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
-
A
- Absorption
- A process by which a
substance may be incorporated or taken into the body (e.g. through the
skin). Penetration of a substance into another substance.
- Accumulate:
- Increase, build up.
- ACGIH:
- Abbreviation for American
Conference of Governmental Industrial Hygienists.
- Acid:
- A chemical which has the
ability to neutralise an alkali to form a salt. Certain acids react
vigorously with metals, releasing hydrogen gas. Acids may also be
corrosive to the skin, eyes and mucous membranes, especially in
concentrated form. Acid turns blue litmus paper red. Sulphuric,
hydrochloric and nitric acid are common examples.
- Acidosis:
- Acid poisoning in the blood.
- Acute
effect:
- An adverse effect on a human
or animal, following a single dose or short exposure with symptoms
developing rapidly.
- Acute
toxicity:
- The toxic effects resulting
from a single dose or short exposure to a substance.
- ADN/ADNR:
- ADN
- Accord relatif au transport de marchandises Dangereuses par voies de
Navigation intérieures (European Provisions concerning the
International Carriage of Dangerous Goods by Inland Waterways). ADNR
- Accord relatif au transport de marchandises Dangereuses par voies de
Navigation intérieures sur le Rhin (Provision concerning the
Carriage of Dangerous Goods on the Rhine).
- ADR:
- An Agreement drawn up by the
United Nations Economic Commission for Europe in Geneva, whereby most
States in Europe have agreed common rules for the movement of dangerous
goods by road across their frontiers and through their territories. The
abbreviated name "ADR" comes from key words in the French title Accord
européen relatif au transport international des marchandises
Dangereuses par Route (European Agreement concerning the international
carriage of dangerous goods by road).
- Administrative
controls:
- Controls designed to limit
the amount of time a worker spends at a potentially hazardous job.
- Adsorption:
- Condensation of gases,
liquids or dissolved substances on the surfaces of solids.
- Adverse
effect
(response:
- Any change from an
organism’s normal state. Producing a toxic adverse effect
depends on the concentration of the active compound at the target site.
Some of these changes may be short-lived, functional and relatively
reversible at low dosages and become chronic and irreversible at higher
dosages.
- Aerobes:
- Micro-organisms that survive
in the presence of oxygen (air).
- Aerosol:
- An airborne mist of a solid
or liquid substance.
- Air
monitoring:
- Air monitoring means
monitoring of the concentrations of airborne hazardous chemical
substances. The sampling and measuring of pollutants in the air.
- Alcohol resistant
foam:
- Medium to fight fires of
highly flammable, water soluble substances. It has less mechanical
strength than other foams.
- Aliphatics:
- Refers to an open-chain or
fatty series of hydrocarbons. Usually applied to petroleum products
derived from a paraffin or olefin base and having a straight or
branched chain molecular structure. Substances such as ethane and
ethylene are typical aliphatic hydrocarbons. Also see "Aromatic".
- Alkali:
- A compound that has the
ability to neutralize an acid to form a salt. A substance which is
somewhat irritating or corrosive to the skin, eyes and mucous
membranes. Turns red litmus paper to blue. Common strong alkalis are
sodium and potassium hydroxide.
- Allergic
reaction:
- An abnormal physiological
response in a person who has become hypersensitive to a specific
substance. Some forms of dermatitis and asthma may be caused by
allergic reactions to chemicals.
- Anaerobe:
- Micro-organisms that survive
without oxygen (air).
- Anaesthetic
effect:
- The temporary loss of
feeling which reduces the ability to feel pain and/or other sensations.
- Antidote:
- An agent that neutralizes or
counteracts the effects of a poison.
- Approved
inspection
authority:
- Defined in the Occupational
Safety Act: An inspection authority approved by the chief inspector:
Provided that an inspection authority approved by the chief inspector
with respect to any particular service shall be an approved inspection
authority with respect to that service only.
- Aromatic:
- The name "aromatics" is
derived from their rather pleasant odour. The chemical may, however, be
carcinogenic. Refers to petroleum products which have a ring molecular
structure. Aromatics tend to burn with black, smoky flames. Benzene,
toluene and xylene are the principal aromatics.
- Asphyxiant:
- A vapour or gas which can
cause unconsciousness or death by suffocation (lack of oxygen).
- Aspiration
hazard:
- The danger of drawing a
fluid into the lungs and causing chemical pneumonia or other
inflammatory response.
- Association:
- The relationship between two
or more events, characteristics, or other variables, often quantified
in statistical terms. Synonyms are correlation, statistical dependence
and relationship. A (numerical) relationship between 2 or more events,
characteristics, or other variables.
- ASTM:
- American Society for Testing
Materials.
- Attenuation:
- Attenuation means the proven
capability of hearing protectors to reduce the equivalent noise level
to which the wearer thereof is exposed.
-
- Auto-ignition
temperature:
- The approximate lowest
temperature at which a flammable gas or vapour-air mixture will
spontaneously ignite without spark or flame.
-
B
- Bar:
- A non SI unit of pressure.
Normal atmospheric pressure = 1.013 bar (= 1013 mbar).
- BEI:
- Abbreviation for Biological
Exposure Index. The Biological Exposure Index (BEI) is a reference
value intended as a guideline for the evaluation of potential health
hazards.
- Bias:
- A systematic deviation from
the truth. Any trend in the collection, analysis, interpretation,
publication, or review of data that can lead to conclusions that are
systematically different from the truth. We understand bias as either
selection or information bias. See confounding.
Selection bias. This occurs where there are systematic differences in
characteristics between those in the population selected for study and
those that are not.
Information bias. This occurs where there are systematic errors in
measurement, recording, management, analysis or reporting of data. Most
often, information bias is an error due to different quality or
accuracy of information between groups compared. It refers to
measurement of exposure or of effect.
- Bioaccumulation:
- The process in and by which
chemical substances are accumulated in living organisms.
- Bioavailability:
- The medium a substance is
found in, its physical and chemical properties, shape, size, reactivity
and solubility, determine how readily it enters the body, how it
distributes within the body, and the rate of its excretion. The
activity of toxicity of a given substance may be dramatically decreased
by the chemical species, protein binding or environmental matrix.
- Biodegradation:
- Natural decomposition of a
substance via biological processes.
- Biological
monitoring:
- Usually consists of blood
and urine tests performed to look for traces of chemicals and
biological indicators of chemical exposure.
- Biolmarkers
- Biomarkers fall into three
principal categories: exposure, susceptibility and effect. Exposure
assessments have traditionally depended almost exclusively on
measurements or model predictions of concentrations of chemical
pollutants in relevant environmental media such as air, water, food and
soil. An example of a biomarker of exposure is a measurement of a
substance or its metabolite and provides an indication of degree of
exposure. A biomarker of effect is a measurable biochemical,
physiologic or other alteration within an organism that, depending on
magnitude can indicate potential or established disease (DNA adducts,
specific enzyme activity etc.). A biomarker of susceptibility is an
indicator of an inherent or acquired variation in an organism's ability
to tolerate a specific substance. Susceptibility may vary due to
combinations of environmental characteristics, genetic predisposition,
age, gender, diet, lifestyle factors, comorbidity and other factors.
Optimally a biomarker should be an indicator of both dose and effect.
- Body
burden:
- A concept related to
bioavailability reflecting the total amount of a substance within the
body at a point in time and depends upon total dosage, metabolism and
elimination or excretion.
- Boiling
point:
- The temperature at which a
liquid changes to a vapour state, at a given pressure. For mixtures,
the initial "boiling point" or the "boiling range" may be given.
- Burns:
- An injury to skin tissue
caused by heat, chemicals, electricity or irradiation.
-
C
- Carcinogen:
- A substance or agent capable
of causing cancer.
- CAS number:
- A number assigned to
specific chemicals by the Chemical Abstracts Service. (An organization
operated by the American Chemical Society which indexes chemical
information). The CAS number is a concise, unique means of chemical
identification.
- Caustic:
- A compound that strongly
irritates, burns, corrodes or destroys living tissue.
- cc:
- An abbreviation for "cubic
centimeter" (cm3.
1 cc = 1 ml (millilitre).
- ºC:
- Degrees Celsius or
Centigrade.
- Chemical
pneumonitis:
- Inflammation of the lungs,
caused by inhalation or aspiration of an irritating substance.
- Chronic
effect:
- An effect that usually
appears a long time after the exposure occurred and persists over time.
- CL:
- The maximum allowable human
exposure limit for an airborne substance; not to be exceeded, even
momentarily. Also see "PEL"
and "TLV.
- COC:
- Material which potentiates
the effect of a carcinogen.
- Cocarcinogen:
- Cleveland Open Cup: a flash point
test method.
- Coma:
- A state of deep
unconsciousness from which one cannot be aroused, even by powerful
stimulation.
- Combustible:
- A substance capable of
fuelling a fire.
- Compatibility:
- Ability of two or more
substances to mix without objectionable changes in their physical or
chemical properties.
- Condensation:
- Change in physical state of
a substance from vapour to liquid (or solid) form.
- Confounding:
- This occurs where the
effects of two concurrent or simultaneous processes in causing an
outcome are not explicitly separated. (Risk factor 1 seemingly causes
an outcome, but in reality another risk factor 2 is mixed-in with risk
factor 1 and distorts the apparent contribution of risk factor 1, by
having an impact on the outcome.) See bias.
- Container:
- Any bag, barrel, bottle,
box, can, drum, reaction vessel, storage tank, road- or rail-tanker, or
the like that contains a hazardous chemical. Pipes or piping systems
are not considered to be containers.
- Corneal
conjunctivitis:
- Burns to the transparent
membrane covering the eyeball and lining of the eyelids.
- Corrosive:
- A material that causes
visible destruction or irreversible alterations in tissue at the site
of contact.
- Cutaneous:
- Of or relating to skin.
-
D
- Danger:
- A danger is anything which
may cause injury to persons or damage to property.
- Dangerous
to the
environment:
- Descriptive of a substance
or preparation that presents an acute or a chronic danger to one or
more components of the environment
- dB(A):
- dB(A) is the unit of
measurement of sound pressure level.
- Decomposition:
- Breakdown of a material or
substance (by heat, chemical reaction, electrolysis, decay or other
processes).
- Defatting:
- The removal of natural oils
from the skin by a fat-dissolving solvent.
- Deflagration:
- To burn rapidly with intense
heat and sparks being given off.
- Dehydration:
- The removal of water from a
substance. A condition that results from an excessive loss of body
fluids. Abnormal depletion of bodily water.
- Denominator:
- The lower portion of a
fraction. Epidemiologists use fractions to calculate rates, or ratios.
The denominator is usually the population at risk, although it may also
be a measure, such as person-time, that quantifies the population's
exposure.
- Dermal:
- Of or pertaining to the skin.
- Dermal
toxicity:
- Toxic effects resulting from
skin exposure to a substance.
- Dermal
sensitisation:
- A hypersensitivity response
of the skin resulting from repeated contact with an allergenic
substance.
- Dermatitis:
- Inflammation of the skin
often characterised by oozing, redness and itching.
- Detonation:
- To explode with sudden force.
- Disability/Disablement:
- The term "disability" refers
to an impairment,
which prevents the person from accomplishing certain tasks, or from
performing an occupation, thereby impacting on his/her ability to live
a normal life, or to earn an income.
- Distribution:
- The complete summary of the
frequency and pattern of the values or categories of a measurement. In
epidemiology, distribution is the frequency and pattern of
health-related characteristics and events in a population. Classically
described in terms of time place and person/ population.
- Dose:
- The amount of a substance
that is actually taken in by the worker's body. The dose depends on how
much of the substance the worker is exposed to and how long he or she
is exposed. Units of measure for dosage may vary but are usually given
as milligrams of chemical per kilogram of body weight (mg/kg) or
milligrams per meter square so that dosages can be compared. The
quantitative dosage as well as temporal patterns, (schedule, duration
and frequency), and how the route by which the dose is administered are
all important parameters in predicting toxic effect.
- Downwind:
- In the direction toward
which the wind is blowing in relation to the object or area in
question. See also upwind.
- Dry
chemical powder:
- A powdered fire
extinguishing agent.
- Dusts:
- Solid particles suspended in
air generated by a mechanical process such as crushing, grinding,
abrasion or blasting.
- E
- Employee
Assistance
Programme (EAP):
- This is the delivery of
support services for employees that are functioning sub-optimally due
to physical, psychological and social problems, and include
counselling, training, rehabilitation, and the mobilisation of
statutory bodies where necessary.
- Employee
Benefits
& Curative Care:
- This includes matters such
as pension or provident fund provision, statutory entitlements, such as
sick leave, perinatal leave, medical aid, hospital insurance and other
negotiated benefits.
- EEC Hazard
classification:
- Hazard and safety
information as provided on the label (symbols and R & S
phrases). Symbol - Pictogram appearing on user labels for packaged
goods, also characterised by a letter (e.g. picture of flame and F+:
very flammable substance).
- EINECS:
- The European Inventory of
Existing Chemical Substances. A list of chemical substances identified
by CAS and EINECS numbers that were marketed in the European Community
between January 11971 and September 18, 1981
- ELINICS:
- A list of approximately 400
chemicals identified by EINECS numbers, established with the European
Community from September 18, 1981 to June 30,1990. The list was
published on May 29, 1991 and is a supplement to EINECS. Additional
supplements will be added as necessary.
- Elimination:
- Getting rid of (a specific
hazard).
- Engineering control
measures:
- Engineering control measures
are control measures that remove or reduce exposure of persons at the
workplace by means of engineering measures, suc as isolation, enclosure
and ventilation.
-
- Epidemic:
- The occurrence of more cases
of a particular type of disease, chronic condition, or injury than
expected in a given area, or among a specific group of people, over a
particular period of time. (Think miles, many people, and months). An
Outbreak is a confined epidemic, in time, place, and population. In the
public's mind, "epidemic" has a far more serious connotation than
"outbreak." A Pandemic is an epidemic occurring over a very wide area
(several countries or continents) and usually affecting a large
proportion of the population. An endemic health condition is a disease,
chronic condition, or type of injury that is constantly present in a
given geographic area or group.
- Epidemiology:
- The study of the
distribution and determinants of health conditions or events in
populations, and the application of this study to control health
problems. The study of disease occurrence and causes in human
populations. Occupational epidemiology is the study of the distribution
and determinants of health in working humans. ( Analytic Epidemiology.
The aspect of epidemiology concerned with why and how a health problem
occurs. Analytic epidemiology uses comparison groups to provide
baseline data so that associations between exposures outcomes can be
quantified and hypotheses about the cause of the problem can be tested.
(Descriptive epidemiology. The aspect of epidemiology concerned with
gathering, organizing, and summarizing data on "person" (Who is ill?),
"time" (When did they become ill?), and "place" (Where could they have
been exposed to the illness?). This information is then used to conduct
analytic epidemiology.
- Eschar:
- A thick crusting or scabbing
on the skin.
- Evaluation:
- Systematic and objective
examination of activities to determine how relevant and effective they
are.
- Explosive:
- A chemical that causes a
sudden, almost instantaneous release of pressure, gas and heat when
subjected to sudden shock, pressure or high temperature.
- Explosive
limits:
- The range of concentration
of a flammable gas or vapour (percent by volume in air) in which
explosion can occur if an ignition source is present.
- Exposure:
- The process of being exposed
to something that is around; exposure can affect people in a number of
different ways
- Exposure
limits:
- Limit set to minimise
occupational exposure to a hazardous substance.
- Extinguishing
agent:
- Media suitable for
controlling or putting out a fire, when properly applied.
- Extremely flammable
gas:
- A gaseous substance or
preparation that is flammable when in contact with air at ambient
temperature and pressure.
- Extremely flammable
liquid:
- A flammable liquid substance
or preparation that has an initial boiling point not exceeding 35
°C.
-
F
- ºF:
- Degrees Fahrenheit:
T(°C) = [T(°F)-32] x 5/9
- Fatal:
- Causing death; deadly.
- Fibrosis:
- A condition marked by the
abnormal increase in the amount of fibrous connective tissue in an
organ or tissue.
- Fire
point:
- The lowest temperature at
which a material can evolve vapours fast enough to support continuous
combustion.
- First
degree burn:
- A mild burn, characterized
by pain and reddening of the skin.
- Fit for work:
- The term "medically fit for
work" means that the person has been medically assessed and found to be
suitable for the occupation’s Occupational Risk Exposure
Profile (OREP), and that the person meets the relevant medical
requirements, as recorded in the linked Worker Allocated Surveillance
Programme (WASP).
- Flammable:
- Said of a material which is
easily ignited.
- Flammable
liquid:
- A liquid substance or
preparation that has a closed-cup flash point not exceeding 60,5
ºC and a boiling point not exceeding 35 ºC.
- Flash
point:
- The minimum temperature at
which a liquid gives off sufficient vapour to form an ignitable mixture
with air.
- Foetal:
- Of or pertaining to a
foetus. The unborn young of an animal while still in the uterus.
- Freezing
point:
- The temperature at which a
liquid substance changes to a solid state.
- Frost
bite:
- Damage to tissues resulting
from exposure to extreme cold or contact with extremely cold liquids or
objects.
- Frothing:
- Bubbles formed on or in a
liquid; foaming.
- Fumes:
- Fumes are formed by
processes such as sublimation or condensation and is the term generally
applied to particles condensed from the gaseous state (e.g. metal
fumes, polymer fumes).
-
G
- Gas:
- A substance which may be
compressed, liquefied or dissolved under pressure.
- Gastric
lavage:
- The irrigation or washing
out of the stomach by means of a gastric tube.
- Gastrointestinal
disturbances:
- A general term used to
describe any symptoms referrable to the stomach or intestines such as
nausea, vomiting, cramping and/or diarrhoea.
- General
ventilation:
- Ventilation designed to keep
the workplace comfortable.
- g/kg:
- Grams per kilogram. An
expression of dosage used in toxicology testing, to indicate the grams
of substance dosed per kilogram of animal body weight.
-
H
- Harmful:
- A substance or preparation
capable of causing death or acute or chronic damage to health if
inhaled or ingested or absorbed through the skin
- Hazard:
- A physical, chemical,
biological, ergonomic or psychosocial agent that can cause disease or
ill-health. Related words are: ( Agent. A factor that is essential for
a disease, chronic conditions, or injury to occur. In occupational
health we divide classify these into the five hazard classes. In
theory, agents can cause a health problem by being introduced, being
present in excess, or being present at deficient levels. ( Determinant.
Any factor that brings about change in a health condition or in other
defined characteristics. ( Environmental factor. An extrinsic factor,
such as geology, climate, insects, sanitation, or health services,
which affect an agent and the opportunity for exposure. ( Exposure.
Coming into contact with a cause of, or possessing a characteristic
that is a determinant of, a particular health problem. ( Exposed group.
A group whose members have had contact with a cause of, or possess a
characteristic that is a determinant of, a particular health problem. (
Host factor. An intrinsic factor (e.g., age, race, sex, behaviours)
that influences an individual's exposure, susceptibility, or response
to an agent. ( Risk factor. An aspect of personal behaviour or
lifestyle, an environmental exposure, or a hereditary characteristic
that is associated with an increase in the occurrence of a particular
disease, chronic condition, or injury. A protective factor is one which
decreases the occurrence of the outcome.
- Hazard
identification:
- The identification of the
inherent adverse effects of a substance or preparation.
- Hazardous
Chemical
Substance (HCS):
- Hazardous chemical substance
is any toxic, harmful, corrosive, irritant or asphyxiant substance, or
a mixture of such substances for which an occupational exposure limit
is prescribed or which creates a hazard to health.
- Hazard
warning:
- Any words, pictures,
symbols, or combination thereof appearing on a label or other
appropriate form of warning which convey the hazards of the chemical(s)
in the container(s).
- Health:
- A state of complete
physical, mental, and social well-being and not merely the absence of
disease or other infirmity. Health indicator. Any of a variety of
measures (e.g., mortality rate) that indicates the state of health of
people in a defined population.
- Health
hazard:
- A chemical for which there
is statistically 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.
- Health
Promotion and
Wellness (HP&W) Programme:
- This is the term which
describes the coordinated activities that aim for a state of health
that exceeds the absence of disease, and seeks to achieve optimal
mental, social and physical function.
- Hearing
protectors:
- Hearing protectors are ear
muffs or earplugs of a type approved by the Chief Inspector.
- Highly flammable
liquid:
- A liquid substance or
preparation that has a closed-cup flash point of less than 23
ºC and a boiling point exceeding 35 ºC.
- Hydrocarbon:
- Compounds composed solely of
carbon and hydrogen.
- Hygiene:
- The principles and practice
of maintaining health. "Occupational Hygiene is the discipline of
anticipating, recognising, evaluating and controlling health hazards in
the working environment with the objective of protecting worker health
and well-being and safeguarding the community at large" (IOHA
definition). These hazards may be physical, chemical, biological,
ergonomic or psychosocial, and may cause injury, illness, impairment,
or affect the well-being of workers and members of the community.
- Hygroscopic:
- Said of a substance which
has a capacity to absorb water from the atmosphere.
-
I
- IATA-DGR and
ICAO-TI:
- International Air Transport
Association (IATA) Dangerous Goods Regulations (DGR) and UN
International Civil Aviation Organization (ICAO) Technical Instructions
for the Safe Transport of Dangerous Goods by Air (TI). The IATA
Dangerous Goods Regulations is a "field manual" version of the ICAO
Technical Instructions. Written and edited by airline dangerous goods
experts, the Dangerous Goods Regulations presents the requirements for
shipping dangerous goods by air in a user friendly, easy to interpret
format. It also includes additional information which can assist
shippers in making sure their consignments are in compliance and will
be accepted quickly and easily by the airlines.
- IATA
class:
- A number corresponding to
one of the nine classes of cargo defined in the IATA Dangerous Goods
Regulations.
- IATA
subsidiary
risk(s):
- The code for any subsidiary
risk (i.e. risk which is secondary but classifiable).
For example, Ammonium Polysulphide Solution (UN number 2818) is listed
as a Class 8 substance. This classification denotes a corrosive
substance. Ammonium Polysulphide also has a subsidiary hazard: Class
6.1 which tells you that it is toxic. Appropriate labels for both
hazards should be displayed on the package.
To deal with goods having multiple risks a `subsidiary risk'
classification is used together with the principal hazard
classification.
- IATA
shipping name:
- The proper shipping name of
the substance, material or article, and any known and commonly used
alternative names (synonyms).
- IDLH:
- Immediately dangerous to
life or health. Description of an environment that is very hazardous
due to a high concentration of toxic chemicals or insufficient oxygen,
or both.
- Ignition
source:
- Anything that provides beat,
spark or flame sufficient to cause combustion and/or explosion.
- IMO/IMDG:
- First published in 1965, the
International Maritime Dangerous Goods Code (IMDG Code) published by
the International Maritime Organization (IMO) has become the standard
guide to all aspects of handling dangerous goods and marine pollutants
in sea transport. The Code is designed to assist in compliance with
legal requirements regarding the carriage of dangerous goods by sea of
the International Convention for the Safety of Life at Sea (SOLAS
Convention).
- IMDG
class number:
- A number corresponding to
one of the nine classes of cargo defined in the IMO International
Maritime Dangerous Goods Code (IMDG Code).
- IMDG EMS
number:
- Emergency Procedures for
Ships Carrying Dangerous Goods (EMS), a supplement to the IMDG Code.
- IMDG MFAG
table
number:
- Medical First Aid Guide for
use in accidents involving dangerous goods. It is intended to provide
advice necessary for diagnosis and treatment of chemical poisoning.
- IMDG marine
pollutants:
- Materials harmful to the
marine environment are designated as MARINE POLLUTANT in the Code.
- IMDG
packaging group:
- The principle of dividing
dangerous goods into three packaging groups according to the degree of
danger they present,i.e.Packaging group I: goods presenting great
danger;Packaging group II: goods presenting medium danger; and
Packaging group III: goods presenting minor danger.
- IMDG
shipping name:
- The proper shipping name of
the substance, material or article, and any known and commonly used
alternative names (synonyms).
- Impairment:
- The term "impairment" refers
to any loss or abnormality of psychological physiological or anatomical
structure or function. I PREFER THIS : WHO ICDIH definition of
impairment -. link
- Incidence:
- A rate that measures the
frequency with which a health problem, such as a new injury or case of
illness, occurs in a population.
Incidence proportion:
The number of new cases occurring in a population during a given period
of time, divided by the total population at risk during that time.
Incidence rate:
The number of new cases occurring in a population, divided by the
person-time at risk.
- Illuminance:
- Illuminance is the intensity
of light falling on a surface, measured in lux.
- Illuminance
meter:
- An instrument used for
measuring illuminance.
- Impervious:
- Said of a material which is
incapable of being penetrated by a substance.
- Ingestion:
- The process of taking a
substance into the body through the mouth.
- Inhalation:
- The process of breathing in.
- Inhibitor:
- A substance which is added
to another substance to prevent an unwanted chemical reaction from
occurring.
- Irritant:
- A substance which will cause
an inflammatory response or reaction of the eye, skin or respiratory
system.
- Isolation:
- An engineering control in
which a hazardous job is moved to a place where fewer people will be
exposed, or a worker is moved to a place where he or she will not be
exposed at all.
-
J
-
K
-
L
- Latency
period:
- The time period between the
exposure and the first signs of disease.
- LC50:
- Lethal Concentration 50%;
the concentration of a material in air which on the basis of laboratory
tests, is expected to cause 50% mortality in a group of test animals
when administered as a single exposure.
- LD50:
- Lethal Dose 50%; a single
dose of material which, on the basis of laboratory tests, is expected
to cause 50% mortality in a group of test animals when administered as
a single exposure.
- Leq:
- Leq (equivalent noise level)
is the value of the equivalent continuous sound level which would
deliver the same amount of sound energy as the actual fluctuating
sound, measured over the same time period.
- LEL or LFL:
- Lowest Explosive Limit or
Lower Flammable Limit.
- Local
effect:
- An effect on the part of the
body where a hazardous substance comes into contact with or enters the
body.
- Local exhaust
ventilation:
- Suction - based ventilation
system designed to remove pollutants from the air at source.
- luminaire:
- A luminaire is a light
fitting which supports a lamp and provides it with electrical
connections.
- lux:
- The lux, (lx) is the SI unit
of illuminance.
- lux meter:
- An instrument used to
measure the amount of light falling on a surface.
-
M
- Material Safety
Data
Sheets:
- Material Safety Data Sheets
(MSDS) are documents used to convey information about safe use of
substances to the user. MSDS contains information on the identity,
chemical and physical properties, potential health effects, and
precautions for the safe use and handling of substances.
- Medically
unfit:
- The term "medically unfit"
refers to the failure to meet the specific inherent requirements of an
occupation due to the presence of a medical condition that is an
exclusion for the relevant occupation, or due to a lack in the capacity
(physical or mental) to perform the work, to the required standard.
- Medical
surveillance
program:
- :Medical programme including
pre - employment and periodic examinations which helps to identify
early warning signs of occupational diseases.
- Melting
point:
- The temperature at which a
solid substance changes to a liquid state.
- mg/kg:
- Milligrams per kilogram. An
expression of toxicological dose.
- mg/m3:
- Milligrams per cubic metre;
a unit for measuring concentrations of particulates or gases in the air
(a weight per unit volume).
- mist:
- Liquid droplets suspended in
the air.
- mm Hg:
- Millimetres (mm) of mercury
(Hg). Unit of pressure. Normal atmospheric pressure = 760 mm Hg.
- Mortality
rate:
- A measure of the frequency
of occurrence of death in a defined population during a specified time
interval. Mortality rates can be given as age-adjusted, age-specific,
cause-specific, or crude. The crude mortality rate is a population's
mortality rate from all causes of death.
- Mucous
membrane:
- A thin layer of
mucous-secreting tissue covering a body surface or lining an organ. For
example: the nose, stomach, intestines and bronchial tubes.
- Mutagen:
- A substance or agent capable
of altering the genetic material of a living cell.
-
N
- Nausea:
- An unpleasant sensation,
often culminating in vomiting.
- Natural
history of
disease:
- The course of a disease from
the time it begins until it is resolved.
- Neutralize:
- To render chemically neutral
or harmless; neither acid nor base.
- Noise
zone:
- A noise zone is an area
where the equivalent noise level is equal to or exceeds 85 dB(A).
- Non
combustible:
- A material which will not
ignite, burn, support combustion or release flammable vapours when
subjected to heat or fire.
- N.O.S.:
- Abbreviation for "Not
Otherwise Specified". Used as a collective entry in transport
regulations to which substances may be assigned if they are not
mentioned by name.
- Notifiable
disease:
- A disease that, by law, must
be reported to public health authorities upon diagnosis. Lung cancer is
one such disease in occupational health.
- Numerator:
- The upper portion of a
fraction. Typically the number of people with disease.
-
O
- Occupational:
- Related to the workplace.
- Occupational
disease:
- Any disease caused by
exposures in the workplace.
- Occupational
Health
Nurse Practitioner:
- This means a registered
nurse who holds a qualification in occupational health, recognised as
such by the South African Nursing Council as referred to in the Nursing
Act, 1978 (Act No. 50 of 1978).
- Occupational
Health
(OH) Programme:
- This is the science of
work-related injury and illness prevention, incorporating the
disciplines of Occupational Hygiene, Safety and Medicine, through
various strategies, including risk assessment and risk control by means
of engineering away hazards, and monitoring for early signs of failure
of these controls.
- Occupational
Hygiene
Assistant:
- This means a person with
suitable training that will conduct the activities required of an
Occupational Hygiene Programme, under the supervision and guidance of
an Occupational Hygienist.
- Occupational
Hygienist:
- This means a person who
holds a qualification in occupational health recognised as such by the
South African Occupational Hygiene Association, and who meets the
requirements of an approved Inspection Authority, as prescribed by
South African Law.
- Occupational
Medical
Practitioner:
- This means a medical
practitioner as defined in the Medical, Dental and Supplementary Health
Service Professions Act, 1974 (Act No. 56 of 1974), who holds a
qualification in occupational medicine or an equivalent qualification
which qualification or equivalent is recognised as such by the South
African Medical and Dental Council referred to in the said Act.
- Occupational
Exposure
Limit:
- The Occupational Exposure
Limit (OEL) is a limit value set by the Minister of Labour for a stress
factor in the workplace as revised from time to time by notice in the
Government Gazette.
- OEL-CL:
- Abbreviation for
Occupational Exposure Limits - Control Limits.
- OEL-RL:
- Abbreviation for
Occupational Exposure Limits - Recommended Limits.
- Occupational
hygiene:
- Occupational hygiene means
the anticipation, recognition, evaluation and control of conditions
arising in or from the workplace, which may cause illness or adverse
health effect to persons.
- Ocular:
- Affecting the eye.
- Odds
ratio:
- A measure of association
used in comparative studies to quantify the relationship between an
exposure and a health outcome; also known as the cross-product ratio.
- Oedema:
- The presence of abnormally
large amounts of fluid in the tissue spaces of the body. May be visible
as swelling of a body part such as the legs or face.
- Olfactory:
- Relating to the sense of
smell.
- Oral:
- Relating to the mouth.
- Oral LD50:
- Oral Lethal Dose 50%; the
concentration of a substance, orally administered which will produce 50
percent mortality in the animals tested.
- Oral
toxicity:
- Adverse effects which result
from taking a substance into the body via the mouth.
- Oxidizing
agent:
- A chemical other than a
blasting agent or explosive that initiates or promotes oxidation in
other materials, possibly causing fire either of itself or through the
release of oxygen or other gases.
- Outcome, or
disease,
or disease outcome:
- Injury, illness, impairment,
or changes in the well-being of workers. Any or all of the possible
results that may stem from exposure to a causal factor or from
preventive or therapeutic interventions. All identified changes in
health status that result from the handling of a health problem.
-
P
- Pa (Pascal):
- The SI unit of pressure. The
normal atmospheric pressure = 101.3 kPa
- Paralysis:
- Partial or complete loss of
function of a sense (such as smell) or partial or complete loss of
motor function of a part of the body.
- Partition
Coefficient
(n-octanol/water):
- Distribution coefficient
used to evaluate the harm the substance can cause to environment.
Higher values indicate higher chance of accumulation of the substance
in biological material.
- Pathological
changes:
- Abnormal structural and/or
functional changes in a body caused by a diseased state or exposure to
a toxic chemical.
- PEL:
- Permissible Exposure Limit.
May be a Time Weighted Average (TWA limit) or a "ceiling" concentration
exposure limit.
- Personal
hygiene:
- The practice of principles
that maintain personal health, e.g. personal cleanliness.
- pH:
- Numerical logarithmic scale
from 0 to 14 indicating whether a product is acid (pH < 7),
alkaline (pH > 7) or neutral (pH = 7).
- Primary Health
Care
(PHC) Programme:
- The Primary Health Care
(PHC) Programme is the delivery of first-level medical interventions,
including curative as well as preventive, for injured and ill employees
at work, and is implied to be an on-site activity.
- Physical
hazard:
- A chemical for which there
is scientifically valid evidence that it is: a combustible liquid, a
compressed gas, explosive, flammable, an organic peroxide, an oxidising
agent, pyrophoric, unstable (reactive) or water-reactive substance.
- PMCC:
- Pensky Martens Closed Cup: a
flash point test method.
- Polymer:
- A high molecular weight
material formed by chemically joining together five or more molecules
(monomers).
- Polymerisation:
- A chemical reaction in which
a large number of relatively simple molecules (monomers) combine to
form a large chainlike molecule. A hazardous polymerisation is a
reaction which takes place at a rate which releases large amounts of
energy.
- Polymerisation:
- A chemical reaction in which
a large number of relatively simple molecules (monomers) combine to
form a large chainlike molecule. A hazardous polymerisation is a
reaction which takes place at a rate which releases large amounts of
energy.
- Polynuclear aromatic
hydrocarbons:
- Organic compounds usually
composed of three or more aromatic rings. Some of these compounds (esp.
4-6 ring compounds) are capable of causing skin tumour formation. Also
known as PNA's or PAH's.
- Population:
- The total number of
inhabitants of a given area or country. In sampling, the population may
refer to the units from which the sample is drawn, not necessarily the
total population of people. A population can be a particular group at
risk, such as everyone who is engaged in a certain occupation. A
population need not be human, eg. farms, households, folders. A group
sharing certain common characteristics, about whom inferences can be
made.
- Potential
hazard:
- Something that may be
hazardous.
- Pour
point:
- The lowest temperature at
which a liquid will flow or pour.
- ppb:
- Parts per billion : a unit
for measuring the concentration of a gas or vapour in air; parts (by
volume) of the gas or vapour in a billion parts of air. Also used to
indicate the concentration of a particular substance in a solution or
solid.
- PPE:
- Personal protective
equipment: equipment a worker wears as a barrier between himself or
herself and the hazardous agent(s).
- ppm:
- Parts per million; a unit
for measuring the concentration of a gas or vapour in air; parts (by
volume) of the gas or vapour in a million parts of air. Concentration
of a particular substance in a liquid or solid.
- Preparation:
- A mixture or solution
composed of two or more substances.
- Prevalence:
- The number or proportion of
cases or events or conditions in a given population, as measured at a
point in time, e.g. if measured now, the number or proportion of people
now who have diabetes.
- Proportion:
- A ratio in which the
numerator is included in the denominator; the ratio of a part to the
whole, expressed as a decimal fraction (e.g. 0.2), a fraction (1/5), or
a percentage (20%). It is a special ratio, where the value is between 0
and 1.
- Protective
clothing:
- Clothing designed to provide
protection to the wearer against contamination from chemical,
biological, radiation or physical hazards.
- psi:
- Pounds per square inch. An
obsolete unit of pressure. Normal atmospheric pressure = 14.7 psi =
101.3 kPa
- Pulmonary
oedema:
- The abnormal accumulation of
fluid in the tissue and air spaces of the lungs.
- Pyrolysis:
- The breaking apart of
complex molecules into simpler units by the use of heat, as in the
pyrolysis of heavy oil into gasoline.
- Pyrophoric:
- A chemical that will ignite
spontaneously in air.
-
Q
-
R
- Radioactive:
- The property of an isotope
or element which is characterised by giving off radiant energy in
particles or rays by the disintegration of atomic nuclei.
- Rate:
- A ratio with an implicit
time-element, often multiplied by 10n.
- Ratio:
- The value obtained by
dividing any one quantity by another, e.g. female: male ratio.
Percentages, proportions and rates are all ratios.
- Reactivity:
- The tendency of a substance
to undergo a chemical change with the release of energy. Undesirable
effects (pressure build-up, temperature increase, formation of noxious,
toxic or corrosive by-products) may occur because of a reaction to
heating, burning, direct contact with other materials or other
conditions when in use or in storage.
- Reducing
agent:
- A material which is oxidised
or which allows easy oxidation.
- Reproductive chemical
hazard:
- A substance or preparation
that, if inhaled or ingested or absorbed through the skin, produces or
increases the incidence of non-heritable. adverse effects in the
progency, or an impairment of male or female reproductive functions or
capacities (or any combination of these).
- Respiratory
hazard:
- Hazards to the body's
breathing system.
- Respiratory
protection:
- Devices for use in
conditions exceeding the exposure levels, which when properly selected,
maintained, and operated by the user, will protect the user's
respiratory system from exposure to airborne contaminants by
inhalation. Respiratory protective equipment are devices which are worn
over at least the mouth and nose to prevent the inhalation of air which
is not safe.
- Respiratory
system:
- The breathing system;
includes the lungs and the air passages (trachea or windpipe, larynx,
mouth and nose) to the air supply outside the body.
- RID:
- Règlement
concernant le transport International ferroviaire des marchandises
Dangereuses (Regulations concerning the International Carriage of
Dangerous Goods by Rail) by the Organisation Intergouvernementale pour
les Transports Internationaux Ferroviaires (OTIF) - Intergovernmental
Organisation for International Carriage by Rail
- Risk:
- (i) The probability that an
individual will be affected by, or die from, an illness or injury
within a stated time or age span, or that serious damage to property
will occur. (ii) In risk assessment it is often used to refer to
likelihood of exposure multiplied by severity of impact. The answer is
often categorical: negligible, low, medium, high, etc. (iii) In
epidemiology, it has the meaning of incidence proportion, i.e. the
proportion of a cohort of workers affected when they are followed up
over time.
- Routes
of entry:
- The different ways hazardous
agents can get into the body.
- R phrases:
- Risk phrases : a set of
numbered standard sentences which appear on user labels for packaged
goods (e.g. R23: Toxic by inhalation).
-
S
- SACAA:
- South African Civil Aviation
Authority.
- SA-CATS-DG:
- South African Civil Aviation
Technical Standards Relating to the Conveyance of Dangerous Goods
- SETA:
- Setaflash Closed Tester; a
flash point test method.
- "Safe"
levels:
- Levels of exposure to
substances below which there will not be a health risk to workers.
- Sample:
- A selected subset of a
population. A sample may be random or non-random and representative or
non-representative.
- Second
degree burns:
- A burn that is more severe
than a first degree burn, and is often characterized by blistering,
reddening of the skin, oedema and destruction of the superficial tissue.
- Short-term
OEL-RL
- The concentration of
airborne dust, fumes or vapours to which workers can be exposed
continuously for a short period without suffering from irritation,
chronic or irreversible tissue damage or narcosis of sufficient degree
to increase the likelihood of accidental injury, impair self-rescue or
materially reduce work efficiency.
- Simple
asphyxiant:
- A substance which induces a
deficiency in the supply of oxygen. Nitrogen, methane and acetylene are
examples.
- Skin
lesion:
- An abnormal change in the
structure of the skin due to injury or disease.
- Solubility
in water:
- The percentage of a material
(by weight) that will dissolve in water at a specified temperature.
negligible or nil - less than 0.1 %
slight - 0.1 to 1.0%
moderate - 1 to 10%
appreciable - more than 10%
complete - soluble in all proportions.
- Solution
- Uniformly dispersed mixture.
All solutions are composed of a solvent (water or other fluid) and the
dissolved substance, called the "solute".
- S phrases:
- Safety phrases : a set of
numbered standard sentences which appear on user labels for packaged
goods (e.g. S 15: Keep away from heat).
- Specific
gravity
(S.G.):
- The ratio of the weight of
material to be weight of an equal volume of water usually at 20
ºC, unless otherwise specified. Specific gravity of water = 1.
- STEL:
- Abbreviation for Short Term
Exposure Limits.
- Storage
depot:
- A storage depot is a site or
tissue which sequesters a toxin without a deleterious effect. Examples
include sequestration of lead into the calcium hydroxyapatite matrix of
bone cortex and DDT or other organochlorines entry and storage in fatty
tissues. Such storage depots allow for decreased bioavailabity of a
sequestered toxin, biologic persistence with chronic low level
exposure, (equilibrium between the storage depot and blood stream),
decreased excretion and biologic persistence.
- Study:
- An epidemiological study
often compares two groups of people who are alike except for one factor
such as exposure to a chemical or the presence of a health effect. The
investigators try to determine if the factor is associated with the
health effect.
Analytic study:
A study examining associations between groups, typically looking for
causality. The common types of analytic study are cross-sectional,
case-control and cohort studies.
Descriptive study:.
A study describing the existing distribution of variables, without
regard to causal or other hypotheses. Classically, there is no
comparison group. Examples are case studies, case series, and
descriptive cross-sectional studies.
Interventional study:
An analytical study where the investigators systematically and
intentionally change the exposure status of the subjects, by e.g.
giving therapy, or removing a risk factor.
Observational study:.
An analytic epidemiologic study in which there is no intervention.
Changes or differences in one characteristic are studied in relation to
changes or differences in others.
Case-control study:
An analytic observational study where cases (with the disease or
outcome) are compared with suitable controls (without the disease or
outcome), by looking at their (historical or current) exposures. The
starting point occurs after the onset of the disease or outcome, and
looks back to find postulated causal factors. It's like taking
snapshots of some sick and some healthy family members, and then paging
through the family album looking for previous snapshots of those same
family members, looking for clues as to why they got sick or not. A
study in which people with a disease (cases) are compared to people
without the disease (controls) to see if their past exposures to
chemicals or other risk factors were different.
Cohort study:
An analytic observational study where a well-defined group of disease
free people who have had a common experience or exposure are followed
up through time, looking for disease outcomes. The starting point
occurs before the onset of the disease or outcome, having already
identified postulated causal factors. It's like a number of snapshots
taken at periodically of all family members who could be present,
looking for clues as to why some got sick. A study in which a group of
people with a past exposure to chemicals or other risk factors are
followed over time and their disease experience compared to that of a
group of people without the exposure.
Cross-sectional study:
(Prevalence study.) A study that examines the relationship between
exposures and outcomes prevalent in a defined population, at a defined
point in time. The start and endpoint are the same, and disease and
postulated causal factors are measured simultaneously. It's like a
single snapshot of everyone in the family who could be gathered for the
photo, looking for clues as to why some are sick.
- Substance
(chemical):
- Chemical elements and their
compound, either in the natural state or obtained by a production
process, including any additive necessary to preserve the stability of
the product and any impurity derived inevitably from the process used,
but excluding any solvents that can be separated without affecting the
stability of the substance or changing its composition.
- Substance identity
number:
- The substance identification
numbers are identical with the UN Numbers, except for those in the 7000
series. These are specific to the UK and are used where there is no
suitable UN number.
- Substance
identity
number:
- Replacing particularly
hazardous chemicals or work processes by safer ones.
- Symbol:
- Pictogram appearing on user
labels for packaged goods, also characterised by a letter (e.g. picture
of flame and F+: very flammable substance).
- Symptom:
- Abnormality in the body
which is noticeable only to the person experiencing it and may indicate
poisoning or disease.
- Synergism:
- The term used when exposure
to two chemicals at the same time produces a much more harmful effect
than the sum of the effects of exposure to the individual chemicals.
- Systemic
toxicity:
- The adverse effects caused
by a substance, affecting the body in a general rather than a local
manner.
-
T
- Target
organs/site:
- Those parts of the body that
particular chemicals always affect. For example, lead affects the
central nervous system (brain and spinal cord) but is stored in the
bones where it accumulates with further exposures. Therefore, the
target organs for lead are both the central nervous system and the
bones. Other target organs for different toxic substances include the
heart, lungs, kidneys and liver. The target site refers to the
location(s) at which adverse effects occur. Toxicity may be relatively
specific to an organ system or even cell type therein but generally
toxicity will occur at several sites. Patterns of physiologic response,
(syndromes), may give clues as to toxic etiologies. An example would be
lead which at very low dosages causes subtle neuropsychiatric effects
which with ongoing exposure become permanent and which as dose
increases will affect bone marrow hemoglobin production and renal
function.
- TCC:
- Tag (Tagliabue) Closed Cup:
a flash point test method.
- Teratogen:
- A substance that upon
exposure to the parent causes malformations and/or alterations in the
appearance or function of the foetus.
- TLV:
- Threshold Limit Value: a
term used to express the airborne concentration of a material to which
nearly all persons can be exposed day after day, without adverse
effects.
TLC-C:
Ceiling Exposure Limit, the concentration that should not be exceeded,
even momentarily.
TLV-STEL:
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 that the
daily TLV-TWA is not exceeded).
TLV-Skin:
(Listed substance followed by the designation "skin"): The skin
designation refers to the potential contribution to the overall
exposure by the cutaneous route, including mucous membranes and the
eye. Exposure can be either by airborne or direct contact with the
substance. This "attention calling" designation suggests appropriate
measures be taken to prevent skin absorption. The TLV is not
invalidated.
TLV-TWA:
The allowable Time Weighted Average concentration for a normal eight
hour workday or 40 hour work week. May also be adjusted for extended
work shifts.
- TOCC:
- Tag (Tagliabue) Open Cup: a
flash point test method.
- Toxicant,
or poison:
- Any agent capable of
producing a deleterious effect in a biological system. As per
Paracelsus’ axiom, all substances are potentially poisonous,
it is the dosage that determines the toxicity.
- Toxicity:
- Inherent capacity to produce
injury. Adverse effects resulting from overexposure to a material,
generally via the mouth, skin, eyes or respiratory tract. It is thus
the potential to cause damage to humans and experimental animals.
- Toxicodynamics:
- The study of the
relationship between the dose of the toxic substance that enters the
body and the measured response or adverse effect.
- Toxicokinetics:
- The study of the movement of
toxic substance within the body. It refers to the absorption,
distribution, metabolism and excretion of xenobiotics (substances
"foreign" to the body). Toxicokinetics takes into consideration
differences in susceptibility among individuals. The factors to
consider in these processes are those of (1) bioavailability, (2)
absorption, (3) distribution, (4) metabolism and (5) excretion and how
they may be affected by genomic or environmental factors or
combinations thereof. It also encompasses the relationship between the
dose that enters the body and the level of the toxic substance in any
biological sample.
- Toxicology:
- The study of the adverse
effects of a toxicant on living organisms. Toxicology is an applied
science that incorporates biology, chemistry, physiology, pathology,
physics, statistics, and sometimes immunology or ecology to help solve
problems in forensic medicine, public health, industrial hygiene,
veterinary medicine, pharmacy and pharmacology, as well as giving basic
insight into how an organism functions. It includes an evaluation of
safety associated with exposure to various agents.
- Toxic
substance or
preparation:
- A substance or preparation
that is capable, in small quantities, of causing dealth or acute or
chronic damage to health if inhaled or ingested or absorbed through the
skin.
- Toxic
substance or
preparation:
- Short in duration.
- Transport Emergency
Card (Tremcard):
- Instructions on how to deal
with emergencies involving hazardous chemicals, transported by road.
- Tumour:
- Abnormal mass of tissue.
- Time Weighted
Average:
- The time-weighted average
(TWA) is the average of a number of representative measurements that
are taken over a period of time and that are calculated as follows:
TWA = (x1t1
+ x2t2
+ ... + xntn)
/ (t1
+ t2
+ ... + tn)
where x1,
x2,
etc. are the observed measurements during corresponding periods t1,
t2,
etc.
- TWA
OE-REL:
- The time-weighted average
concentration of airborne dust, fumes or vapours for a conventional 8
hour workday and a 40 hour workweek, to which it is believed that
nearly all workers can be repeatedly exposed, day after day, without
adverse effect.
- Two-by-two
table:
- A table with 4 cells, which
is the basic numerical method used to compare occurrence of disease in
different groups. The groups are simply divided into those with and
without exposure and those with and without disease. The 4 cells are
labeled a, b, c and d. Cell a contains those with both exposure and
disease, and cell d contains those free of both exposure and disease.
-
U
- Ulcer:
- A lesion (wound/injury) on
the surface of the skin or mucous surface.
- Unconscious:
- Not conscious : incapable of
responding to sensory stimuli.
- UN number:
- United Nations substance
numbers are four-digit numbers, which have been assigned by the United
Nations Committee of Experts on the Transport of Dangerous Goods, to
individual substances (e.g. sulphuric acid) or groups of similar
substances (e.g. carbamate pesticides). The numbers are primarily
intended to facilitate the identification of substances without the
need for a knowledge of the language in which the chemical name is
printed. They have also proved to be of great value for emergency
services in the correct relaying of long or complex names of
substances, thus allowing error-free identification.
- Unstable:
- Tending toward decomposition
or other unwanted chemical change during normal handling or storage.
- Unstable
(Reactive):
- A chemical which in the pure
state, or as produced or transported, will vigorously polymerise,
decompose, condense, or will become self-reactive under conditions or
shocks, pressure or temperature.
- Upper
Flammable Limit
(UFL):
- The highest concentration of
a flammable vapour or gas in air (usually expressed in percent by
volume) above which propagation of a flame will not occur in the
presence of an ignition source. Also called upper explosive limit or
UEL.
- Upwind:
- In the direction from which
the wind is blowing. Also see downwind.
-
V
- Vapour
density:
- The relative weight of a
vapour compared to an equal volume of air (indicates whether vapours
will rise or sink). If the vapour density of a substance is less than
one, it will tend to rise in air; if the vapour density is greater than
one, it will fall in air. Substances with high vapour densities will
collect in the bottom of tanks.
- Vapour
pressure:
- Pressure of saturated vapour
above liquids or solids (usually provided at 20 ºC). The
higher the vapour pressure, the higher the concentration will be in
unventilated spaces.Materials with high vapour pressures can be
especially hazardous when they are being used in an enclosed area or in
an area with poor circulation.
- Variable:
- Any characteristic or
attribute that can be measured and can have different values.
- Very
toxic substance
or preparation:
- A substance or preparation
that is capable, in very low concentrations, of causing death or acute
or chronic damage to health if inhaled or ingested or absorbed through
the skin.
- Viscous:
- Having resistance to flow.
- Volatile:
- A term often used to
describe a liquid that evaporates or vaporizes easily. This is
important to know because air concentrations can build up quickly when
the material is used in its liquid form.
-
W
- Waste,
chemical:
- Unusable products from
chemical and metal processing operations, that contain dangerous or
polluting materials that pose a threat to humans or animals or the
environment if improperly disposed of.
- Water
reactive:
- A chemical that reacts with
water to release a gas that is either flammable or presents a health
hazard.
- Wet bulb globe
temperature (WBGT):
- The wet bulb globe
temperature (WBGT) index is a number which characterises the thermal
conditions in the environment to which that number applies.
- Wet
method:
- Spraying water over a dusty
surface to keep dust down, or mixing water with the material used to
prevent dust from being created.
-
X
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Postgraduate Diploma in Occupational Health (DOH) - Modules 3:
Occupational Medicine & Toxicology (Basic) by Profs Mohamed
Jeebhay and Rodney
Ehrlich,
Health
Sciences UCT is licensed under a
Creative
Commons Attribution-Noncommercial-Share Alike 2.5 South Africa License.
Major contributors: Mohamed Jeebhay, Rodney Ehrlich, Jonny Myers,
Leslie London, Sophie Kisting, Rajen Naidoo, Saloshni Naidoo. Source available
from here.
For any updates to the material, or more permissions beyond the scope
of this license, please email healthoer@uct.ac.za
or visit www.healthedu.uct.ac.za.
Last updated Jan 2007.
Disclaimer note: Some resources and descriptions may be out-dated. For
suggested updates and feedback, please contact healthoer@uct.ac.za.