(a) (1) Absorbed: amount of a substance penetrating the exchange boundaries of an organism after contact. Calculated from intake and absorption efficiency, and expressed as mg/kg-day. (2) Administered: mass of a substance given to an organism and in contact with an exchange boundary, expressed as mg/kg-day. (3) Applied: amount of a substance given to an organism, especially through dermal contact. [AIHA, 2000: Risk Assessment Principles for the Industrial Hygienist, attributed to USEPA RAGS, 1989]; (b) The amount of substance to which a person is exposed. Dose often takes body weight into account. [ATSDR, 1999: Online Glossary]; (c) The amount of a pollutant that is absorbed. A level of exposure which is a function of a pollutant's concentration, the length of time a subject is exposed, and the amount of the pollutant that is absorbed. The concentration of the pollutant and the length of time that the subject is exposed to that pollutant determine dose. [CARB, 2000: Glossary of Air Pollution Terms]; (d) (1) pharmacology. A quantity to be administered at one time, such as a specified amount of medication. (2) radiobiology. A general term denoting the quantity of radiation or energy absorbed. For special purposes it must be appropriately qualified. If unqualified, it refers to absorbed dose. Unit of absorbed dose is the rad. The SI unit is the gray (1 Gy = 1 J kg_1 = 100 R). Origin: Gr. Dosis = a giving [Graham, 1998: The on Line Medical Dictionary]; (e) The amount of substance to which a person is exposed. Dose often takes body weight into account. For example, to receive equivalent doses of medicine, children are given smaller amounts than adults. [New York Department of Health, 1999: Glossary of Environmental Health Terms]; (f) The amount of a contaminant that is absorbed or deposited in the body of an exposed organism for an increment of time usually from a single medium. Total dose is the sum of doses received by a person from a contaminant in a given interval resulting from interaction with all environmental media that contain the contaminant. Units of dose and total dose (mass) are often converted to units of mass per volume of physiological fluid or mass of tissue. [NRC, 1991: Human Exp. for Airborne Pollutants]; (g) The amount of a pesticide systemically available. [OECD, 1997: Occupational Exposure to Pesticides]; (h) The amount of substance available for interaction with metabolic processes or biologically significant receptors after crossing the outer boundary of an organism (See: Potential Dose, Applied Dose, and Internal Dose Definitions). The amount of the agent available for interaction by any particular organ or cell is termed the delivered dose for that organ or cell. [REAP, 1995: Residential Exposure Assessment Project]; (i) The amount or concentration of undesired matter or energy deposited at the site of effect. See also: Absorbed Dose. [SRA, 1999: Glossary of Risk Analysis Terms]; (j) The amount of a substance that enters the body. The amount depends on the rate at which the substance enters the body and the length of time the substance continues to enter the body, eg., a worker may inhale 10 milligrams of dust per day for 10 days. The total dose is 100 milligrams. Not all of the substance may remain in the body; some is eliminated, possibly as fast as it enters. [University of Kentucky, 1999: Glossary of Safety Terms]; (k) The amount of energy deposited in body tissue due to radiation exposure. Various technical terms, such as dose equivalent, effective dose equivalent and collective dose, are used to evaluate the amount of radiation an exposed worker receives. These terms are used to describe the differing interactions of radiation with tissue as well as to assist in the management of personnel exposure to radiation. Some types of radiation, such as neutron and alpha, deposit their energy more densely in affected tissue than gamma radiation and thereby causing more damage to tissue. The term dose equivalent, measured in units of rem, is used to take into account this difference in tissue damage. Therefore 1 rem from gamma radiation causes damage equivalent to 1 rem from alpha radiation. However, it takes one-twentieth as much energy from alpha radiation, as compared with gamma radiation, to produce this 1 rem dose equivalent. Definitions for dose terms necessary for various exposure calculations and recordkeeping purposes include the following: [USDOE, 1998: Radiological Control Manual]; (l) The absorbed dose, given in rads (or the international system of units, grays), that represents the energy absorbed from the radiation in a gram of any material. Furthermore, the biological dose or dose equivalent, given in rem or sieverts, is a measure of the biological damage to living tissue from the radiation exposure. [USDOE, 2000: RAIS Glossary]; (m) The amount of a substance available for interaction with metabolic processes or biologically significant receptors after crossing the outer boundary of an organism. The potential dose is the amount ingested, inhaled, or applied to the skin. The applied dose is the amount of a substance presented to an absorption barrier and available for absorption (although not necessarily having yet crossed the outer boundary of the organism). The absorbed dose is the amount crossing a specific absorption barrier (e.g., the exchange boundaries of skin, lung, and digestive tract) through uptake processes. Internal dose is a more general term denoting the amount absorbed without respect to specific absorption barriers or exchange boundaries. The amount of the chemical available for interaction by any particular organ or cell is termed the delivered dose for that organ or cell. [USEPA, 1992: GL for Exposure Assessment] [USEPA, 1997b: Exposure Factors Handbook]; (n) The amount of a substance available for interaction with metabolic processes after crossing the outer boundary of an organism. The applied dose is the amount of a substance presented to an absorption barrier and available for absorption (although not necessarily having yet crossed the outer boundary of the organism). The internal dose is the amount crossing an absorption barrier (e.g., the exchange boundaries of skin, lung, and digestive tract) through uptake processes. The amount of the chemical available for interaction by any particular organ or cell is termed the delivered dose for that organ or cell. [USEPA, 1992a: Dermal Exposure Assessment]; (o) (1) The actual quantity of a chemical administered to an organism or to which it is exposed. (2) The amount of a substance that reaches a specific tissue (e.g., the liver). (3) The amount of a substance available for interaction with metabolic processes after crossing the outer boundary of an organism. [USEPA, 1997a: EPA Terms of Environment]; (p) A term referring generically to the amount of chemical to which an organism is exposed by any of several routes. Specifying the routes within the environmental context and especially the point of measurement is made possible via subcategories of dose (See: Potential Dose, Applied Dose, Absorbed Dose, Internal Dose, and Delivered Dose). Dose is normally expressed as a mass per unit body weight per unit time and is frequently expressed in units of mg/kg/day. [USEPA, 1998: Postapp. Exposure Test GL.]; (q) The amount of agent that enters the target over a specified time interval by crossing a contact boundary [Zartarian, et al., 1997: Quant. Def. of Exp. & Related Concepts]