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Pure Appl. Chem.,
Vol. 65, No. 9, pp. 2003-2122, 1993.
CLINICAL
CHEMISTRY DIVISION
COMMISSION ON TOXICOLOGY
Glossary for chemists of terms used in toxicology
(IUPAC Recommmendations 1993)
Alphabetical entries
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
tachy-: Prefix meaning rapid as in tachycardia
and tachypnoea.
tachycardia: Abnormally
fast heartbeat.
AN bradycardia.
tachypnoea: Abnormally
fast breathing.
AN bradypnoea.
taeniacide: Substance intended to kill tapeworms.
target (biological):
Any organism, organ, tissue, cell or cell constituent that is subject
to the action of a pollutant or other chemical, physical, or biological
agent.
WHO, 1979
RT receptor.
target (of environmental pollution): Human
being or any organism, organ tissue, cell, resource, or any constituent
of the environment, living or not, that is subject to the activity
of a pollutant or other chemical or physical activity or other agent.
WHO, 1979
RT receptor.
target organ(s):
Organ(s) in which the toxic injury manifests itself in terms of
dysfunction or overt disease.
WHO, 1979
RT receptor.
target population (epidemiology):
1. Collection of individuals, items, measurements, etc. about which
we want to make inferences: the term
is sometimes used to indicate the population from which
a sample is drawn and sometimes to denote any
reference population about which inferences are required.
2. Group of persons for whom an intervention is planned.
Last, 1988
temporary acceptable daily intake: Value
for the acceptable daily intake proposed for guidance when data
are sufficient to conclude that use of the substance is safe over
the relatively short period of time required to generate and evaluate
further safety data, but are insufficient to conclude that use of
the substance is safe over a lifetime. A higher-than-normal safety
factor is used when establishing a temporary ADI and an expiration
date is established by which time appropriate data to resolve the
safety issue should be available.
RT acceptable daily
intake.
After de Koning, 1987
temporary maximum residue limit: Temporary
maximum residue limit is established for a specified, limited period
when:
1. Only a temporary acceptable daily intake has been established
for the pesticide concerned.
2. Although an acceptable daily intake has been established, the
residue data are inadequate for firm
maximum residue recommendations.
WHO, 1976
teratogen: Agent
that, when administered prenatally (to the mother), induces permanent
structural malformations or defects in the offspring.
testing of chemicals:
1. In toxicology, evaluation of the therapeutic and potentially
toxic effects of substances by their
application through relevant routes of exposure with
appropriate organisms or biological systems so as to
relate effects to dose following
application.
2. In chemistry, qualitative or quantitative analysis by the application
of one or more fixed methods and
comparison of the results with established standards.
tetanic: Pertaining to tetanus, characterized
by tonic muscle spasm.
therapeutic index:
Ratio between toxic and therapeutic doses (the higher the ratio,
the greater the safety of the therapeutic dose).
threshold: Dose or
exposure concentration below which an effect is not expected.
threshold
limit value (TLV): Concentration in air of a substance to which
it is believed that most workers can be exposed daily without adverse
effect (the threshold between safe and dangerous concentrations).
These values are established (and revised annually) by the American
Conference of Governmental Industrial Hygienists) and are time-weighted
concentrations for a 7 or 8 hour workday and a 40 hour workweek.
For most substances the value may be exceeded, to a certain extent,
provided there are compensatory periods of exposure below the value
during the workday (or in some cases the week). For a few substances
(mainly those that produce a rapid response) the limit is given
as a ceiling concentration (maximum permissible concentration -
designated by "C") that should never be exceeded.
thrombocytopenia: Decrease in the number
of blood platelets (thrombocytes).
tidal volume: Quantity of air or test gas
that is inhaled and exhaled during one respiratory cycle.
time-weighted
average exposure (TWAE) or concentration (TWAC): Concentration
in the exposure medium at each measured time interval multiplied
by that time interval and divided by the total time of observation:
for occupational exposure a working shift of eight hours is commonly
used as the averaging time.
WHO, 1979
tinnitus: Continual noise in the ears, such
as ringing, buzzing, roaring, or clicking.
tissue dose: Amount of a substance or physical
agent (radiation) absorbed by a tissue.
T lymphocyte:
Animal cell which possesses specific cell surface receptors through
which it binds to foreign substances or organisms, or those which
it identifies as foreign, and which initiates immune responses.
RT B lymphocyte, immune
response, lymphocyte.
tolerable
daily intake (TDI): Regulatory value equivalent to the acceptable
daily intake established by the European Commission Scientific Committee
on Food. Unlike the ADI, the TDI is expressed in mg/person, assuming
a body weight of 60 kg. TDI is normally used for food contaminants.
RT acceptable daily
intake.
tolerable risk:
Probability of suffering disease or injury that can, for the time
being, be tolerated, taking into account the associated benefits,
and assuming that the risk is minimized by appropriate control procedures.
PS acceptable risk.
tolerance:
1. Adaptive state characterized by diminished effects of a particular
dose of a substance: the process
leading to tolerance is called "adaptation."
2. In food toxicology, dose that an individual can tolerate without
showing an effect.
3. Ability to experience exposure to potentially harmful amounts
of a substance without showing an adverse
effect.
4. Ability of an organism to survive in the presence of a toxic
substance: increased tolerance may be
acquired by adaptation to constant exposure.
5. In immunology, state of specific immunological unresponsiveness.
tonic:
1. Characterised by tension, especially muscular tension.
2. Medical preparation that increases or restores normal muscular
tension.
topical: Pertaining to a particular area,
as in a topical effect that involves only the area to which the
causative substance has been applied.
total diet study:
1. Study designed to establish the pattern of pesticide residue
intake by a person consuming a defined diet.
WHO, 1976.
2. Study undertaken to show the range and amount of various foodstuffs
in the typical diet or to estimate
the total amount of a specific substance in a typical
diet.
After WHO, 1989a
toxic: Able to cause injury to living organisms
as a result of physicochemical interaction.
toxic dose: Amount
of a substance which produces intoxication without lethal outcome.
SN super-threshold dose.
toxicity:
1. Capacity to cause injury to a living organism defined with reference
to the quantity of substance
administered or absorbed, the way in which the substance
is administered (inhalation, ingestion, topical
application, injection) and distributed in time (single
or repeated doses), the type and severity of
injury, the time needed to produce the injury, the
nature of the organism(s) affected and other relevant
conditions.
2. Adverse effects of a substance on a living organism defined with
reference to the quantity of substance
administered or absorbed, the way in which the substance
is administered (inhalation, ingestion, topical
application, injection) and distributed in time (single
or repeated doses), the type and severity of
injury, the time needed to produce the injury, the
nature of the organism(s) affected, and other relevant
conditions.
3. Measure of incompatibility of a substance with life: this quantity
may be expressed as the reciprocal of
the absolute value of median lethal dose (1/LD 50)
or concentration (1/LC 50).
RT acute toxicity, chronic
toxicity, subacute toxicity, subchronic
toxicity.
toxicity equivalency factor (TEF): Factor
used in risk assessment to estimate the toxicity of a complex mixture,
most commonly a mixture of chlorinated dibenzo-p-dioxins,
furans and biphenyls: in this case, TEF is based on relative toxicity
to 2,3,7,8 -tetrachlorodibenzo-p-dioxin (TEF = 1).
toxicity equivalent (TEQ): Contribution of
a specified component (or components) to the toxicity of a mixture
of related substances. The amount-of-substance (or substance concentration)
of total toxicity equivalent
is the sum of that for the components B, C.....N:
S n(TEQ) = n(TEQ)B + n(TEQ)C
+ ... n(TEQ)N
Toxicity equivalent is most commonly used in relation to the reference
toxicant 2,3,7,8-tetrachlorodibenzo-p-dioxin, 2,3,7,8-TCDD
by means of the toxicity equivalency factor (TEF, f) which
is 1 for the reference substance, hence:
S n(TEQ) = fBnB + fCnC
+ ... fNnN
toxicodynamics:
Process of interaction of potentially toxic substances with target
sites, and the biochemical and physiological consequences leading
to adverse effects.
RT adverse effect, pharmacodynamics,
target.
toxicokinetics:
Process of the uptake of potentially toxic substances by the body,
the biotransformation they undergo, the distribution of the substances
and their metabolites in the tissues, and the elimination of the
substances and their metabolites from the body. Both the amounts
and the concentrations of the substances and their metabolites are
studied. The
term has essentially the same meaning as pharmacokinetics, but the
latter term should be restricted to the study of pharmaceutical
substances.
BT chemobiokinetics.
RT biotransformation,
pharmacokinetics.
WHO, 1979
toxicological data sheet: Document that gives
in a uniform manner data relating to the toxicology of a substance,
its production and application, properties and methods of identification;
the data sheet may also include recommendations on protective measures.
PS toxicological profile, toxicological dossier.
IRPTC, 1982
toxicology: Scientific
discipline involving the study of the actual or potential danger
presented by the harmful effects of substances (poisons) on living
organisms and ecosystems, of the relationship of such harmful effects
to exposure, and of the mechanisms of action, diagnosis, prevention
and treatment of intoxications.
NT chemical toxicology.
toxicometry: Term sometimes used to indicate
a combination of investigative methods and techniques for making
a quantitative assessment of toxicity and the hazards of potentially
toxic substances.
toxicophoric (toxophoric)
group: Structural moiety that upon metabolic activation exerts
toxic effects: the presence of a toxicophoric group indicates only
potential and not necessarily actual toxicity of a drug or other
substances.
SN toxogenic group.
toxicovigilance: Active process of identification,
investigation, and evaluation of various toxic effects in the community
with a view to taking measures to reduce or control exposure(s)
involving the substance(s) which produces these effects.
toxification: Metabolic conversion of a potentially
toxic substance to a product that is more toxic.
toxin: Poisonous substance
produced by a biological organism such as a microbe, animal or plant.
PS venom.
toxinology: Scientific discipline involving
the study of the chemistry, biochemistry, pharmacology and toxicology
of toxins.
RT toxicology, toxin.
tracer:
1. Means by which something may be followed; for example a radioactive
isotope may replace a stable chemical element in a
toxic compound enabling the toxicokinetics to be followed.
2. Labelled member of a population used to measure certain properties
of that population.
Gold, Loening, McNaught
and Sehmi, 1987
transcription: Process by which the genetic
information encoded in a linear sequence of nucleotides in one strand
of DNA is copied into an exactly complementary sequence of RNA.
RT reverse transcription.
1. Alteration of a cell by incorporation of foreign
genetic material and its subsequent expression in a new phenotype.
RT phenotype.
2. Conversion of cells growing normally to a state of rapid division
in culture resembling that of a tumour.
3. Chemical modification of substances in the environment. transgenic: Adjective used to describe animals
carrying a gene introduced by micro-injecting DNA into the nucleus
of the fertilized egg.
treatability: In relation to waste water,
the amenability of substances to removal without adversely affecting
the normal operation of biological treatment processes (such as
a sewage treatment plant).
triage: Assessment of sick, wounded and injured
persons following a disaster to determine priority needs for efficient
use of available medical facilities.
trophic level: Amount of energy in terms
of food that an organism needs: organisms not needing organic food,
such as plants, are said to be on a low trophic level, whereas predator
species needing food of high energy content are said to be on a
high trophic level. The trophic level indicates the level of the
organism in the food chain.
WHO, 1979
tumorigenic: Able to cause tumours.
tumour:
1. Any abnormal swelling or growth of tissue, whether benign or
malignant.
2. An abnormal growth, in rate and structure, that arises from normal
tissue, but serves no physiological function.
SN neoplasm.
tumour progression: Sequence of changes by
which a benign tumour develops from the initial lesion to a malignant
stage.
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
Page last modified 12 September 2001.
Copyright ©1997-2001 International Union of Pure and Applied
Chemistry.
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