UPPER EXPLOSIVE LIMIT

ACGIH

The American Conference of Governmental Industrial Hygienists is a voluntary membership organization of professional industrial hygiene personnel in governmental or educational institutions. The ACGIH develops and publishes recommended occupational exposure limits each year called Threshold Limit Values (TLVs) for hundreds of chemicals, physical agents, and biological exposure indices.

ACUTE

Severe, often dangerous conditions in which relatively rapid changes occur.

ACUTE EXPOSURE

An intense exposure over a relatively short period of time.

ANSI

The American National Standards Institute is a voluntary membership organization (run with private funding) that develops consensus standards nationally for a wide variety of devices and procedures.

ASPHYXIANT

A chemical (gas or vapor) that can cause death or unconsciousness by suffocation. Simple asphyxiants such as nitrogen, either use up or displace oxygen in the air. They become especially dangerous in confined or enclosed spaces. Chemical asphyxiants, such as carbon monoxide and hydrogen sulfide, interfere with the body's ability to absorb or transport oxygen to the tissues.

BOILING POINT

The temperature at which the vapor pressure of a liquid equals atmospheric pressure or at which the liquid changes to a vapor. The boiling point is usually expressed in degrees Fahrenheit. If a flammable material has a low boiling point, it indicates a special fire hazard.

"C" or CEILING

A description usually used with a published exposure limit. It refers to the concentration that should not be exceeded, even for an instant. It may be written as TLV-C or Threshold Limit Value — Ceiling. See also

CARCINOGEN

A substance or physical agent that may cause cancer in animals or humans.

C.A.S. NUMBER

Identifies a particular chemical by the Chemical Abstracts Service, a service of the American Chemical Society that indexes and compiles abstracts of worldwide chemical literature called "Chemical Abstracts."

CC

Cubic centimeter, a volumetric measurement that is also equal to one milliliter (mL).

CHEMICAL

An element or a compound, produced by chemical reactions on a large scale for direct industrial and consumer use, or for reaction with other chemicals.

CHEMICAL REACTION

A change in the arrangement of atoms or molecules to yield substances of different composition and properties. SEE REACTIVITY

CHP

Chemical Hygiene Plan

CHRONIC

Persistent, prolonged, or repeated conditions.

CHRONIC EXPOSURE

A prolonged exposure occurring over a period of days, weeks, or years.

COMBUSTIBLE

According to the DOT and NFPA, combustible liquids are those having a flash point at or above l00^oF (37.8^oC), or liquids that will burn. They do not ignite as easily as flammable liquids. However, combustible liquids can be ignited under certain circumstances, and must be handled with caution. Substances, such as wood, paper, etc., are termed "Ordinary Combustibles".

CONCENTRATION

Ten thousand parts per million is equal to one percent.

CORROSIVE

A substance defined by DOT, as causing visible destruction or permanent changes in human skin tissue at the site of contact, or is highly corrosive to steel.

CUBIC METER (m³)

A measure of volume in the metric system.

CUTANEOUS

Pertaining to or affecting the skin.

DECOMPOSITION

The breakdown of a chemical or substance into different parts or simpler compounds. Decomposition can occur due to heat, chemical reaction, decay, etc.

DERMAL

Pertaining to, or affecting the skin.

DERMATITIS

An inflammation of the skin.

DESIGNATED AREA

Means an area that may be used for work with select carcinogens, reproductive toxins, or substances that have a high degree of acute toxicity. A designated area may be an entire laboratory, an area of a laboratory, or a device such as a laboratory hood.Designated areas must be demarcated with designated area caution tape (available from EHRS, the Cell Center, or Chemistry stockroom) and/or posted with designated area caution signs. Storage areas must be segregated from other chemical storage. This includes all fume hoods and bench tops where the acutely toxic, carcinogenic, or reproductive hazards are handled.

DILUTION VENTILATION

See GENERAL VENTILATION

DOT

The United States Department of Transportation is the federal agency that regulates the labeling and transportation of hazardous materials.

DYSPNEA

Shortness of breath. Difficult or labored breathing.

EPA

The Environmental Protection Agency is the governmental agency responsible for administration of laws to control and reduce pollution of air, water, and land systems.

EPA NUMBER

The number assigned to chemicals (typically hazardous wastes regulated by the Environmental Protection Agency (EPA).

EPIDEMIOLOGY

The study of diseases in populations.

ERYTHEMA

A reddening of the skin.

EVAPORATION RATE

The rate at which a material is converted to vapor (evaporates) at a given temperature and pressure compared to the evaporation rate of water. Health and fire hazard evaluations of materials involve consideration of evaporation rates as one aspect of the evaluation.

EXPLOSIVE

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

^oF

Degrees, Fahrenheit. A temperature scale.

FLAMMABLE LIQUID

According to the DOT and NFPA, a flammable liquid is one that has a flash point below l00^oF (37.8^oC). See FLASH POINT.

FLASH POINT

The lowest temperature at which a liquid gives off enough vapor to form an ignitable mixture and burn when a source of ignition (sparks, open flames, cigarettes, etc.) is present. Two tests are used to determine the flash point: open cup and closed cup. The test method is indicated on the MSDS after the flash point.
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g

See GRAM

GENERAL VENTILATION

Also known as general dilution ventilation, this is a system of ventilation consisting of either natural or mechanically induced fresh air movements to mix with and dilute contaminants in the workroom air. Dilutional ventilation is not the preferred method to control contaminants that are highly toxic; when there may be corrosion problems from the contaminant; when the worker is close to where the contaminant is being generated; or where fire or explosion hazards are generated close to sources of ignition.

g/kg

See GRAMS PER KILOGRAM

GRAM (g)

A metric unit of weight. One ounce equals 28.4 grams.

GRAMS PER KILOGRAM (g/kg)

This indicates the dose of a substance given to test animals in toxicity studies. For example, a dose may be 2 grams (of substance) per kilogram of body weight (of the experimental animal).
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HAZARDOUS MATERIAL

Any substance or compound that has the capability of producing adverse effects on the health and safety of humans.

IGNITABLE

A solid, liquid, or compressed gas that has a flash point of less than 140^oF. Ignitable material may be regulated by the EPA as a hazardous waste, as well.

INCOMPATIBLE

The term applied to two substances, to indicate that one material cannot be mixed or stored with the other, without the possibility of a dangerous reaction.

INGESTION

Taking a substance into the body through the mouth.

INHALATION

The breathing in of an airborne substance that may be in the form of gases, fumes, mists, vapors, dusts, or aerosols.

INHIBITOR

A substance that is added to another to prevent, or slow down an unwanted reaction or change.

IRRITANT

A substance that produces an irritating effect when in contact with skin, eyes, nose, or respiratory system.

kg

See KILOGRAM

KILOGRAM (Kg)

A unit of weight in the metric system equal to 2.2 pounds.

L

See LITER

LC50

See LETHAL CONCENTRATION 50

LD50

See LETHAL DOSE 50

LEL

See LOWER EXPLOSIVE LIMIT

LETHAL CONCENTRATION 50

The concentration of an air contaminant (LC50) that kills 50 percent of the test animals in a group, within the first 30 days following exposure.

LETHAL DOSE 50

A calculated dose of a substance which is expected to cause the death of 50% of the entire defined experimental animal population.

LFL

See LOWER EXPLOSIVE LIMIT

LITER (L)

A measure of volume. One quart approximately equals 0.946 liters

LOCAL EXHAUST VENTILATION

(Also known as exhaust ventilation)
A ventilation system that captures, and removes the contaminants, at the point they are being produced, before they escape into the workroom air. The system consists of hoods, duct work, a fan, and possibly an air cleaning device. Advantages of local exhaust ventilation over general ventilation include: requires less air volume; more economical over the long term. However, the system must be properly designed, with properly designed and located hoods, and correctly sized fans and duct work.

LOWER EXPLOSIVE LIMIT

The lower limit of flammability of a gas or vapor. It is usually expressed in percentage of gas or vapor in air by volume.

m³

See CUBIC METER

MELTING POINT

The temperature at which a solid changes to a liquid. A melting range may be given for mixtures.

mg

See MILLIGRAM

mg/kg

See MILLIGRAMS PER KILOGRAM

mg/m³

See MILLIGRAMS PER CUBIC METER

MILLIGRAM (mg)

A unit of weight in the metric system One thousand milligrams equal one gram.

MILLIGRAMS PER CUBIC METER

Units used to measure (mg/m³) concentration of dusts, gases, mists, and fumes in air.

MILLIGRAMS PER KILOGRAM

This indicates the dose of a substance (mg/kg) given to test animals in toxicity studies. For example, a dose may be 2 milligrams (of substance) per kilogram of body weight (of the experimental animal).

MILLILITER (mL)

A metric unit used to measure VOLUME. One milliliter equals one cubic centimeter. One thousand milliliters equal one liter.

mL

See MILLILITER

MSHA

The Mine Safety and Health Administration; a federal agency that regulates the mining industry in the safety and health area.

MUTAGEN

Anything that can cause a change (or mutation) in the genetic material of a living cell.

NARCOSIS

Stupor or unconsciousness caused by exposure to a chemical.

NFPA

The National Fire Prevention Association is a voluntary membership organization whose aims are to promote and improve fire protection and prevention. NFPA has published 16 volumes of codes known as the National Fire Codes. Within these codes is Standard No. 704, "Identification of the Fire Hazards of Materials". This is a system that rates the hazard of a material during a fire. These hazards are divided into health, flammability, and reactivity hazards and appear in a well-known diamond system using from zero through four to indicate the severity of the hazard.

NIOSH

The National Institute of Occupational Safety and Health is a federal agency that among its various responsibilities, trains occupational health and safety professionals. NIOSH conducts research on health and safety concerns and tests and certifies respirators for work place use.

ODOR THRESHOLD

The minimum concentration of a substance at which a majority of test subjects can detect and identify the substance's characteristic odor.

EHRS

Office of Environmental Health & Radiation Safety located in 3160 Chestnut Street, Suite 400, phone 898-4453.

ORAL

Having to do with the mouth.

OSHA

The Occupational Safety and Health Administration — a federal agency under the Department of Labor that publishes and enforces safety and health regulations for most businesses and industries in the United States.

OXIDATION

The process of combining oxygen with some other substance or a chemical change in which an atom loses electrons.

OXIDIZER

Is a substance that gives up oxygen easily, to stimulate combustion of organic material.

OXYGEN DEFICIENCY

An atmosphere having less than 21% oxygen.

PEL

See PERMISSIBLE EXPOSURE LIMIT

PERMISSIBLE EXPOSURE LIMIT (PEL)

An exposure limit that is published and enforced by OSHA as a legal standard. PEL may be either a time-weighted-average (TWA) exposure limit (8 hour), a 15 minute short term exposure limit (STEL), or a ceiling (C). The PELs are found in Tables Z-1, Z-2, or Z-3 of OSHA REGULATIONS 1910.1000. SEE ALSO TLV.

PERSONAL PROTECTIVE EQUIPMENT

Any device or clothing worn by the worker to protect against hazards in the environment. Examples are: respirators; gloves; and chemical splash goggles.

POLYMERIZATION

A chemical reaction in which two or more small molecules combine to form larger molecules.

ppm

Parts (of vapor or gas) per million (parts of air) by volume.

REACTIVITY

A substance's susceptibility to undergoing a chemical reaction or change that may result in dangerous side effects, such as explosion, burning, and corrosive, or toxic emissions. The conditions that cause the reaction, such as heat, other chemicals, and dropping, will usually be specified as "Conditions to Avoid": when a chemical's reactivity is discussed on a MSDS.

RESPIRATOR

A device that is designed to protect the wearer from inhaling harmful contaminants.

RESPIRATORY HAZARD

A particular concentration of an airborne contaminant that, when it enters the body by way of the respiratory system, or by being breathed into the lungs, results in some bodily function impairment.
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SELECT AGENT TOXINS

A group of toxins regulated by USA PATRIOT ACT of 2001.

SENSITIZER

A substance that may cause no reaction in a person during initial exposures, but afterwards, further exposures will cause an allergic response to the substance.

SHORT TERM EXPOSURE LIMIT

Represented as STEL or TLV-STEL, this is: a maximum concentration to which workers can be exposed for a 15 minute period, four times a day, with at least one hour between exposures. Also the daily TLV-TWA must not be exceeded.

SKIN

This designation sometimes appears alongside a TLV or PEL. It refers to the likelihood of absorption of the chemical through the skin and eyes.

STEL

See SHORT TERM EXPOSURE LIMIT.

SUBSTANCE

Any chemical entity.

SYNONYM

Another name by which the same chemical may be known.

SYSTEMIC

Spread throughout the body; affecting many or all body systems or organs, not localized in one spot or area.

TERATOGEN

An agent or substance that may cause physical defects in the developing embryo or fetus when a pregnant female is exposed to the substance.

THRESHOLD LIMIT VALUE

Airborne concentrations of substances devised by the ACGIH, that represents conditions under which it is believed that nearly all workers may be exposed day after day, with no adverse effect. TLVs are advisory exposure guidelines, not legal standards, that are based on evidence from industrial experience, animal studies, or human studies when they exist. There are three different types of TLVs. They are:

• Time Weighted Average (TLV-TWA)
• Short Term Exposure Limit (TLV-STEL)
• Ceiling (TLV-C). See also PEL.

TIME WEIGHTED AVERAGE

The average time, over a given work period (e.g., 8-hour workday), of a person's exposure to a chemical or an agent. The average is determined by sampling for the contaminant throughout the time period. Represented as TLV-TWA.

TLV

See THRESHOLD LIMIT VALUE

TOXICITY

The potential of a substance to exert a harmful effect, on humans or animals, and a description of the effect and the conditions or concentration, under which the effect takes place.

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 manufacturers or distributors involved.

TWA

See TIME WEIGHTED AVERAGE

UEL

See UPPER EXPLOSIVE LIMIT

UFL

See UPPER EXPLOSIVE LIMIT.

UNSTABLE LIQUID

A liquid that in its pure state or as commercially produced, will react vigorously in some hazardous way under shock conditions (i.e., dropping), certain temperatures, or pressures.

UPPER EXPLOSIVE LIMIT

(Also known as Upper Flammable Limit) It is the highest concentration (expressed in percentage of vapor or gas in the air by volume) of a substance that will burn or explode, when an ignition source is present. Theoretically, above this limit, the mixture is said to be too "rich" to support combustion. The range between the LEL and the UEL, constitutes the flammable range, or explosive range of a substance. That is, if the LEL is 1 ppm and UEL is 5 ppm, then the explosive range of the chemical is 1 ppm to 5 ppm. See also LEL.

VAPOR

The gaseous form of substances that are normally in the liquid, or solid state (at normal room temperature and pressure). Vapors evaporate into the air from liquids, such as solvents. Solvents with low boiling points will evaporate.