Emergency Response Safety and Health Database: Glossary




Terms Description
Acetylcholine A substance that transmits nerve impulses (neurotransmitter).
Acetylcholinesterase An enzyme that occurs especially in some nerve endings and in the blood and promotes the breakdown of acetylcholine. Nerve agents inhibit the action of this enzyme.
Acid Any of various typically water-soluble and sour compounds that in solution are capable of reacting with a base to form a salt, that redden litmus, that have a pH less than 7, and that are hydrogen-containing molecules or ions able to give up a proton to a base or are substances able to accept an unshared pair of electrons from a base.
Acidosis An abnormal increase in the acidity of the body’s fluids, caused either by accumulation of acids or by depletion of bicarbonates.
Acrid Unpleasantly sharp, pungent, or bitter to the taste or smell.
Acuity Acuteness of vision or perception.
Acute Having a sudden onset, sharp rise, and short course.
Acute Exposure Guideline Level (AEGL) Guideline intended to describe the risk to humans resulting from once-in-a-lifetime, or rare, exposure to airborne chemicals. Acute exposures are defined as single, non-repetitive exposures for not more than 8 hours.
There are three AEGL values:
AEGL-1: Discomfort, non-disabling.
AEGL-2: Irreversible or other serious, long-lasting effects or impaired ability to escape.
AEGL-3: Life-threatening effects or death.
Aerosol A suspension of fine solid or liquid particles in gas.
Afebrile Free from fever.
Agent A factor such as a microorganism, chemical substance, or form of radiation that can result in illness or injury.
Agonist A chemical substance (such as a drug) that is capable of combining with a receptor on a cell and initiating the same reaction or activity typically produced by the binding of a substance that normally occurs in the body (i.e., is endogenous).
Air-purifying respirator (APR) An air-filtering device that covers the nose and mouth and removes contaminants from the surrounding air by passing it through a filter, cartridge, or canister. A variety of filter cartridges are designed to capture specific particles and/or gases. Filters must be replaced once absorption capacity is depleted.
Alopecia Loss of hair; baldness.
Ambient Surrounding or encompassing, e.g., the ambient environment.
Ampule A small glass vial that is sealed after filling; often used as a container for a solution to be given by hypodermic injection.
Analgesic A drug that alleviates pain without causing loss of consciousness; a pain-reliever.
Anemia An abnormal deficiency in the oxygen-carrying component of the blood, measured in unit volume concentrations of hemoglobin, red blood cell volume, or red blood cell number.
Anesthetic An agent that causes loss of sensation with or without the loss of consciousness.
Anion A negatively charged ion, especially the ion that migrates to an anode in electrolysis.
Anoxia Deficiency of oxygen, especially one so severe as to result in permanent damage.
Antagonist A chemical that acts within the body to reduce the physiological activity of another chemical substance (as an opiate), especially one that opposes the action on the nervous system of a drug or a substance occurring naturally in the body by combining with and blocking its nervous receptor.
Antibody Any of a large number of proteins that are produced normally by specialized cells after stimulation by an antigen (e.g., a bacterium, virus, parasite, etc.) and act specifically against the antigen in an immune response. Also called immunoglobulin.
Antiemetic A drug that prevents or alleviates nausea and vomiting.
Antimitotic agent An agent that prevents or interferes with cell division (mitosis).
Anxiolytic An anti-anxiety drug.
Aplasia Incomplete or faulty development of an organ or tissue.
Apnea Temporary absence or cessation of breathing.
APR See definition for Air-purifying respirator
Aqueous solubility The amount of a substance (solute) that can be dissolved in a given amount of water(solvent). Aqueous solubility is based on the chemical’s respective Log Kow values:
Log Kow = 1, soluble
Log Kow 1-5, slightly soluble
Log Kow > 5, insoluble
Arsenic A highly poisonous metallic element existing in three forms, yellow, black, and gray, of which the brittle, crystalline gray is the most common. Arsenic and its compounds are used in insecticides, weed killers, solid-state doping agents, and various alloys.
Arthralgia Pain in a joint or joints.
Ascending peripheral neuropathy Numbness that begins in the limbs.
Ascorbic acid Vitamin C.
Asphyxiant A substance capable of inducing asphyxia, which is a lack of oxygen or an excess of carbon dioxide in the body, usually caused by the interruption of breathing and resulting in unconsciousness.
Asthma A chronic respiratory disease, often arising from allergies, that is characterized by sudden recurring attacks of labored breathing, chest constriction, and coughing.
Asymptomatic Exhibiting no symptoms of disease.
Ataxia Inability to coordinate muscular movement.
Atelectasis Total or partial collapse of the lung.
Atrophy A wasting or decrease in size of a body organ, tissue, or part owing to disease, injury, or lack of use.

Top of Page


Terms Description
BAL British Anti-Lewisite, an antidote for Lewisite exposure.
Barbiturate Any of a class of drug used especially as sedatives, hypnotics, and antispasmodics.
Benzodiazepine Any of a class of drug used as antianxiety agents, muscle relaxants, sedatives, hypnotics, and sometimes as anticonvulsants.
Beta particle A subatomic particle that is ejected from the nucleus of unstable atoms. Beta particles can travel through several layers of human skin, and exposure to large sources of beta radiation can cause burns or skin reddening. Beta particles that enter the body can damage cells, which can lead to cell death or, later in life, to cancer.
Beta radiation See definition of Beta particle.
Beta-adrenergic Pertaining to a certain type of receptor, the beta-receptor, postulated to exist on the surface of certain cells and reacting to adrenaline or adrenaline-like agents.
Biological agent A living organism that can cause disease, sickness, and mortality in humans.
Biotoxin A substance produced by a living organism, such as a plant or fish, that has toxic effects.
Blanching Whitening of the skin.
Blepharospasm Spasmodic blinking.
Blister agent (vesicant) A substance that causes blistering of the skin and mucous membranes. Exposure is through liquid or vapor contact with any tissue (i.e., eyes, skin, lungs).
Bradycardia Slow heart rate, usually fewer than 60 beats per minute in an adult human.
Bronchi The large airways leading to the lungs. Singular = bronchus.
Bronchiole One of the small airways leading to the lungs.
Bronchitis Chronic or acute inflammation of the large airways.
Bronchoconstriction Narrowing of the large airways.
Bronchodilation Expansion of the large airways.
Bronchodilator A drug which enlarges the large airways.
Bronchopneumonia Inflammation of small areas of the lung.
Bronchospasm Spasmodic narrowing of the large airways.
Bulla A large blister or vesicle. Plural = bullae.

Top of Page


Terms Description
Cachexia Physical wasting and malnutrition.
Camphor An aromatic crystalline compound, obtained naturally from the wood or leaves of the camphor tree or synthesized and used as an insect repellent, in the manufacture of film, plastics, lacquers, and explosives, and in medicine chiefly in external preparations to relieve mild pain and itching.
Capillaries The smallest blood vessels.
Carcinogenic Causing or producing cancer.
Carcinogenicity Cancer-causing potential (of an agent or substance).
Cardiac arrest Temporary or permanent cessation of the heartbeat.
Cardiac arrhythmia Alteration of the heart rhythm
Cardiac dysrhythmia An abnormality in an otherwise normal rhythmic pattern of the heart.
Cardiac sensitization Increased responsiveness or susceptibility of the heart to stimulating hormones following exposure to a chemical, which can lead to irregular heart rhythms (arrhythmias), cardiac arrest, or death.
Cardiopulmonary Of, relating to, or involving both the heart and the lungs.
Cardiopulmonary failure Heart and respiratory failure.
Cardioversion Application of an electric shock to restore normal heartbeat.
Cast A mass formed in cavities of diseased organs.
Cathartic An agent for purging the bowels, especially a laxative.
Caustic Capable of burning, corroding, and dissolving, or eating away by chemical action.
CBRN Chemical, Biological, Radiological, Nuclear
Central nervous system (CNS) The brain and spinal cord.
Cerebral edema Accumulation of fluid in and resultant swelling of the brain.
Chelating agent An agent that removes a heavy metal, such as lead or mercury, from the bloodstream.
Chemical agent A chemical substance that is intended for use in military operations to kill, seriously injure, or incapacitate people through its physiological effects.
Chemical protective clothing and equipment Any item of clothing (e.g., gloves, boots, suits) used to isolate parts of the body from direct contact with potentially hazardous substances. Safe use of this type of protective clothing and equipment requires specific skills developed through training and experience. This type of special clothing may protect against one chemical, yet be readily permeated by chemicals for which it was not designed. Therefore, protective clothing should not be used unless it is compatible with the released material. This type of special clothing offers little or no protection against heat and/or cold.
Chemosis Swelling of the outer membranes of the eye.
Chemotherapeutic agent A chemical agent or drug used in the treatment of disease; chemotherapeutic agents are selectively toxic to the causative agent of the disease, such as a virus, bacterium, or other microorganism.
Cholinesterase An enzyme found primarily at nerve endings that catalyzes the breakdown of acetylcholine.
Chorea Any of various nervous disorders of infectious or organic origin marked by spasmodic movements of the limbs and facial muscles and by incoordination.
Choreiform Spasmodic and uncoordinated. See also chorea.
Chronic Marked by long duration, by frequent recurrence over a long time, and often by slow progression to become more serious.
Clonic Intermittent (e.g., movements).
CNS Central nervous system.
CNS depression Reduced level of consciousness.
CNS excitation Increased level of consciousness.
Coagulopathy A disease or condition affecting the ability of the blood to clot (coagulate).
Coma State of profound unconsciousness.
Combustible Will ignite, burn, or support combustion.
Combustible liquid A liquid that has a flash point greater than 60.5°C (141°F) and below 93°C (200°F). U.S. regulations permit a flammable liquid with a flash point between 38°C (100°F) and 60.5°C (141°F) to be re-classed as a combustible liquid.
Concussion An injury to an organ, especially the brain, produced by a violent blow and followed by a temporary or prolonged loss of function.
Conjuctival injection Accumulation of blood in the membranes of the eye (see also “injected conjuctiva”).
Conjunctiva The mucous membrane that lines the inner surface of the eyelid and the exposed surface of the eyeball. Plural = conjunctivae.
Conjunctivitis Inflammation of the membranes of the eye (conjuctiva).
Contact dermatitis Inflammation of the skin caused by direct contact with an irritant.
Convulsion An intense, paroxysmal, involuntary muscular contraction. During convulsions, the patient’s body shakes rapidly and uncontrollably and his/her muscles contract and relax repeatedly. The term “convulsion” is often used interchangeably with “seizure,” although there are many types of seizure, some of which have subtle or mild symptoms instead of convulsions.
Copious Large in quantity; abundant.
Cornea The transparent part of the coat of the eyeball that covers the iris and pupil and admits light to the interior.
Corneal epithelium The outer layer of the cornea (of the eye).
Corticosteroid Any of the steroid hormones produced by the adrenal cortex or their synthetic equivalents, such as cortisol and aldosterone.
Cranial nerve palsy A form of paralysis.
Crystalline Being, relating to, or composed of crystals.
Cyanosis Bluish discoloration of the skin due to deficient oxygenation of the blood.
Cylindruria Presence of casts (masses) in the urine.
Cytotoxic Having a harmful effect on cells; cell-killing or cell-harming.

Top of Page


Terms Description
Decontamination The removal of a dangerous material from any person, object, or area to the extent necessary to prevent potential adverse health effects.
Decontamination The destruction, physical removal, or reduction of a toxic substance to an acceptable level.
Decubitus ulcers Bed sores.
Defecation The discharge of feces.
Deliquescent Tending to dissolve and become liquid by the absorption of moisture from the air.
Dementia Marked decline in mental function.
Depersonalization A feeling of loss of identity.
Derealization A feeling of altered reality.
Dermal Of or relating to the skin (dermis).
Dermatitis Inflammation of the skin.
Dermatosis A skin disease, especially one that is not accompanied by inflammation. (Plural = dermatoses.)
Detoxification The metabolic process by which the toxic qualities of a poison or toxin are reduced by the body.
Detoxify To treat (an individual), usually under a medically supervised program designed to rid the body of toxic substances.
Deviations (conjugate or dissociated) Abnormal movements of one or both eyes.
Diaphoresis Sweating, especially when profuse and medically induced.
Diatomaceous Consisting of diatoms or their skeletons; diatomaceous earth is a light, crumbly silica-containing material used in filtration.
Dike A barrier blocking a passage, especially for protection.
Diplopia Double vision.
Disseminated intravascular coagulation Widespread formation of clots in the blood vessels.
Diuretic Tending to increase the discharge of urine.
DNA A nucleic acid that carries the genetic information in the cell and is capable of self-replication and synthesis of RNA.
Don To put on (clothing).
Dysarthria Difficulty in articulating words, resulting in slurred speech.
Dysphagia Difficulty in swallowing.
Dysphasia Difficulty in using or understanding language.
Dysphonia Defective use of the voice; slurred speech.
Dyspnea Difficulty in breathing, or shortness of breath.
Dysrhythmia Abnormal or disordered heart rhythm.

Top of Page


Terms Description
ECG See “electrocardiogram”
Ectropion Abnormal turning out of the eyelid.
Eczematoid Resembling eczema, an inflammatory condition of the skin characterized by redness, itching, and oozing blister-like lesions, which become scaly, crusted, or hardened.
Edema An abnormal, excessive accumulation of thin, watery fluid in tissue spaces or a body cavity.
Effluent Something that flows out, especially a discharge of waste into the environment.
Electrocardiogram (ECG) A recording of the electrical activity of the heart.
Electrolyte Any of the ions (as of sodium, potassium, calcium, or bicarbonate) that in a biological fluid regulate or affect most metabolic processes (as the flow of nutrients into and waste products out of cells).
Emesis The act of vomiting.
Emphysema A disease of the lungs characterized by air-filled expansions in lung tissues.
Encephalopathy A disease of the brain.
Endophthalmitis Inflammation of the interior of the eyeball.
Endoscopic A medical procedure that uses an instrument (endoscope) to examine visually the interior of a bodily canal or a hollow organ such as the colon, bladder, or stomach.
Endotracheal Within or passing through the trachea (windpipe), e.g., an endotracheal tube.
Endotracheal intubation Insertion of a tube within the trachea.
Enteritis Inflammation of the intestinal tract, especially of the small intestine.
Epigastric Abdominal, specifically, over or above the stomach.
Epistaxis Nosebleed.
Epithelium The covering of internal and external surfaces of the body, including the lining of vessels and other small cavities.
ERPG Emergency Response Planning Guidelines developed by the American Industrial Hygiene Association (AIHA).
ERPG-1 The maximum airborne concentration below which it is believed nearly all individuals could be exposed for up to 1 hour without experiencing more than mild, transient adverse health effects or without perceiving a clearly defined objectionable odor.
ERPG-2 The maximum airborne concentration below which it is believed nearly all individuals could be exposed for up to 1 hour without experiencing or developing irreversible or other serious health effects or symptoms that could impair an individual’s ability to take protective action.
ERPG-3 The maximum airborne concentration below which it is believed nearly all individuals could be exposed for up to 1 hour without experiencing or developing life-threatening health effects.
Erythema Redness of the skin.
Erythrocyte Red blood cell.
Ethanol A colorless, volatile, flammable liquid that is the intoxicating agent in liquors and is also used as a solvent.
Euphoria A disproportionate feeling of well-being.
Evolve To give off or emit (e.g., a gas).
Exothermic Releasing heat.

Top of Page


Terms Description
Face shield A supplementary protective device worn to shield the wearer’s face from certain hazards. Face shields are secondary protectors only and must be worn with safety glasses or goggles.
Fasciculation Muscular twitching.
Fatal Causing death.
Febrile Showing symptoms indicating fever; feverish.
Fibrosis An increase in fibrous tissue situated within but not restricted to or characteristic of a particular organ or tissue.
Flaccid Lacking firmness, resilience, or muscle tone.
Flaccid paralysis Paralysis with reduced muscle tone and reflexes.
Flammable Capable of being ignited and rapidly consumed by fire.
Flammable liquid A liquid that has a flash point of 60.5°C (141°F) or lower.
Flash point Lowest temperature at which a liquid or solid gives off vapor in such a concentration that, when the vapor combines with air near the surface of the liquid or solid, a flammable mixture is formed. Hence, the lower the flash point, the more flammable the material.
Fog See Water spray.
Fomepizole A drug that is a competitive inhibitor of an enzyme (alcohol dehydrogenase) that catalyzes the breakdown of methanol and ethylene glycol into their toxic metabolites, and is used to treat poisoning by those substances.
Friction Rubbing of one body against another.


Terms Description
Gamma radiation A packet of energy, called a photon, that is emitted from the nucleus of an unstable atom. Gamma radiation is high-energy electromagnetic radiation that can penetrate most substances (lead is the best barrier against gamma radiation). Because of its high energy, gamma radiation can penetrate the human body from the outside and damage cells, which could lead to cancer later in life.
Gas mask A face covering device used to protect the wearer from injurious gases and other noxious materials by filtering and purifying inhaled air. It usually consists of a face cover with two eyepieces and a mouthpiece that contacts a canister containing a filter; the filter absorbs noxious gases as they pass through the canister to the mouth. The face cover also has a one-way outlet valve for exhaled air.
Gastric Pertaining to the stomach.
Gastric hypomotility Slowing of muscular movement of the stomach.
Gastric lavage A procedure to empty the contents of the stomach, usually for analysis or removal of irritating elements such as poisons. Also called stomach pumping or gastric suction.
Gastritis Inflammation of the lining of the stomach.
Gastroenteritis Inflammation of the lining of the stomach and intestines.
Gastrointestinal (GI) Relating to or affecting both the stomach and the intestines.
General population limit (GPL) An airborne exposure limit designed to protect the general public.
Germinal Of, relating to, or having the nature of a germ cell (sperm, egg, or their precursors).
GI Gastrointestinal.
Glottis The vocal apparatus of the larynx, consisting of the vocal cords and the opening between them.
Goggles A wraparound, protective device that fits the face, surrounding the eyes in order to shield them from impact, splash and vapor hazards. Goggles are available non-vented or with direct or indirect vents.
Gonad An organ in an animal that produce gametes, e.g., a testis or ovary.
Gout A metabolic disease marked by a painful inflammation of the joints, deposits of uric acid salts in and around the joints, and usually an excessive amount of uric acid in the blood.
GPL See: General population limit.
Green Zone An area where contamination with chemical, biological, radiological, or nuclear (CBRN) agents is unlikely. This zone covers the area beyond the expected significant dispersal range of the initial event and secondary contamination range caused by traffic and emergency responders.

Top of Page


Terms Description
Half-life The time required for half of the atoms of a radioactive substance to decay or disintegrate.
Halon Any of several halocarbons used as fire-extinguishing agents.
Hematemesis Vomiting blood.
Hematologic Of or relating to the blood.
Hematopoietic Relating to the formation of blood or blood cells in the body.
Hematuria The presence of blood in the urine.
Hemodialysis A medical procedure to remove wastes or toxins from the blood and adjust fluid and electrolyte imbalances.
Hemoglobinuria The presence of hemoglobin (the oxygen-carrying pigment in the blood) in the urine.
Hemolysis Lysis (destruction) of red blood cells (see also “intravascular hemolysis”).
Hemolytic anemia Anemia caused by the destruction of blood cells.
Hemoptysis Spitting up of blood.
Hemorrhage Excessive bleeding.
Hemorrhagic Pertaining to a hemorrhage.
Hemorrhagic gastritis Inflammation of the lining of the stomach with bleeding.
Hemorrhagic gastroenteritis Inflammation of the lining of the stomach and intestines with severe bleeding.
HEPA High Efficiency Particulate Air filters
HEPA PAPR High Efficiency Particulate Air Powered Air-Purifying Respirator
Hepatic encephalopathy Central nervous system disease, which is a result of liver failure.
Hepatomegaly Abnormal enlargement of the liver.
High Efficiency Particulate Air (HEPA) filters Used in ventilation systems, HEPA filters remove 99.7% of particles 0.3 microns and smaller, which include dust, mold spores, dust mites, pet dander, allergens, and many biological agents such as anthrax spores. They do not purify the air for most chemical agents.
Hydrolysis Decomposition of a chemical compound by reaction with water, such as the dissociation of a dissolved salt or the catalytic conversion of starch to glucose.
Hydrolyze To subject to or undergo hydrolysis.
Hygroscopic Readily taking up and retaining water or moisture.
Hyperemia Abnormal accumulation of blood.
Hyperkalemia High blood levels of potassium.
Hyperkeratosis Thickening of the outer layer of the skin.
Hyperpigmentation Darkening of a body part or tissue.
Hyperpnea Increase in the rate and depth of breathing.
Hyperreflexia Overactive body reflexes.
Hypertension Abnormally elevated blood pressure.
Hyperthermia Exceptionally high body temperature.
Hyperventilation Excessive rate and depth of respiration.
Hypocalcemia Low blood levels of calcium.
Hypoglycemia Low blood levels of sugar (glucose).
Hypokalemia Low blood levels of potassium.
Hypomagnesemia Low blood levels of magnesium
Hyporeflexia Underactive body reflexes.
Hypotension Abnormally low blood pressure.
Hypothermia Abnormally low body temperature.
Hypovolemia A decrease in the volume of circulating blood.
Hypovolemic shock A life-threatening condition in which the heart is unable to supply enough blood to the body because of inadequate blood volume or blood loss. May occur subsequent to serious dehydration.
Hypoxemia Oxygen deficiency in the blood.
Hypoxia Decreased oxygen supply to the tissues.

Top of Page


Terms Description
IDLH See: Immediately dangerous to life and health.
Ileus Obstruction of the intestines.
IM Intramuscularly.
Immediately Dangerous to Life or Health As defined by NIOSH, an immediately dangerous to life or health condition is a situation “that poses a threat of exposure to airborne contaminants when that exposure is likely to cause death or immediate or delayed permanent adverse health effects or prevent escape from such an environment.” NIOSH also states that the purpose of establishing an IDLH is to “ensure that the worker can escape from a given contaminated environment in the event of failure of the respiratory protection equipment.”
Immiscible Not mixing readily with water.
Incapacitating agent An agent that produces 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, although treatment may speed recovery.
Inebriation Drunkenness (intoxication).
Inert Not readily reactive with other elements; forming few or no chemical compounds.
Inflammation A local response to cellular injury that is marked by redness, heat, pain, swelling, cellular and blood vessel changes, and often loss of function and that serves as a mechanism initiating the elimination of noxious agents and of damaged tissue.
Inflammatory Accompanied with, or tending to cause, inflammation.
Inhalation The act of drawing in breath.
Inhibitor An agent that slows or interferes with a chemical reaction; a substance that reduces the activity of another substance (as an enzyme).
Initial isolation and protective action distances Two types of recommended safe distances listed in the U.S. Department of Transportation ERG 2000 for toxic inhalation hazard (TIH) substances, which are poisonous by inhalation and/or water-reactive materials, which produce toxic gases upon contact with water. The “Initial Isolation Distance” is a distance within which all persons should be considered for evacuation in all directions from the actual spill/leak source. The “Protective Action Distance” represents a downwind distance from the spill/leak source within which Protective Actions, those steps taken to preserve the health and safety of emergency responders and the public, could be implemented.
Injected conjuctiva Accumulation of blood in the membranes of the eye (see also “conjuctival injection”).
Inspiratory Of, relating to, or used for the drawing air into the lungs.
Intracranial Occurring or situated within the skull (cranium).
Intracranial hypertension Elevated pressure of the fluid surrounding the brain and spinal cord (cerebrospinal fluid, or CSF).
Intravascular Within blood vessels or a blood vessel.
Intravascular hemolysis Lysis (destruction) or red blood cells (see also “hemolysis”).
Intubation Insertion of a tube into a hollow organ or body passage; to intubate.
Ion An atom or a group of atoms that has acquired a net electric charge by gaining or losing one or more electrons.
Ipecac A medicinal preparation made from the dried roots and rhizomes of a shrub, sometimes used to induce vomiting, particularly in cases of poisoning and drug overdose.
Iritis Inflammation of the iris of the eye.
Irrigation Continuous washing.
IV Intravenously.


Terms Description
Jaundice Yellowish pigmentation of the skin and tissues.


Terms Description
Keratitis Corrosion of the cornea of the eye.


Terms Description
Lability The state of constantly undergoing or likely to undergo change; unstable.
Lacrimation Excessive tear production.
Lacrimator A tear-producing chemical.
Laryngeal Relating to, affecting, or near the larynx (voice box).
Laryngitis Inflammation of the voice box.
Laryngospasm Involuntary contraction of the vocal cords that impedes airflow to the lungs.
Latent Existing in hidden or dormant form; not currently showing signs of activity or existence.
Latent period Symptom-free period.
Lavage Washing out a hollow organ (such as the stomach) by flushing with water.
Lesion An abnormal change in structure of an organ or part due to injury or disease, especially such a change that is circumscribed and well-defined.
Lethal Capable of causing death
Lethargy Abnormal drowsiness (see also somnolence).
Leukocyte White blood cell.
Leukocytosis Abnormal increase in the number of circulating white blood cells.
Leukopenia A reduced white blood cell count.
Lipids Substances, such as fats, that are some of the principal structural constituents of the cells of living organisms.
Lobular emphysema Small areas of lung disease (see also “emphysema”)
Localized Restricted to a definite part of the body; not general or systemic.
Lorazepam A drug used therapeutically to control seizures.
Luminescent Glowing.
Lung damaging agent A substance that causes physical injury to the respiratory tract, including the lungs. In extreme cases, membranes swell and lungs become filled with fluid; death results from lack of oxygen.
Lymphocytosis Abnormal increase in the number of lymphocytes (a kind of white blood cell).

Top of Page


Terms Description
Malaise Vague feeling of generalized weakness.
Mandible The lower jaw.
Mechanical ventilation Artificial ventilation of the lungs (as by positive end-expiratory pressure) using means external to the body.
Mees’ lines White lines in the nails.
Melanosis Abnormal darkening of the skin or tissues.
Melena The passage of bloody stools.
Metabolic acidosis Accumulation of acid in the blood and tissues.
Metabolism The process by which a substance is broken down in the body.
Metaplasia Abnormal replacement of cells.
Methemoglobinemia Excessive accumulation of an inactive form of hemoglobin in the blood.
Mg Milligram.
Micturition Urination.
Miosis Contracted or pinpoint pupils.
Miscible Capable of mixing readily, usually with water.
Mitosis The process of cell division.
Motor dysfunction Difficulty moving.
Mucosa The lining of certain body passages, such as the gastrointestinal tract or the airways (see also “mucous membrane”).
Mucous membrane A membrane rich in mucous glands; specifically, a membrane lining body passages and cavities that communicate directly or indirectly with the exterior, which functions in protection, support, nutrient absorption, and secretion of mucus, enzymes, and salts; the membrane is always soft and smooth and kept lubricated by the secretions of the cells and numerous glands embedded in the membrane. Also called mucosa.
Mucus A gummy, slippery secretion produced by mucous membranes, which it moistens and protects.
Myalgia Muscle pain.
Mydriasis Dilated pupils.
Myelosuppression Suppression of the bone marrow’s production of blood cells and platelets.
Myocardial Pertaining to the muscular tissue of the heart.
Myocardial depression A decrease in the heart’s ability to pump blood.
Myocardial failure Heart failure.
Myocardium The muscular tissue of the heart.
Myoclonic A sudden, involuntary twitching of muscles or parts of muscles, without any rhythm or pattern, occurring in various disorders of the nervous system.


Terms Description
n.o.s. Not otherwise specified, e.g., where the name of a specific chemical is not listed in the applicable regulations, a generic name such as “Corrosive liquid, n.o.s.”is used on shipping papers.
Narcotic A drug (as opium) that in moderate doses dulls the senses, relieves pain, and induces profound sleep, but in excessive doses causes stupor, coma, or convulsions.
Necrosis Death of living tissue; specifically, death of a portion of tissue differentially affected by local injury (as through loss of blood supply, corrosion, burning, or the local lesion of a disease).
Necrotic Affected with, characterized by, or producing necrosis.
Necrotizing bronchiolitis Destruction of tissue and irritation of the airways.
Neoplasm Abnormal growth of tissue, such as cancer.
Neoprene A synthetic rubber produced by polymerization of chloroprene and used in weather-resistant products, adhesives, shoe soles, sportswear, paints, and rocket fuels.
Nerve agent An agent that interferes with the function of the central nervous system. Exposure is primarily through contact with the liquid (via skin and eyes) and secondarily through inhalation of the vapor.
Nettle agent An agent that causes severe irritation to the skin and mucous membranes, as well as pain; also called urticant. (Note that in this database, nettle agents are included in the Blister Agent category.)
Neuromyopathy A disease of the nerves and associated muscle tissue.
Neuropathy A disease or abnormality of the nervous system.
Neuropsychiatric In medicine, pertaining to disorders with both neurological and psychiatric features.
Neutralization The state or quality of being neutralized. A reaction between an acid and a base that yields a salt and water.
NFPA National Fire Protection Association
NFPA 704 Standard System for the Identification of the Hazards of Materials for Emergency Response. A standard providing a readily recognized, easily understood system for identifying specific hazards and their severity using spatial, visual, and numerical methods to describe in simple terms the relative hazards of a material. It addresses the health, flammability, instability, and related hazards that may be presented as short-term, acute exposures that are most likely to occur as a result of fire, spill, or similar emergency.
NFPA 704 Flammability The red (upper) quadrant of the NFPA 704 symbol. The values are:
4 – Danger. Flammable gas or extremely flammable liquid.
3 – Warning. Flammable liquid, flash point below 100°F (38°C).
2 – Caution. Combustible liquid, flash point of 100° to 200°F (38° to 93°C).
1 – Combustible if heated.
0 – Not combustible.
NFPA 704 Health The blue (left-hand) quadrant of the NFPA 704 symbol. The values are:
4 – Danger. May be fatal on short exposure. Specialized protective equipment required.
3 – Warning. Corrosive or toxic. Avoid skin contact or inhalation.
2 – Warning. May be harmful if inhaled or absorbed
1 – Caution. May be irritating.
0 – No unusual hazard.
NFPA 704 Reactivity The yellow (right-hand) quadrant of the NFPA 704 symbol. The values are:
4 – Danger. Explosive material at room temperature
3 – Danger. May be explosive if shocked, heated under confinement or mixed with water.
2 – Warning. Unstable or may react violently if mixed with water.
1 – Caution. May react if heated or mixed with water, but not violently.
0 – Stable. Not reactive when mixed with water.
NFPA 704 Special The white (lower) quadrant of the NFPA 704 symbol. The values are:
W – Water Reactive.
OX – Oxidizing Agent.
NIOSH National Institute for Occupational Safety and Health.
Non-polar Not polar; not having an electric charge.
Not established/determined This term is used when information is not available for a given agent.
Not Recommended This term is used when there is insufficient data for the agent.
NPO Nothing by mouth; from the Latin nil per os. May also be written n.p.o.
NPPTL National Personal Protective Technology Laboratory
Nucleophile A chemical compound or group that is attracted to nuclei and tends to donate or share electrons.
Nystagmus Involuntary movement (oscillation) of the eyeballs.

Top of Page


Terms Description
Ocular Of or relating to the eye.
Off-gassing The release of chemicals from non-metallic substances under ambient or greater pressure conditions.
Oliguria Reduced excretion of urine.
Opacification The act or process of becoming opaque; clouding.
Opaque Impenetrable by light; neither transparent nor translucent.
Ophthalmic Of or relating to the eye; ocular.
Ophthalmologist A physician who specializes in ophthalmology, the treatment of diseases and conditions of the eye.
Opiate A drug, hormone, or other chemical substance having sedative or narcotic effects similar to those from substances containing opium or its derivatives.
Opioid A synthetic substance with opiate-like qualities.
Opisthotonos A condition of spasm of the muscles of the back, which causes the body to arch backwards in hyperextension, e.g. during convulsions or seizures.
Optic neuritis Inflammation of the optic nerve.
Optic neuropathy Degeneration of the optic nerve.
Organ congestion Accumulation of blood in the organs.
Organophosphate An organophosphorus compound.
Organophosphorus Of, relating to, or being a phosphorus-containing organic pesticide (as malathion) that acts by inhibiting cholinesterase.
Oropharyngeal The part of the pharynx between the soft palate and the epiglottis.
OSHA Occupational Safety and Health Administration.
Osteosclerosis Abnormal hardening of the bone or bone marrow.
Oxidant A substance that oxidizes another substance; an oxidizing agent.
Oxidation Generally, the chemical reaction of a substance with oxygen (O2) or an oxygen-containing material, which adds oxygen atom(s) to the compound being oxidized. More rigorously, “the loss of electrons from an atom, compound or molecule.” Oxidation reactions frequently generate heat (are exothermic).
Oxidizer A substance that oxidizes another substance, especially one that supports the combustion of fuel; an oxidizing agent.
Oxidizing agent A substance that oxidizes another substance. Oxdizing agents can cause other materials to combust more readily (or upon contact) or make fires burn more strongly.


Terms Description
Pallor Deficiency of color especially of the face; paleness.
Palpitation Irregular, rapid beating or pulsation of the heart.
Pancreatitis Inflammation of the pancreas.
Pancytopenia An abnormal reduction in the number of red blood cells, white blood cells, and blood platelets in the blood.
Paralysis Loss or impairment of the ability to move a body part, usually as a result of damage to its nerve supply.
Parenteral introduced otherwise than by way of the intestines, e.g., parenteral drug administration can be by intravenous, intramuscular, or subcutaneous injection
Paresthesia Sensation of prickling tingling or creeping on the skin, with no apparent physical cause.
Parkinsonism A condition causing tremor and weakness of the resting muscles and shuffling gait.
Paroxysmal Suddenly recurring or intensifying (e.g., pain or symptoms).
PEL OSHA Permissible Exposure Limit.
Pellet A small, solid or densely packed ball or mass.
Peripheral Related to, located in, or constituting an outer boundary, surface, or periphery.
Peripheral Nervous System The part of the nervous system that is outside the central nervous system and comprises the cranial nerves (except the optic nerve), the spinal nerves, and the autonomic nervous system.
Peripheral neuropathy Degeneration of certain nerves.
Perseveration Continual, involuntary repetition of behaviors.
Pesticide A pesticide is any substance or mixture of substances intended to be used to control, repel, or kill any pest. Pests compete with humans for food, destroy property, spread disease, or are considered a nuisance. They include insects, mice and other animals, unwanted plants (weeds), fungi, or microorganisms like bacteria and viruses. (U.S. EPA)
Pharyngitis Inflammation of the throat (pharynx).
Phenytoin An anticonvulsant drug used most commonly in the treatment of epilepsy. Also called diphenylhydantoin.
Photophobia A painful sensitivity to light.
Platelet A minute body found in the blood of mammals that functions to promote blood clotting; also called thrombocyte.
Pneumonia An inflammatory lung disease (see also pneumonitis).
Pneumonitis A disease characterized by inflammation of the lungs (see also pneumonia).
Pocket resuscitation mask A device that protects a rescuer from being contaminated by a victim when giving emergency mouth-to-mouth resuscitation. It consists of a curved plastic cup that rests over a victim’s mouth and has a short tube attached for the rescuer to blow into.
Poison or Poisonous The words “poison” or “poisonous” are synonymous with the word “toxic”.
Polar Exhibiting polarity, i.e., having electric charges.
Polydipsia Excessive thirst.
Polymerized Having undergone polymerization, a process in which two or more smaller molecules are joined to form larger molecules that contain repeating structural units.
Polyneuropathy A degenerative disease of the nerves.
Positive Pressure Self-Contained Breathing Apparatus (SCBA) An apparatus providing a constant, positive pressure flow of air within the face piece, even if one inhales deeply while doing heavy work. Use apparatus certified by NIOSH and the Department of Labor/Mine Safety and Health Administration in accordance with 42 CFR Part 84. Use it in accordance with the requirements for respiratory protection specified in OSHA 29 CFR 1910.134 (Respiratory Protection) and/or 29 CFR 1910.156 (f) (Fire Brigades Standard).
Powered Air-Purifying Respirator (PAPR) A motorized respirator system that uses a filter to clean surrounding air before deliveringto the wearer to breathe. It typically includes a blower/battery box worn on the belt, headpiece, and breathing tube.
ppm Parts per million.
Prodromal syndrome Premonitory or precursory symptoms.
Proptosis Abnormal bulging (forward projection) of the eyeball.
Prostration Complete physical or mental exhaustion.
Proteinuria The presence of excess protein in the urine.
Pruritus Severe itching.
Pseudomembrane A false membrane or fibrous deposit formed in some disease processes.
psia A unit of pressure, pounds per square inch absolute
psig A unit of pressure, pounds per square inch gauge
Psychic Of or relating to the mind; mental.
Psychosis A serious mental disorder.
Ptosis Drooping of the upper eyelid.
Ptyalism Excessive salivation.
Pulmonary Related to or associated with the lungs.
Pulmonary aspiration The inhalation of foreign materials such as stomach contents into the lungs.
Pulmonary edema Accumulation of fluid in the lungs.
Pulmonary fibrosis An increase in fibrous tissue in the lungs.
Pulmonary hemorrhage Bleeding in the lungs.
Pulmonary hypertension High blood pressure in the lungs.
Pulmonary thrombosis The presence of blood clots in the lungs.
Pungent Affecting the organs of taste or smell with a sharp acrid sensation.
Pustular Containing pus.
Pustule A small elevation of the skin containing pus and having an inflamed base.
PVC A polymer of vinyl chloride used instead of rubber in electric cables.

Top of Page


Terms Description
QID Four times per day or four daily doses; from the Latin quater in die. May also be written q.i.d.


Terms Description
RADS Reactive Airways Dysfunction Syndrome.
Rales An abnormal respiratory sound.
Red Zone Areas where significant contamination with chemical, biological, radiological, or nuclear (CBRN) agents has been confirmed or is strongly suspected but area has not been characterized. The Area is presumed to be life threatening from both skin contact and inhalation.
Refractory Resistant to treatment or cure.
Refractory cardiogenic shock Shock resulting from failure of the heart’s ability to pump sufficient blood.
REL NIOSH Recommended Exposure Limit. The designation “(skin)” in this section “indicates the potential for dermal absorption; skin exposure should be prevented as necessary through the use of good work practices and gloves, coveralls, goggles, and other appropriate equipment,” according to the NIOSH Pocket Guide to Chemical Hazards.
Renal Of, relating to, or in the region of the kidneys.
Renal failure Kidney failure.
Residual The quantity left over at the end of a process.
Respiration The act of breathing. The physical and chemical process by which an organism supplies its cells and tissues with the oxygen needed for metabolism and relieves them of the carbon dioxide formed in energy-producing reactions.
Respirator A device (“approved”) that has met the requirements of 42 CFR part 84, has been designed to protect the wearer from inhalation of harmful atmospheres, and has been approved by the National Institute for Occupational Safety and Health (NIOSH) and the Mine Safety and Health Administration (MSHA).
Respiratory depression Reduced respiratory function.
Respiratory failure The loss of lung function, either acute or chronic, that results in subnormal oxygenation of blood or abnormally increased carbon dioxide. The inability to breathe by a person’s own means.
Resuscitation Restoration of consciousness.
Retinal hemorrhage Bleeding of the membrane in the rear of the eye.
Rhabdomyolysis Destruction or degeneration of skeletal muscle tissue.
Rhinorrhea Runny nose; excessive secretion of mucus from the nose.
Rhonchi A coarse rattling sound somewhat like snoring, usually caused by secretion in a bronchial tube.
Riot Control/Tear agent A substance that causes intense irritation to the eyes and upper respiratory tract, including profuse tearing.
Risus sardonicus Muscle spasm resulting in distortion of the face into a grinning expression, such as during convulsions or seizures.
RTECs Registry of Toxic Effects of Chemical Substances (RTECS).

Top of Page


Terms Description
SCBA Self-Contained Breathing Apparatus.
Sedation Induced state of relaxation, especially by the use of sedative drugs.
Seizure A sudden attack (as of a disease). A sudden change in behavior due to excessive electrical activity in the brain.
Self-Contained Breathing Apparatus (SCBA) A respiratory filter mask that contains its own air supply. It is composed of a face piece connected by a hose to a wearable, compressed, clean-air supply pack much like a scuba tank.
Sepsis A toxic condition resulting from the spread of infection.
Sequela A secondary consequence or result; aftereffect. (Plural = sequelae.)
Serum The clear yellowish fluid obtained upon separating whole blood into its solid and liquid components after it has been allowed to clot. Also called blood serum.
Severe Serious (for a health effect); of high intensity (for an exposure).
Shock A state of profound depression of the vital processes of the body that is characterized by paleness (pallor), rapid but weak pulse, rapid and shallow respiration, reduced total blood volume, and low blood pressure and that is caused usually by severe especially crushing injuries, hemorrhage, burns, or major surgery.
Short-Term Exposure Limit (STEL) An airborne exposure limit designed to address short-term upward deviations in exposure. Typically, exposures at the STEL should not be longer than 15 minutes and should not occur more than 4 times per day, and at least 60 minutes should elapse between successive exposures in this range.
Sloughing Separating or casting off dead tissue from living tissue, as in a wound.
Slurry A thin mixture of a liquid, especially water, and any of several finely divided insoluble substances.
Sodium hypochlorite The active ingredient in household liquid chlorine bleach. It is ordinarily about 5% strength in a water-based solution of bleach.
Somatic Pertaining to or characteristic of the body (physical).
Somnolence A state of abnormal drowsiness (see also lethargy).
Sorbent A substance that takes up and holds, e.g., liquids, by absorption or adsorption.
Spasm Abnormal and involuntary contraction of a muscle or of a hollow organ (such as an artery).
Spasmodic Relating to, characterized by, or resulting from spasm.
Spermatogenesis Formation and development of spermatozoa.
Sputum Matter ejected from the lungs and air passages during cough.
Stabilizer A substance that renders or maintains a solution, mixture, suspension, or state resistant to chemical change.
STB Super Tropical Bleach slurry.
STEL See: Short-Term Exposure Limit.
Stomatitis Inflammatory disease of the mouth.
Street Clothing and Work Uniforms These garments, such as uniforms worn by police and emergency medical services personnel, provide almost no protection from the harmful effects of dangerous goods.
Stricture formation Abnormal narrowing of the digestive tract.
Structural Fire Fighters’ Protective Clothing (SFPC) Turnout or bunker gear; the protective clothing normally worn by fire fighters during structural fire fighting operations. It includes a helmet, coat, pants, boots, gloves and a hood to cover parts of the head not protected by the helmet and face piece. This clothing must be used with full-face piece positive pressure self-contained breathing apparatus (SCBA).
Stupor A state of diminished responsiveness and impaired consciousness.
Subacute Less marked than acute in character; falling between acute and chronic in nature.
Subcutaneous Located or placed just beneath the skin.
Sublethal Slightly less than lethal; e.g., less than the amount of an agent required to cause death
Sublime To pass directly from the solid to the vapor state and condense back to solid form.
Suffocation Sensation of inability to get enough air.
Syncope A brief loss of consciousness caused by a temporary deficiency of oxygen in the brain; a black out; fainting.
Synesthesias Mixed sensory perceptions (e.g., seeing sounds or feeling colours).
Synthetic Produced artificially; not of natural origin.
Systemic Affecting the body generally; not localized.
Systemic agent A substance with whole-body (systemic) or multi-organ-system effects. This category includes so-called “Blood Agents,” as well as other agents with systemic effects.
Systemic toxicity Whole-body toxicity.

Top of Page


Terms Description
T wave The third and last common wave in an electrocardiogram. It reflects the electrical activity produced when the ventricles are recharging for the next contraction (repolarizing)./td>
Tachycardia A rapid heart rate, especially one above 100 beats per minute in an adult.
Tachypnea Rapid breathing.
TEEL Department of Energey Temporary Emergency Exposure Limit
TEEL-0 The threshold concentration below which most people will experience no appreciable risk of health effects.
TEEL-1 The maximum concentration in air below which it is believed nearly all individuals could be exposed without experiencing other than mild transient adverse health effects or perceiving a clearly defined objectionable odor.
TEEL-2 The maximum concentration in air below which it is believed nearly all individuals could be exposed without experiencing or developing irreversible or other serious health effects or symptoms that could impair their abilities to take protective action.
TEEL-3 The maximum concentration in air below which it is believed nearly all individuals could be exposed without experiencing or developing life-threatening health effects.
Tepid Lukewarm (referring to liquids)
Tetany An abnormal phase of prolonged muscular contractions.
Thrombocyte A type of blood cell, also called platelet.
Thrombocytopenia An abnormal decrease in the number of platelets in circulating blood.
Thrombosis The formation or presence of blood clots.
Time-weighted average (TWA) An average value of exposure over the course of an 8-hour (typically) work shift
Tinnitus A sound in one ear or both ears, such as buzzing, ringing, or whistling.
Totally-Encapsulating Chemical Protective (TECP) Suit A full body garment which is constructed of protective clothing materials; covers the wearer’s torso, head, arms, legs and respirator; may cover the wearer’s hands and feet with tightly attached gloves and boots; completely encloses the wearer and respirator by itself or in combination with the wearer’s gloves and boots.
Toxic Poisonous, injurious to health or dangerous to life.
Toxic Inhalation Hazard (TIH) Term used in the U.S. Department of Transportation ERG 2000 guidebook to describe gases and volatile liquids that are toxic when inhaled.
Toxicity The quality, state, or relative degree of being toxic or poisonous.
Toxin A poisonous substance formed during the metabolism and growth of certain living microorganisms and some plants and animals. It is usually very unstable, notably toxic when introduced into the tissues, and typically capable of inducing antibody formation.
Transdermal Through or by way of the skin, such as a skin patch.
Transfusion The transfer of whole blood or blood products from one individual to another.
Transient Existing temporarily; passing away in time.
Triage A process for sorting injured people into groups based on their need for or likely benefit from immediate medical treatment. Triage is used in hospital emergency rooms, on battlefields, and at disaster sites when limited medical resources must be allocated.
Trismus Muscle spasm which causes the jaw to be rigidly clamped, such as during convulsions or seizures.
TWA See: Time-weighted average.


Terms Description
Ulcer A break in skin or mucous membrane with loss of surface tissue, disintegration and death of tissue, and often pus.
Ulceration Tissue damage (e.g., of the cornea, airway lining, stomach or intestine lining).
Unknown This term is used when information for a section has not been identified for the agent.
Urticant An agent that causes severe irritation to the skin and mucous membranes, as well as pain; also called nettle agent.
Urticaria Hives.


Terms Description
Vapor The state of a substance that exists below its critical temperature and that may be liquefied by application of sufficient pressure.
Vapor density Weight of a volume of pure vapor or gas (with no air present) compared to the weight of an equal volume of dry air at the same temperature and pressure. A vapor density less than 1 (one) indicates that the vapor is lighter than air and will tend to rise. A vapor density greater than 1 (one) indicates that the vapor is heavier than air and may travel along the ground.
Vapor pressure Pressure at which a liquid and its vapor are in equilibrium at a given temperature. Liquids with high vapor pressures evaporate rapidly.
Vaporize To convert into vapor, as by the application of heat, whether naturally or artificially.
Vascular collapse Collapse of the blood vessels.
Vasoconstriction Narrowing of the interior diameter of blood vessels.
Vasodilation Widening of the interior diameter of blood vessels.
Vasopressor Of, relating to, or causing constriction of blood vessels, and thereby an increase in blood pressure.
Ventilation The circulation and exchange of gases in the lungs that is basic to respiration.
Vermiculite A lightweight, highly absorbent material made from mica.
Vertigo A sensation that one’s self or one’s surroundings are whirling dizzily.
Vesicant An agent that produces blisters on exposed tissue.
Vesication Formation of blisters; blistering.
Vesicular Blister-like.
Volatile Evaporating readily at normal temperatures and pressures.
Vomiting agent An agent that causes exposed persons to vomit.
Vomitus Vomited matter.


Terms Description
Water spray (fog) Method or way to apply or distribute water. The water is finely divided to provide for high heat absorption. Water spray patterns can range from about 10 to 90 degrees. Water spray streams can be used to extinguish or control the burning of a fire or to provide exposure protection for personnel, equipment, buildings, etc. (From U.S. DOT ERG 2000)
Wheal A small elevation or swelling on the skin that usually itches or burns.
Worker population limit (WPL) An airborne exposure limit designed to protect workers. It is expressed as a time-weighted average (TWA) for exposure over an 8-hour work shift.
WPL See: Worker population limit.


Terms Description
Xerostomia Abnormal dryness of the mouth.


Terms Description
Yellow Zone Areas where contamination with chemical, biological, radiological, or nuclear (CBRN) agents is possible but active release has ended and initial monitoring exists.


Terms Description
µg Microgram; one-millionth of a gram.

Top of Page

Page last reviewed: May 12, 2011