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Definitions are provided for many common terms used in Material Safety Data Sheets,
labels and other documents related to hazard communication. You may encounter other terms, not listed here, that are unfamiliar to you. If you do not know or understand a term, ask
your supervisor for help.
GLOSSARY OF COMMON HAZARD COMMUNICATION TERMS
Acrylic:
A family of synthetic resins made by polymerizing esters of acrylic acids.
Action level:
A term used by OSHA and NIOSH (see entries) to express the level of
toxicant that requires medical surveillance, usually one half of the permissible exposure limit.
Activated charcoal:
Charcoal is an amorphous form of carbon formed by
burning wood, nutshells, animal bones, and other carbonaceous materials. Charcoal becomes activated by heating it with steam to 800-900 degrees C. During this treatment, an aporous,
submicroscopic internal structure is formed that gives it an extensive internal surface area. Activated charcoal is commonly used as a gas or vapor adsorbent in air-purifying respirators
and as a solid sorbent in air sampling.
Additives:
An inclusive name for a wide range of chemical substances that are added in low percentage to stabilize certain
end products, such as antioxidants in rubber.
Aden- (prefix):
Pertaining to a gland. Adenoma is a tumor of gland-like tissue.
Adenoma:
An
epithelial tumor, usually benign, with a gland-like structure (the cells lining gland-like depressions or cavities in the stroma).
Administrative controls:
Methods of
controlling employee exposures by job rotation, work assignment, time periods away from the hazard, or training in specific work practices designed to reduce the exposure.
Adsorption:
The condensation of gases, liquids, or dissolved substances on the surfaces of solids.
AIHA:
American Industrial Hygiene Association.
Air:
The mixture of gases that surrounds the earth; its major components are as follows: 78.08 percent nitrogen, 20.95 percent oxygen, 0.03 percent carbon dioxide, and 0.93 percent
argon. Water vapor (humidity) varies. See standard air.
Air monitoring:
The sampling for and measuring of pollutants in the atmosphere.
Air mover:
Any
device that is capable of causing air to be moved from one space to another. Such devices are generally used to exhaust, force, or draw gases through specific assemblies.
Air quality criteria:
The amounts of pollution and lengths of exposure at which specific adverse effects to health and welfare take place.
Air-purifying respirator:
Respirators that use filters or sorbents to remove harmful substances from the air.
Air-supplied respirator:
Respirator that provides a supply of breathable air
from a clean source outside of the contaminated work area.
Alloy:
A mixture of metals (and sometimes a non-metal), as in brass.
Alveoli:
Tiny air
sacs of the lungs, formed at the ends of bronchioles; through the thin walls of the alveoli, the blood takes in oxygen and gives up carbon dioxide in respiration.
Alveolus:
A general term used in anatomical nomenclature to designate a small sac-like dilation.
Anaerobic bacteria:
Any bacteria that can survive in a partial or complete absence of air.
Anaphylaxis:
Hypersensitivity resulting from sensitization following prior contact with a chemical or protein.
Andro- (prefix):
Man, male. An androgen is an agent that produces masculinizing effects.
Anemia:
Deficiency in the hemoglobin and erythrocyte content of the blood. Term refers to a number
of pathological states that may be attributed to a large variety of causes and appear in many different forms.
Angi-, angio- (prefix):
Blood or lymph vessel. Angiitis is the inflammation of a blood vessel.
ANSI:
American National Standards Institute: a voluntary membership organization (run with
private funding) that develops consensus standards nationally for a wide variety of devices and procedures.
Anthracosilicosis:
A complex form of pneumoconiosis; a
chronic disease caused by breathing air containing dust that has free silica as one of its components and that is generated in the various processes in mining and preparing anthracite
(hard) coal, and, to a lesser degree, bituminous coal.
Anthracosis:
A disease of the lungs caused by prolonged inhalation of dust that contains particles of carbon
and coal.
Antibiotic:
A substance produced by a microorganism that in dilute solutions kills other organisms, or retards or completely represses their growth,
normally in doses that do not harm higher orders of life.
Antibody:
Any of the body globulins that combine specifically with antigens to neutralize toxins, agglutinate
bacteria, or cells, and precipitate soluble antigens. It is found naturally in the body or produced by the body in response to the introduction into its tissues of a foreign
substance.
Antigen:
A substance that when introduced into the body stimulates antibody production.
Antioxidant:
A compound that retards deterioration by
oxidation. Antioxidants for human food and animal feeds, sometimes referred to as freshness preservers, retard rancidity of fats and lessen loss of fat-soluble vitamins (A, D, E, K).
Antioxidants also are added to rubber, motor lubricants, and other materials to inhibit deterioration:
Argyria:
A slate-gray or bluish discoloration of the skin and
deep tissues caused by the deposit of insoluble albuminate of silver, occurring after the medicinal administration for a long period of a soluble silver salt; formerly fairly common after
the use of insufflations of silver-containing materials into the nose and sinuses. Also seen with occupational exposure to silver-containing chemicals.
Asbestos:
A hydrated magnesium silicate in fibrous form.
Asbestosis:
A disease of the lungs caused by inhalation of fine airborne asbestos fibers.
ASHRAE:
American Society of Heating, Refrigeration, and Air Conditioning Engineers.
Asphyxia:
Suffocation from lack of oxygen. Chemical asphyxia is produced by a substance
such as carbon monoxide that combines with hemoglobin to reduce the blood's capacity to transport oxygen. Simple asphyxia is the result of exposure to a substance, such as methane, that
displaces oxygen.
Assigned Protection Factor (APF):
The level of respiratory protection expected from a respirator that its properly functioning, has been properly
fitted, and is worn by a worker trained in its use. APFs can be used to help provide an estimate of the maximum concentrations of a contaminant in which a particular respirator can
be used.
Asthma:
Constriction of the bronchial tubes in response to irritation, allergy, or other stimulus.
Atmospheric pressure:
The pressure
exerted in all directions by the atmosphere. At sea level, mean atmospheric pressure is 29.92 in. Hg, 14.7 psi, or 407 in. wg.
Atrophy:
Arrested development or wasting away of cells and tissue.
Baritosis:
An inert pneumoconiosis produced by the inhalation of insoluble barium compounds.
Base:
A compound that reacts with an acid to form a salt; another term for alkali. It turns litmus paper blue.
Bauxite pneumoconiosis:
Shaver's disease. Found in
workers exposed to fumes containing aluminum oxide and minute silica particles arising from smelting bauxite in the manufacture of corundum.
BEI:
See Biological exposures indices.
Benign:
Not malignant. A benign tumor is one that does not metastasize or invade tissue. Benign tumors may still be lethal because
of pressure on vital organs.
Berylliosis:
Chronic beryllium intoxication.
Biological Exposure Indices (BEI):
Advisory biological limit values
adopted by the ACGIH for some substances. Indices are based on urine, blood, or expired air samples. A BEI may be a value for the substance itself or it may refer to a level of a
metabolite. BEIs represent the value of the biological determinant that is most likely to be the value of that determinant obtained from a worker exposed at the 8-hour TLV-TWA for
the substance in question.
Biological oxygen demand (BOD):
Quantity of oxygen required for the biological and chemical oxidation of waterborne substances under test
conditions.
Biopsy:
Careful removal of small bits of living tissue from the body for further study and examination, usually under the microscope.
Black liquor:
A liquor composed of alkaline and organic matter resulting from digestion of wood pulp and cooking acid during the manufacture of paper.
Bone marrow:
A soft
tissue that constitutes the central filling of many bones and that produces blood corpuscles.
Bradycardia:
Abnormal slowness of the heartbeat, as evidenced by the slowing of the pulse rate to 50 or less.
Braze:
To solder with any relatively infusible alloy.
Breathing zone:
Imaginary globe of two foot radius surrounding the head.
Breathing zone sample:
An air-sample collected in the breathing zone of workers to assess
their exposure to airborne contaminants.
Bronchial tubes:
Branches or subdivisions of the trachea (windpipe). A bronchiole is a branch of a bronchus, which is a branch
of the windpipe.
Bronchiectasis:
A chronic dilation of the bronchi or bronchioles marked by fetid breath and paroxysmal coughing, with the expectoration of
mucopurulent matter. It may affect the tube uniformly, or may occur in irregular pockets, or the dilated tubes may have terminal bulbous enlargements.
Bronchiole:
The slenderest of the many tubes that carry air into and out of the lungs.
Bronchiolitis:
See Bronchopneumonia.
Brochoalveolitis:
Bronchopneumonia.
Bronchopneumonia:
A name given to an inflammation of the lungs that usually begins in the terminal bronchioles. These become clogged with a mucopurulent exudate
forming consolidated patches in adjacent lobules. The disease is essentially secondary in character, following infections of the upper respiratory tract, specific infectious fevers,
and debilitating diseases.
Buffer:
Any substance in a fluid that tends to resist the change in ph when acid or alkali is added.
Bursa:
A synovial lined sac that facilitates the motion of tendons; usually near a joint.
Bursitis:
Inflammation of a bursa.
Byssinosis:
Disease occurring to
those who experience prolonged exposure to heavy air concentrations of cotton or flax dust.
Cancer:
A cellular tumor the natural course of which is fatal and
usually associated with formation of secondary tumors.
Carbon black:
Essentially a pure carbon, best known as common soot. Commercial carbon black is produced by making
soot under controlled conditions. It is sometimes times called furnace black, acetylene black, or thermal black.
Carbon monoxide:
A colorless, odorless, toxic gas
produced by any process that involves the incomplete combustion of carbon-containing substances. It is emitted through the exhaust of gasoline-powered vehicles.
Carboy:
A large glass bottle, usually protected by a crate.
Carboxyhemoglobin:
The reversible combination of carbon monoxide with hemoglobin.
Carcinoma:
Malignant tumors derived from epithelial tissues, that is, the outer skin, the membranes lining the body cavities, and certain glands.
Cardiac:
(1) Pertaining to the heart; (2) a cordial or restorative medicine; (3) a person with heart disorder.
Cardiovascular:
Relating to the heart and to the blood vessels or circulation.
Cas number:
Identifies a particular chemical by the Chemical Abstract Service, a service of the
American Chemical Society that indexes and compiles abstracts of worldwide chemical literature called Chemical Abstracts.
Catalyst:
A substance that changes the
speed of a chemical reaction but that undergoes no permanent change itself. In respirator use, a substance that converts a toxic gas (or vapor) into a less toxic gas (or vapor). Usually
catalysts greatly increase the reaction rate, as in conversion of petroleum to gasoline by cracking. In paint manufacture, catalysts, which hasten film-forming, sometimes become part of
the final product. In most uses, however, they do not, and can often be used over again.
Caustic:
Something that strongly irritates, burns, corrodes, or destroys living tissue. See Alkali.
Chemical cartridge:
The type of absorption unit used with a respirator for
removal of low concentrations of specific vapors and gases.
Chemical reaction:
A change in the arrangement of atoms or molecules to yield substances of different
compositions and properties. Common types of reactions are combination, decomposition, double decomposition, replacement, and double replacement.
Chronic:
Persistent, prolonged, repeated.
Combustible Liquid:
As defined by OSHA, it is any liquid having a flash point as determined by a closed cup method, of equal to or
greater than 100 degrees F. Combustible liquids are divided into two classes:
· "Class II liquids" include those with flashpoints at or above 100 degrees F. and below 140
degrees F., except any mixture having components with flashpoints of 200 degrees F. or higher, the volume of which make up 99 percent or more of the total volume of the mixture.
·
"Class III liquids" include those with flashpoints at or above 140 degrees F. Class III liquids are divided into two subclasses:
· "Class IIIA liquids" include
those with flashpoints at or above 140 degrees F. and below 200 degrees F., except any mixture having components with flashpoints of 200 degrees F., or higher, the total volume of
which make up 99 percent or more of the total volume of the mixture.
· "Class IIIB liquids" include those with flashpoints at or above 200 degrees F. This standard does not
cover Class IIIB liquids. Where the term "Class III liquids" is used in this section, it means only Class IIIA liquids.
Compound:
A substance composed of two or more
elements joined according to the laws of chemical combination. Each compound has its own characteristic properties different from those of its constituent elements.
Concentration:
The amount of a given substance in a stated unit of measure. Common methods of stating concentration are percent by weight or by volume, weight per unit volume,
normality, and so on.
Condensate:
The liquid resulting from the process of condensation. In sampling, the term is generally applied to the material that is removed
from a gas sample by means of cooling.
Condensation:
Act or process of reducing from one form to another denser form such as steam to water.
Confined space:
Any enclosed area not designed for human occupancy that has a limited means of entry and egress and in which existing ventilation is not sufficient to ensure
that the space is free of a hazardous atmosphere, oxygen deficiency, or other known or potential hazards. Examples are storage tanks, boilers, sewers, and tank cars. A permit-required
confined space, as defined by the OSHA standard, is one that requires a permit process and implementation of a comprehensive confined space entry program prior to entry.
Conjunctiva:
The delicate mucous membrane that lines the eyelids and covers the exposed surface of the eyeball.
Conjunctivitis:
Inflammation of the conjuctiva.
Contact dermatitis:
Dermatitis caused by contact with a substance - gaseous, liquid, or solid. May be caused by primary irritation
or an allergy.
Copolymers:
Mixed polymers or heteropolymers. Products of the polymerization of two or more substances at the same time.
Cornea:
Transparent membrane covering the anterior portion of the eye.
Corrosion:
Physical change, usually deterioration or destruction, brought about through chemical or
electrochemical action, as contrasted with erosion, caused by mechanical action.
Cristobalite:
A crystalline form of free silica, extremely hard and inert
chemically, and very resistant to heat. Quartz in refractory bricks and amorphous silica in diatomaceous earth are altered to cristobalite when exposed to high temperatures
(calcined).
Cryogenics:
The field of science dealing with the behavior of matter at very low temperatures.
Cubic centimeter (cm3):
A volumetric measurement that is equal to one milliliter (ml).
Culture (biology):
A population of microorganisms or tissue cells cultivated in a medium.
Cyanosis:
Blue appearance of the skin, especially on the face and extremities, indicating a lack of sufficient oxygen in the arterial blood.
Cytotoxin:
A substance, developed in the blood serum, having a toxic effect upon cells.
Dangerous to life or health, immediately (IDLH):
Used to describe very hazardous
atmospheres where employee exposure can cause serious injury or death within a short time or serous delayed effects.
Decontaminate:
To make safe by eliminating
poisonous or otherwise harmful substances, such as noxious chemicals or radioactive material.
Density:
The ratio of mass to volume.
Dilution:
The
process of increasing the proportion of solvent or diluent (liquid) to solute or particulate matter (solid).
Dispersion:
The general term describing systems
consisting of particulate matter suspended in air or other fluid; also, the mixing and dilution of contaminant in the ambient environment.
Diuretic:
Anything that promotes excretion of urine.
DNA:
Deoxyribonucleic acid. The genetic material within the cell.
Dose:
(1) Used to express the amount of a
chemical or of ionizing radiation entry absorbed in a unit volume or an organ or individual. Dose rate is the dose delivered per unit of time. Dose rate is the dose delivered per
unit of time. (see also Roentgen, Rad, Rem.) (2) Used to express amount of exposure to a chemical substance.
Dyspnea:
Shortness of breath, difficult or labored breathing.
More strictly, the sensation of shortness of breath.
Dysuria:
Difficulty or pain in urination.
Ecology:
The science of the relationships between living organisms and their environments.
Eczema:
A skin disease or disorder. Dermatitis.
Effluent:
Generally
something that flows out or forth, like a stream flowing out into a lake. In terms of pollution, an outflow of a sewer, storage tank, canal, or other channel.
Elastomer:
In a chemical industry sense, a synthetic polymer with rubber-like characteristics; a synthetic or natural rubber or a soft, rubbery plastic with some degree of elasticity at
room temperature.
Element:
Solid, liquid, or gaseous matter that cannot be further decomposed into simpler substances by chemical means. The atoms of an element may
differ physically but do not differ chemically. All atoms of an element contain a definite number of protons and thus have the same atomic number.
Embryo:
The name for
the early stage of development of an organism. In humans, the period from conception to the end of the second month.
Emission factor:
Statistical average of the
amount of a specific pollutant emitted from each type of polluting source in relation to a unit quality of material handled, processed, or burned.
Emission standards:
The maximum amount of pollutant permitted to be discharged from a single polluting source.
Emphysema:
A lung disease in which the walls of the air sacs (alveoli) have
been stretched too thin and have broken down.
Emulsion:
A suspension, each in the other, of two or more unlike liquids that usually do not dissolve in each other.
Enamel:
A paint-like oily substance that produces a glossy finish to a surface to which it is applied, often containing various synthetic resins. It is lead free, in
contrast to the ceramic enamel, that is, porcelain enamel, which contains lead.
Endemic:
(1) Present in a community of among a group of people; usually refers to a
disease prevailing continually in a region. (2) The continuing prevalence of a disease, as distinguished from an epidemic.
Endocrine:
Secreting without the means of
a duct or tube. The term is applied to certain glands that produce secretions that enter the bloodstream or the lymph directly and are then carried to the particular gland or tissue whose
function they regulate.
Endothermic:
Characterized by or formed with absorption of heat.
Endotoxin:
A toxin that is part of the wall of a microorganism and is released when that organism dies.
Engineering controls:
Methods of controlling employee exposures by
modifying the source or reducing the quantity of contaminants released into the work environment.
Enteric:
Intestinal.
Enterotoxin:
A toxin specific for cells of the intestine; gives rise to symptoms of food poisoning.
Enzymes:
Delicate chemical substances, mostly proteins, that enter into and
bring about chemical reactions in living organisms.
Epicondylitis:
Inflammation of certain bony prominences in the area of the elbow, for example, tennis elbow.
Epidermis:
The superficial scarfskin or upper (outer) layer of skin.
Epilation:
Temporary or permanent loss of body hair.
Epithelioma:
Carcinoma of the epithelial cells of the skin and other epithelial surfaces.
Erythema:
Reddening of the skin.
Eschar:
The crust formed after injury by a caustic chemical or heat.
Esters:
Organic compounds that may be formed by interaction between an alcohol and an acid, or by other
means. Esters are nonionic compounds, including solvents and natural fats.
Exhalation valve:
A device that allows exhaled air to leave a respirator and prevents
outside air from entering through the valve.
Exhaust ventilation:
The removal of air, usually by mechanical means, from any space. The flow of air between two points is
because of a pressure difference between the two points. This pressure difference causes air to flow from the high-pressure to the low-pressure zone.
Exothermic, Exothermal:
Characterized by or formed with evolution of heat.
Exposure:
Contact with a chemical, biological, or physical hazard.
Facepiece:
That portion of a respirator that coves the wearer's nose and mouth in a half-mask facepiece, or the nose, mouth, and eyes in a full facepiece. It is designed to make a
gas-tight or dust-tight fit with the face and includes the headbands, exhalation valves, and connections for air-purifying device, or respirable gas source, or both.
Federal Register:
Publication of U.S. government documents officially promulgated under the law, documents whose validity depends upon such publication. It is published on
each day following a government working day. It is, in effect, the daily supplement to the Code of Federal Regulations (CFR).
Fibrillation:
Very rapid irregular
contractions of the muscle fibers of the heart resulting in a lack of synchronism of the heartbeat.
Filter, HEPA:
High efficiency particulate air filter. A
disposable, extended-medium, dry-type filter with a particle removal efficiency of no less than 99.97 percent for 0.3 um particles.
Flammable Liquid:
As defined by OSHA,
it is any liquid having a flashpoint below 100 F (37.8 C), except any mixture having components with flashpoints of 100 degrees F. or higher, the total of which make up 99 percent
or more of the total volume of the mixture. Flammable liquids are known as Class I liquids. Class I liquids are divided into three classes:
· Class IA includes liquids having
flashpoints below 73 degrees F. and a boiling point below 100 degrees F.
· Class IB includes liquids having flashpoints below 73 degrees F. and a boiling point at or above 100
degrees F.
· Class IC includes liquids having flashpoints at or above 73 degrees F. and below 100 degrees F.
Fume fever:
Metal fume fever is an acute
condition caused by a brief high exposure to the freshly generated fumes of metals, such as zinc or magnesium, or their oxides.
Gastritis:
Inflammation of the stomach.
General ventilation:
System of ventilation consisting of either natural or mechanically induced fresh air movements to mix with and
dilute contaminants in the workroom air. This is not the recommended type of ventilation to control contaminates that are toxic.
Genetic effects:
Mutations or other changes produced by irradiation of the germ plasm.
Gland:
Any body organ that manufactures some liquid product and secretes it from its cells.
Grams per kilogram (g/kg):
This indicates the dose of a substance given to test animals in toxicity studies.
Gravity, specific:
The ratio of the mass of a
unit volume of a substance to the mass of the same volume of a standard substance at a standard temperature. Water at 39.2 F (4 C) is the standard substance usually referred to. For
gases, dry air, at the same temperature and pressure as the gas, is often taken as the standard substance.
Halogenated hydrocarbon:
A chemical material that has
carbon plus one or more of these elements: chlorine, fluorine, bromine, and iodine.
Hemoptysis:
Bleeding from the lungs, spitting blood, or blood-stained sputum.
Hemorrhage:
Bleeding; especially profuse bleeding, as from a ruptured or cut blood vessel (artery or vein).
HEPA filter:
High-efficiency particulate air filter.
A disposable, extended-medium, dry-type filter with a particle removal efficiency of no less than 99.97 percent for 0.3 um particles.
Hepatitis:
Inflammation of the liver.
Hepatotoxin:
Chemicals that produce liver damage.
HVAC system:
Heating, ventilating, and air conditioning system.
Hydration:
The process of converting raw material into pulp by prolonged beating in water; to combine with water or the elements of water.
Hypertension:
Abnormally high tension; especially high blood pressure.
Hypothermia:
A systemic effect of cold stress; condition of reduced body temperature.
IDLH:
Immediately dangerous to life or health.
Immiscible:
Not miscible. Any liquid that does not mix another liquid, in which case the result is two separate layers or
cloudiness or turbidity.
Incompatible:
A term applied to liquid and solid systems to indicate that one material cannot be mixed with another specified material without
the possibility of a dangerous reaction.
Inert (chemical):
Not having active properties.
Inert gas:
A gas that does not normally combine chemically with the base metal or filler metal.
Ingestion:
(1) The process of taking substances into the stomach, such as food,
drink, or medicine. (2) With regard to certain cells, the act of engulfing or taking up bacteria and other foreign matter.
Inhalation valve:
A device that allows
respirable air to enter the facepiece and prevents exhaled air from leaving the facepiece through the intake opening.
Innocuous:
Harmless.
Inorganic:
Used to designate compounds that generally do not contain carbon, whose source is matter other than vegetable or animal. Examples are sulfuric acid and salt. Exceptions are carbon
monoxide and carbon dioxide.
Intermediate:
A chemical formed as a middle step in a series of chemical reactions, especially in the manufacture of organic dyes and pigments. In
many cases, it may be isolated and used to form a variety of desired products. In other cases, the intermediate may be unstable or used up at once.
Intoxication:
Either drunkenness or poisoning.
Intraperitoneal:
Inside the space formed by the membrane that lines the interior wall of the abdomen and covers the abdominal
organs.
Intrinsically safe:
Said of an instrument that is designed and certified to be operated safely in flammable or explosive atmospheres.
Jaundice:
Icterus. A serious symptom of disease that causes the skin, the whites of the eyes, and even the mucous membranes to turn yellow.
Keratitis:
Inflammation of the cornea.
Lacquer:
A colloidal dispersion or solution of nitrocellulose or similar film-forming compounds, resins, and plasticizers in solvents
and diluents used as a protective and decorative coating for various surfaces.
Laryngitis:
Inflammation of the larynx.
Latex:
Originally, a milky extract
from the rubber tree, containing about 35 percent rubber hydrocarbon, with the remainder being water, proteins, and sugars. Also applied to water emulsions of synthetic rubbers or
resins.
In emulsion paints, the film-forming resin is in the form of latex.
Lethal:
Capable of causing death.
Leukemia:
A group of malignant blood diseases distinguished by overproduction of white blood cells.
Leukocytosis:
An abnormal increase in the number of white blood cells.
Liquefied petroleum gas:
A compressed or liquefied gas usually composed of propane, some butane, and lesser quantities of other light hydrocarbons and impurities; obtained
as a by-product in petroleum refining. Used chiefly as a fuel and in chemical synthesis.
Lower explosive limit (LEL):
The lower limit of flammability of gas or vapor
at ordinary ambient temperatures expressed by a percentage of the gas or vapor in air by volume. This limit is assumed constant for temperatures up to 250 F (120 C); above this, it
should be decreased by a factor of 0.7, because of explosibility increases with higher temperatures.
Lymph node:
Small oval bodies with a gland-like structure scattered
throughout the body in the course of the lymph vessels. Also known as lymphatic nodes, lymph glands, and lymphatic glands.
Malaise:
A vague feeling of bodily discomfort.
Malignant:
As applied to a tumor, cancerous and capable of undergoing metastasis (invasion of surrounding tissue).
Material safety data sheet (MSDS):
As part of hazard communication standards (right-to-know laws), federal and state OSHA programs require manufacturers and importers of chemicals
to prepare compendia of information on their products. Categories of information that must be provided on MSDSs include physical properties, recommended exposure limits, personal
protective equipment, spill-handling procedures, first aid, health effects, and toxicological data.
Maximum permissible concentration (MPC):
Concentrations set by the
National Committee on Radiation Protection (NCRP); recommended maximum average concentrations of radionuclides to which a worker may be exposed assuming that he works 8 hours a day, 5
days a week, and 50 weeks a year.
Melanoderma:
Abnormal darkening of the skin.
Melting point:
The transition point between the solid and liquid
states. Expressed as the temperature at which this change occurs.
Membrane:
A thin, pliable layer of animal tissue that covers a surface, lines the interior of a cavity
or organ, or divides a space.
Metal fume fever:
A flu-like condition caused by inhaling heated metal fumes.
Mica:
A large group of silicates of
varying composition that are similar in physical properties. All have excellent cleavage and can be split into very thin sheets. Used in electrical insulation.
Mineral spirits:
A petroleum fraction with a boiling range between 300 and 400 F (149 and 240 C).
Monomer:
A compound of relatively low molecular weight that, under certain
conditions, either alone or with another monomer, forms various types and lengths of molecular chains called polymers or copolymers of high molecular weight. Styrene, for example,
is a monomer that polymerizes readily to form polystyrene. See polymer.
MPE:
Maximum permissible exposure.
MPL:
May be either maximum permissible level,
limit, or dose; refers to the tolerable dose rate for humans exposed to nuclear radiation.
MSHA:
The Mine Safety and Health Administration; a federal agency that
regulates safety and health in the mining industry.
MSDS:
Material safety data sheet.
Musculoskeletal system:
The combined system of muscles and
bones that comprise the internal biomechanical environment.
Mutation:
A transformation of the gene that may result in the alteration of characteristics of offspring.
NA or N.A.:
An abbreviation for "Not Applicable".
Narcosis:
Stupor or unconsciousness produced by chemical substances.
Narcotics:
Chemical agents that completely or partially induce sleep.
Necrosis:
Death of body tissue.
Nephrotoxins:
Chemicals that produce kidney damage.
Nephritis:
Inflammation of the kidneys.
Neuritis:
Inflammation of a nerve.
Neurotoxin:
Chemicals that produce their primary effect on the nervous system.
NFPA:
The National Fire Protection Association; a voluntary membership organization whose aim is to
promote and improve fire protection and prevention. The NFPA publishes the National Fires Codes.
NIOSH:
The National Institute for Occupational Safety and Health; a
federal agency that conducts research on health and safety concerns, tests and certifies respirators, and trains occupational health and safety professionals.
Nuisance dust:
Dust with a long history of little adverse effect on the lungs; does not produce significant organic disease or toxic effect when exposures are kept at reasonable levels.
Odor threshold:
The minimum concentration of a substance at which a majority of test subjects can detect and identify the characteristic odor of a substance.
Olefins:
A class of unsaturated hydrocarbons characterized by relatively great chemical activity. Obtained from petroleum and natural gas. Examples are butene, ethylene, and
propylene. Generalized formula: CnH2n.
Oncogenic:
Tumor-generating.
Opacity:
The condition of being nontransparent; a cataract.
Organic:
Chemicals that contain carbon. To date, nearly one million organic compounds have been synthesized or isolated. See also Inorganic.
Os-, oste-, osteo- (prefix):
Pertaining to bone. The Latin os- is most often associated with anatomical structures, whereas the Greek osteo- usually refers to conditions involving bone. Osteogenesis means
formation of bone.
Overexposure:
Exposure beyond the specified limits.
Paraffins, Paraffin series:
(from parum affinis - small affinity.) Straight- or
branched-chain hydrocarbon components of crude oil and natural gas whose molecules are saturated (that is, carbon atoms attached to each other by single bonds) and therefore very stable.
Examples are methane and ethane. Generalized formula: CnH2n+2.
Particle concentration:
Concentration expressed in terms of number of particles per unit volume of
air or other gas. When expressing particle concentrations, the method of determining the concentration should be stated.
Particulate matter:
A suspension of fine solid
or liquid particles in air, such as dust, fog, fume, mist, smoke, or sprays. Particulate matter suspended in air is commonly known as an aerosol.
Pathogen:
Any microorganism capable of causing disease.
Percutaneous:
Performed through the unbroken skin, as by absorption of an ointment through the skin.
Permeation:
Process by which a chemical moves through a protective clothing material on a molecular level.
Personal protective equipment:
Devices worn by the
worker to protect against hazards in the environment. Respirators, gloves, and hearing protectors are examples.
Pesticides:
General term for chemicals used to kill
such pests as rats, insects, fungi, bacteria, weeds, and so on, that prey on humans or agricultural products. Among these are insecticides, herbicides, rodenticides, miticides, fumigants,
and repellants.
pH:
The degree of acidity or alkalinity of a solution, with neutrality indicated as 7.
Pharmaceuticals:
Drugs and related chemicals
reaching the public primarily through drug suppliers. In government reports, this category includes not only such medicinals as aspirin and antibiotics but also such nutriments as
vitamins and amino acids for both human and animal use.
Phenolic resins:
A class of resins produced as the condensation product of phenol or substituted phenol and
formaldehyde or other aldehydes.
Pigment:
A finely divided, insoluble substance that imparts color to a material.
Plasticizers:
Organic chemicals
used in modifying plastics, synthetic rubber, and similar materials to facilitate compounding and processing, and to impart flexibility to the end product.
Pneumo- (Greek), pulmo- (Latin) (prefix):
Pertaining to the lungs.
Pneumoconiosis:
Dusty lungs; a result of the continued inhalation of various kinds of dust or other particles.
Pneumonitis:
Inflammation of the lungs.
Polar solvents:
Solvents (such as alcohols and ketones) that contain oxygen and that have high dielectric constants.
Polystyrene resins:
Synthetic resins formed by polymerization of styrene.
Pressure, vapor:
The pressure exerted by a vapor. If a vapor is kept in confinement at a constant temperature
over its liquid so that it can accumulate above the liquid, the vapor pressure approaches a fixed limit called the maximum, or saturated, vapor pressure, dependent only on the temperature
and the liquid.
Process safety management (PSM):
Encompassing safety concept for the chemical processing industry that is mandated and regulated in OSHA's process safety
management standard. In PSM, potential hazards are systematically analyzed for each step of a chemical process.
Propagation of flame:
The spread of flame through
the entire volume of a flammable vapor-air mixture for a single source of ignition. A vapor-air mixture below the lower flammable limit may burn at the point of ignition without
propagating from the ignition source.
Protection factor (PF):
In respiratory protective equipment, the ratio of the ambient airborne concentration of the contaminant
to the concentration inside the facepiece.
Pulmonary:
Pertaining to the lungs.
Pupil:
The variable aperture in the iris through which light travels
toward the interior regions of the eye. The pupil size varies from 2 mm to 8 mm.
Qualitative fit testing:
A method of assessing the effectiveness of a particular size and
brand of respirator based on an individual's subjective response to a test atmosphere. The most common test agents are isoamyl acetate (banana oil), irritant smoke, and sodium
saccharin. Proper respirator fit is indicated by the individual reporting no indication of the test agent inside the facepiece during the performance of a full range of facial movements.
Quantitative fit testing:
A method of assessing the effectiveness of a particular size and brand of respirator on an individual. Instrumentation is used to measure both
the test atmosphere (a gas, vapor or aerosol, such as DOP) and the concentration of the test contaminants inside the facepeice of the respirator. The quantitative fit factor thus
obtained is used to determine if a suitable fit has been obtained by referring to a table or to the software of the instrumentation. Quantitative fit factors obtained in this way do not
correlate well with Assigned Protection Factors, which are based on actual measurements of levels of contaminant inside the facepiece during actual work.
Reagent:
Any
substance used in a chemical reaction to produce, measure, examine, or detect another substance.
REL:
Recommended exposure limit. An exposure limit, generally a
time-weighted average, to a substance; developed by NIOSH based on toxicological and industrial hygiene data.
Renal:
Having to do with the kidneys.
Resin:
A sold or semisolid amorphous (noncrystalline) organic compound or mixture of such compounds with no definite melting point and no tendency to crystallize. May be of vegetable (gum
arabic), animal (shellac), or synthetic (celluloid) origin. Some resins may be molded, cast, or extruded. Others are used as adhesives, in the treatment of textiles and paper, or as
protective coatings.
Respirable-size particulates:
Particulates in a size range that permits them to penetrate deep into the lungs upon inhalation.
Respirator:
A device to protect the wearer from inhalation of harmful contaminants.
Rhinitis:
Inflammation of the mucous membrane lining in the nasal passages.
Route of entry:
A path by which chemicals can enter the body. There are three main routes of entry: inhalation, ingestion, and skin absorption.
RTECS:
Registry of Toxic Effects of Chemical Substances.
Salivation:
An excessive discharge of saliva; ptyalism.
Sampling:
The withdrawal or isolation of
a fractional part of a whole. In air analysis, the separation of a portion of an ambient atmosphere with subsequent analysis to determine concentration.
Scleroderma:
Hardening of the skin.
SCBA:
Self-contained breathing apparatus.
Siderosis:
The deposition of iron pigments in the lung - can be associated with disease.
Silicates:
Compounds of silicon, oxygen, and one or more metals with or without hydrogen.
These dusts cause nonspecific dust reactions, but generally do not interfere with pulmonary function or result in disability.
Silicosis:
A disease of the lungs caused by the inhalation of silica dust.
Slurry:
A thick, creamy liquid resulting from the mixing and grinding of limestone, clay, water, and
other raw materials.
Solution:
Mixture in which the components lose their individual properties and are uniformly dispersed. All solutions are composed of a solvent
(water or other fluid) and a solute (the dissolved substance). A true solution is homogeneous, as salt in water.
Solvent:
A substance that dissolves another substance. Usually refers to organic solvents.
Soot:
Agglomerations of carbon particles impregnated with tar; formed in the incomplete
combustion of carbonaceous material.
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
at a standard temperature. Water at 39.2 F (4 C) is usually the standard for liquids; for gases, dry air (at the same temperature and pressure as the gas) is often taken as the standard
substance. See Density.
Specific weight:
The weight per unit volume of a substance; same as density.
Sterilization:
The process of making sterile; the killing of all forms of life.
Stupor:
Partial unconsciousness or nearly complete unconsiousness.
Suspect carcinogen:
A material believed to be capable of causing cancer, based on limited scientific evidence.
Synergistic:
Pertaining to an action of two or more substances,
organs, or organisms to achieve an effect greater than the additive effects of the separate elements.
Systemic:
Spread throughout the body; affecting all body systems and
organs, not localized in one spot or area.
Threshold:
The level where the first effects occur; also, the point at which a person begins to notice a tone becoming
audible.
Toxin:
A poisonous substance derived from an organism.
Trade name:
The commercial name or trademark by which a chemical is known. One chemical
may have a variety of trade names depending on the manufacturing or distributors involved.
Turbid:
Cloudy.
Vapor pressure:
Pressure (measured in
pounds per square inch absolute-psia) exerted by a vapor. If a vapor is kept in confinement over its liquid so that the vapor can accumulate above the liquid (the temperature being held
constant), the vapor pressure approaches a fixed limit called the maximum (or saturated) vapor pressure, dependent only on the temperature and the liquid.
Ventilation:
One of the principal methods to control health hazards, may be defined as causing fresh air to circulate to replace foul air simultaneously removed.
Ventilation, dilution:
Airflow designed to dilute contaminants to acceptable levels. Also called general ventilation.
Ventilation, local exhaust:
Ventilation near the point of generation of a contaminant.
Ventilation, mechanical:
Air movement caused by a fan or other air-moving device.
Ventilation, natural:
Air movement caused by wind, temperature difference, or other nonmechanical factors.
Viscosity:
The property of a fluid the resists internal flow by releasing counteracting forces.
Volatility:
The tendency or ability of a liquid to vaporize. Such liquids as
alcohol and gasoline, because of their well-known tendency to evaporate rapidly, are called volatile liquids.
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