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Glossary BlO~ OR Indicators of changes or events in human biological systems. Biological markers of exposure refer to cellular, biochemical, or molecular measures that are obtained from biological media such as human tissues, cells, or fluids and are indicative of exposure to environmental contaminants. BlO~GI~Y ~ The amount of the deposited or absorbed contaminant that reaches the cells or target site where an adverse effect occurs or where an interaction of that contaminant with a membrane surface occurs. Dose The amount of a contaminant that is absorbed or deposited in the body of an exposed organism for an increment of tune usually from a single medium. Total dose is the sum of doses received by a person from a contaminant in a given intermural 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. ENVIRONMEN17. Comprises air, water, food, and soil media. Regarding air, it refers to all indoor and outdoor microenvironments, including residential and occupational settings. EXPOSURE An event that occurs when there is contact at a boundary be- tween a human and the environment with a contaminant of a specific con- centration for an interval of time; the units of exposure are concentration multiplied by time. osuR8AssEssMcNr. Involves numerous techniques to identify the conta- minant, contaminant sources, environmental media of exposure, transport through each medium, chemical and physical transformations, routes of entry to the body, intensity and frequency of contact, and spatial and tem- poral concentration patterns of the contaminant. An array of techniques can be employed, ranging from estimating the number of people exposed 257

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258 ASSESSING NU~N E=OSU~ and contaminant concentrations to sophisticated methodology employing contaminant monitoring, modeling, and human biological marker measure- ment. DOSE Refers to the amount of the environmental contaminant absorbed In body tissue or interacting with an organ's membrane surface. M'cRoiNv'RoNr~:r. A three-dimensional space with a volume In which contaminant concentration is spatially uniform during some specific inter- val. NUISANCE E~clr. A subjectively unpleasant effect (e.g., headache) that occurs as a consequence of exposure to a contaminant; it may be associated with some physiological response, but is not permanent. P~nAL Dose An exposure value multiplied by a contact rate (e.g., rates of inhalation, ingestion, or absorption through the skin) and assumes total absorption of the contaminant. Throw HUMAN ENSURE Accounts for all exposures a person has to a spe- cific contaminant, regardless of environmental medium or route of entry (inhalation, ingestion, and dermal absorption). Sometimes total exposure sed incorrectly to refer to exposure to all pollutants in an environment. Total exposure to more than one pollutant should be stated explicitly as such.