MSDS Glossary

Glossary of MSDS terms:

Acute Toxicity

The adverse effects resulting from a single exposure to a substance.


In chemistry, an alkali is a basic, ionic salt of an alkali metal or alkaline earth metal chemical element. An alkali also can be defined as a base that dissolves in water. A solution of a soluble base has a pH greater than 7.0.

American Association of Poison Control Centers (AAPCC)

The American Association of Poison Control Centers supports the nation’s 55 poison centers in their efforts to prevent and treat poison exposures.

Poison Help line at 1-800-222-1222 and online at

Autoignition temperature

The autoignition temperature of a substance is the temperature at or above which a material will spontaneously ignite (catch fire) without an external spark or flame.


Biodegradation is the process by which a substance biodegrades;  chemically decomposed (broken down to simpler components) by natural biological processes (e.g. soil bacteria, weather, plants, animals).  See Decomposition.


Biochemical oxygen demand / chemical oxygen demand.

Boiling Point

Boiling point is the temperature at which a liquid changes to a gas (vapor) at normal atmospheric pressure.

The temperature at which the vapor pressure of a liquid is equal to the external pressure.


A material that contains or can form carcinogens.  A carcinogen causes cancer in living cells.  A known human carcinogen means there is sufficient evidence of a cause and effect relationship between exposure to the material and cancer in humans.

CAS #   (Chemical Abstracts Service Registry Number)

A Chemical Abstracts Service Registry Number is a unique identifier that tells you, for example, that acetone and dimethyl ketone are actually the same substance.

The Chemical Abstracts Service, is a division of the American Chemical Society.

CFR   (U.S. Code of Federal Regulations)

The U.S. Code of Federal Regulations is a compilation of the general and permanent rules published in the Federal Register by the Executive departments and agencies of the Federal Government. The U.S. Federal Register is the official daily publication for Rules, Proposed Rules, and Notices of Federal agencies and organizations, as well as Executive Orders and other Presidential Documents.

Combustible Liquid

OSHA defines a combustible liquid as “any liquid having a flash point at or above 100 deg. F (37.8 deg. C), but below 200 deg. F (93.3 deg. C), except any mixture having components with flashpoints of 200 deg. F (93.3 deg. C), or higher, the total volume of which make up 99 percent or more of the total volume of the mixture.”

Critical Temperature

The temperature above which a pure gas cannot be liquefied, regardless of the degree of compression.


Decomposition is the breakdown or change of a material or substance (by heat, chemical reaction, or other processes) into other chemical compounds.

Typed of Decomposition:

Biodegradation is the process by which a substance biodegrades;  chemically decomposed (broken down to simpler components) by natural biological processes (e.g. soil bacteria, weather, plants, animals).

Chemical decomposition is decomposition induced by the addition of one or more chemicals to a substance.

Thermal decomposition is decomposition initiated by heating.

Hazards of Decomposition:

1.  New substances may be formed, some or all of which are explosive, flammable, or toxic.  Peroxide-forming materials are particularly dangerous.

2.  Decomposition may result in the release of a large amount of heat, possibly resulting in a fire or explosion. The phrase “explosive decomposition” may appear on the MSDS.

3.  Partial decomposition can introduce toxins or other unstable materials as well as degrade the physical properties of the material.

4.  Polymerization of the material may occur, changing an easily handled liquid into an insoluble solid.

DOT   (U.S. Department of Transportation)

The U.S. Department of Transportation. Their mission is to serve the U.S. by ensuring a fast, safe, efficient, accessible and convenient transportation system that meets our vital national interests and enhances the quality of life of the American people.

Contact:   (855) 368-4200

Web Site:


Dangerous Substances Classification and Labeling.

 EC50   (50% Effective Concentration)

The effective concentration of a substance that causes 50% of the maximum response.

EC Number   (European Community Number)

The European Community number (EC Number) is a unique seven-digit identifier that was assigned to substances for regulatory purposes within the European Union by the European Commission. The so-called EC Inventory comprises three individual inventories, EINECS, ELINCS and the NLP list.

 EINECS #  (European Inventory of Existing Commercial Substances)

The European Inventory of Existing Commercial Substances (EINECS) originally listed all substances that were reported to be on the market in Europe between 1 January 1, 1971 and September 18, 1981. The substances placed on the market for the first time after this target date are “new”. There are 100,196 different substances in the EINECS.


Moisturizers or emollients are complex mixtures of chemical agents specially designed to make the external layers of the skin softer and more pliable. They increase the skin’s hydration by reducing evaporation

EPA   (Environmental Protection Agency)

The Environmental Protection Agency. Their mission is to protect human health and the environment. Since 1970, EPA has been working for a cleaner, healthier environment for the American people.  Contact Region 4 (South Eastern states)  404-562-9900

Web Site:

ERG    (Emergency Response Guidebook)

The Emergency Response Guidebook: A Guidebook for First Responders During the Initial Phase of a Dangerous Goods/Hazardous Materials Transportation Incident (ERG) is used by emergency response personnel (such as firefighters, and police officers) in Canada, Mexico, and the United States when responding to a transportation emergency involving hazardous materials.


A solid or liquid substance (or mixture of substances) which is in itself capable by chemical reaction of producing gas at such a temperature and pressure and at such a speed as to cause damage to the surroundings. Pyrotechnic substances are included even when they do not emit gases.

 Eye Irritation

The production of changes in the eye following the application of test substance to the front surface of the eye, which are fully reversible within 21 days of application.


A fetotoxin is a substance or agent that can poison or cause degenerative effects in a developing fetus or embryo. The effects are generally similar to those an adult would suffer from exposure. This is closely related to a teratogen, which causes malformations of an embryo or fetus. Both fetotoxins and teratogens are reproductive toxins, substances which cause damage to one’s reproductive and/or endocrine system and/or a developing fetus.

Flammable limits 

Flammable limits apply generally to vapors and are defined as the concentration range in which a flammable substance can produce a fire or explosion when an ignition source (such as a spark or open flame) is present. The concentration is generally expressed as percent fuel by volume.

Above the upper flammable limit (UFL) the mixture of substance and air is too rich in fuel (deficient in oxygen) to burn. This is sometimes called the upper explosive limit (UEL).

Below the lower flammable limit (LFL) the mixture of substance and air lacks sufficient fuel (substance) to burn. This is sometimes called the lower explosive limit (LEL).

Any concentration between these limits can ignite or explode — use extreme caution! Being above the upper limit is not particularly safe, either. If a confined space is above the upper flammable limit and is then ventilated or opened to an air source, the vapor will be diluted and the concentration can drop into the flammable limit range.

Flammable Liquid

OSHA defines a flammable liquid as “any liquid having a flash point below 100 deg. F. (37.8 deg. C.), except any mixture having components with flash points of 100 deg. F. (37.8 deg. C.) or higher, the total of which make up 99 percent or more of the total volume of the mixture. Flammable liquids shall be known as Class I liquids.”


The lowest temperature at which a liquid can form an ignitable mixture in air near the surface of the liquid. The lower the flash point, the easier it is to ignite the material.

Hazard Class

The nature of the physical, health or environmental hazard, e.g., flammable solid, flammable liquid, or poisonous material.  Note several Hazard Classes have subcategories such as 1.1 (mass explosion hazard), 1.2 (projection hazard explosive), 1.3 (fire hazard explosive), etc.

  • Class 1  =  Explosive
  • Class 2  =  Compressed Gas
  • Class 3  =  Flammable Liquid
  • Class 4  =  Flammable Solid
  • Class 5  =  Oxidizer
  • Class 6  =  Poisonous Material
  • Class 7  =  Radioactive
  • Class 8  =  Corrosive Material
  • Class 9  =  Miscellaneous Hazardous Material

HMIS   (Hazardous Materials Identification System)

The Hazardous Materials Identification System (HMIS) is a numerical hazard rating that incorporates the use of labels with color developed by the American Coatings Association as a compliance aid for the OSHA Hazard Communication Standard.

HTS Code  (Harmonized Tariff Schedule)

The Harmonized Tariff Schedule of the United States (HTS) sets out the tariff rates and statistical categories for all merchandise imported into the United States.

Layman’s Guide to HTS

HTS / Schedule B (Model Fuel) = 3824.90.9140

ICSC   (International Chemical Safety Cards)

An ICSC summarizes essential health and safety information on chemicals for their use at the “shop floor” level by workers and employers in factories, agriculture, construction and other work places.

ICSC are not legally binding documents, but consist of a series of standard phrases, mainly summarizing health and safety information collected, verified and peer reviewed by internationally recognized experts, taking into account advice from manufacturers and Poison Control Centers.

IMO    (International Maritime Organization)

International Maritime Organization.  a specialized agency of the United Nations, IMO is the global standard-setting authority for the safety, security and environmental performance of international shipping. Its main role is to create a regulatory framework for the shipping industry that is fair and effective, universally adopted and universally implemented.  Responsible for the safety and security of shipping and the prevention of marine pollution by ships.


The substance contains or can form Ions.  Ion: An atom or group of atoms with an electrical charge resulting from the loss or gain of one or more electrons during chemical reactions: the loss of electrons results in a positively charged ion (cation), the gain of electrons in a negatively charged ion (anion).


a chemical, which is not corrosive, but which causes a reversible inflammatory effect on living tissue by chemical action at the site of contact.

LC50   (50% lethal concentration)

The concentration of a chemical in air or of a chemical in water which causes the death of 50% (one-half) of a group of test animals.

LD50   (50% lethal dose)

Means the amount of a chemical, given all at once, which causes the death of 50% (one half) of a group of test animals.

Melting Point

The temperature at which a solid becomes a liquid at normal atmospheric pressure.

MSDS   (Material Safety Data Sheet)

Material Safety Data Sheet. These are documents that are required to be developed for every chemical or material that is deemed hazardous by OSHA.


The substance contains or can form mutagens.  A mutagen is a substance or agent that causes an increase in the rate of change in genes (subsections of the DNA of the body’s cells). These mutations (changes) can be passed along as the cell reproduces, sometimes leading to defective cells or cancer.


neurotoxin is a toxic agent or substance that inhibits, damages or destroys the tissues of the nervous system, especially neurons, the conducting cells of your body’s central nervous system.

NFPA   (National Fire Protection Association)

The National Fire Protection Association (NFPA) is a United States trade association, albeit with some international members, that creates and maintains private, copyrighted, standards and codes for usage and adoption by local governments. This includes publications from model building codes to the many on equipment utilized by firefighters while engaging in hazardous material (hazmat) response, rescue response, and some firefighting.

NFPA – Fire Diamond

A Diamond shaped Symbol with 4 sections ( Red / Blue / Yellow / White ).

There are four colored sections on the diamond. Each section is labelled with a number from 0-4 to indicate the level of hazard. On this scale, 0 indicates “no hazard” while 4 means “severe hazard”. The red section indicates flammability. The blue section indicates health risk. Yellow indicates reactivity or explosivity. The white is section is used to describe any.

NIOSH   (National Institute for Occupational Safety and Health)

The National Institute for Occupational Safety and Health is the only federal Institute responsible for conducting research and making recommendations for the prevention of work-related illnesses and injuries.  Contact  800-CDC-INFO  (800-232-4636)

NRC    (National Response Center)

The National Response Center (NRC) is the federal government’s national communications center, which is staffed 24 hours a day by U.S. Coast Guard officers and marine science technicians. The NRC is the sole federal point of contact for reporting all hazardous substances releases and oil spills. The NRC receives all reports of releases involving hazardous substances and oil that trigger federal notification requirements under several laws.

Anyone witnessing an oil spill, chemical release or maritime security incident should call the NRC hotline at 1-800-424-8802.

 OSHA   (Occupational Safety and Health Administration)

The Occupational Safety and Health Administration aims to ensure worker safety and health in the U.S. by working with employers and employees to create better working environments. Since its inception in 1971, OSHA has helped to cut workplace fatalities by more than 60 percent and occupational injury and illness rates by 40 percent.  OSHA contact 1-800-321-OSHA (6742).

PEL   (Permissible Exposure Limit)

A Permissible Exposure Limit (PEL) is the maximum amount or concentration of a chemical that a worker may be exposed to under OSHA regulations.

PEL’s can be defined in two different ways as discussed in the OSHA regulation on air contaminants, 29 CFR 1910.1000

Ceiling values – at no time should this exposure limit be exceeded. Sometimes denoted with the letter C.

8-hour Time Weighted Averages (TWA) – are an average value of exposure over the course of an 8 hour work shift.

TWA levels are usually lower than ceiling values. Thus, a worker may be exposed to a level higher than the TWA for part of the day (but still lower than the ceiling value) as long as he is exposed to levels below the TWA for the rest of the day. See 1910.1000 for the formulas used in the calculations.


A permeator is a chemical which can pass through the outer protective dermal layers (skin) and into the body, and can either expose the body to toxic effects of that chemical OR act as a carrier for other toxic/hazardous chemicals.


pH tells you whether a solution is acidic, basic or neutral. The corresponding ranges are:

1. Acidic – the pH is between zero and 7.0

2. Neutral – the pH is 7.0

3. Basic Solution (also called alkaline) – the pH is between 7.0 and 14.


Polymerization is the process by which monomers (smaller chemical units) are combined to form a polymer.

A polymer is a substance made up of many repeating units (called monomer units). Polymers are usually distinguished by a high molar mass (formula weight), often ranging into thousands or millions of grams per formula unit.

Polymerization of monomers is often an exothermic process (one that evolves heat). If polymerization begins when it is not desired, the result could be a fire or explosion. Materials that have this kind of behavior are often described as HAZARDOUS POLYMERIZATION on their MSDS.


Parts per million.  This measurement is the mass of a chemical or contaminate per unit volume of air or water.

RTECS   (Registry of Toxic Effects of Chemical Substances)

The Registry of Toxic Effects of Chemical Substances is a toxicology database of over 140,000 chemicals compiled, maintained, and updated by NIOSH.

SANS    (South African National Standards – Transportation of Dangerous Goods)

A set of standards set forth by The South African Bureau of Standards (SABS).


SDS  –  Safety Data Sheet.  ( new standard for the MSDS ).

Skin Irritation

The production of reversible damage to the skin following the application of a test substance for up to 4 hours.


The solubility of a substance is the maximum amount of a material (called the solute) that can be dissolved in given quantity of solvent at a given temperature.  When a solute is dissolved in a solvent to give a homogeneous mixture, one has a solution.

Solubility is generally expressed as the number of grams of solute in one liter of saturated solution.  For example, 12 g/L at 25oC.


The substance contains or can form teratogens.  A teratogen is an agent that can cause malformations of an embryo or fetus. This can be a chemical substance, a virus or ionizing radiation. This is closely related to a fetotoxin, an agent that causes poisoning effects on a developing fetus.  Both fetotoxins and teratogens are reproductive toxins, substances which cause damage to one’s reproductive and/or endocrine system and/or a developing fetus.

TLV    (Threshold Limit Value)

Threshold Limit Values (TLV’s) are guidelines (not standards) prepared by the American Conference of Governmental industrial Hygienists, Inc (ACGIH) to assist industrial hygienists in making decisions regarding safe levels of exposure to various hazards found in the workplace.

A TLV reflects the level of exposure that the typical worker can experience without an unreasonable risk of disease or injury. TLVs are not quantitative estimates of risk at different exposure levels or by different routes of exposure.

Whereas OSHA sets regulatory exposure limits such as the PEL and TWA, TLVs are a scientific opinion based solely on health factors; there is no consideration given to economic or technical feasibility of implementing controls to keep workers exposure levels below this level.  These health risk/factors are determined by ACGIH from a review of existing peer-reviewed scientific literature by committees of experts in public health and related sciences.  TLVs are not consensus standards (i.e. formulated by a broad based committee across a particular industry), but ACGIH’s opinion.


Defined by OSHA as a chemical which falls in any of these three categories:

1. 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 weighing between 200 and 300 grams each.

2. 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.

3. 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 milligrams 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 one hour) to albino rats weighing between 200 and 300 grams each.

Transport Emergency Cards    (TREC  /  TREMcard)

A Tremcard or a Transport Emergency Card as it is also known as is a document that is used when transporting dangerous goods. The Tremcard contains important safety information about the vehicles load. In an emergency scenario, the driver of the vehicle or rescue personnel can refer to the Tremcard to determine what dangerous goods are being transported and how the load should be treated. If there are different types of dangerous goods being transport on the same vehicle, then a Tremcard will be required for each type of dangerous item.

Transport emergency cards must be carried in the cab of any vehicle carrying dangerous goods in quantities exceeding the exempt quantities. The purpose is to instruct the driver in the event of an incident. They may also assist emergency response workers, as they carry information which is specific to the particular goods being carried. There must be a card for each dangerous goods item in the load.

The consignor must either supply the card/s or give enough information for the operator to obtain the correct card/s. However, this does not absolve the carrier from a legal obligation to ensure that cards are in fact appropriate to the load. It is vital that the driver read and understand the card for any product before loading it.

TREMcards of CEFIC (European Council of Chemical Manufacturers’ Federation) origin are now obsolete and transport emergency cards must be compiled using prescribed phrases listed in SANS 10232-4 (S A National Standards Transportation of Dangerous Goods).

TREC – Transport Emergency Card generated by SANS10232-4 (South African National Standards).

TREMcard – Transport Emergency Card generated by CEFIC (European Council of Chemical Manufacturers’ Federation).

 TSCA   (The Substances Control Act of 1976)

The Substances Control Act of 1976 authorizes the EPA to track the 75,000 industrial chemicals currently produced or imported into the U.S.

TWA   (Time-Weighted Average)

Time-Weighted Average (TWA).  The average amount of allowable exposure to a substance over time.  also see PEL (Permissible Exposure Limit).  TWA levels are usually lower than ceiling values. Thus, a worker may be exposed to a level higher than the TWA for part of the day (but still lower than the ceiling value) as long as he is exposed to levels below the TWA for the rest of the day. See 1910.1000 for the formulas used in the calculations.

UN / NA #

United Nations (UN) Numbers are four-digit numbers used to identify hazardous chemicals or classes of hazardous materials worldwide. North American (NA) Numbers are identical to UN numbers. If a material does not have a UN number, it may be assigned an NA number. These numbers are required for the shipment of hazardous materials.

Vapor Pressure

The pressure exerted when the liquid and vapor are in dynamic equilibrium. If a substance were put in a closed container, some of it would vaporize. The pressure in the space above the liquid would increase from zero and eventually stabilize at a constant value – the vapor pressure. Liquids that aren’t in a closed container still have a vapor pressure.

WHMIS    (Workplace Hazardous Materials Information System)

The Workplace Hazardous Materials Information System is Canadian legislation covering the use of hazardous materials in the workplace. It includes assessment, signage, labeling, material safety data sheets and worker training.  Contact  Toll free: 1-866-225-0709

WHMIS Classes (Hazard Classes)


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