Right to Know Laws and The Employee

According to O.S.H.A. Law 29 CFR 1910.1200, as amended in May of 1988, all employers must inform their employees about potential hazards associated with the handling, use and disposal of chemical products used in the work place.  Material Safety Data Sheets (MSDS) are one of the most important links in the chain of information communication from chemical producer to end user. The glossary of MSDS terminology on the following pages is provided to clarify the terminology used in the preparation of these forms.

Two points about MSDS applications should be understood.  First, their sole function is to communicate safety information ...they are not intended for use as product sales specifications or an indication of product performance.  Attempting to compare competitive products by comparing listed ingredients can be extremely misleading. For accurate product evaluation no method is as valid as simple on job, in use testing. Second, mere possession of MSDS information does not constitute an adequate hazard communication program.  The law requires employers to:

 Draft and maintain a written hazard communication program for each worksite that describes how the employer is complying with the standard; Collect and make available to employees and customers MSDSs that identify on site hazardous chemicals and effects of exposure, and provide general and emergency safety procedures; Ensure that each container of hazardous chemicals is properly labeled, tagged or marked to identify its contents and warn employees as to the nature of the hazard, and, Provide employees with information and training on the safe handling of hazardous chemicals at the time of their initial assignment and whenever a new hazard is introduced into their work area.

 Your Wayne representative will be happy to work with you in training your employees in the safe and responsible handling of our chemical products.

A B C D E F G H I L M N O P R S T U V W X Y Z

ACGIH:  American Conference of Governmental Industrial Hygienists is an organization of professional personnel in governmental agencies or educational institutions engaged in occupational safety and health programs. ACGIH establishes recommended occupational exposure limits for chemical substances and physical agents.  See TLV

Acid:  Any chemical that undergoes dissociation in water with the formation of hydrogen ions. Acids have a sour taste and may cause severe skin burns. Acids turn litmus paper red and have pH values of 0 to 6.

Acute Effect: Adverse effect on a human or animal that has severe symptoms developing rapidly and coming quickly to crisis.

Acute Toxicity:  Acute effects resulting from a single dose of, or exposure to, a substance. Ordinarily used to denote effects in experimental animals.

Air-Line Respirator:  A respirator that is connected to a compressed breathable air source by a hose of small inside diameter. The air is delivered continuously or intermittently in a sufficient volume to meet the wearer's breathing requirements.

Air-Purifying Respirator: A respirator that uses chemicals to remove specific gases and vapors from the air or that uses a mechanical filter to remove particulate matter. An air-purifying respirator must only be used when there is sufficient oxygen to sustain life and the air contaminant level is below the concentration limits of the device.

Alkali:  Any chemical substance that forms soluble soaps with fatty acids.  Alkalis are also referred to as bases. The may cause severe burns to the skin.  Alkalis turn litmus paper blue and have pH value from 8 to 14.

Allergic Reaction:  An abnormal physiological response to chemical or physical stimuli.

Antidote:  A remedy to relieve, prevent or counteract the effects of a poison.

Appearance: A description of a substance at normal room temperature and normal atmospheric conditions. Appearance includes the color, size and consistency of a material.

Asphyxiant:  A vapor or gas that can cause unconsciousness or death by suffocation (lack of oxygen). Most simple asphyxiants are harmful to the body only when they become so concentrated that they reduce oxygen in the air (normally about 21 percent) to dangerous levels (18 percent or lower). Asphyxiation is one of the principal potential hazards of working in confined and enclosed spaces.

Auto-Ignition Temperature: The temperature to which a closed, or nearly closed container must be heated in order that the flammable liquid, when introduced into the container, will ignite spontaneously or burn.

Base:  A substance that (1) liberates hydroxide (OH) ions when dissolved in water, (2) receives hydrogen ions from a strong acid to form a weaker acid, and (3) neutralizes an acid.  Bases react with acids to form salts and water. Bases have a pH greater than 7 and turn litmus paper blue. See Alkali.

Biodegradable:  Capable of being broken down into innocuous products by the action of living things.

Boiling Points - BP: The temperature at which a liquid changes to a vapor state at a given pressure. The boiling point usually expressed in degrees Fahrenheit at sea level pressure (760 mmHg, or one atmosphere). For mixtures, the initial boiling point or the boiling range may be given. Flammable materials with low boiling points generally present special fire hazards.  Some approximate boiling points:

            Propane            -44o F
            Anhydrous Ammonia     -28o F
            Butane              31o F
            Gasoline          100o F
            Ethylene Glycol            387o F

Carcinogen:  A substance or agent capable of causing or producing cancer in mammals, including humans. A chemical is considered to be a carcinogen if
(a)        It has been evaluated by the International Agency of Research on Cancer (IARC) and found to be a carcinogen or potential carcinogen; or
(b)        It is listed as a carcinogen or potential carcinogen in the Annual Report on Carcinogens published by the National Toxicology Program (NTP) (latest edition); or
(c)        It is regulated by O.S.H.A. as a carcinogen.

CAS:  Chemical Abstracts Service is an organization under the American Chemical Society. CAS abstracts and indexes chemical literature from all over the world in "Chemical Abstracts." "CAS Numbers" are used to identify specific chemical or mixtures.

Ceiling Limits (PEL or TLV):  The maximum allowable human exposure limit for an airborne substance which is not to be exceeded even momentarily.  Also see PEL and TLV.

CFR:  Code of Federal Regulations.  A collection of the regulations that have been promulgated under United States Law.

Chemical:  An element (e.g.: chlorine) or a compound (e.g.: sodium bicarbonate) produced by chemical reaction.

Chemical Cartridge Respirator:  A respirator that uses various chemical substances to purify inhaled air of certain gases and vapor. This type respirator is effective for concentrations no more than ten times the TLV of the contaminant, if the contaminant has warning properties (odor or irritation) below the TLV.

Chemical Family:  A group of single elements or compounds with a common general name.  Example: Acetone, methyl ethyl ketone (MEK) and methyl isobutyl ketone (MIBK) are of the "Ketone" family; acrolein, furfural and acetaldehyde are of the "aldehyde" family.

Chemical Name:  The name given to a chemical in the nomenclature system developed by the International Union of Pure and Applied Chemistry (IUPAC) or the Chemical Abstracts Service (CAS). The scientific designation of a chemical or a name that will clearly identify the chemical for hazard evaluation purposes.

CHEMTREC: Chemical Transportation Emergency Center is a national center established by the Chemical Manufacturers Association (CMA) to relay pertinent emergency information concerning specific chemicals on request from individuals. CHEMTREC has a 24 hour toll-free telephone number (800-424-9300) to help respond to chemical transportation emergencies.

Chronic Effect:  An adverse effect on a human or animal body, with symptoms that develop slowly over a long period of time or that recur frequently. Also see Acute.

Chronic Exposure:  Long-term contact with a substance.

Chronic Toxicity: Adverse (Chronic) effects resulting from repeated doses of or exposures to a substance over a relatively prolonged  period of time. Ordinarily used to denote effects in experimental animals.

Combustible:  A term used by NFPA, DOT and others to classify certain liquids that will burn, on the basis of flash points. Both NFPA and DOT generally define "combustible liquids" as having a flash point of 100o F (37.8o C) or higher but below 200o F (93.3o C). Also see "flammable". Non-liquid substances such as wood and paper are classified as "ordinary combustibles" by NFPA.

Combustible Liquid:  Any liquid having a flash point at or above100oF (37.8o C), but below 200o F (93.3o C), except any mixture having components with flash points of 200o F (93.3o C) or higher, the total volume of which makes up ninety-nine (99) percent or more of the total volume of the mixture.

Common Name: Any means used to identify a chemical other than its chemical name, (e.g.: code name, code number, trade name, brand name or generic name).  See Generic.

Conditions to Avoid:  Conditions encountered during handling or storage that could cause a substance to become unstable.

Confined Space:  Any area that has limited openings for entry and exit that would make escape difficult in an emergency, has a lack of ventilation, contains known and potential hazards and is not intended nor designated for continuous human occupancy.

Corrosive:  A chemical that causes visible destruction of, or irreversible alterations in, living tissue by chemical action at the site of contact. For example, a chemical is considered to be corrosive if, when tested on the intact skin of albino rabbits by the method described by the DOT in Appendix A to 49 CFR Part 173, it destroys or changes irreversibly the structure of the tissue at the site of contact following an exposure period of 4 hours. This term shall not refer to action on inanimate surfaces.

Decomposition:  Breakdown of a material or substance (by heat, chemical reaction, electrolysis, decay or other processes) into parts or elements or simpler compounds.

Density: The mass (weight) per unit volume of a substance. For example, lead is much more dense than aluminum.

DOT:  U.S. Department of Transportation regulates transportation of chemicals and other substances.

Dry Chemical:  A powdered fire-extinguishing agent usually composed of sodium bicarbonate, potassium bicarbonate, etc.

Environmental Toxicity:  Information obtained as a result of conducting environmental testing designed to study the effects on aquatic and plant life.

EPA:  U.S. Environmental Protection Agency.

Evaporation Rate: The rate at which a material will vaporize (evaporate) when compared to the known rate of vaporization of a standard material. The evaporation rate can be useful in evaluation the health and fire hazard of a material. The designated standard material is usually normal butyl acetate (NBUA or n-BuAc), with a vaporization rate designated as 1.0.  Vaporization rates of other solvents or materials are then classified as:

FAST evaporation if greater than 3.0
Examples:  Methyl Ethyl Ketone = 3.8, Acetone: 5.60, Hexane = 8.3
MEDIUM evaporation if 0.8 to 3.0
Examples: 190 proof (95%) Ethyl Alcohol = 1.4, VM&P Naphtha = 1.4,    MIBK = 1.6
SLOW evaporation if less than 0.8
Examples:  Xylene = 0.6, Isobutyl Alcohol = 0.6, Normal Butyl Alcohol = 0.4, Water = 0.3, Mineral Spirits = 0.1

Explosive:  A chemical that causes a sudden, almost instantaneous release of pressure, gas and heat when subjected to sudden shock, pressure or high temperature.

Exposure or Exposed:  State of being open and vulnerable to a hazardous chemical by inhalation, ingestion, skin contact, absorption or any other course; includes potential (accidental or possible) exposure.

Extinguishing Media:  The fire fighting substance to be used to control a material in the event of a fire. It is usually identified by its generic name, such as fog, foam, water, etc.

Eye Protection:  Recommended safety glasses, chemical splash goggles, face shields, etc. to be utilized when handling a hazardous material.

FIFRA:  Federal Insecticide, Fungicide, and Rodenticide Act requires that certain useful poisons, such as chemical pesticides, sold to the public contain labels that carry health hazard warnings to protect users.  It is administered by EPA.

Flammable: A chemical that includes one of the following categories:
(a)            "Aerosol, flammable".  An aerosol that, when tested by the method described in 16 CFR 1500.45 yields a flame projection exceeding 18 inches at full value opening, or a flashback ( a flame extending back to the valve) at any degree of valve opening.

(b)        "Gas, flammable". (1) A gas that, at ambient temperature and pressure, forms a flammable mixture with air at a concentration of 13 percent by volume or less; or (2) A gas that, at ambient temperature and pressure, forms a range of flammable mixtures with air wider than 12 percent by volume, regardless of the lower limit;

(c)        "Liquid, flammable". Any liquid having a flash point below 100o F (37.8 C), except any mixture having components with flash points of 100 F (37.8 C) or higher, the total of which make up 99 percent or more of the total volume of mixture.

(d)        "Solid, flammable".  A solid, other than a blasting agent or explosive as defined in 1910.109 (a), that is liable to cause fire through friction, absorption of moisture, spontaneous chemical change, or retained heat from manufacturing or processing, or which can be ignited readily and when ignited burns so vigorously and persistently as to create a serious hazard.  A solid is a flammable solid if, when tested by the method described in 16CFR 1500.44, it ignites and burns with a self-sustaining flame at a rate greater than one-tenth of an inch per second along its major axis.

Flashback: Occurs when flame from a torch burns back into the tip, the torch or the hose. It is often accompanied by a hissing or squealing sound with a smoky or sharp-pointed flame.

Flash Point:  The minimum temperature at which a liquid gives off a vapor in sufficient concentration to ignite when tested by the following methods:

(a)             Tagliabue Closed Tester (See American National Standard Method of Test for Flash Point by Tag Closed Tester, Z11.24 1979 [ASTM D56-79]).

(b)        Pensky-Martens Closed Tester (See American National Standard Method of Test for Flash Point by Pensky-Martens Closed Tester, Z11.7 1979 [ASTM D93-79]])

(c)             Setaflash Closed Tester (See American National Standard Method of Test for Flash Point by Setaflash Closed Tester [ASTM D3278-78])

Formula:  The scientific expression of the chemical composition of a material (e.g.: water is H20, sulfuric acid is H2SO4, sulfur dioxide is SO2).

General Exhaust:  A system for exhausting air containing contaminants from a general work area. Also see Local Exhaust.

Generic Name:  A designation of identification used to identify a chemical by other than its chemical name (e.g: code name, code number, trade name and brand name).

Grounding:  The procedure used to carry an electrical charge to ground through a conductive path. A typical ground may be connected directly to a conductive water pipe or to a grounding bus and ground rod.

Hand Protection:  Specific type of gloves or other hand protection required to prevent harmful exposure to hazardous materials.

Hazardous Chemical:  Any chemical whose presence or use is a physical hazard or a health hazard.

Hazardous Warning:  Words, pictures, symbols or combination thereof presented on a label or other appropriate form to inform of the presence of various materials.

HCS:  Hazard Communication Standard is an O.S.H.A. regulation issued under 29 CFR Part 1910.1200.

Health Hazard:  A chemical for which there is significant evidence, based on at least one study conducted in accordance with established scientific principles, that acute or chronic health effects may occur in exposed employees. The term "health hazard" includes chemicals that are carcinogens, toxic or highly toxic agents, reproductive toxins, irritants, corrosives, sensitizers, hepatotoxins, nephrotoxins, neurotoxins, agents that act on the hematopoietic system and agents that damage the lungs, skin, eyes or mucous membranes. Highly Toxic:  A chemical in any of the following categories:

(a)        A chemical with a median lethal dose (LD50) of 50 milligrams or less per kilogram of body weight when administered orally to albino rats weighing between 200 and 300 grams each.

(b)        A chemical with a median lethal dose (LD50) of 200 milligrams or less per kilogram of body weight when administered by continuous contact for 24 hours (or less if death occurs within 24 hours) with the bare skin of albino rabbits weighing between 2 and 3 kilograms each.

(c)        A chemical that has a median lethal concentration (LC50) in air of 200 parts per million by volume or less of gas or vapor, or 2 milligrams per liter or less of mist, fume or dust when administered by continuous inhalation for 1 hour (or less if death occurs within 1 hour) to albino rats weighing between 200 and 300 grams each.

IARC:  International Agency for Research on Cancer.

Ignitable:  Capable of being set afire.

Impervious:  A material that does not allow another substance to pass through or penetrate it.

Incompatible:  Materials that could cause dangerous reactions by direct contact with one another.

Ingestion: Taking in by the mouth.

Inhalation:  Breathing in of a substance in the form of a gas, vapor, fume, mist or dust.

Insoluble:  Incapable of being dissolved in a liquid.

Irritant:  A chemical, which is not corrosive, that causes a reversible inflammatory effect on living tissue by chemical action at the site of contact. A chemical is a skin irritant if, when tested on the intact skin of albino rabbits by the methods of 16 CFR 1500.41 for 4 hours exposure or by other appropriate techniques, it results in an empirical score of 5 or more. A chemical is an eye irritant if so determined under the procedure listed in 16 CFR 1500.42 or other appropriate techniques.

Label:  Notice attached to a container, bearing information concerning its contents.

LC50:  The concentration of a material in air that will kill 50 percent of a group of test animals with a single exposure (usually 1 to 4 hours).  The LC50 is expressed as parts of material per million parts of air, by volume (ppm) for gasses and vapors, or as micrograms of material per liter of air (g/l) or micrograms of material per cubic meter of air (mg/m3) for dusts and mists, as well as for gases and vapors.

LD50:  A single dose of material expected to kill 50 percent of a group of test animals. The LD50 dose is usually expressed as milligrams or grams of material per kilogram of animal body weight (mg/kg or g/kg). The material may be administered by mouth or applied to the skin.

LEL or LFL:  Lower explosive limit, or lower flammable limit, of a vapor or gas; the lowest concentration (lowest percentage of the substance in air) that will produce a flash of fire when an ignition source (heat, arc or flame) is present. At concentrations lower than the LEL, the mixture is to "lean" to burn.  Also see UEL

Local Exhaust: A system for capturing and exhausting contaminants from the air at the point where the contaminants are produced (welding, grinding, sanding, other processes or operations).  Also see General Exhaust.

Mechanical Exhaust:  A powered device, such as a motor-driven fan or air steam venturi tube, for exhausting contaminants from a work place, vessel or enclosure.

Mechanical Filter Respirator:  A respirator used to protect against airborne particulate matter like dusts, mists, metal fume and smoke. Mechanical filter respirators do not provide protection against gases, vapors or oxygen deficient atmospheres.

Melting Point:  The temperature at which a solid substance changes to a liquid state. mg/m3:  Milligrams per cubic meter is a unit for expressing concentrations of dusts, gases, or mists in air.

Mixture:  Any combination of two or more chemicals if the combination is not, in whole or part, the result of a chemical reaction.

ml:  Milliliter is a metric unit of capacity, equal in volume to 1 cubic centimeter (cc) or approximately one-sixteenth of a cubic inch. One-thousandth  of a liter.

Molecular Weight:  Weight (mass) of a molecule based on the sum of the atomic weights of the atoms that make up the molecule.

MSDS: Material Safety Data Sheet

Nausea:  Tendency to vomit, feeling of sickness at the stomach. 

Neutralize:  To eliminate potential hazards by inactivating strong acids, caustics and oxidizers.  For example, acids can be neutralized by adding an appropriate amount of caustic substance to the spill.

NIOSH:  National Institute for Occupational Safety and Health, U.S. Public Health Service, U.S. Department of Health and Human Services (DHHS), among other activities, tests and certifies respiratory protection devices and air sampling detector tubes, recommends occupational exposure limits for various substances and assists O.S.H.A. and MSHA in occupational safety and health investigations and research.

Nonflammable:  Not easily ignited or if ignited, not burning rapidly.

NTP:  National Toxicology Program. The NTP publishes an Annual Report on Carcinogens.

Odor:  A description of the smell of the substance.

Odor Threshold:  The lowest concentration of a substance's vapor, in air, that can be smelled.

Oral:  Used in or taken into the body through the mouth.

Oral Toxicity:  Adverse effects resulting from taking a substance into the body by mouth. Ordinarily used to denote effects in experimental animals.

Overexposure:  Exposure to a hazardous material beyond the allowable exposure limits.

Oxidation:  In a literal sense, oxidation is a reaction in which a substance combines with oxygen provided by an oxidizer or oxidizing agent. See Oxidizing Agent.

Oxidizer:  A chemical other than a blasting agent or explosive that initiates or promotes combustion in other materials, causing fire either by itself or through the release of oxygen or other gases.

Oxidizing Agent:  A chemical or substance that brings about an oxidation reaction. The agent may (1) provide the oxygen to the substance being oxidized (in which case the agent has to be oxygen or contain oxygen), or (2) it may receive electrons being transferred from the substance undergoing oxidation (chlorine is a good oxidizing agent for electron-transfer purposes, even though it contains no oxygen).

PEL:  Permissible Exposure Limit is an occupational exposure limit established by O.S.H.A.'s regulator authority.  It may be a time-weighted average (TWA) limit or a maximum concentration exposure limit.

Percent Volatile:  Percent volatile by volume is the percentage of a liquid or solid (by volume) that will evaporate at an ambient temperature of 70o F (unless some other temperature is specified).  Examples: Butane, gasoline and paint thinner (mineral spirits) are 100 percent volatile; their individual evaporation rates vary, but in time, each will evaporate completely.

pH:  The symbol relating the hydrogen ion (H+) concentration to that of a given standard solution. A pH of 7 is neutral. Numbers increasing from 7 to 14 indicate greater alkalinity.  Numbers decreasing from 7 to 0 indicate greater acidity.

Physical Hazard: Means a chemical for which there is a scientifically valid evidence that is is a combustive liquid, a compressed gas, explosive, flammable, an organic peroxide, an oxidizer, pyrophoric, unstable (reactive) or water-reactive.

PMCC:  Pensky-Martens Closed Cup.  See Flash Point

Poison, Class A:  A DOT term for extremely dangerous poisons - poisonous gases or liquids that, in very small amounts, either as gas or as vapor of the liquid, mixed with air, are dangerous to life.  Examples: Phosgene, cyanogen, hydrocyanic acid, nitrogen peroxide.

Poison, Class B:  A DOT term for liquid, solid, paste or semisolid substances - other than Class A poisons or irritating materials - that are known (or presumed on the basis of animal tests) to be so toxic to humans that they are a hazard to health during transportation.

Polymerization:  A chemical reaction in which one or more small molecules combine to form larger molecules. A hazardous polymerization is such a reaction that takes place at a rate that releases large amounts of energy. If hazardous polymerization can occur with a given material, the MSDS usually will list condition that could start the reaction and - since the material usually contains a polymerization inhibitor - the length of time during which the inhibitor will be effective.

ppb:  Parts per billion is the concentration of a gas or vapor in air-parts (by volume) of the gas or vapor in a billion parts of air.  Usually used to express extremely low concentrations of unusually toxic gases or vapors; also the concentration of a particular substance in a liquid or solid.

ppm:  Parts per million is the concentration of a gas or vapor in air-parts (by volume) of the gas or vapor in a million parts of air; also the concentration of a particulate in a liquid or solid.

psi:  Pounds per square inch (for MSDS purposes) is the pressure a material exerts on the walls of a confining vessel or enclosure. For technical accuracy, pressure must be expressed a psig (pounds per square inch gauge) or psia (pounds per square inch absolute; that is gauge pressure plus sea level atmospheric pressure, or psig plus approximately 14.7 pounds per square inch). Also see mmHg.

Reaction: A chemical transformation or change. The interaction of two or more substances to form new substances.

Reactivity: Chemical reaction with the release of energy.  Undesirable effects - such as pressure build-up, temperature increase, formation of noxious, toxic or corrosive by-products - may occur because of the reactivity of a substance to heating, burning, direct contact with other materials, or other conditions in use or in storage.

Reducing Agent:  In a reduction reaction (which always occurs simultaneously with an oxidation reaction) the reducing agent is the chemical or substance which (1) combines with oxygen or (2) loses electrons to the reaction.  See Oxidation.

Reproductive Toxin: Substances that affect either male or female reproductive systems and may impair the ability to have children.

Respiratory Protection:  Device that will protect the wearer's respiratory system from overexposure by inhalation to airborne contaminants. Respirator protection is used when a worker must work in an area where he/she might be exposed to concentration in excess of the allowable exposure limit.

Routes of Entry:  The means by which material may gain access to the body, for example, inhalation, ingestion, and skin contact.

RCRA:  Resources Conservation and Recovery Act is environmental legislation aimed at controlling the generation, treating, storage, transportation and disposal of hazardous wastes. It is administered by EPA.

Self-Contained Breathing Apparatus:  A respiratory protection device that consists of a supply or a means of respirable air, oxygen, or oxygen-generating material, carried by the wearer.

Sensitizer: A chemical that causes a substantial proportion of exposed people or animals to develop an allergic reaction on normal tissue after repeated exposure to the chemical.

"Skin":  A notation (sometimes used with PEL or TLV exposure data) that indicates that the stated substance may be absorbed by the skin, mucous membranes and eyes - either airborne or by direct contact - and that this additional exposure must be considered part of the total exposure to avoid exceeding the PEL or TLV for that substance.

Skin Absorption:  Ability of some hazardous chemicals to pass directly through the skin and enter the blood stream.

Solubility in Water:  A term expressing the percentage of a material (by weight) that will dissolve in water at ambient temperature.  Solubility information can be useful in determining spill clean up methods and re-extinguishing agents and methods for a material.

Solvent: A substance, usually a liquid, in which other substances are dissolved. The most common solvent is water.

Specific Chemical Identity:  The chemical name, Chemical Abstracts Service (CAS) Registry Number, or any precise chemical designation of a substance.

Specific Gravity:  The weight of a material compared to the weight of an equal volume of water is an expression of the density (or heaviness) of a material. Insoluble materials with specific gravity of less than 1.0 will  float in (or on) water.  Insoluble materials with specific gravity greater than 1.0 will sink in water. Most (but not all) flammable liquids have specific gravity less than 1.0 and, if not soluble, will float on water - an important consideration for fire suppression.

Spill or Leak Procedures: The methods, equipment and precautions that should be used to control or clean up a leak or spill.

Stability:  The ability of a material to remain unchanged. For MSDS purposes, a material is stable if it remains in the same form under expected and reasonable conditions of storage or use. Conditions that may cause instability (dangerous change) are stated; for example: temperatures above 150o F, shock from dropping.

STEL:  Short-Term Exposure Limit (ACGIH terminology). See TLV.

Supplied-Air Respirators: Air line respirators of self-contained breathing apparatus.

Systemic Poison: A poison that spreads throughout the body, affecting all body systems and organs.  Its adverse effect is not localized in one spot or area.

Systemic Toxicity:  Adverse effects caused by a substance that affects the body in general rather than local manner.

Target Organ Effects:  The following is a target organ categorization of effects that may occur, including examples of signs and symptoms and chemicals that have been found to cause such effects.  These examples are presented to illustrate the range and diversity of effects and hazards found in the work place, and the broad scope employers must consider in this area, but they are not intended to be all inclusive.

(a) Hepatotoxins: Chemicals that produce liver damage.
    Signs and Symptoms:  Jaundice; liver enlargement.
    Chemicals: Carbon tetrachloride; nitrosamines

(b) Nephrotoxins: Chemicals that produce kidney damage.
    Signs and Symptoms: Edema; proteinuria
    Chemicals: Halogenated hydrocarbons; uranium

(c) Neurotoxins: Chemicals that produce their primary toxic effect on the nervous system.
    Signs and Symptoms:  Narcosis; behavioral changes; decrease in motor functions.
    Chemicals:   Mercury, carbon disulfide.

(d) Agents that act on blood hematopoietic system: Decrease hemoglobin function;
    deprive the body tissue of oxygen.
    Signs and Symptoms:  Cyanosis; loss of consciousness.
    Chemicals: Carbon monoxide, cyanides

(e) Agents that damage the lung: Chemicals that irritate or damage the pulmonary tissue.
    Signs and Symptoms:  Cough, tightness in chest, shortness of breath.
    Chemicals: Silica; asbestos.

(f) Reproductive Toxins:  Chemicals that adversely affect the reproductive capabilities
    including chromosomal damage (mutations) and effects on fetuses (teratogenesis).
    Signs and Symptoms:  Birth defects; sterility.
    Chemicals:  Lead; DBCP.

(g) Cutaneous hazards: Chemicals that affect the dermal layer of the body.
     Signs and Symptoms:   Defatting of the skin; rashes; irritation.
     Chemicals:  Ketones; chlorinated compounds.

(h) Eye hazards:  Chemicals that affect the eye or visual capacity.
     Signs and Symptoms:  Conjunctivitis; corneal damage.
     Chemicals: Organic solvents; acids.

TCC:  Tag (Tagliabue) Closed Cup.  See Flash Point.

TLV:  Threshold Limit Value is a term used by ACGIH to express the airborne concentration of material to which nearly all persons can be exposed day after day without adverse effects. ACGIH expresses TLVs in three ways:

TLV-TWA:  The allowable Time-Weighted Average concentration for a normal 8 hour workday or 80 hour workweek.

TLV-STEL:  The Short-Term Exposure Limit; or maximum concentration for a continuous 15 minute exposure period (maximum of four such periods per day, with at least 60 minutes between exposure periods, and provided the daily TLV-TWA is not exceeded).

TLV-C:  The Ceiling Exposure Limit; the concentration that should not be exceeded even instantaneously.

Toxic:  A chemical falling within any of the following categories:

(a) A chemical that has a median lethal dose (LD50) of more than 50 milligrams per kilogram but not more than 500 milligrams per kilogram of body weight when administered orally to albino rats weighting between 200 and 300 grams each.

(b) A chemical that has a median lethal dose (LD50) of more than 200 milligrams per kilogram but not more than 1,000 milligrams per kilogram of body weight when administered by continuous contact for 24 hours ( or less if death occurs within 24 hours) with the bare skin of albino rabbits weighing between two and three kilograms each. 

(c) A chemical that has a median lethal concentration (LC50) in air of more than 200 parts per million but not more than 2,000 parts per million by volume of gas or vapor, or more than two millgrams per liter but not more than 20 milligrams per liter of mist, fume or dust, when administered by continuous inhalation for one hour (or less if death occurs within 1 hour) to albino rats weighing between 200 and 300 grams each.

Toxic Substances:  Any substance that can cause acute or chronic injury to the human body, or which is suspected of being able to cause diseases or injury under some conditions.

TWA:  Time-Weighted Average exposure is the airborne concentration of a material to which a person is exposed, averaged over the total exposure time-generally the total workday (8 to 12 hours).  Also see TLV.

UEL or UFL:  Upper Explosive Limit or Upper Flammable Limit of a vapor or gas; the highest concentration (highest percentage of the substance in air) that will produce a flash of fire when an ignition source (heat, arc or flame) is present. At higher concentrations, the mixture is too "rich" to burn. Also see LEL.

Unstable:  Tending toward decomposition or other unwanted chemical change during normal handling or storage.

Vapor:  The gaseous form of a solid or liquid substance as it evaporates.