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Indiana Department of Environmental Management
Risk Assessment Definitions
The process of taking in, as when a sponge takes up water. Chemicals can be absorbed through the skin into the bloodstream and then transported to other organs.
Any toxic effect that occurs within a short period of time (minutes to a few days) following an exposure.
A dose (or exposure) occurring within a short time relative to the life of a person or organism (24 hours or less in humans).
Atmospheric pressure (1 atm)
The normal pressure of the air.
Any air pollutant that causes or may cause adverse health effects in humans.
The accumulation of a chemical in an organism (plant, animal, etc.) which takes place when the rate of intake is greater than the rate of excretion of that chemical.
A group of related diseases characterized by the uncontrolled growth of abnormal cells.
Cancer risk estimate
The probability of developing cancer from exposure to a chemical or mixture of chemicals over a period of time.
A chemical capable of inducing cancer.
A substance with a distinct molecular composition that is produced by or used in a chemical process.
An effect that occurs as a result of repeated or long-term exposure (years to lifetime).
The amount of a chemical present in a medium (i.e. water, air) compared to the volume of the medium.
Pollutant or chemicals mixing with the medium around it (i.e. water, air).
The concentration and length of time that a person is exposed to a chemical.
A determination of the relationship between the magnitude of a dose and the biological response.
The removal of airborne substances to available surfaces that occurs as a result of settling due to gravity, diffusion, and thermophoresis (temperature differences) without precipitation (rains, snows, etc.).
A substance or chemical being discharged into the air.
When water or a chemical leaves water and goes into the air.
When the body gets rid of a chemical from the body. This can be through the pores in the skin, breathing or by the kidneys.
Contact made between a chemical and a person.
Anything that has potential to cause harm. The likelihood of experiencing a non-cancer health effect is called hazard.
A change that occurs to human health as a result of a chemical.
When faced with two equally scientifically defensible inputs during risk estimations, selecting the input that is more protective of human health.
Indiana Department of Environmental Management
Swallowing, such as eating or drinking.
The process where a chemical crosses the outer boundary of a person without being absorbed, for example, through ingestion or inhalation.
Micrograms per cubic meter (µg/m3)
Unit of measure for air concentrations. How many micrograms (unit of weight) are contained in a theoretical cube of air one meter tall by one meter wide by one meter deep.
Parts per billion (ppb)
Unit of measure for concentration. How many parts of a chemical are contained per billion parts total in a medium (air, water, land).
Parts per million (ppm)
Unit of measure for concentration. How many parts of a chemical are contained per million parts total in a medium (air, water, land).
The relative frequency with which an event occurs or is likely to occur. For example, the odds of a coin landing heads up.
When a chemical evaporates from water but is then reabsorbed by the water body.
The cumulative combination and results from the scientific method of evaluating the toxic properties of chemicals and how humans and the ecosystem are exposed. A risk assessment generally determines the likelihood, to what extent, and/or characterizes how humans and the ecosystem are adversely affected.
The last phase of risk assessment where all information from toxicity and exposure are combined to calculate estimates of risk. This will include all the assumptions and scientific information used to estimate risk, the uncertainty associated with the assessment, and any other information that may be useful to decision makers.
A measure of how toxic a chemical is at a certain dose. Sometimes referred to as a dose-response value.
The lowest dose of a chemical at which a specified measurable effect is observed and below which it is not observed.
The amount to which a chemical or mixture of chemicals can harm humans or the environment.
When a chemical changes from one chemical to another.
Toxics Release Inventory. A collection of emissions information from industries in the United States.
United States Environmental Protection Agency
The process where a chemical is absorbed into the body. This usually refers to absorption through the skin.
Volume of air
A defined amount of air. In most situations, a cubic meter is used for air concentrations.
The removal of airborne substances to available surfaces that occurs as a result of settling due to gravity, diffusion, and thermophoresis (temperature differences), with precipitation (rain, snow, etc.).