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Glossary: G H I J K
Game Fish:
Species like trout, salmon, or bass, caught for sport. Many of them show more
sensitivity to environmental change than "rough" fish.
Garbage:
Animal and vegetable waste resulting from the handling, storage, sale,
preparation, cooking, and serving of foods.
Gas Chromatograph/Mass Spectrometer:
Instrument that identifies the molecular composition and concentrations of
various chemicals in water and soil samples.
Gasohol:
Mixture of gasoline and ethanol derived from fermented agricultural products
containing at least nine percent ethanol. Gasohol emissions contain less carbon
monoxide than those from gasoline.
Gasification:
Conversion of solid material such as coal into a gas for use as a fuel.
Gasoline Volatility:
The property of gasoline whereby it evaporates into a vapor. Gasoline vapor is a
mixture of volatile organic compounds.
General Permit:
A permit applicable to a class or category of dischargers.
General Reporting Facility:
A facility having one or more hazardous chemicals above the 10,000 pound
threshold for planning quantities. Such facilities must file MSDS and emergency
inventory information with the SERC, LEPC, and local fire departments.
Generally Recognized as Safe (GRAS):
Designation by the FDA that a chemical or substance (including certain
pesticides) added to food is considered safe by experts, and so is exempted from
the usual FFDCA food additive tolerance requirements.
Generator:
1. A facility or mobile source that emits pollutants into the air or releases
hazardous waste into water or soil. 2. Any person, by site, whose act or process
produces regulated medical waste or whose act first causes such waste to become
subject to regulation. Where more than one person (e.g. doctors with separate
medical practices) are located in the same building, each business entity is a
separate generator.
Genetic Engineering:
A process of inserting new genetic information into existing cells in order to
modify a specific organism for the purpose of changing one of its
characteristics.
Genotoxic:
Damaging to DNA; pertaining to agents known to damage DNA.
Geographic Information System (GIS):
A computer system designed for storing, manipulating, analyzing, and displaying
data in a geographic context.
Geological Log:
A detailed description of all underground features (depth, thickness, type of
formation) discovered during the drilling of a well.
Geophysical Log:
A record of the structure and composition of the earth encountered when drilling
a well or similar type of test hold or boring.
Geothermal/Ground Source Heat Pump:
These heat pumps are underground coils to transfer heat from the ground to the
inside of a building. (See: heat pump; water source heat pump)
Germicide:
Any compound that kills disease-causing microorganisms.
Giardia Lamblia:
Protozoan in the feces of humans and animals that can cause severe
gastrointestinal ailments. It is a common contaminant of surface waters.
Glass Containers:
For recycling purposes, containers like bottles and jars for drinks, food,
cosmetics and other products. When being recycled, container glass is generally
separated into color categories for conversion into new containers, construction
materials or fiberglass insulation.
Global Warming:
An increase in the near surface temperature of the Earth. Global warming has
occurred in the distant past as the result of natural influences, but the term
is most often used to refer to the warming predicted to occur as a result of
increased emissions of greenhouse gases. Scientists generally agree that the
Earth's surface has warmed by about 1 degree Fahrenheit in the past 140 years.
Global Warming Potential:
The ratio of the warming caused by a substance to the warming caused by a
similar mass of carbon dioxide. CFC-12, for example, has a GWP of 8,500, while
water has a GWP of zero. (See: Class I Substance and Class II Substance.)
Glove bag:
A polyethylene or polyvinyl chloride bag-like enclosure affixed around an
asbestos-containing source (most often thermal system insulation) permitting the
material to be removed while minimizing release of airborne fibers to the
surrounding atmosphere.
Gooseneck:
A portion of a water service connection between the distribution system water
main and a meter. Sometimes called a pigtail.
Grab Sample:
A single sample collected at a particular time and place that represents the
composition of the water, air, or soil only at that time and place.
Grain Loading:
The rate at which particles are emitted from a pollution source. Measurement is
made by the number of grains per cubic foot of gas emitted.
Granular Activated Carbon Treatment:
A filtering system often used in small water systems and individual homes to
remove organics. Also used by municipal water treatment plants. GAC can be
highly effective in lowering elevated levels of radon in water.
Grassed Waterway:
Natural or constructed watercourse or outlet that is shaped or graded and
established in suitable vegetation for the disposal of runoff water without
erosion.
Gray Water:
Domestic wastewater composed of wash water from kitchen, bathroom, and laundry
sinks, tubs, and washers.
Greenhouse Effect:
The warming of the Earth's atmosphere attributed to a buildup of carbon dioxide
or other gases; some scientists think that this build-up allows the sun's rays
to heat the Earth, while making the infra-red radiation atmosphere opaque to
infra-red radiation, thereby preventing a counterbalancing loss of heat.
Greenhouse Gas:
A gas, such as carbon dioxide or methane, which contributes to potential climate
change.
Grinder Pump:
A mechanical device that shreds solids and raises sewage to a higher elevation
through pressure sewers.
Gross Alpha/Beta Particle Activity:
The total radioactivity due to alpha or beta particle emissions as inferred from
measurements on a dry sample.
Gross Power-Generation Potential:
The installed power generation capacity that landfill gas can support.
Ground Cover:
Plants grown to keep soil from eroding.
Groundwater:
The supply of fresh water found beneath the Earth's surface, usually in
aquifers, which supply wells and springs. Because groundwater is a major source
of drinking water, there is growing concern over contamination from leaching
agricultural or industrial pollutants or leaking underground storage tanks.
Groundwater Under the Direct Influence (UDI) of Surface Water:
Any water beneath the surface of the ground with: 1. significant occurrence of
insects or other microorganisms, algae, or large-diameter pathogens; 2.
significant and relatively rapid shifts in water characteristics such as
turbidity, temperature, conductivity, or pH which closely correlate to
climatological or surface water conditions. Direct influence is determined for
individual sources in accordance with criteria established by a state.
Ground-Penetrating Radar:
A geophysical method that uses high frequency electromagnetic waves to obtain
subsurface information.
Ground-Water Discharge:
Groundwater entering near coastal waters which has been contaminated by landfill
leachate, deep well injection of hazardous wastes, septic tanks, etc.
Ground-Water Disinfection Rule:
A 1996 amendment of the Safe Drinking Water Act requiring USEPA to promulgate
national primary drinking water regulations requiring disinfection as for all
public water systems, including surface waters and groundwater systems.
Gully Erosion:
Severe erosion in which trenches are cut to a depth greater than 30 centimeters
(a foot). Generally, ditches deep enough to cross with farm equipment are
considered gullies.
Glossary: H
Habitat:
The place where a population (e.g. human, animal, plant, microorganism) lives
and its surroundings, both living and non-living.
Habitat Indicator:
A physical attribute of the environment measured to characterize conditions
necessary to support an organism, population, or community in the absence of
pollutants; e.g. salinity of estuarine waters or substrate type in streams or
lakes.
Half-Life:
1. The time required for a pollutant to lose one-half of its original
co-concentration or example, the biochemical half-life of DDT in the environment
is 15 years. 2. The time required for half of the atoms of a radioactive element
to undergo self-transmutation or decay (half-life of radium is 1620 years). 3.
The time required for the elimination of half a total dose from the body.
Halogen:
A type of incandescent lamp with higher energy-efficiency that standard ones.
Halon:
Bromine-containing compounds with long atmospheric lifetimes whose breakdown in
the stratosphere causes depletion of ozone. Halons are used in firefighting.
Hard Water:
Alkaline water containing dissolved salts that interfere with some industrial
processes and prevent soap from sudsing.
Hazard:
1. Potential for radiation, a chemical or other pollutant to cause human illness
or injury. 2. In the pesticide program, the inherent toxicity of a compound.
Hazard identification of a given substances is an informed judgment based on
verifiable toxicity data from animal models or human studies.
Hazard Assessment:
Evaluating the effects of a stressor or determining a margin of safety for an
organism by comparing the concentration which causes toxic effects with an
estimate of exposure to the organism.
Hazard Communication Standard:
An OSHA regulation that requires chemical manufacturers, suppliers, and
importers to assess the hazards of the chemicals that they make, supply, or
import, and to inform employers, customers, and workers of these hazards through
MSDS information.
Hazard Evaluation:
A component of risk evaluation that involves gathering and evaluating data on
the types of health injuries or diseases that may be produced by a chemical and
on the conditions of exposure under which such health effects are produced.
Hazard Identification:
Determining if a chemical or a microbe can cause adverse health effects in
humans and what those effects might be.
Hazard Quotient:
The ratio of estimated site-specific exposure to a single chemical from a site
over a specified period to the estimated daily exposure level, at which no
adverse health effects are likely to occur.
Hazard Ratio:
A term used to compare an animal's daily dietary intake of a pesticide to its LD
50 value. A ratio greater than 1.0 indicates that the animal is likely to
consume an a dose amount which would kill 50 percent of animals of the same
species. (See: LD 50 /Lethal Dose.)
Hazardous Air Pollutants:
Air pollutants which are not covered by ambient air quality standards but which,
as defined in the Clean Air Act, may present a threat of adverse human health
effects or adverse environmental effects. Such pollutants include asbestos,
beryllium, mercury, benzene, coke oven emissions, radionuclides, and vinyl
chloride.
Hazardous Chemical:
An USEPA designation for any hazardous material requiring an MSDS under OSHA's
Hazard Communication Standard. Such substances are capable of producing fires
and explosions or adverse health effects like cancer and dermatitis. Hazardous
chemicals are distinct from hazardous waste. (See: Hazardous Waste.)
Hazardous Ranking System:
The principal screening tool used by USEPA to evaluate risks to public health
and the environment associated with abandoned or uncontrolled hazardous waste
sites. The HRS calculates a score based on the potential of hazardous substances
spreading from the site through the air, surface water, or groundwater, and on
other factors such as density and proximity of human population. This score is
the primary factor in deciding if the site should be on the National Priorities
List and, if so, what ranking it should have compared to other sites on the
list.
Hazardous Substance:
1. Any material that poses a threat to human health and/or the environment.
Typical hazardous substances are toxic, corrosive, ignitable, explosive, or
chemically reactive. 2. Any substance designated by USEPA to be reported if a
designated quantity of the substance is spilled in the waters of the United
States or is otherwise released into the environment.
Hazardous Waste:
By-products of society that can pose a substantial or potential hazard to human
health or the environment when improperly managed. Possesses at least one of
four characteristics (ignitability, corrosivity, reactivity, or toxicity), or
appears on special USEPA lists.
Hazardous Waste Landfill:
An excavated or engineered site where hazardous waste is deposited and covered.
Hazardous Waste Minimization:
Reducing the amount of toxicity or waste produced by a facility via source
reduction or environmentally sound recycling.
Hazards Analysis:
Procedures used to (1) identify potential sources of release of hazardous
materials from fixed facilities or transportation accidents; (2) determine the
vulnerability of a geographical area to a release of hazardous materials; and
(3) compare hazards to determine which present greater or lesser risks to a
community.
Hazards Identification:
Providing information on which facilities have extremely hazardous substances,
what those chemicals are, how much there is at each facility, how the chemicals
are stored, and whether they are used at high temperatures.
Headspace:
The vapor mixture trapped above a solid or liquid in a sealed vessel.
Health Advisory Level:
A non-regulatory health-based reference level of chemical traces (usually in ppm)
in drinking water at which there are no adverse health risks when ingested over
various periods of time. Such levels are established for one day, 10 days,
long-term and life-time exposure periods. They contain a wide margin of safety.
Health Assessment:
An evaluation of available data on existing or potential risks to human health
posed by a Superfund site. The Agency for Toxic Substances and Disease Registry
(ATSDR) of the Department of Health and Human Services (DHHS) is required to
perform such an assessment at every site on the National Priorities List.
Heat Island Effect:
A "dome" of elevated temperatures over an urban area caused by structural and
pavement heat fluxes, and pollutant emissions.
Heat Pump:
An electric device with both heating and cooling capabilities. It extracts heat
from one medium at a lower (the heat source) temperature and transfers it to
another at a higher temperature (the heat sink), thereby cooling the first and
warming the second. (See: geothermal, water source heat pump.)
Heavy Metals:
Metallic elements with high atomic weights; (e.g. mercury, chromium, cadmium,
arsenic, and lead); can damage living things at low concentrations and tend to
accumulate in the food chain.
Heptachlor:
An insecticide that was banned on some food products in 1975 and in all of them
1978. It was allowed for use in seed treatment until 1983. More recently it was
found in milk and other dairy products in Arkansas and Missouri where dairy
cattle were illegally fed treated seed.
Herbicide:
A chemical pesticide designed to control or destroy plants, weeds, or grasses.
Herbivore:
An animal that feeds on plants.
Heterotrophic Organisms:
Species that are dependent on organic matter for food.
High End Exposure (dose) Estimate:
An estimate of exposure, or dose level received anyone in a defined population
that is greater than the 90th percentile of all individuals in that population,
but less than the exposure at the highest percentile in that population. A high
end risk descriptor is an estimate of the risk level for such individuals. Note
that risk is based on a combination of exposure and susceptibility to the
stressor.
High Intensity Discharge:
A generic term for mercury vapor, metal halide, and high pressure sodium lamps
and fixtures.
High-Density Polyethylene:
A material used to make plastic bottles and other products that produces toxic
fumes when burned.
High-Level Nuclear Waste Facility:
Plant designed to handle disposal of used nuclear fuel, high-level radioactive
waste, and plutonium waste.
High-Level Radioactive Waste (HLRW):
Waste generated in core fuel of a nuclear reactor, found at nuclear reactors or
by nuclear fuel reprocessing; is a serious threat to anyone who comes near the
waste without shielding. (See: low-level radioactive waste.)
High-Line Jumpers:
Pipes or hoses connected to fire hydrants and laid on top of the ground to
provide emergency water service for an isolated portion of a distribution
system.
High-Risk Community:
A community located within the vicinity of numerous sites of facilities or other
potential sources of environmental exposure/health hazards which may result in
high levels of exposure to contaminants or pollutants.
High-to-Low-Dose Extrapolation:
The process of prediction of low exposure risk to humans and animals from the
measured high-exposure-high-risk data involving laboratory animals.
Highest Dose Tested:
The highest dose of a chemical or substance tested in a study.
Holding Pond:
A pond or reservoir, usually made of earth, built to store polluted runoff.
Holding Time:
The maximum amount of time a sample may be stored before analysis.
Hollow Stem Auger Drilling:
Conventional drilling method that uses augurs to penetrate the soil. As the
augers are rotated, soil cuttings are conveyed to the ground surface via augur
spirals. Drilling and sampling tools can be used inside the hollow augers.
Homeowner Water System:
Any water system which supplies piped water to a single residence.
Homogeneous Area:
In accordance with Asbestos Hazard and Emergency Response Act (AHERA)
definitions, an area of surfacing materials, thermal surface insulation, or
miscellaneous material that is uniform in color and texture.
Hood Capture Efficiency:
Ratio of the emissions captured by a hood and directed into a control or
disposal device, expressed as a percent of all emissions.
Host:
1. In genetics, the organism, typically a bacterium, into which a gene from
another organism is transplanted. 2. In medicine, an animal infected or
parasitized by another organism.
Household Hazardous Waste:
Hazardous products used and disposed of by residential as opposed to industrial
consumers. Includes paints, stains, varnishes, solvents, pesticides, and other
materials or products containing volatile chemicals that can catch fire, react
or explode, or that are corrosive or toxic.
Household Waste (Domestic Waste):
Solid waste, composed of garbage and rubbish, which normally originates in a
private home or apartment house. Domestic waste may contain a significant amount
of toxic or hazardous waste.
Human Equivalent Dose:
A dose which, when administered to humans, produces an effect equal to that
produced by a dose in animals.
Human Exposure Evaluation:
Describing the nature and size of the population exposed to a substance and the
magnitude and duration of their exposure.
Human Health Risk:
The likelihood that a given exposure or series of exposures may have damaged or
will damage the health of individuals.
Hydraulic Conductivity:
The rate at which water can move through a permeable medium. (i.e. the
coefficient of permeability.)
Hydraulic Gradient:
In general, the direction of groundwater flow due to changes in the depth of the
water table.
Hydrocarbons (HC):
Chemical compounds that consist entirely of carbon and hydrogen.
Hydrogen Sulfide (H2S):
Gas emitted during organic decomposition. Also a by-product of oil refining and
burning. Smells like rotten eggs and, in heavy concentration, can kill or cause
illness.
Hydrogeological Cycle:
The natural process recycling water from the atmosphere down to (and through)
the earth and back to the atmosphere again.
Hydrogeology:
The geology of groundwater, with particular emphasis on the chemistry and
movement of water.
Hydrologic Cycle:
Movement or exchange of water between the atmosphere and earth.
Hydrology:
The science dealing with the properties, distribution, and circulation of water.
Hydrolysis:
The decomposition of organic compounds by interaction with water.
Hydronic:
A ventilation system using heated or cooled water pumped through a building.
Hydrophilic:
Having a strong affinity for water.
Hydrophobic:
Having a strong aversion for water.
Hydropneumatic:
A water system, usually small, in which a water pump is automatically controlled
by the pressure in a compressed air tank.
Hypersensitivity Diseases:
Diseases characterized by allergic responses to pollutants; diseases most
clearly associated with indoor air quality are asthma, rhinitis, and pneumonic
hypersensitivity.
Hypolimnion:
Bottom waters of a thermally stratified lake. The hypolimnion of a eutrophic
lake is usually low or lacking in oxygen.
Hypoxia/Hypoxic Waters:
Waters with dissolved oxygen concentrations of less than 2 ppm, the level
generally accepted as the minimum required for most marine life to survive and
reproduce.
Glossary: I
Identification Code or USEPA I.D. Number:
The unique code assigned to each generator, transporter, and treatment, storage,
or disposal facility by regulating agencies to facilitate identification and
tracking of chemicals or hazardous waste.
Ignitable:
Capable of burning or causing a fire.
Imhoff Cone:
A clear, cone-shaped container used to measure the volume of settleable solids
in a specific volume of water.
Immediately Dangerous to Life and Health (IDLH):
The maximum level to which a healthy individual can be exposed to a chemical for
30 minutes and escape without suffering irreversible health effects or impairing
symptoms. Used as a "level of concern." (See: level of concern.)
Imminent Hazard:
One that would likely result in unreasonable adverse effects on humans or the
environment or risk unreasonable hazard to an endangered species during the time
required for a pesticide registration cancellation proceeding.
Imminent Threat:
A high probability that exposure is occurring.
Immiscibility:
The inability of two or more substances or liquids to readily dissolve into one
another, such as soil and water. Immiscibility The inability of two or more
substances or liquids to readily dissolve into one another, such as soil and
water.
Impermeable:
Not easily penetrated. The property of a material or soil that does not allow,
or allows only with great difficulty, the movement or passage of water.
Imports:
Municipal solid waste and recyclables that have been transported to a state or
locality for processing or final disposition (but that did not originate in that
state or locality).
Impoundment:
A body of water or sludge confined by a dam, dike, floodgate, or other barrier.
In Situ:
In its original place; unmoved unexcavated; remaining at the site or in the
subsurface.
In-Line Filtration:
Pre-treatment method in which chemicals are mixed by the flowing water; commonly
used in pressure filtration installations. Eliminates need for flocculation and
sedimentation.
In-Situ Flushing:
Introduction of large volumes of water, at times supplemented with cleaning
compounds, into soil, waste, or groundwater to flush hazardous contaminants from
a site.
In-Situ Oxidation:
Technology that oxidizes contaminants dissolved in groundwater, converting them
into insoluble compounds.
In-Situ Stripping:
Treatment system that removes or "strips" volatile organic compounds from
contaminated ground or surface water by forcing an airstream through the water
and causing the compounds to evaporate.
In-Situ Vitrification:
Technology that treats contaminated soil in place at extremely high
temperatures, at or more than 3000 degrees Fahrenheit.
In Vitro:
Testing or action outside an organism (e.g. inside a test tube or culture dish.)
In Vivo:
Testing or action inside an organism.
Incident Command Post:
A facility located at a safe distance from an emergency site, where the incident
commander, key staff, and technical representatives can make decisions and
deploy emergency manpower and equipment.
Incident Command System (ICS):
The organizational arrangement wherein one person, normally the Fire Chief of
the impacted district, is in charge of an integrated, comprehensive emergency
response organization and the emergency incident site, backed by an Emergency
Operations Center staff with resources, information, and advice.
Incineration:
A treatment technology involving destruction of waste by controlled burning at
high temperatures; e.g., burning sludge to remove the water and reduce the
remaining residues to a safe, non-burnable ash that can be disposed of safely on
land, in some waters, or in underground locations.
Incineration at Sea:
Disposal of waste by burning at sea on specially-designed incinerator ships.
Incinerator:
A furnace for burning waste under controlled conditions.
Incompatible Waste:
A waste unsuitable for mixing with another waste or material because it may
react to form a hazard.
Indemnification:
In the pesticide program, legal requirement that USEPA pay certain end-users,
dealers, and distributors for the cost of stock on hand at the time a pesticide
registration is suspended.
Indicator:
In biology, any biological entity or processes, or community whose
characteristics show the presence of specific environmental conditions. 2. In
chemistry, a substance that shows a visible change, usually of color, at a
desired point in a chemical reaction. 3.A device that indicates the result of a
measurement; e.g. a pressure gauge or a moveable scale.
Indirect Discharge:
Introduction of pollutants from a non-domestic source into a publicly owned
waste-treatment system. Indirect dischargers can be commercial or industrial
facilities whose wastes enter local sewers.
Indirect Source:
Any facility or building, property, road or parking area that attracts motor
vehicle traffic and, indirectly, causes pollution.
Indoor Air:
The breathable air inside a habitable structure or conveyance.
Indoor Air Pollution:
Chemical, physical, or biological contaminants in indoor air.
Indoor Climate:
Temperature, humidity, lighting, air flow and noise levels in a habitable
structure or conveyance. Indoor climate can affect indoor air pollution.
Industrial Pollution Prevention:
Combination of industrial source reduction and toxic chemical use substitution.
Industrial Process Waste:
Residues produced during manufacturing operations.
Industrial Sludge:
Semi-liquid residue or slurry remaining from treatment of industrial water and
wastewater.
Industrial Source Reduction:
Practices that reduce the amount of any hazardous substance, pollutant, or
contaminant entering any waste stream or otherwise released into the
environment. Also reduces the threat to public health and the environment
associated with such releases. Term includes equipment or technology
modifications, substitution of raw materials, and improvements in housekeeping,
maintenance, training or inventory control.
Industrial Waste:
Unwanted materials from an industrial operation; may be liquid, sludge, solid,
or hazardous waste.
Inert Ingredient:
Pesticide components such as solvents, carriers, dispersants, and surfactants
that are not active against target pests. Not all inert ingredients are
innocuous.
Infectious Agent:
Any organism, such as a pathogenic virus, parasite, or bacterium, that is
capable of invading body tissues, multiplying, and causing disease.
Infectious Waste:
Hazardous waste capable of causing infections in humans, including: contaminated
animal waste; human blood and blood products; isolation waste, pathological
waste; and discarded sharps (needles, scalpels or broken medical instruments).
Infiltration:
1. The penetration of water through the ground surface into sub-surface soil or
the penetration of water from the soil into sewer or other pipes through
defective joints, connections, or manhole walls. 2. The technique of applying
large volumes of waste water to land to penetrate the surface and percolate
through the underlying soil. (See: percolation.)
Infiltration Gallery:
A sub-surface groundwater collection system, typically shallow in depth,
constructed with open-jointed or perforated pipes that discharge collected water
into a watertight chamber from which the water is pumped to treatment facilities
and into the distribution system. Usually located close to streams or ponds.
Infiltration Rate:
The quantity of water that can enter the soil in a specified time interval.
Inflow:
Entry of extraneous rain water into a sewer system from sources other than
infiltration, such as basement drains, manholes, storm drains, and street
washing.
Influent:
Water, wastewater, or other liquid flowing into a reservoir, basin, or treatment
plant.
Information Collection Request (ICR):
A description of information to be gathered in connection with rules, proposed
rules, surveys, and guidance documents that contain information-gathering
requirements. The ICR describes what information is needed, why it is needed,
how it will be collected, and how much collecting it will cost. The ICR is
submitted by the USEPA to the Office of Management and Budget (OMB) for
approval.
Information File:
In the Superfund program, a file that contains accurate, up-to-date documents on
a Superfund site. The file is usually located in a public building (school,
library, or city hall) convenient for local residents.
Inhalable Particles:
All dust capable of entering the human respiratory tract.
Initial Compliance Period (Water):
The first full three-year compliance period this begins at least 18 months after
promulgation.
Injection Well:
A well into which fluids are injected for purposes such as waste disposal,
improving the recovery of crude oil, or solution mining.
Injection Zone:
A geological formation receiving fluids through a well.
Innovative Technologies:
New or inventive methods to treat effectively hazardous waste and reduce risks
to human health and the environment.
Innovative Treatment Technologies:
Technologies whose routine use is inhibited by lack of data on performance and
cost.
Inoculum:
1. Bacteria or fungi injected into compost to start biological action. 2. A
medium containing organisms, usually bacteria or a virus, that is introduced
into cultures or living organisms.
Inorganic Chemicals:
Chemical substances of mineral origin, not of basically carbon structure.
Insecticide:
A pesticide compound specifically used to kill or prevent the growth of insects.
Inspection and Maintenance (I/M):
1. Activities to ensure that vehicles' emission controls work properly. 2. Also
applies to wastewater treatment plants and other anti-pollution facilities and
processes.
Institutional Waste:
Waste generated at institutions such as schools, libraries, hospitals, prisons,
etc.
Instream Use:
Water use taking place within a stream channel; e.g., hydro-electric power
generation, navigation, water quality improvement, fish propagation, recreation.
Integrated Exposure Assessment:
Cumulative summation (over time) of the magnitude of exposure to a toxic
chemical in all media.
Integrated Pest Management (IPM):
A mixture of chemical and other, non-pesticide, methods to control pests.
Integrated Waste Management:
Using a variety of practices to handle municipal solid waste; can include source
reduction, recycling, incineration, and landfilling.
Interceptor Sewers:
Large sewer lines that, in a combined system, control the flow of sewage to the
treatment plant. In a storm, they allow some of the sewage to flow directly into
a receiving stream, thus keeping it from overflowing onto the streets. Also used
in separate systems to collect the flows from main and trunk sewers and carry
them to treatment points.
Interface:
The common boundary between two substances such as a water and a solid, water
and a gas, or two liquids such as water and oil.
Interfacial Tension:
The strength of the film separating two immiscible fluids (e.g. oil and water)
measured in dynes per, or millidynes per centimeter.
Interim (Permit) Status:
Period during which treatment, storage and disposal facilities coming under RCRA
in 1980 are temporarily permitted to operate while awaiting a permanent permit.
Permits issued under these circumstances are usually called "Part A" or "Part B"
permits.
Internal Dose:
In exposure assessment, the amount of a substance penetrating the absorption
barriers (e.g. skin, lung tissue, gastrointestinal tract) of an organism through
either physical or biological processes. (See: absorbed dose)
Interstate Carrier Water Supply:
A source of water for drinking and sanitary use on planes, buses, trains, and
ships operating in more than one state. These sources are federally regulated.
Interstate Commerce Clause:
A clause of the U.S. Constitution which reserves to the federal government the
right to regulate the conduct of business across state lines. Under this clause,
for example, the U.S. Supreme Court has ruled that states may not inequitably
restrict the disposal of out-of-state wastes in their jurisdictions.
Interstate Waters:
Waters that flow across or form part of state or international boundaries; e.g.
the Great Lakes, the Mississippi River, or coastal waters.
Interstitial Monitoring:
The continuous surveillance of the space between the walls of an underground
storage tank.
Intrastate Product:
Pesticide products once registered by states for sale and use only in the state.
All intrastate products have been converted to full federal registration or
canceled.
Inventory (TSCA):
Inventory of chemicals produced pursuant to Section 8 (b) of the Toxic
Substances Control Act.
Inversion:
A layer of warm air that prevents the rise of cooling air and traps pollutants
beneath it; can cause an air pollution episode.
Ion:
An electrically charged atom or group of atoms.
Ion Exchange Treatment:
A common water-softening method often found on a large scale at water
purification plants that remove some organics and radium by adding calcium oxide
or calcium hydroxide to increase the pH to a level where the metals will
precipitate out.
Ionization Chamber:
A device that measures the intensity of ionizing radiation.
Ionizing Radiation:
Radiation that can strip electrons from atoms; e.g. alpha, beta, and gamma
radiation.
IRIS:
USEPA's Integrated Risk Information System, an electronic data base containing
the Agency's latest descriptive and quantitative regulatory information on
chemical constituents.
Irradiated Food:
Food subject to brief radioactivity, usually gamma rays, to kill insects,
bacteria, and mold, and to permit storage without refrigeration.
Irradiation:
Exposure to radiation of wavelengths shorter than those of visible light (gamma,
x-ray, or ultra- violet), for medical purposes, to sterilize milk or other
foodstuffs, or to induce polymerization of monomers or vulcanization of rubber.
Irreversible Effect:
Effect characterized by the inability of the body to partially or fully repair
injury caused by a toxic agent.
Irritant:
A substance that can cause irritation of the skin, eyes, or respiratory system.
Effects may be acute from a single high level exposure, or chronic from repeated
low-level exposures to such compounds as chlorine, nitrogen dioxide, and nitric
acid.
Isoconcentration:
More than one sample point exhibiting the same isolate concentration.
Isopleth:
The line or area represented by an isoconcentration.
Isotope:
A variation of an element that has the same atomic number of protons but a
different weight because of the number of neutrons. Various isotopes of the same
element may have different radioactive behaviors, some are highly unstable..
Isotropy:
The condition in which the hydraulic or other properties of an aquifer are the
same in all directions.
Glossary: J
Jar Test:
A laboratory procedure that simulates a water treatment plant's
coagulation/flocculation units with differing chemical doses, mix speeds, and
settling times to estimate the minimum or ideal coagulant dose required to
achieve certain water quality goals.
Joint and Several Liability:
Under CERCLA, this legal concept relates to the liability for Superfund site
cleanup and other costs on the part of more than one potentially responsible
party (i.e. if there were several owners or users of a site that became
contaminated over the years, they could all be considered potentially liable for
cleaning up the site.)
Glossary: K
Karst:
A geologic formation of irregular limestone deposits with sinks, underground
streams, and caverns.
Kinetic Energy:
Energy possessed by a moving object or water body.
Kinetic Rate Coefficient:
A number that describes the rate at which a water constituent such as a
biochemical oxygen demand or dissolved oxygen rises or falls, or at which an air
pollutant reacts.
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