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Dictionary

Additional Dictionaries

Adapted from

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


A

Absorption: The incorporation of liquids or gases into the body. Absorption is also the process by which liquid hazardous materials are soaked up by sand, sawdust, or other material to limit the spread of contamination.

Acetylcholinesterase: An enzyme that hydrolyzes the neurotransmitter acetylcholine. The action of this enzyme is inhibited by nerve agents.

Acidosis: Pathological condition in which the hydrogen(1+) (hydron) amount concentration of body fluids is above normal and hence the pH of blood falls below the reference interval.

Active metabolite: Metabolite causing biological and (or) toxicological effects.

Acute effect: A pathologic process caused by a single substantial exposure.

Acute exposure: A single encounter to toxic concentrations of a hazardous material or multiple encounters over a short period of time (usually 24 hours).

Acute toxicity: Adverse effects of finite duration occurring within a short time (up to 14 d) after administration of a single dose (or exposure to a given concentration) of a test substance or after multiple doses (exposures), usually within 24 h of a starting point (which may be exposure to the toxicant, or loss of reserve capacity, or developmental change etc.).

Adaptation: The tendency of certain receptors to become less responsive or cease to respond to repeated or continued stimuli.

Adsorption: The property of a substance to attract and hold to its surface a gas, liquid, or other substance.

Adverse effect: Change in biochemistry, physiology, growth, development morphology, behavior, or lifespan of an organism which results in impairment of functional capacity or impairment of capacity to compensate for additional stress or increase in susceptibility to other environmental influences.

Aerosol: Fine liquid or solid particles suspended in a gas; for example, fog or smoke.

Aerosolized: The production of an aerosol -- a fine mist or spray containing minute particles.

Air purification devices: Respirators or filtration devices that remove particulate matter, gases, or vapors from the atmosphere. These devices range from full-facepiece, dual-cartridge respirators with eye protection to halfmask, facepiece-mounted cartridges with no eye protection.

Air-supplied respirators: A device that provides the user with compressed air for breathing.

Airways: Any parts of the respiratory tract through which air passes during breathing.

Albuminuria: The presence of protein (primarily albumin) in the urine; usually indicative of transient dysfunction or disease.

Alkali: A basic substance (pH greater than 7) that has the capacity to neutralize an acid and form a salt.

Alveolar ducts: The smallest of the lungs' airways that connect terminal bronchioles and alveolar sacs. Sometimes called bronchioles.

Alveoli (singular alveolus): Microscopic air sacs in which gas exchange between the blood and the lungs occurs.

Anemia: Any condition in which the number of red blood cells, the amount of hemoglobin, and the volume of packed red blood cells per 100 milliliters of blood are less than normal.

Anesthetic: Substance which produces loss of feeling or sensation: general anesthetic produces loss of consciousness; local or regional anesthetic renders a specific area insensible to pain.

Anhydrous: Containing no water.

Anisocytosis: Considerable variation in the size of blood cells.

Anorexia: Lack of appetite; aversion to food.

Anoxia: Lack of oxygen in inspired air, blood, or tissues.

Anterior chamber of the eye: The fluid-filled front portion of the eye between the cornea and the lens.

Antidote: An agent that neutralizes a poison or counteracts its effects.

Anticoagulant: Substance which prevents blood clotting, e.g., warfarin.

Anuria: Absence of urine production.

Anxiety: a feeling of apprehension, uncertainty, and fear without apparent stimulus, associated with physiological changes (tachycardia, sweating, tremor, etc.).

Aplastic anemia: A condition characterized by a decrease in the amount of hemoglobin in the blood due to incomplete or defective development of red blood cells; usually accompanied by defective regeneration of white blood cells and platelets.

Apnea: Cessation of breathing.

Arrhythmia: Any variation from the normal rhythm of the heartbeat.

Asphyxia: A condition in which the exchange of oxygen and carbon dioxide in the lungs is absent or impaired.

Aspiration pneumonia: Inflammation of the lungs due to inhalation of foreign material, usually food or vomitus, into the bronchi.

Asthma: A chronic condition in which constriction (spasm) of the bronchial tubes occurs in response to irritation, allergy, or other stimuli.

Ataxia: Incoordination of voluntary movement, especially affecting gait and speech.

Atelectasis: Lung collapse.

Atomic weight: The average weight (or mass) of all the isotopes of an element, as determined from the proportions in which they are present in a given element, compared with the mass of the 12 isotope of carbon (taken as precisely 12.000), which is the official international standard; measured in daltons.

Atopy: A tendency or predisposition to allergic reactions.

Atropine: A compound used as an antidote for nerve agents.

Autoignition temperature: The lowest temperature at which a gas or vapor-air mixture will ignite from its own heat source or a contacted heated surface without a spark or flame.

Axonal: Pertaining to an axon.

Axon: The part of a nerve cell that conducts nervous impulses away from the nerve cell body to the remainder of the cell (i.e., dendrites); large number of fibrils enveloped by a segmented myelin sheath.

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B

Bilirubin: A red pigment that results from normal and abnormal destruction of red blood cells.

Blepharospasm: Involuntary spasmodic blinking or closing of the eyelids due to severe irritation.

Blister Agents: Substances that cause blistering of the skin. Exposure is through liquid or vapor contact with any exposed tissue (eyes, skin, lungs).

Blood Agents: Substances that injure a person by interfering with cell respiration (the exchange of oxygen and carbon dioxide between blood and tissues).

Boiling point: The temperature at which the vapor pressure of a liquid equals the atmospheric pressure and the liquid becomes vapor.

Bradycardia: Slow heart rate, usually under 60 beats per minute.

Bronchiole: A small-diameter airway branching from a bronchus.

Bronchi (singular bronchus): Large divisions of the trachea that convey air to and from the lungs.

Bronchitis: Inflammation of the mucous membrane of the bronchial tubes, usually associated with a persistent cough and sputum production.

Bronchorrhea: Increased bronchial secretions.

Bronchospasm: Contraction of the smooth muscle of the bronchi, causing narrowing of the bronchi. This narrowing increases the resistance of air flow into the lungs and may cause a shortness of breath, typically associated with wheezing.

Bullae: Large fluid-filled blisters.

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C

Carcinogenic: Causing cancer.

Cardiac dysrhythmia: Abnormality in the rate, regularity, or sequence of the heart beat. Formerly referred to as cardiac arrhythmia.

Casualty (toxic) agents: Produce incapacitation, serious injury, or death. They can be used to incapacitate or kill victims. These agents are the choking, blister, nerve, and blood agents.

Cataract: Loss of transparency (clouding) of the lens of the eye.

Catecholamines of biochemical interest am those produced by the nervous system (e.g., epinephrine [adrenaline] or dopamine) to increase heart rate and blood pressure, or medicines with the same general chemical structure and effect: (Managing Hazardous Materials Incidents, CDC/ATSDR)

Catecholamines: Substances of a specific chemical nature (pyrocatechols with an alkylamine side chain).

Caustic: Substance that strongly irritates, burns, corrodes, or destroys living tissue.

Central nervous system depressants: Compounds that have the predominant effect of depressing or blocking the activity of the central nervous system. The primary mental effects include the disruption of the ability to think, sedation, and lack of motivation.

Central nervous system stimulants: Compounds that have the predominant effect of flooding the brain with too much information. The primary mental effect is loss of concentration, causing indecisiveness and the inability to act in a sustained, purposeful manner.

Cerebellar abnormalities: Any irregularity in the cerebellum of the brain.

Cerebellum: The large brain mass located at the posterior base of the brain, responsible for balance and coordination of movement.

Cerebral infarctions: Death of tissue in the cerebrum due to lack of blood flow to the area.

Cerebrum: The largest portion of the brain; includes the cerebral hemispheres (cerebral cortex and basal ganglia).

Chemexfoliation: Chemical skin peeling; use of chemicals to remove scars or pigmentation defects.

Chemical agent: A chemical substance that is intended for use in military operations to kill, seriously injure, or incapacitate people through its physiological effects. Excluded from consideration are riot control agents, and smoke and flame materials. The agent may appear as a vapor, aerosol, or liquid; it can be either a casualty/toxic agent or an incapacitating agent.

Chemical formula: The collection of atomic symbols and numbers that indicates the chemical composition of a pure substance.

Chemical-protective clothing: Clothing specifically designed to protect the skin and eyes from direct chemical contact. Descriptions of chemical-protective apparel include nonencapsulating and encapsulating (referred to as liquid-splash protective clothing and vapor-protective clothing, respectively).

Chemical threat agents: Toxic chemicals that could be used in a terrorist attack against civilians, or chemicals that could be released at toxic levels by accident or natural disaster. This is a term used by federal and Department of Defense agencies such as United States Army Medical Institute of Chemical Defense (USAMICD), Centers for Disease Control and Preventuion(CDC), National Institutes of Health (NIH), and Department of Homeland Security (DHS).

Choking Agents: Substances that cause physical injury to the lungs. Exposure is through inhalation. In extreme cases, membranes swell and lungs become filled with liquid. Death results from lack of oxygen; hence, the victim is "choked" (Chemical/Biological/Radiological Incident Handbook, CIA)

Chronic effect: A pathologic process caused by repeated exposures over a period of long duration.

Chronic exposure: Repeated encounters with a hazardous substance over a period of long duration.

Cognitive function: The ability to think.

Coma: State of profound unconsciousness from which the patient cannot be aroused.

Combustible liquid: Any liquid that has a flash point at or above 100 EF (37.7 EC) and below 200 EF (93.3 EC).

Comorbid: pertaining to a disease or other pathological process that occurs simultaneously with another (Dorland's Medical Dictionary for Health Consumers)

Comorbidity: The simultaneous presence of two or more morbid conditions or diseases in the same patient, which may complicate a patients's hospital stay; in the US health care system, comorbidity carries considerable weight in determining the reasonable length of hospitalization under the DRG classification of diseases (McGraw-Hill Concise Dictionary of Modern Medicine)

Compressed gas: Gas whose volume has been reduced by pressure.

Congenital anomalies: Birth defects.

Conjunctiva (plural conjuctivae): The delicate mucous membrane that covers the exposed surface of the eyeball and lines the eyelids.

Conjunctivitis: Inflammation of the conjunctiva; can result in redness, irritation, and tearing of the eye.

Contact dermatitis (allergic): A delayed-onset skin reaction caused by skin contact with a chemical to which the individual has been previously sensitized.

Contact dermatitis (irritant): Inflammatory skin reaction caused by a skin irritant.

Contamination: The presence of extraneous, especially infectious, material that renders a substance or preparation impure or harmful; the deposition of radioactive material in any place where it is not desired.

Control zones: Areas at a hazardous materials incident whose boundaries are based on safety and the degree of hazard; generally includes the Hot Zone, Decontamination Zone, and Support Zone.

Corneal opacification: Clouding of the cornea.

Cornea: Transparent membrane that covers the colored part of the eye.

Corrosive: Ability to destroy the texture or substance of a tissue.

Critical Care Area: That area in a hospital designated for the treatment of severely ill patients.

Cutaneous: Pertaining to the skin.

Cyanosis: Bluish discoloration of the skin and mucous membranes due to deficient oxygenation of the blood; usually evident when reduced hemoglobin (i.e., hemoglobin unable to carry oxygen) exceeds 5%.

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D

Decontamination: The process of making any person, object, or area safe by absorbing, destroying, neutralizing, making harmless, or removing the hazardous material.

Decontamination: The process of removing hazardous materials from exposed persons and equipment at a hazardous materials incident.

Decontamination Zone: The area surrounding a chemical hazard incident (between the Hot Zone and the Support Zone) in which contaminants are removed from exposed victims.

Defat: To remove natural oils from the skin.

Degradation: The process of decomposition. When applied to protective clothing, a molecular breakdown of material because of chemical contact; degradation is evidenced by visible signs such as charring, shrinking, or dissolving. Testing clothing material for weight changes, thickness changes, and loss of tensile strength will also reveal degradation.

Delirium: A condition of extreme mental (and sometimes motor) excitement marked by defective perception, impaired memory, and a rapid succession of confused and unconnected ideas, often with illusions and hallucinations.

Dementia: A general deterioration of mental abilities.

Demyelination: Removal (destruction) of the myelin sheath that surrounds and protects nerves.

Denervation atrophy: Shrinkage or wasting of muscles due to loss of nerve supply.

Dermal: Relating to the skin.

Dermatitis: Skin inflammation.

Dermis: The layer of the skin just below the epidermis or outer layer. The dermis has a rich supply of blood vessels, nerves, and skin structures.

Desiccant effect: Drying of the skin caused by removal of soluble oils.

Desiccation: Removal of moisture; drying.

Detoxification: The metabolic process by which the toxic qualities of a poison or toxin are reduced by the body.

Dialysis: medical procedure in which this technique of molecular separation is used to remove metabolic waste products or toxic substances from the blood. Dialysis is required for individuals with severe kidney failure.

Diaphoresis: Excessive perspiration.

Dilution: The use of water to lower the concentration or amount of a contaminant.

Diplopia: Double vision.

Dyscrasia: Blood disorder.

Dysphagia: Difficulty in swallowing.

Dyspnea: Shortness of breath; difficult or labored breathing.

Dysuria: Painful or difficult urination.

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E

Edema: Accumulation of fluid in body cells or tissues; usually identified as swelling.

Embolization: Obstruction of a blood vessel by a transported clot or other mass.

Embryo: In humans, the developing conceptus up to 8 weeks after fertilization of the egg. See also fetus.

Embryotoxicity: Ability to harm the embryo.

Emergency: A sudden and unexpected event requiring immediate remedial action.

Emesis: Vomiting.

Encephalopathy: Any disease of the brain.

Environmental hazard: A condition capable of posing an unreasonable risk to air, water, or soil quality, or plant or animal life.

Epidermis: The outermost layer of the skin.

Erythema: Redness of the skin.

Erythroderma: Intense, widespread reddening of the skin.

Esophageal strictures: Narrowing of the esophagus that causes difficulty in swallowing; often due to scar formation following extensive burns.

Esophagus: The portion of the digestive canal extending from the throat to the stomach. Also referred to as the gullet.

Euphoria: An intense and exaggerated feeling of well-being.

Excretion: the process of eliminating, shedding, or getting rid of substances by body organs or tissues, as part of a natural metabolic activity. Ordinarily, what is meant by excretion is the evacuation of feces. Technically, excretion can refer to the expulsion of any matter, whether from a single cell or from the entire body, or to the matter excreted.

Exfoliative dermatitis: A skin condition that involves scaling or shedding of the superficial cells of the epidermis.

Exothermic reaction: Chemical reactions that produce heat.

Explosives: Compounds that are unstable and break down with the sudden release of large amounts of energy.

Explosivity: The characteristic of undergoing very rapid decomposition (or combustion) to release large amounts of energy.

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F

Fasciculation: Muscle twitching.

Fetotoxic: Having the ability to harm the fetus.

Fetus: In humans, the conceptus from 8 weeks after fertilization until birth. See also embryo.

Flame-resistant: Slow or unable to burn.

Flammable (explosive) range: The range of gas or vapor concentration (percentage by volume in air) that will burn or explode if an ignition source is present. Limiting concentrations are commonly called the lower explosive limit and upper explosive limit. Below the lower explosive limit, the mixture is too lean to burn; above the upper explosive limit, the mixture is too rich to burn.

Flammable: The ability of a substance to ignite and burn.

Flashback: The movement of a flame to a fuel source; typically occurs via the vapor of a highly volatile liquid or by a flammable gas escaping from a cylinder.

Flash point: The minimum temperature at which a liquid produces enough vapor to ignite.

Fluorosis: Accumulation of excessive fluoride in the body; characterized by increased bone density and mineral deposits in tendons, ligaments, and muscles.

Followup: Constant or intermittent contact with a patient after diagnosis or therapy.

Freezing point: Temperature at which crystals start to form as a liquid is slowly cooled; alternatively, the temperature at which a solid substance begins to melt as it is slowly heated.

Fume: Fine particles (typically of a metal oxide) dispersed in air that may be formed in various ways (e.g., condensation of vapors, chemical reaction).

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G

Gangrene: Death of tissue due to lack of blood supply.

Gas: A physical state of matter that has low density and viscosity, can expand and contract greatly in response to changes in temperature and pressure, readily and uniformly distributes itself throughout any container.

Genetic polymorphism: Existence of inter-individual differences in DNA sequences coding for one specific gene, giving rise to different functional and (or) morphological traits (IUPAC)

Glaucoma: A disease of the eye characterized by abnormal and damaging high pressure inside the eye; usually due to a blockage of the channel that normally allows the outflow of fluid from the eye.

Glomerulus (plural glomeruli): A tuft formed of capillary loops that filter blood in the kidney.

G-series nerve agents: Chemical agents of moderate to high toxicity developed in the 1930s. Examples are tabun (GA), sarin (GB), soman (GD), and GF.

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H

Hazard: A circumstance or condition that can cause harm.

Hazardous materials incident: The uncontrolled release or potential release of a hazardous material from its container into the environment.

Hazardous materials: Substances that, if not properly controlled, pose a risk to people, property, or the environment.

Hematuria: Condition in which the urine contains an abnormal amount of blood or red blood cells.

Hemodialysis: Removal of soluble substances from the blood by their diffusion through a semipermeable membrane.

Hemoglobinuria: Condition in which the urine contains an abnormal amount of hemoglobin.

Hemolysis: Destruction or dissolution of red blood cells in such a manner that hemoglobin is liberated into the medium in which the cells are suspended.

Hemolytic anemia: Any anemia resulting from destruction of red blood cells.

Hemoptysis: The spitting of blood derived from hemorrhage in the lungs or bronchial tubes.

Hepatic: Pertaining to the liver.

Hepatomegaly: Enlargement of the liver.

Hot Zone: The area immediately surrounding a chemical hazard incident, such as a spill, in which contamination or other danger exists.

Hyperbilirubinemia: A condition in which an abnormally large amount of bilirubin is found in the blood. Jaundice becomes apparent when the level of bilirubin is double the normal level.

Hyperesthesia: Increased sensitivity to touch, pain, or other sensory stimuli.

Hyperpigmentation: An excess of pigment in a tissue or part of the body.

Hyperreflexia: A condition in which the deep tendon reflexes are exaggerated.

Hypersensitization: Increased sensitivity of the immune system; induced by initial exposure with subsequent exposures eliciting a greater than expected immunologic response.

Hypertension: High blood pressure.

Hypocalcemia: A condition in which an abnormally low concentration of calcium ions is present in the blood.

Hypokalemia: A condition in which an abnormally low concentration of potassium ions is present in the blood.

Hypomagnesemia: A condition in which the plasma concentration of magnesium ions is abnormally low; may cause convulsions and concurrent hypocalcemia.

Hypophosphatemia: Condition in which an abnormally low concentration of phosphate is found in the blood.

Hypotension: Low arterial blood pressure.

Hypotonia: A condition in which there is a loss of muscle tone.

Hypoxemia: A condition in which inadequate oxygen is present in arterial blood, short of anoxia.

Hypoxia: Condition in which below-normal levels of oxygen are present in the air, blood, or body tissues, short of anoxia.

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I

Ignition (autoignition) temperature: The minimum temperature required to ignite gas or vapor without a spark or flame being present.

Immediately dangerous to life and health (IDLH): That atmospheric concentration of a chemical that poses an immediate danger to the life or health of a person who is exposed but from which that person could escape without any escape-impairing symptoms or irreversible health effects. A companion measurement to the permissible exposure limit (PEL), IDLH concentrations represent levels at which respiratory protection is required. IDLH is expressed in parts per million (ppm) or mg/m3.

Inadequate warning property: Characteristic (e.g., odor, irritation) of a substance that is not sufficient to cause a person to notice exposure.

Incapacitating agents: Produce temporary physiological and/or mental effects via action on the central nervous system. Effects may persist for hours or days, but victims usually do not require medical treatment. However, such treatment speeds recovery.

Incident commander: The person responsible for establishing and managing the overall operational plan at a hazardous material incident. The incident commander is responsible for developing an effective organizational structure, allocating resources, making appropriate assignments, managing information, and continually attempting to mitigate the incident.

Industrial agents: Chemicals developed or manufactured for use in industrial operations or research by industry, government, or academia. These chemicals are not primarily manufactured for the specific purpose of producing human casualties or rendering equipment, facilities, or areas dangerous for use by man. Hydrogen cyanide, cyanogen chloride, phosgene, chloropicrin and many herbicides and pesticides are industrial chemicals that also can be chemical agents.

Insecticide: An agent that has the ability to kill insects.

Intention tremor: Trembling of the extremities during movement.

Interstitial pneumonitis: Inflammation of the alveolar walls and the spaces between them.

Iritis: Inflammation of the colored part of the eye (iris).

Ischemia: Obstruction of blood flow (usually by arterial narrowing) that causes lack of oxygen and other bloodborne nutrients.

Ischemic necrosis: Death of cells as a result of decreased blood flow to affected tissues.

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J

Jaundice: Yellowing of the skin and whites of the eyes due to an accumulation of bile pigments (e.g., bilirubin) in the circulating blood.

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K

Keratitis: Inflammation of the cornea.

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L

Lacrimation: Secretion of tears, especially in excess.

Laryngeal edema: Swelling of the voice box due to fluid accumulation.

Laryngitis: Inflammation of the mucous membrane of the larynx.

Laryngospasm: Spasmodic closure of the vocal apparatus.

Lesions: any pathological or traumatic discontinuity of tissue or loss of function of a part. Lesion is a broad term, including wounds, sores, ulcers, tumors, cataracts and any other tissue damage. They range from the skin sores associated with eczema to the changes in lung tissue that occur in tuberculosis.

Lethargy: A state of extreme tiredness or fatigue.

Leukemia: Progressive proliferation of abnormal leukocytes found in blood and blood-forming tissues and organs; due to cancer of the bone marrow cells that form leukocytes.

Leukocyte: White cell normally present in circulating blood.

Liquid agent: A chemical agent that appears to be an oily film or droplets. The color ranges from clear to brownish amber.

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M

Material safety data sheet (MSDS): Documents prepared by the chemical industry to transmit information about the physical properties and health effects of chemicals, and about emergency response plans.

Metabolism: Sum total of all physical and chemical processes that take place within an organism from uptake to elimination. In a narrower sense, the physical and chemical changes that take place in a substance within an organism, including biotransformation to metabolites.

Methemoglobin: A transformation product of hemoglobin in which normal Fe+2 is oxidized to Fe+3.

Methemoglobin contains oxygen that is firmly bound to the Fe+3 ion, which prevents the release of oxygen to the tissues.

Methemoglobinemia: Condition in which methemoglobin is present in the circulating blood.

Methemoglobinuria: Condition in which methemoglobin is present in the urine.

Miosis: Contraction of the pupil to a pinpoint.

Miscible: Able to mix (but not chemically combine) in any ratio without separating into two phases (e.g., water and alcohol).

Mist: Liquid droplets dispersed in air.

Mitigation: Actions taken to prevent or reduce the severity of harm.

Molecular weight: The sum of the atomic weights (q.v.) of the atoms in a molecule; measured in daltons.

Monocytic leukemia: A form of bone marrow cancer characterized by an increase in the number of large, mononuclear white blood cells in tissues, organs, and the circulating blood.

Mutant cells: a cell that has undergone genetic mutation; Resulting from or undergoing mutation.

Myalgia: Severe muscle pain.

Mydriasis: Dilation of the pupil.

Myelocytic leukemia: A form of bone marrow cancer characterized by the presence of large numbers of granular white blood cells in tissues, organs, and the circulating blood.

Myocardial ischemia: Insufficient oxygen supply to meet the metabolic demands of heart muscles.

Myocarditis: Inflammation of the muscles of the heart.

Myoclonus: Involuntary spasm or twitching of a muscle or group of muscles.

Myoglobin: The oxygen-transporting, pigmented protein of muscle; resembles blood hemoglobin in function.

Myoglobinuria: Presence of myoglobin in urine.

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N

Nasopharynx: Relating to the nasal cavity and that part of the throat that lies above the level of the soft palate.

Necrosis: Death of one or more cells or a portion of a tissue or organ.

Nephrotoxic: Capable of damaging the kidney.

Nerve Agents: Substances that interfere with the central nervous system. Exposure is primarily through contact with the liquid (skin and eyes) and secondarily through inhalation of the vapor. Three distinct symptoms associated with nerve agents are: pin-point pupils, an extreme headache, and severe tightness in the chest.

Neuropathy: A disorder of the nervous system; in contemporary usage, a disease involving the cranial or spinal nerves.

Noncardiogenic pulmonary edema: An accumulation of an excessive amount of fluid in the lungs as a result of leakage from pulmonary capillaries; not due to heart failure.

Nonpersistent agent: An agent that upon release loses its ability to cause casualties after 10 to 15 minutes. It has a high evaporation rate and is lighter than air and will disperse rapidly. It is considered to be a short-term hazard. However, in small unventilated areas, the agent will be more persistent.

Nystagmus: Involuntary rapid movements of the eyeballs, either rhythmical or jerky.

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O

Ocular: Pertaining to the eye.

Odor threshold: The lowest concentration of a vapor or gas that can be detected by smell.

Off-gassing: Giving off a vapor or gas.

Olfactory fatigue: Temporary loss of the sense of smell due to repeated or continued stimulation.

Oliguria: Condition in which abnormally small amounts of urine are produced.

Opisthotonos: Tetanic spasm in which the spine and extremities are bent up and forward so that a reclining body rests on the head and the heels.

Optic atrophy: Shrinkage or wasting of the optic nerve that may lead to partial vision loss or blindness.

Optic neuritis: Inflammation of the optic nerve.

Organophosphorous compound: A compound, containing the elements phosphorus and carbon, whose physiological effects include inhibition of acetylcholinesterase. Many pesticides (malathione and parathion) and virtually all nerve agents are organophosphorous compounds.

Osteosclerosis: Abnormal hardening or increase in density of the bone.

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P

Paresthesias: An abnormal sensation such as burning, prickling, or tingling.

Percutaneous absorption: Passage of a substance through unbroken skin.

Percutaneous agent: Able to be absorbed by the body through the skin.

Peripheral neuropathy: A disorder of the peripheral nerves.

Permeability: The degree to which one substance allows another substance to pass through it.

Permeation: The passage of chemicals, on a molecular level, through intact material such as protective clothing.

Permissible exposure limit (PEL): The maximum time-weighted average concentration mandated by the Occupational Safety and Health Administration (OSHA) to which workers may be repeatedly exposed for 8 hours per day, 40 hours per week without adverse health effects.

Persistent agent: An agent that upon release retains its casualty-producing effects for an extended period of time, usually anywhere from 30 minutes to several days. A persistent agent usually has a low evaporation rate and its vapor is heavier than air. Therefore, its vapor cloud tends to hug the ground. It is considered to be a long-term hazard. Although inhalation hazards are still a concern, extreme caution should be taken to avoid skin contact as well.

Photophobia: Abnormal sensitiveness to light, especially of the eyes.

Physical state: The state (solid, liquid, or gas) of a chemical under specific conditions of temperature and pressure.

Pneumonitis: Inflammation of the lungs.

Poikilocytosis: The presence of irregularly shaped red blood cells in the peripheral blood.

Posthypoxic encephalopathy: Condition in which the brain has been damaged as a result of insufficient oxygen.

Proliferation: the reproduction or multiplication of similar forms. The term is usually applied to increases of cells or cysts.

Protection: Any means by which an individual protects his body. Measures include masks, self-contained breathing apparatuses, clothing, structures such as buildings, and vehicles.

Proteinuria: A condition in which an abnormal amount of protein is present in the urine. See also albuminuria.

Protocol: an explicit, detailed plan of an experiment, procedure, or test; The plan for a course of medical treatment or for a scientific experiment.

Pruritic: Pertaining to itching.

Psychosis: A mental disorder characterized by derangement of personality and loss of touch with reality.

Pulmonary edema: Accumulation of extravascular fluid in the lungs that impairs gas exchange; usually due to either increased intravascular pressure or increased permeability of the pulmonary capillaries.

Pupil: The circular opening in the center of the iris through which light rays enter the eye.

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R

Reactivity: The ability of a substance to chemically interact with other substances.

Rescuer protection equipment: Gear necessary to prevent injury to workers responding to chemical incidents.

Respiratory depression: Slowing or cessation of breathing due to suppression of the function of the respiratory center in the brain.

Response organization: An organization prepared to provide assistance in an emergency (e.g., fire department).

Response personnel: Staff attached to a response organization (e.g., HAZMAT team).

Retrobulbar neuritis: Inflammation of the portion of the optic nerve behind the eyeball.

Rhinitis: Inflammation of the mucous membranes of the nasal passages.

Rhinorrhea: A discharge from the nasal mucous membrane.

Risk assessment: The identification and assessment of hazards (first two steps of risk management process).

Routes of exposure: The manner in which a chemical contaminant enters the body (e.g., inhalation, ingestion).

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S

Sclera: The tough, white supporting tunic of the eyeball.

Secondary contamination: Transfer of a harmful substance from one body (primary body) to another (secondary body), thus potentially permitting adverse effects to the secondary body.

Self-contained breathing apparatus (SCBA): Protective equipment consisting of an enclosed facepiece and an independent, individual supply (tank) of air; used for breathing in atmospheres containing toxic substances or underwater.

Sensory neuropathy: Damage to the nerves that carry information about sensation (e.g., touch, pain, temperature) to the brain.

Sequela (plural sequelae): A condition that follows as a consequence of injury or disease.

Sloughing: The process by which necrotic cells separate from the tissues to which they have been attached.

Solubility: The ability of one material to dissolve in or blend uniformly with another.

Soluble: Capable of being dissolved.

Solution: A homogeneous mixture of two or more substances, usually liquid.

Solvent: A substance that dissolves another substance.

Specific gravity: The ratio of the mass of a unit volume of a substance to the mass of the same volume of a standard substance (usually water) at a standard temperature.

Status epilepticus: Severe seizures in which recovery does not occur between major episodes.

Stridor: A harsh, high-pitched respiratory sound often heard in acute respiratory obstruction.

Support Zone: That area beyond the Decontamination Zone that surrounds a chemical hazard incident in which medical care can be freely administered to stabilize a victim.

Surfactant: An agent that reduces surface tension (e.g., wetting agents, detergents, dispersing agents).

Surge Capacity: Health Care system's ability to expand quickly to meet an increased demand for medical care in the event of bioterrorism or other large-scale public health emergency (AHRQ)

Susceptible population: a group of people who share a characteristic that causes each member to be susceptible to a particular event, such as non-immunized children who are exposed to poliovirus or immunosuppressed people who are exposed to herpesvirus. Also called vulnerable population or population at risk.

Syncope: A transient loss of consciousness and postural tone caused by diminished blood flow to the brain.

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T

Tachycardia: Rapid heartbeat (typically greater than 100 beats per minute).

Tachypnea: Rapid breathing.

Tear (riot control) agents: Produce irritating or disabling effects that rapidly disappear within minutes after exposure ceases.

Teratogenic: Having the ability to cause congenital anomalies.

Tetany: A condition marked by involuntary muscle contractions or spasms.

Thrombocytopenia: A condition in which there is an abnormally small number of platelets in the blood.

Thrombosis: Blood vessel clotting.

Time-weighted average (TWA) air concentration: That concentration of a substance in air that is measured by collecting it on a substrate at a known rate for a given period of time.

Tinnitus: Ringing in the ears.

Toxic: Having the ability to harm the body, especially by chemical means.

Toxic potential: The inherent ability of a substance to cause harm.

Toxicology: the scientific study of poisons, their detection, their effects, and methods of treatment for conditions they produce.

Tracheitis: Inflammation of the membrane lining the trachea.

Transdermal: entering through the dermis, or skin, as in administration of a drug via ointment or patch.

Triage: the sorting of and allocation of treatment to patients and especially battle and disaster victims according to a system of priorities designed to maximize the number of survivors; the sorting of patients (as in an emergency room) according to the urgency of their need for care.

Trismus: Lockjaw.

Tubular necrosis: Death of the cells lining the kidney tubules.

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U

Uremia: Condition in which an abnormally high level of urea or other nitrogenous waste is found in the blood; due to kidney dysfunction.

Urticaria: Hives.

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V

Vapor agent: A gaseous form of a chemical agent. If heavier than air, the cloud will be close to the ground. If lighter than air, the cloud will rise and disperse more quickly.

Vapor density: The weight of a given volume of vapor or gas compared to the weight of an equal volume of dry air, both measured at the same temperature and pressure.

Vapor pressure: A measure of the tendency of a liquid to become a gas at a given temperature.

Vapor: The gaseous form of a substance that is normally a solid or liquid at room temperature and pressure.

Vascular: Pertaining to blood vessels.

Vasodilation: Increased diameter of the blood vessels.

Ventricular fibrillation: Rapid, tremulous movement of the ventricle that replaces normal contractions of the heart muscle; results in little or no blood being pumped from the heart.

Vertigo: Sensation of spinning or revolving.

Vesicant: An agent that produces blisters.

Vesiculation: The presence or formation of blisters.

Volatility: A measure of how readily a substance will vaporize.

Vomiting agents: Produce nausea and vomiting effects, can also cause coughing, sneezing, pain in the nose and throat, nasal discharge, and tears.

V-series nerve agents: Chemical agents of moderate to high toxicity developed in the 1950s. They are generally persistent. Examples are VE, VG, VM, VS, and VX.

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W

Water-reactive material: A substance that readily reacts with water or decomposes in the presence of water, typically with substantial energy release.

Wheezing: Breathing noisily and with difficulty; usually a sign of spasm or narrowing of the airways.


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