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Abiotic: Not caused by or resulting from the activity of living organisms.

Acute Toxicity: The effect of a single large dose of a substance.

Airborne particulates: Total suspended particulate matter found in the atmosphere as solid particles or liquid droplets, including windblown dust, emissions from industrial processed, smoke from the burning of wood and coal, and the exhaust of motor vehicles.

Baseline Environmental Assessment (BEA): An evaluation of environmental conditions which exist at a facility at the time of purchase, occupancy, or foreclosure that reasonably defines the existing conditions and circumstance at the facility so that in the event of a subsequent release, there is a means of distinguishing the new release from existing contamination.

Biodegradable: Capable of being decomposed by living organisms.

Brownfields: Abandoned, idled, or under-used industrial and commercial facilities where expansion or redevelopment is complicated by real or perceived environmental contamination.

Carcinogen: A cancer causing agent.

Chronic Toxicity: The effect of low-level, long-term exposure (e.g. occupational exposure).

Concentration: The relative amount of a substance mixed with another substance. An example is five parts per million of carbon monoxide in air or 1 milligram/liter of iron in water.

Exposure: Radiation or pollutants that come into contact with the body and present a potential health threat. The most common routes of exposure are through the skin, mouth, or by inhalation.

Exposure Route: The way in which people come into contact with a substance. The main routes are ingestion, inhalation, and adsorption through the skin.

Geomembrane: A synthetic membrane, often made of polyvinyl chloride (PVC) or high density polyethylene (HDPE). Often used to line landfills.


Groundwater: Water beneath the surface of the earth which saturates the pores and fractures of sand, gravel, and rock formations.

Hydrophilic: Having a strong attraction to water. Hydrophilic molecules are soluble in water and travel with the groundwater.

Hydrophobic: Having a strong aversion for water. Hydrophobic molecules are relatively insoluble in water and tend to sorb to soil particles.

Leaching: The process by which soluble chemicals are dissolved and carried down through the soil by water or some other fluid such as gasoline.

Metabolism: A chemical and physical process in which substances (such as sugar) are transformed into energy and waste products.

Milligrams/liter (mg/l): The measure of concentration used in the measurement of chemicals in fluids. This is the most common way to present a concentration in water and is roughly equivalent to parts per million.

Monitoring: Periodic or continuous surveillance or testing to determine the level of compliance with federal, state or local regulations or to assess pollutant levels in various media (such as soil or water) or in humans, animals and other living things.

Opacity: A measure of the amount of light obscured by very small particles in the air; clear window glass has a zero opacity, a brick wall has 100 percent opacity. Opacity is used when measuring fugitive dust.

Parts per billion (ppb): One ppb is comparable to one kernel of corn in a filled, 45-foot silo, 16 feet in diameter. A part per billion is roughly equivalent to one-thousandth teaspoon of water in a 21-foot diameter, 4-foot deep swimming pool.

Parts per million (ppm): Parts per million may also be expressed as micrograms per gram, milligrams per kilogram or milligrams per liter. A part per million is roughly equivalent to one teaspoon of water in a 21 foot diameter, 4 foot deep swimming pool.

Phase I Environmental Audit: An initial environmental investigation that is limited to a historical records search to determine ownership of a site and to identify the kinds of chemical processes that were carried out at the site.

Phase II Environmental Audit: An investigation that includes tests performed at the site to confirm the location and identity of environmental hazards. The audit includes preparation of a report that includes recommendations for cleanup alternatives.

Polychlorinated Biphenyls (PCBs): A group of toxic, persistent chemicals used in electrical transformers and capacitors for insulating purposes, and in gas pipeline systems as a lubricant. The sale and new use of PCBs were banned by law in 1979.

Polynuclear Aromatic Hydrocarbon (PAH): A group of chemical compounds that contain more than one fused benzene ring. Commonly found in petroleum fuels, coal products, and tar.

Recalcitrant: Difficult to degrade under natural conditions and usually not responsive to treatment.

Remedial Action Plan (RAP): A plan submitted by a site owner to the MDEQ outlining the planned action to reduce the contamination of a site to acceptable levels.

Remedial Design and Remedial Action (RD/RA): The step in the cleanup process that follows the remedial investigation and feasibility study and selection of a remedy. A RD is the preparation of the engineering plans and specifications to properly and effectively implement the remedy. The RA is the actual construction or implementation of the remedy.

Remedial Investigation and Feasibility Study (RI/FS): The RI/FS is the step in the cleanup process that is conducted to gather sufficient information to support the selection of a site remedy that will reduce or eliminate the risks associated with the contamination at the site. The RI involves site characterization (collection of data) and determines if whether the contamination presents a significant risk to human health or the environment. The FS focuses on the development of specific response alternatives for addressing contamination at a site.

Risk: A measure of the chance (probability) that damage to life, health, property, or the environment will occur.

Risk Assessment: A scientific process that estimates the type and magnitude of risk to human health posed by exposure to chemical substances.

Semivolatile Organic Compound (SVOC): A substance that evaporates slowly at standard temperature (20° C and 1 atm pressure).

Sorption: The action by which molecules are attracted to or attach to solid particles, including soil.

Surface Water: All water naturally open to the atmosphere (rivers, lakes, reservoirs, ponds, streams, seas, estuaries).

Toxicity Characteristic Leaching Procedure (TCLP): A test designed to determine the potential for toxic chemicals to move through soils and groundwater. Also used for determining the effectiveness of treatment processes designed to contain wastes or toxic chemicals in a solid matrix such as concrete or polyethylene.

Threshold Level: The minimum concentration of a substance at which negative health effects begin to appear.

Toxic: Acting as a poisonous or hazardous substance; having poisonous or harmful qualities.

Toxicity: A measure of the poisonous or harmful nature of a substance.

Toxicology: The study of adverse effects of chemicals on living organisms.

Volatile: Any substance which evaporates quickly.

Volatilization: A process by which a chemical evaporates.

Volatile Organic Compound (VOC): Any organic compound which evaporates readily to the atmosphere. VOCs contribute significantly to photochemical smog production and certain health problems.

The Midwest Hazardous Substance Research Center, Michigan State University.
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