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    Environmental and Injury Epidemiology and Toxicology Unit

    1100 West 49th Street
    Austin, TX 78756

    Phone: 1-800-588-1248
    Fax: 512-776-7222


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Definitions of Key Terms

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A B C D E F G H I J K L M N O P Q R S T U V W X Y Z


Asbestosis
an occupational lung disease caused by breathing in asbestos fibers and characterized by scarring of the lining of the lungs, resulting in decreased lung function; long-term exposure to airborne asbestos fibers in materials like insulation and fireproofing increases the risk of asbestosis

Biomarkers
indicators signaling the presence of a chemical or substance in the body used to identify exposure

Cancer
a group of more than 100 diseases that occur when some cells in the body become abnormal and grow, or multiply, out of control into more abnormal cells creating a tumor; malignant tumors are called cancerous

Case-Control Study
a study that compares one group of people that have a health problem ("cases") with a second group of people that do not have a health problem ("controls") in order to better understand the health problem. 

Cluster
a group of cases of a disease or other health-related condition –particularly cancer or birth defects–that occur in a relatively small area and time-span.

Comparison Value
a chemical-specific value that indicates a level of exposure that would not be expected to cause health effects

Consultation
an analysis of an environmental exposure scenario in response to a specific question or concern

Down Syndrome
a condition characterized by a small, anteroposteriorly flattened skull, short, flat-bridged nose, epicanthal fold, short phalanges, with moderate to severe mental retardation due to an extra chromosome 21

Epidemiology
the study of epidemics, or, the study of the relationships of various factors that determine the frequency and distribution of diseases among populations

Exposure
coming into contact with a chemical or substance through breathing (inhalation exposure), eating or drinking (ingestion exposure), or through the skin (dermal exposure)

Health Study
a controlled analysis which compares a population that has been (or may have been) exposed to a chemical to a similar population that has not been exposed

Incidence
the amount of a given disease or other health-related condition in a given population over the course of a period of time, usually a year time

Investigation
an analysis of an environmental exposure scenario to determine the nature of any public health risks that may be present

LOAEL
stands for the Lowest Observable Adverse Effects Level," meaning the lowest level of exposure at which adverse health effects have been observed in a laboratory experiment; a LOAEL is specific to a chemical, a method of exposure, an animal or human organ system, and an effect in that system

Methane Gas
a gas that, when present in sufficient quantity in the inspired air, prevents body tissues from receiving an adequate oxygen supply; also can create an explosion hazard indoors

Minimal Risk Level (MRL)
an estimate of the daily human exposure to a chemical that is likely to be without appreciable risk of non-cancer health effects

Multiple Sclerosis (MS)
an autoimmune disease that attacks the nerve fibers, causing scarring of the nerve cells; while the cause of MS is not clearly understood, scientists are currently investigating the role of genetics, viruses, and exposure to metals

National Priorities List (NPL) Site
a site containing hazardous wastes that has been placed on the Environmental Protection Agency's list of the most serious environmental hazards; sites are placed on the NPL due to risk of actual or potential exposures causing harm to people, wildlife, or the environment

NOAEL
stands for “No Observable Adverse Effects Level," meaning a level of exposure at which no adverse health effects would be expected

Parts Per Billion (ppb)
parts of a chemical in a billion parts of another substance; contaminants in air, water, and soil samples may be expressed in ppb. (i.e. one drop of water in an Olympic size swimming pool)

Parts Per Million (ppm)
parts of a chemical in a million parts of another substance; contaminants in air, water, and soil samples may be expressed in ppm. (i.e. one grain of salt in a million grains of sugar)

Pathway of Exposure
also called "exposure pathway" refers to a route by which a chemical can move from the air, water, soil, or food chain into our body

Pesticide
a chemical used to kill insects and other pests that may be used in residences, places of work, or in agriculture

Prevalence
the amount of a given disease or other health-related condition in a given population at a designated time

Public Health Assessment (PHA)
an investigation of potential pathways of exposure to chemicals at a site—through the air, water, or soil—to determine any risk to public health; a PHA is not a medical exam but an analysis of information about chemicals at a site and their toxic properties to determine any public health risks due to exposure

Rate
the incidence or occurrence of a certain disease within a population; rates are expressed as a ratio, often as the number of cases of a disease per 100,000 population in a given area

Significance
a "significant" rate of disease for a given population exceeds the number of cases that reasonably could be due to random chance occurrence

Silicosis
a lung disease caused by breathing in crystalline silica and characterized by scarring of the lining of the lungs, resulting in decreased lung function; silicosis is most prevalent among sand blasters, miners, quarry workers, foundry workers, and others who work in dusty conditions

Superfund
the common name given to the program created by CERCLA (Comprehensive Environmental Response, Compensation, and Liability Act), passed by the U.S. Congress in 1980. CERCLA created a fund to clean up abandoned hazardous waste sites through a tax on petrochemical companies. The CERCLA or “Superfund" program is administered by the U.S. Environmental Protection Agency

Toxicology
the scientific study of poisons, their actions, their detection, and the treatment of the conditions produced by them

Last updated February 10, 2011