Laboratory Terms H

A glossary of science, chemistry, environmental and laboratory terms.

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72 results match your search term:  H


Habitat
The place where a population (e.g. human, animal, plant, microorganism) lives...

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Habitat Indicator
A physical attribute of the environment measured to characterize conditions n...

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Half-Life
1. The time required for a pollutant to lose one-half of its original coconce...

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Halogen
A type of incandescent lamp with higher energy-efficiency that standard ones.

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Halon
Bromine-containing compounds with long atmospheric lifetimes whose breakdown ...

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Hammer Mill
A high-speed machine that uses hammers and cutters to crush, grind, chip, or ...

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Hard Water
Alkaline water containing dissolved salts that interfere with some industrial...

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Hauler
Garbage collection company that offers complete refuse removal service; many ...

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Hazard
1. Potential for radiation, a chemical or other pollutant to cause human illn...

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Hazard Assessment
Evaluating the effects of a stressor or determining a margin of safety for an...

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Hazard Communication Standard
An OSHA regulation that requires chemical manufacturers, suppliers, and impor...

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Hazard Evaluation
A component of risk evaluation that involves gathering and evaluating data on...

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Hazard Identification
Determining if a chemical or a microbe can cause adverse health effects in hu...

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Hazard Quotient
The ratio of estimated site-specific exposure to a single chemical from a sit...

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Hazard Ratio
A term used to compare an animal's daily dietary intake of a pesticide to its...

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Hazardous Air Pollutants
Air pollutants which are not covered by ambient air quality standards but whi...

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Hazardous Chemical
An EPA designation for any hazardous material requiring an MSDS under OSHA's ...

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Hazardous Ranking System
The principal screening tool used by EPA to evaluate risks to public health a...

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Hazardous Substance
1. Any material that poses a threat to human health and/or the environment. T...

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Hazardous Waste
By-products of society that can pose a substantial or potential hazard to hum...

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Hazardous Waste Landfill
An excavated or engineered site where hazardous waste is deposited and covered.

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Hazardous Waste Minimization
Reducing the amount of toxicity or waste produced by a facility via source re...

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Hazards Analysis
Procedures used to (1) identify potential sources of release of hazardous mat...

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Hazards Identification
Providing information on which facilities have extremely hazardous substances...

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Headspace
The vapor mixture trapped above a solid or liquid in a sealed vessel.

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Health Advisory Level
A non-regulatory health-based reference level of chemical traces (usually in ...

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Health Assessment
An evaluation of available data on existing or potential risks to human healt...

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Heat Island Effect
A "dome" of elevated temperatures over an urban area caused by structural and...

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Heat Pump
An electric device with both heating and cooling capabilities. It extracts he...

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Heavy Metals
Metallic elements with high atomic weights; (e.g. mercury, chromium, cadmium,...

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Heptachlor
An insecticide that was banned on some food products in 1975 and in all of th...

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Herbicide
A chemical pesticide designed to control or destroy plants, weeds, or grasses.

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Herbivore
An animal that feeds on plants.

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Heterotrophic Organisms
Species that are dependent on organic matter for food.

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Hexavalent Chromium
Hexavalent chromium (Chromium-6) compounds are a group of chemical substances...

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High End Exposure Estimate
An estimate of exposure, or dose level received anyone in a defined populatio...

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High Intensity Discharge
A generic term for mercury vapor, metal halide, and high pressure sodium lamp...

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High-Density Polyethylene
A material used to make plastic bottles and other products that produces toxi...

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High-Level Nuclear Waste Facility
Plant designed to handle disposal of used nuclear fuel, high-level radioactiv...

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High-Level Radioactive Waste HLRW
Waste generated in core fuel of a nuclear reactor, found at nuclear reactors ...

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High-Line Jumpers
Pipes or hoses connected to fire hydrants and laid on top of the ground to pr...

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High-Risk Community
A community located within the vicinity of numerous sites of facilities or ot...

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High-to-Low-Dose Extrapolation
The process of prediction of low exposure risk to humans and animals from the...

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Highest Dose Tested
The highest dose of a chemical or substance tested in a study.

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Holding Pond
A pond or reservoir, usually made of earth, built to store polluted runoff.

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Holding Time
The maximum amount of time a sample may be stored before analysis.

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Hollow Stem Auger Drilling
Conventional drilling method that uses augurs to penetrate the soil. As the a...

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Homeowner Water System
Any water system which supplies piped water to a single residence.

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Homogeneous Area
In accordance with Asbestos Hazard and Emergency Response Act (AHERA) definit...

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Hood Capture Efficiency
Ratio of the emissions captured by a hood and directed into a control or disp...

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Host
1. In genetics, the organism, typically a bacterium, into which a gene from a...

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Household Hazardous Waste
Hazardous products used and disposed of by residential as opposed to industri...

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Household Waste
Solid waste, composed of garbage and rubbish, which normally originates in a ...

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Human Equivalent Dose
A dose which, when administered to humans, produces an effect equal to that p...

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Human Exposure Evaluation
Describing the nature and size of the population exposed to a substance and t...

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Human Health Risk
The likelihood that a given exposure or series of exposures may have damaged ...

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Hydraulic Conductivity
The rate at which water can move through a permeable medium. (i.e. the coeffi...

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Hydraulic Gradient
In general, the direction of groundwater flow due to changes in the depth of ...

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Hydrocarbons HC
Chemical compounds that consist entirely of carbon and hydrogen.

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Hydrogen Sulfide H2S
Gas emitted during organic decomposition. Also a by-product of oil refining a...

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Hydrogeological Cycle
The natural process recycling water from the atmosphere down to (and through)...

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Hydrogeology
The geology of ground water, with particular emphasis on the chemistry and mo...

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Hydrologic Cycle
Movement or exchange of water between the atmosphere and earth.

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Hydrology
The science dealing with the properties, distribution, and circulation of water.

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Hydrolysis
The decomposition of organic compounds by interaction with water.

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Hydronic
A ventilation system using heated or cooled water pumped through a building.

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Hydrophilic
Having a strong affinity for water.

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Hydrophobic
Having a strong aversion for water.

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Hydropneumatic
A water system, usually small, in which a water pump is automatically control...

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Hypersensitivity Diseases
Diseases characterized by allergic responses to pollutants; diseases most cle...

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Hypolimnion
Bottom waters of a thermally stratified lake. The hypolimnion of a eutrophic ...

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Hypoxia-Hypoxic Waters
Waters with dissolved oxygen concentrations of less than 2 ppm, the level gen...

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