous that a single microgram of it could be deadly, while other substances take much more. For example, even water is toxic when consumed in large enough quantities. Water intoxication (also known as hyperhydration or water poisoning) is a potentially fatal disturbance in Brain functions that results when the

Effects are dose dependent

Dosage (the size of each dose) determines the strength and duration of the health benefits of nutrients, and also of the therapeutic effects of medical treatments. Quantity is a kind of property which exists as magnitude or multitude A therapeutic effect is a consequence of a medical treatment of any kind the results of which are judged to be desirable and beneficial Dosage also determines the severity of adverse effects of treatments and toxins. In Medicine, an adverse effect is a harmful and undesired effect resulting from a medication or other intervention such as Chemotherapy or Surgery.

Duration of exposure, that is, the period of time over which the dose was received (all at once or gradually) also determines its effects (the body may build tolerance to gradual exposure to a drug, while a large immediate dose could be deadly). A tone may be sustained for varying lengths of time. duration is a property of tone that becomes one of the bases rhythem or an amount of Time or a particular time

The route by which a dose is exposed to, may affect the outcome, because some medications have different effects depending on whether they are inhaled, ingested, taken transdermally, injected, or inserted. Drug delivery is the method or process of administering a Inhalation (also known as respiration) is the movement of air from the external environment through the air ways and into the Alveoli. Ingestion is the consumption of a substance by an Organism. In Animals it normally is accomplished by taking in the substance through the Mouth into the A transdermal patch or skin patch is a Medicated Adhesive patch that is placed on the Skin to deliver a specific Dose of medication An injection is an infusion method of putting Liquid into the Body, usually with a hollow needle and a Syringe which is pierced through A suppository is a drug delivery system that is inserted either into the Rectum (rectal suppository Vagina (vaginal suppository or Urethra (urethral

The dosage, route, concentration, and division over time may all be critical considerations in the administering of drugs, or in responding to exposure to a toxin. In nutrition, the route is usually a given, as nutrients are generally eaten; while dosage and the frequency of ingestion of nutrients are very important variables in preventing disease and promoting overall health.

Biological agents

Biological agents (bacteria, viruses, parasites) may have different dosage units. This is because it is the ability of the organism to cause effects that is the important unit, not a specific quantity by weight, volume or even numerical count. Often the unit used is CFU (colony forming units), which is proportionate to the number of organisms present multiplied times the number able to reproduce on a culture medium such as a Petri dish.

Toxicology

In the realm of toxicology, several measures are commonly used to describe toxic dosages according to the degree of effect on an organism or a population, and some are specifically defined by various laws or organizational usage. Toxicology (from the Greek words toxicos and logos) is the study of the adverse effects of Chemicals on living organisms These include:

• LD50 = Median lethal dose, a dose which will kill 50% of an exposed population;
• NOEL = No Observed Effect Level, the highest dose known to show no effect;
• NOAEL = No Observed Adverse Effect Level, the highest dose known to show no adverse effects;
• PEL = Personal Exposure Limit, the highest concentration permitted under US OSHA regulations;
• STEL = Short Term Exposure Limit, the highest concentration permitted for short periods of time, generally 15-30 minutes;
• TWA = Time Weighted Average, the average amount of an agent's concentration over a specified period of time, usually 8 hours;