SECTION XVII - GLOSSARY

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

ACGIH (top)

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

 

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 or hydrogen sulfide, interfere with the body's ability to absorb or transport oxygen to the tissues.

 

BOILING POINT (top)

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 (top)

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 THRESHOLD LIMIT VALUE.

 

CARCINOGEN

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

 

CAS 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 or used 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; a document such as this one, required under OSHA regulations.

 

CHRONIC

Persistent, prolonged, or repeated conditions.

 

CHRONIC EXPOSURE

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 100oF (37.80C), 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

The relative content of a component; strength (for example, ten thousand parts per million equal 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 destructive to steel.

 

CUBIC METER (m3)

A measure of volume in the metric system (one meter by one meter by one meter).

 

CUTANEOUS

Pertaining to or affecting the skin.

  

DECOMPOSITION (top)

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

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 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 any acutely toxic, carcinogenic, or reproductive hazard chemicals are handled.

 

DILUTION VENTILATION

See GENERAL VENTILATION.

 

DOT

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

 

DYSPNEA

Shortness of breath; difficult or labored breathing.

 

EPA (top)

The Environmental Protection Agency (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). EPA also assigns “Generator Numbers to designate hazardous waste generators (those who generate and dispose of hazardous waste).

 

EPIDEMIOLOGY

The study of disease patterns in populations.

 

ERYTHEMA

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 another known substance (e.g., water or butyl acetate).

Evaporation rate is an important aspect of health and fire hazard evaluations of materials.

 

EXPLOSIVE

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

 

oF (top)

Degrees, Fahrenheit.  A temperature scale in which water freezes at 32o  and boils at 212o .

 

FLAMMABLE LIQUID

According to the DOT and NFPA, a flammable liquid is one that has a flash point below 100oF (37.8oC).  See FLASH POINT.

 

FLASHPOINT

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 value.

 

g (top)

See GRAM (sometimes abbreviated gm).

 

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 a given space (room). Dilution ventilation is not the preferred method to control contaminants that are highly toxic, or when there may be corrosion problems from the contaminant, when a person 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) or (gm)

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

 

GRAMS PER KILOGRAM (g/kg)

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).

HAZARDOUS MATERIAL (top)

Any substance or compound that has the capability of producing adverse effects on the health and safety of humans or the environment (includes almost all chemical substances under the broad OSHA definition of “hazardous”).

 

IGNITABLE (top)

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

 

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 (top)

See KILOGRAM.

 

KILOGRAM (Kg)

A unit of mass in the metric system equal to 1,000 grams.  1 kg equals 2.2 pounds.

 

L (top)

See LITER (sometimes abbreviated Lt).

 

LD50

See LETHAL DOSE 50.

 

LEL

See LOWER EXPLOSIVE LIMIT.

 

LETHAL CONCENTRATION 50 (LC50)

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 (LD50)

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

 

LEL

See LOWER EXPLOSIVE LIMIT.

 

LITER (L)

A measure of volume in the metric system.  One quart equals approximately 0.946 liters.

 

LOCAL EXHAUST VENTILATION

(Also known as exhaust ventilation)

A ventilation system that captures, and removes the contaminants, near the point they are being produced, before they escape into the workroom air.  The system consists of hoods, ductwork, 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 (top)

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 mass in the metric system.  One thousand milligrams equal one gram.

MILLIGRAMS PER CUBIC METER (mg/m3)

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

 

MILLIGRAMS PER KILOGRAM (mg/kg)

Indicates the dose of a substance 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.

 

MUTAGEN

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

 

NARCOSIS (top)

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, 4 being the most severe.

 

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 workplace use.

 

ODOR THRESHOLD (top)

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

 

OHS

San Juan College Office of Health & Safety, located in the Educational Services Center, (505) 566-3775.

 

ORAL

Having to do with the mouth (typically relates to ingestion).

 

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 (OXIDIZING CHEMICAL)

A substance that gives up oxygen easily, to stimulate or support combustion of organic material.

 

OXYGEN DEFICIENCY

An atmosphere having less than a defined standard concentration of oxygen (19.5% or less is considered life-threatening).

 

PEL (top)

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 (PPE)

Any device or clothing worn by a person to protect against hazards in the environment.  Examples are:  respirators, gloves, chemical splash goggles, etc..

 

POLYMERIZATION

A chemical reaction in which two or more small molecules combine to form larger molecules. May be a hazardous process, depending on the particular chemicals involved).

 

ppm

Parts (of vapor or gas) per million (parts of air) by volume. 10,000 ppm equal one percent.

 

REACTIVITY (top)

A substance's susceptibility to undergoing a chemical reaction or change that may result in dangerous side effects.  Examples include explosion, burning, and corrosive or toxic emissions.  The conditions that may cause the reaction, such as heat, the presence of other chemicals, or dropping (shock), will usually be specified as "Conditions to Avoid" when a chemical's reactivity is discussed, or under “Special Storage Considerations” on a Material Safety Data Sheet (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 lungs, results in some adverse health effect.

 

SELECT CARCINOGEN (top)

A substance meeting special carcinogenic criteria as specified by OSHA and other agencies (see p. 9).

 

SENSITIZER

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

 

SHORT-TERM EXPOSURE LIMIT (STEL)

Represented as STEL or TLV-STEL, i.e., a maximum average concentration to which workers can be exposed for a 15 minute period, four times a day, with at least one hour between exposures, without adverse health effects in most persons.

 

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 (e.g., Methanol).

 

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 (possibly affecting many or all body systems or organs, not localized in one spot or area).

 

TERATOGEN (top)

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 (TLV)

Airborne concentrations of substances published by the ACGIH, that represent 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), and Ceiling TLV-C). See also PEL.

 

TIME WEIGHTED AVERAGE (TWA)

The average concentration, 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 inherent ability 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 (top)

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 (UEL)

(Also known as Upper Flammable Limit); 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.  For example, 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 (top)

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.

Gary Lee
Director of Environmental Health
4601 College Blvd.
Farmington, NM  87401
(505) 566-3063 or (505) 566-3190