COMMISSION ON TOXICOLOGY
Glossary for chemists of terms used in toxicology
(IUPAC Recommmendations 1993)
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back-mutation: Process which reverses the effect of a mutation
which had inactivated a gene; thus it restores the wild phenotype.
bactericide: Substance intended to kill bacteria.
bagassosis: Lung disease caused by the inhalation of dust from
base pairing: Linking of the complementary pair of polynucleotide
chains of nucleic acids by means of hydrogen bonds between complementary
purine and pyrimidine bases, adenine with thymine or uracil, cytosine
B-cell: See B lymphocyte.
benefit: Advantage to or improvement in condition of an individual
or a population.
1. Of a disease, producing no persisting harmful effects.
2. Tumour which does not invade other tissues (metastasize), having
lost growth control but not positional control.
berylliosis: See SN beryllium
beryllium disease: Serious and
usually permanent lung damage resulting from chronic inhalation of beryllium.
bias: Deviation of results or inferences from the truth, or
processes leading to such deviation. Any trend in the collection, analysis,
interpretation, publication, or review of data which can lead to conclusions
which are systematically different from the truth. Among the ways in
which deviation from the truth can occur are the following:
1. Systematic (one-sided) variation of measurements from the true values
SN systematic error.
2. Variation of statistical summary measures (means, rates, measures
of association, etc.) from their true values as a
result of systematic variation of measurements, other flaws
in data collection, or flaws in study design or analysis.
3. Deviation of inferences from the truth as a result of flaws in study
design, data collection, or the analysis or
interpretation of results.
4. A tendency of procedures (in study design, data collection, analysis,
interpretation, review or publication) to yield
results or conclusions which depart from the truth.
5. Prejudice leading to the conscious or unconscious selection of study
procedures which depart from the truth in a
particular direction, or to one-sidedness in the interpretation
biased sample: Any sample which
is not a random sample.
AN random sample.
RT stratified sample, systematic
bilirubin: Orange-yellow pigment (C33H36O6N4),
a breakdown product of haem-containing proteins (haemoglobin, myoglobin,
cytochromes), which circulates in the blood plasma bound to albumin
or as water soluble glucuronides, and is excreted in the bile by the
bioaccumulation: Progressive increase
in the amount of a substance in an organism or part of an organism which
occurs because the rate of intake exceeds the organism's ability to
remove the substance from the body.
PS bioconcentration, biomagnification.
bioaccumulation potential: Ability of living organisms to concentrate
a substance obtained either directly from the environment or indirectly
through its food.
bioactivation: Any metabolic conversion
of a xenobiotic to a more toxic derivative.
bioassay: Procedure for estimating the concentration or biological
activity of a substance (vitamin, hormone, plant growth factor, antibiotic
etc.) by measuring its effect on an organism compared to an appropriate
Nagel et al. (eds), 1991
1. Extent to which a substance to which the body is exposed (by ingestion,
inhalation, injection, or skin contact) reaches
the systemic circulation, and the rate at which this occurs.
SN biological availability, physiological availability.
2. Pharmacokinetic term relating systemic exposure from extravascular
exposure (ev) to that following intravenous exposure
(iv) by the equation:
F = AUCev*Div / AUCiv*Dev
where F is the bioavailability, AUCev and AUCiv
are the areas under the plasma concentration time curve following extravascular
and intravenous administration and Dev and Div
are the administered extravascular and intravenous doses.
biochemical mechanism: Reaction or series of reactions, usually
enzyme-catalysed, associated with a specific physiological event in
a living organism.
(biological) oxygen demand (BOD): Substance concentration of oxygen
taken up through the respiratory activity of micro-organisms growing
on organic compounds present when incubated at a specified temperature
(usually 20 o C) for a fixed period (usually 5 days). It is regarded
as a measure of that organic pollution of water which can be degraded
but includes the oxidation of inorganic material such as sulfide and
iron(II). The empirical test used in the laboratory to determine BOD
also measures the oxygen used to oxidize reduced forms of nitrogen unless
their oxidation is prevented by an inhibitor such as allyl thiourea.
RT chemical oxygen demand.
Nagel et al. (eds), 1991
biocid/e n., -al adj.: Substance intended to kill living
bioconcentration: Process leading
to a higher concentration of a substance in an organism than in environmental
media to which it is exposed.
PS bioaccumulation, biomagnification.
After WHO, 1979
bioconcentration factor (BCF): Measure of the tendency for a
substance in water to accumulate in fish tissue or in tissues of other
organisms. The equilibrium concentration of a substance in fish can
be estimated by multiplying the concentration of the substance in the
surrounding water by the fish bioconcentration factor for that chemical.
This parameter is an
important determinant for human intake by the aquatic food ingestion
After USEPA, 1986
bioconversion: See SN biotransformation.
biodegradation: Breakdown of a
substance catalysed by enzymes in vitro or in vivo. This
may be characterized for purposes of hazard assessment as:
1. Primary. Alteration of the chemical structure of a substance resulting
in loss of a specific property of that substance.
2. Environmentally acceptable. Biodegradation to such an extent as to
remove undesirable properties of the compound. This
often corresponds to primary biodegradation but it depends
on the circumstances under which the products are discharged
into the environment.
3. Ultimate. Complete breakdown of a compound to either fully oxidised
or reduced simple molecules (such as carbon
dioxide/methane, nitrate/ammonium, and water.
It should be noted that the products of biodegradation can be more harmful
than the substance degraded.
bio-elimination: Removal, usually from the aqueous phase, of
a test substance in the presence of living organisms by biological processes
supplemented by physico-chemical reactions.
bio-equivalen/ce n., -t adj.: Relationship between two
preparations of the same drug in the same dosage form that have a similar
biological absorption: See absorption,
biological acclimatization: See acclimatization,
1. Assessment of exposure to a substance by the analysis of specimens
taken in the environment such as foodstuffs, plants,
animals, biological material in air or water samples, or
biological material from exposed subjects. When human samples
are analysed, they are usually urine and blood; other possible
samples include expired air, faeces, saliva, bile, hair,
and biopsy or autopsy material. When other organisms are
being considered, the whole organism may be analysed as well as
selected tissues such as fat in pigs or birds. In these
samples, the content(s) of the substance(s) or metabolite(s)
is determined and, on this basis, the exposure level (concentration
in the air, absorbed amount of the substance) or the
probability of health impairment due to exposure are derived.
2. Biochemical changes in the components of an organism, such as changes
in enzyme activity or in the excretion of
metabolic intermediates, can also be used for this purpose
if they show a relationship to the exposure.
BT biological monitoring, monitoring.
biological cycle: Complete circulatory
process through which a substance passes in the biosphere. It may involve
transport through the various media (air, water, soil), followed by
environmental transformation, and carriage through various ecosystems.
RT biosphere, ecosystem.
biological effect monitoring
(BEM): Continuous or repeated measurement of early biological effects
of exposure to a substance to evaluate ambient exposure and health risk
by comparison with appropriate reference values based on knowledge of
the probable relationship between ambient exposure and biological effects.
BT biological monitoring, environmental
biological half-life or half-time(t1/2):
Time required for the amount of a substance in a biological system to
be reduced to one-half, predominantly by biological processes, when
the rate of removal is approximately exponential.
Gold, Loening, McNaught and Sehmi, 1987
biological monitoring: Continuous
or repeated measurement of potentially toxic substances or their metabolites
or biochemical effects in tissues, secreta, excreta, expired air or
any combination of these in order to evaluate occupational or environmental
exposure and health risk by comparison with appropriate reference values
based on knowledge of the
probable relationship between ambient exposure and resultant adverse
NT biological effect monitoring
BT environmental monitoring,
RT biological assessment
biological oxygen demand: See SN biochemical
biological preparation: Compound derived from living organisms
and their products for use in medicine or as a pesticide etc.
SN biological, biopreparation.
1. Organ, tissue (including blood), secretion or excretion product taken
from an organism as a sample reflecting the state
of the whole organism.
2. Organism taken as a sample reflecting the state of a population or
biomagnification: Sequence of
processes in an ecosystem by which higher concentrations are attained
in organisms at higher trophic levels (at higher levels in the food
web); at its simplest, a process leading to a higher concentration of
a substance in an organism than in its food.
SN ecological magnification.
RT bioaccumulation, bioconcentration.
1. Parameter that can be used to identify a toxic effect in an individual
organism and can be used in extrapolation between
2. Indicator signalling an event or condition in a biological system
or sample and giving a measure of exposure, effect, or
1. Total amount of biotic material, usually expressed per unit surface
area or volume, in a medium such as water.
2. Material produced by the growth of micro-organisms, plants or animals.
Nagel et al. (eds),
biomineralization: Complete conversion of organic substances
to inorganic derivatives by living organisms, especially micro-organisms.
biomonitoring: See SN biological
biopsy: Excision of a small piece of living
tissue for microscopic or biochemical examination; usually performed
to establish a diagnosis.
biosphere: Portion of the planet earth
which supports and includes life.
biostatic: Arresting the growth or multiplication of living
biota: All living organisms as a totality.
biotransformation: Any chemical
conversion of substances that is mediated by living organisms or enzyme
preparations derived therefrom.
Nagel et al. (eds), 1991
blood substitution: See SN exchange
B lymphocyte: Type of lymphocyte
which synthesizes and secretes antibodies in response to the presence
of a foreign substance or one identified by it as foreign. The protective
effect can be mediated to a certain extent by the antibody alone (contrast
RT immune response, lymphocyte,
body burden: Total amount of substance of a chemical present
in an organism at a given time.
1. Single dose of a substance, originally a large pill.
2. Dose of a substance administered by a single rapid intravenous injection.
3. Concentrated mass of food ready to be swallowed.
brady-: Prefix meaning slow as in bradycardia or bradypnoea.
bradycardia: Abnormal slowness of
bradypnoea: Abnormally slow breathing.
breathing zone: Space within a radius of 0.5 m from a person's
British anti-Lewisite (BAL):
See SN 2,3-dimercaptopropan-1-ol.
of the air passages through the bronchi of the lungs.
bronchodilation: Expansion of
the air passages through the bronchi of the lungs.
bronchospasm: Intermittent violent contraction of the air passages
of the lungs.
builder: Material which enhances or maintains the cleaning efficiency
of a surfactant, in a detergent, principally by inactivating water hardness;
complex phosphates (especially sodium tripolyphosphate, i.e. pentasodium
triphosphate), sodium carbonate, and sodium silicate are the builders
most commonly used.
byssinosis: Pneumoconiosis caused by
inhalation of dust and associated microbial contaminants and observed
in cotton, flax, and hemp workers.
bystander exposure: Liability
of members of the general public to come in contact with substances
arising from operations or processes carried out by other individuals
in their vicinity.
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