GLOSSARY OF SAFETY TERMS
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A (Top of Page)
An Acute Effect is one which involves severe symptoms which
develop rapidly and may quickly reach a crisis.
Acid a proton donor
An Acute Hazard is one to which a single exposure may
cause harm, but which is unlikely to lead to permanent
damage.
Adsorption The condensation of gasses, liquids, or dissolved substances on the surfaces of solids.
Aerosols Liquid droplets or solid particles dispersed in the air that are of fine enough particle size (0.01-100um) to remain so dispersed for a period of time
Air-Purifying Respirator Respirators that use filters or sorbents to remove harmful substances from the air.
Allergic Contact Dermatitis is a type of skin
hypersensitivity. Its onset may be delayed by several days to as much
as several years, for weaker sensitizers. Once sensitized, fresh exposure to the
sensitizing material can trigger itching and
dermatitis within a few hours.
The Ames Test is used to assess whether a chemical might
be a carcinogen. It assumes that carcinogens possess
mutagenic activity, and uses bacteria and mammalian microsomes to determine whether a
chemical is a mutagen.
Approximately 85% of known carcinogens are mutagens. The Ames test, therefore, is a
helpful but not perfect predictor
of carcinogenic potential.
Argyria or Argyrism is an irreversible blueish-black
discolouration of the skin, mucous membranes or internal organs
caused by ingestion of, or contact with, various silver compounds.
The Auto-ignition Temperature of a chemical is the lowest temperature at which the
material will ignite without an
external source of ignition.
Asbestos a hydrated magnesium silicate in fibrous form.
Audible range Frequency across which normal ears hear: approximately 20 Hz to 20,000 Hz.
Autoclave An apparatus using
pressurized steam for sterilization
B (Top of Page)
Bel a unit of sound level based on a logarithmic scale.
Biohazard an abbreviation of biological hazard.
The Breakthrough Time is the time taken in standard tests
for permeation of a chemical through a protective barrier
(such as a rubber glove) to be detected.
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A Carcinogen is a chemical known or believed to cause cancer
in humans. The number of known carcinogens is
comparatively small, but many more chemicals are suspected to be carcinogenic.
The CAS Registry number is a unique number assigned to a
chemical; by the Chemical Abstracts Service.
A Chronic Hazard is a chemical which has the potential to
cause long-term damage to health, often as a consequence
of repeated or prolonged exposure to it.
Chrysiasis is the development of a blue-grey pigmentation in
skin and mucous membranes. May be caused by
exposure to gold compounds.
COSHH (the Control of Substances Hazardous to Health). The
COSHH regulations impose a number of
obligations on employers; the object of the regulations is to promote safe working with
potentially hazardous chemicals.
A Cutaneous Hazard is a chemical which may cause harm to the
skin, such as defatting, irritation, skin rashes or
dermatitis.
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D O T Common abbreviation for the U.S. Department of
Transportation, which regulates the transport of chemicals in
the U.S.A.
DOT hazard codes
1 Explosive
2.1 Flammable gas
2.2 Non-flammable gas
2.3 Poisonous gas
3 Flammable liquid
4.1 Flammable solid
4.2 Spontaneously combustible
4.3 Dangerous when wet
5.1 Oxidizer
5.2 Organic peroxide
6.1 Poison - keep away from food
6.2Infectious material
7 Radioactive
8 Corrosive
9Miscellaneous
E (Top of Page)
ED50: (Effective Dose 50) is the amount of material required
to produce a specified effect in 50% of an animal
population. (See qualification in the definition of LD50).
EINECS Acronym for European Inventory of Existing Commercial
Chemical Substances.
ELINCS Acronym for European List of Notified Chemical
Substances.
Embryotoxins retard the growth or affect the development of
the unborn child. In serious cases they can cause
deformities or death. Mercury compounds and certain heavy metals, aflatoxin, formamide and
radiation are known
embryotoxins.
Etiologic agents: microscopic organisms such as bacteria or
viruses, which can cause disease.
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f/cc Fibres per cubic centimetre of air.
FDA U.S. Food and Drug Administration.
Flashback occurs when the flame in a gas torch burns back
into the torch or hose; this is often accompanied by a
hissing or squealing sound, and a pointed or smoky flame.
The Flash Point of a chemical is the lowest temperature at which a flame will
propagate through the vapour of a
combustible material to the liquid surface. It is determined by the vapour pressure of the
liquid, since only when a
sufficiently high vapour concentration is reached, can it support combustion. It should be
noted that the source of ignition
need not be an open flame, but could equally be, for example, the surface of a hot plate,
or a steam pipe.
H (Top of Page)
Hazard Codes - see UN hazard codes.
A Hematopoietic Agent is a chemical which interfers with the
blood system by decreasing the oxygen-carrying ability
of haemoglobin. This can lead to cyanosis and unconsiousness. Carbon monoxide is one such
agent, familiar to smokers.
A Hepatotoxin is a chemical capable of causing liver damage.
HSE The Health and Safety Executive. The HSE web site can be
reached through
www.open.gov.uk/hse/hsehome.htm. The HSE is responsible for proposing and enforcing safety
regulations throughout
UK industry and academia. Publications are available on a wide variety of safety-related
issues.
Hypoxia is a condition defined by a low supply of oxygen.
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An Inhibitor is a material which is added to a chemical to
prevent an unwanted reaction. For example, BHT
(2,6-di-t-butyl-p-cresol) is often added to tetrahydrofuran to prevent potentially
dangerous polymerisation.
IARC International Agency for Research in Cancer. The IARC
home page is at http://www.iarc.fr/
IOSH Institute for Occupational Safety and Health. IOSH has
its home page at http://www.iosh.co.uk/home.html
An Irritant is a chemical which may cause reversible inflammation on contact.
L (Top of Page)
LC50: (Lethal Concentration 50) is the concentration of a
chemical which kills 50% of a sample population. This
measure is generally used when exposure to a chemical is through the animal breathing it
in, while the LD50 is the
measure generally used when exposure is by swallowing, through skin contact, or by
injection. (See also LD50).
LD50: (Lethal Dose 50) is the dose of a chemical which kills
50% of a sample population. In full reporting, the
dose, treatment and observation period should be given. Further, LD50, LC50, ED50 and
similar figures are strictly only
comparable when the age, sex and nutritional state of the animals is specified.
Nevertheless, such values are widely
reported and used as an effective measure of the potential toxicity of chemicals. (See
also LC50).
LDLO Lethal Dose Low.
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Median Lethal Dose (MDL): see LD50.
The MEL (Maximum Exposure Limit) is the maximum permitted
concentration of a chemical to which a worker
may be exposed over an extended period of time. Typically, MELs are quoted in ppm for an
8-hour reference period,
though shorter periods may be quoted for some materials. MELs are, in many countries,
enforceable by law.
MSDS A widely used abbreviation for Material Safety Data Sheet, which contains details
of the hazards associated
with a chemical, and gives information on its safe use.
A Mutagen is an agent that changes the hereditary genetic material which is a part of
every living cell. Such a mutation
is probably an early step in the sequence of events that ultimately leads to the
development of cancer.
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NIOSH National Institute for Occupational Safety and Health.
This sets OELs and provides services in occupational
health and safety investigations in the USA. The NIOSH home page is at http://www.cdc.gov/niosh/
A Nephrotoxin is a chemical which may cause kidney damage.
Common examples include antimony compounds,
dimethyl sulphoxide, dimethylformamide and tetrahydrofuran.
A Neurotoxin is a chemical whose primary action is on the CNS (Central Nervous System).
Many neurotoxins, such
as some mercury compounds, are highly toxic, and must only be used under
carefully-controlled conditions.
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OEL (Occupational Exposure Limit) A (generally
legally-enforcable) limit on the amount or concentration of a
chemical to which workers may be exposed.
The Odour Threshold is the lowest concentration of a vapour in air which can be detected
by smell.
OES (Occupational Exposure Standard)
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PEL: Permissible Exposure Limit is a time-weighted average
(TWA) or absolute value (usually prescribed by
regulation) setting out the maximum permitted exposure to a hazardous chemical.
Peroxidizable materials can form peroxides in storage, generally when in contact with the
air. These peroxides
present their most serious risk when the peroxide-contaminated material is heated or
distilled, but they may also be
sensitive to mechanical shock. The quantity of peroxides in a sample may be determined
using a simple peroxide test
strip.
Photoallergic Contact Dermatitis is a skin condition brought
on by exposure to light following skin contact with
certain types of chemicals, such as sulphonamides.
Poison Class A or B Poisons are classified by the DOT into
two classes. Those in Class A are highly toxic materials
which, even in very small quantities, present a hazard to life. Examples of such gases are
cyanogen, phosgene and
hydrocyanic acid. Class B poisons, though less toxic, are presumed to present a serious
threat to health during
transportation.
Pictographs widely-used pictorial representations of the
hazards presented by chemicals.
PPB Parts Per Billion. Used to specify the concentration (by
volume) of a gas or vapour at very low concentration, or a
dissolved material at high dilution.
PPM Parts Per Million. Used to specify the concentration (by
volume) of a gas or vapour at low concentration, or a
dissolved material at high dilution.
Pyrophoric materials ignite spontaneously in air. Since a
wide variety of chemicals will burn if heated sufficiently, it is
usual to define a pyrophoric material as one which will ignite spontaneously at
temperatures below about 45 C.
R (Top of Page)
A Reproductive Toxin, such as vinyl chloride or PCBs, is a
chemical which may cause birth defects or sterility.
Risk phrases, coded in the form R34, R61 etc are now included in MSDS sheets for chemicals
purchased in the UK.
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A Sensitizer is a chemical which may lead to the development
of allergic reactions after repeated exposure.
STEL (Short Term Exposure Limit) is the maximum permissible concentration of a material,
generally expressed
in ppm in air, for a defined short period of time (typically 5 minutes). These values,
which may differ from country to
country, are often backed up by regulation and therefore may be legally enforceable.
Systemic poisons have an effect which is remote from the site
of entry into the body.
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TCSA Toxic Substances Control Act. This regulates the
manufacture, transport and use of toxic substances in the
USA.
A Teratogen is a chemical which may cause genetic mutations
or malformations in the developing foetus.
TLV (Threshold Limit Value)T is the maximum permissible
concentration of a material, generally expressed in parts
per million in air for some defined period of time (often 8 hours). These values, which
may differ from country to country,
are often backed up by regulation and therefore may be legally enforceable.
TLV-C Ceiling exposure limit - an exposure limit which should
not be exceeded under any circumstances.
TSCA Acronym for Toxic Substances Control Act.
TWA (Time Weighted Average) This term is used in the
specification of Occupational Exposure Limits (OELs) to
define the average concentration of a chemical to which it is permissible to expose a
worker over a period of time,
typically 8 hours.
U (Top of Page)
UN Hazard codes
Class 1 Explosive
Class 2 Gases
Class 3.1 Flammable liquids, flash point below -18C
Class 3.2 Flammable liquids, flash point between -18C and 23C
Class 3.3 Flammable liquids, flash point between 23C and 61C
Class 4.1 Flammable solids
Class 5.1 Oxidizing agents
Class 5.2 Organic peroxides
Class 6.1 Poisonous substances
Class 7 Radioactive substances
Class 8 Corrosive substances
Class 9 Miscellaneous dangerous substances
NR Non-regulated
V (Top of Page)
A Vesicant is a chemical which, if it can escape from the
vein, causes extensive tissue damage, with vesicle formation or
blistering.
VOCs Volatile Organic Compounds.