IUPAC Glossary of Terms Used in Toxicology – S
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S9 fraction
Supernatant fraction obtained from an organ (usually liver)
homogenate by centrifuging at 9000 g for 20 minutes in a
suitable medium; this fraction contains cytosol and
microsomes.
safety
Reciprocal of risk:
practical certainty that injury will not result from a
hazard under defined
conditions.
Note 1. Safety of a drug or
other substance in the context of human health: the extent to which a
substance may be used in the amount necessary for the intended
therapeutic purpose with a minimum risk of adverse health
effects.
Note 2. Safety (toxicological): The high probability that injury
will not result from exposure to a substance under
defined conditions of quantity and manner of use, ideally
controlled to minimize exposure.
safety data sheet
Single page giving toxicological and other safety advice, usually associated with a
particular preparation, substance or process.
safety factor (SF)
See uncertainty factor
safety pharmacology
Science directed to the discovery, development and safe
therapeutic use of biologically active substances as a result of
the identification, monitoring and characterization of
potentially undesirable pharmacodynamic activities of these
substances in nonclinical studies.
saluretic
See natriuretic
- Group of individuals often taken at random from a population for research purposes.
- One or more items taken from a population or a process and intended to provide information on the population or process.
- Portion of material selected from a larger quantity so as to be representative of the whole.
sampling error
That part of the total error (the estimate from a sample minus the population value) associated
with using only a fraction of the population and extrapolating to
the whole, as distinct from analytical or test error.
Note: Sampling error arises from a lack of homogeneity in the
parent population.
[2]
sarcoma
Malignant tumor arising in a connective tissue
and composed primarily of anaplastic cells resembling
supportive tissue (see anaplasia).
saturable elimination
Elimination that
becomes concentration-independent at a
concentration at which the elimination process is functioning
maximally.
[2]
saturnia
Pain in a joint resulting from lead poisoning.
saturnism
plumbism
Intoxication caused by lead.
Scatchard plot
Method for analysing data for freely reversible
ligand/receptor binding
interactions.
Note: The graphical plot is [bound ligand]/[free ligand] against
[bound ligand], with slope the negative reciprocal of the binding
affinity and intercept on the x-axis the number of
receptors.
[2]
scotoma
Area of diminished or lost vision within the visual field,
surrounded by an area of less affected or normal vision.
sclerosis
Hardening of an organ or tissue, especially that due to excessive
growth of fibrous tissue.
- Carrying out of a test or tests, examination(s) or procedure(s) in order to expose undetected abnormalities, unrecognized (incipient) diseases, or defects: examples are mass X-rays and cervical smears.
- Pharmacological or toxicological screening consists of a specified set of procedures to which a series of compounds is subjected to characterize pharmacological and toxicological properties and to establish dose-effect and dose-response relationships.
screening level
Decision limit or cut-off point at which a screening test is regarded as positive.
secondary metabolite
Product of biochemical processes other than the normal metabolic
pathways, mostly produced in micro-organisms or plants after the
phase of active growth and under conditions of nutrient
deficiency.
secondhand smoke
See sidestreamsmoke
second messenger
Intracellular effector substance increasing or decreasing as a
result of the stimulation of a receptor by an agonist, considered as the
‘first messenger’.
[2]
- Process by which a substance such as a hormone or enzyme produced in a cell is passed through a plasma membrane No Entry to the outside, for example the intestinal lumen or the blood (internal secretion).
- Solid, liquid or gaseous material passed from the inside of a cell through a plasma membrane to the outside as a result of cell activity.
sedative
Substance that exerts a soothing or tranquillizing effect.
self-cleaning of water (in a reservoir)
Water purification by natural biological and physico-chemical
processes.
self-purification of the atmosphere
Purification of the atmosphere from contaminants by natural
biological and physico-chemical processes.
semichronic
See subchronic
semiochemical
Substance produced by plants or animals, or a synthetic analogue
thereof, that evokes a behavioral response in individuals of the
producing species or other species (e.g. allomones, kairomones,
pheromones, and synomones).
semipermeable (selectively or differentially
permeable) membrane
Membrane that will preferentially allow certain molecules or ions
to pass through it while preventing the passage of others.
sensibilization
See sensitization
- Quotient of the change in the indication and the corresponding
change in the value of the quantity being measured.
[7] - Slope of the calibration curve. If the curve is in fact a
‘curve’, rather than a straight line, then of course
sensitivity will be a function of analyte concentration or
amount. If sensitivity is to be a unique performance
characteristic, it must depend only on the chemical measurement
process, not upon scale factors.
[3]
sensitivity (of a screening test)
Extent (usually expressed as a percentage) to which a method
gives results that are free from false negatives.
Note 1: The fewer the false negatives, the greater the
sensitivity.
Note 2: Quantitatively, sensitivity is the proportion of truly
diseased persons in the screened population who are identified as
diseased by the screening test.
sensitization
Immune response
whereby individuals become hypersensitive to
substances, pollen, dandruff, or other agents that make them
develop a potentially harmful allergy when they are subsequently
exposed to the
sensitizing material (allergen).
sensitizer
Substance causing sensitization.
- Intensity, where the detection threshold level is defined as the lower limit of the perceived intensity range (by convention the lowest concentration that can be detected in 50% of the cases in which it is present).
- Quality, where the recognition threshold level is defined as the lowest concentration at which the sensory effect can be recognized correctly in 50% of the cases.
- Acceptability and annoyance, where the nuisance threshold
level is defined as the concentration at which not
more than a small proportion of the population, less than 5%,
experiences annoyance for a small part of the time, less than
2%.
Note: Since annoyance will be influenced by a number of factors, a nuisance threshold level cannot be set on the basis of concentration alone.
serum
Clear watery fluid especially that moistening the surface of
serous membranes or that exuded through inflammation of any of these
membranes.
[2]
serum
blood serum
Watery proteinaceous portion of the blood that remains after
clotting.
[2]
shellfish poisoning
Serious illness which is a consequence of consumption of bivalve
shellfish (mollusks) such as mussels, oysters and clams that have
ingested, by filter feeding, large quantities of micro-algae.
See amnesic
shellfish poisoning, diarrheal
shellfish poisoning, neurologic
shellfish poisoning, paralytic shellfish
poisoning
short-term effect
See acute effect
short-term exposure limit (STEL)
Fifteen minute time weighted
average (TWA) exposure recommended by ACGIH which
should not be exceeded at any time during a workday, even if the
8-hour TWA is within the threshold
limit value-time-weighted average, TLV-TWA.
Note: Workers can be exposed to a maximum of four STEL periods
per 8 hour shift, with at least 60 minutes between exposure
periods.
[2]
short-term toxicity
See acute
toxicity.
side-effect
Action of a drug other than
that desired for beneficial pharmacological effect.
- Pneumoconiosis resulting from the inhalation of iron dust.
- Excess of iron in the urine, blood or tissues, characterized by hemosiderin granules in urine and iron deposits in tissues.
sidestream smoke
environmental tobacco smoke (ETS)
secondhand smoke
Cloud of small particles and gases that is given off from the end
of a burning tobacco product (cigarette, pipe, cigar) between
puffs and is not directly inhaled by the smoker.
Note: This is the smoke that gives rise to passive inhalation on
the part of bystanders.
sign
Objective evidence of a disease, deformity or an effect induced
by an agent, perceptible to an examining physician.
signal transduction
Molecular pathways through which a cell senses changes in its
external or internal environment and changes its pattern of
gene expression or enzyme
activity in response.
After [9]
silicosis
Pneumoconiosis
resulting from inhalation of silica dust.
simulation test
Procedure designed to predict the rate of biodegradation of a compound
under relevant environmental conditions.
single nucleotide polymorphism (SNP)
Single base variation at a chromosomal locus which exists stably
within populations (typically defined as each variant form being
present in at least 1-2% of individuals).
After [8]
sink
In environmental chemistry, an area or part of the environment in
which, or a process by which, one or more pollutants is removed from the
medium in which it is dispersed.
Note: For example - moist ground acts as a sink for sulfur
dioxide in the air.
sister chromatid exchange (SCE)
Reciprocal exchange of chromatin between two replicated
chromosomes that
remain attached to each other until anaphase of mitosis; used as a measure of
mutagenicity of
substances that produce this effect.
skeletal fluorosis
Osteosclerosis due to fluoride.
slimicide
Substance intended to kill slime-producing organisms.
Note: Used on paper stock, water cooling systems, paving stones
etc.
slope factor
Value, in inverse concentration or dose units, derived from the slope of a
dose-response
curve; in practice, limited to carcinogenic effects with the
curve assumed to be linear at low concentrations or doses.
Note: The product of the slope factor and the exposure is taken to reflect the
probability of producing the related effect.
societal risk
Total probability of harm to a human population including the
probability of adverse
effects to health of descendants and the
probability of disruption resulting from loss of services such as
industrial plant or loss of material goods and electricity.
soil partition coefficient (soil
Kd)
Experimental ratio of a substance's concentration in the soil to
that in the aqueous (dissolved) soil phase at equilibrium: it is
valid only for the specific concentration and solid/solution
ratio of the test.
See also organic carbon
partition coefficient
[6]
solvent abuse
solvent sniffing
Deliberate inhalation (or drinking) of volatile solvents, in
order to become intoxicated.
‘solvent sniffing’
See solvent abuse
- Pertaining to the body as opposed to the mind.
- Pertaining to nonreproductive cells or tissues.
- Pertaining to the framework of the body as opposed to the viscera.
soporific
Substance producing sleep.
sorption
Noncommittal term used instead of adsorption or absorption when it is difficult
to discriminate experimentally between these two processes.
speciation (in chemistry)
Distribution of an
element amongst defined chemical species in a system.
[3]
speciation analysis (in chemistry)
Analytical activities of identifying and (or) measuring the
quantities of one or more individual chemical species in a
sample.
[3]
- In biological systematics, group of organisms of common ancestry that are able to reproduce only among themselves and that are usually geographically distinct.
- See chemical species
species differences in sensitivity
Quantitative or qualitative differences of response to the
action(s) of a potentially toxic substance on various species of
living organisms.
species-specific sensitivity
Quantitative and qualitative features of response to the
action(s) of a potentially toxic substance that are
characteristic for a particular species of living organism.
specific death rate
Death rate computed for a subpopulation of individual organisms
or people having a specified characteristic or attribute, and
named accordingly.
Example: age-specific death rate, the number of deaths of persons
of a specified age during a given period of time, divided by the
total number of persons of that age in the population during that
time.
specificity (of a screening test)
Proportion of truly non-diseased persons who are identified by
the screening test.
specific pathogen free (SPF)
Describing an animal removed from its mother under sterile
conditions just prior to term and subsequently reared and kept
under sterile conditions.
specimen
Specifically selected portion of any substance, material,
organism (specifically tissue, blood, urine or faeces) or
environmental medium assumed to be representative of the parent
substance etc. at the time it is taken for the purpose of
diagnosis, identification, study or demonstration.
spectral radiant power
The radiant power at wavelength lambda (λ) per unit wavelength interval.
splicing
Processes through which introns are removed from a messenger RNA
prior to translation and the exons joined.
[9]
spreader
Agent used in some pesticide formulations to extend
the even disposition of the active ingredient.
stability half-life (half-time)
Time required for the amount of a substance in a formulation to
decrease, for any reason, by one-half (50%).
See also half life,
half time
standard
That which is established as a measure or model to which others
of a similar nature should conform.
standard (in law or regulation)
technical directive
Technical specification, usually in the form of a document
available to the public, drawn up with the consensus or general
approval of all interests affected by it, based on the
consolidated results of science, technology and experience, aimed
at the promotion of optimum community benefits and approved by a
body recognized on the national, regional or international
level.
standard (in analytical chemistry)
See reference
material, standard
material
- Making any substance, drug or other preparation conform to type or precisely defined characteristics.
- Establishment of precisely defined characteristics, or precisely defined methods, for future reference.
- Definition of precise procedures for administering, scoring and evaluating the results of a new method that is under development.
standard material (in analytical
chemistry)
standard
See reference
material
standard(ized) mortality (morbidity) ratio
SMR
Ratio of the number of deaths observed in the study group or
population to the number of deaths that would be expected if the
study population had the same specific rates as the standard
population, multiplied by 100.
Note: This ratio is usually expressed as a percentage.
stannosis
Pneumoconiosis resulting from inhalation of tin dust.
steady state (in chemistry and
toxicology)
State of a system in which the conditions do not change in
time.
Note: For further information, see [3].
[2]
stem cell
Multipotent cell
with mitotic potential that may serve as a precursor for many
kinds of differentiated cells.
[2]
stereoselective synthesis
Chemical reaction (or reaction sequence) in which one or more new
elements of chirality are formed in a substrate molecule and
which produces the stereoisomeric (enantiomeric or
diastereoisomeric) products in unequal amounts.
Note: Traditionally called asymmetric synthesis.
[2]
stereoselectivity
Specificity of chemical reactivity of stereoisomers based on
their three-dimensional molecular structure.
[2]
stochastic
Pertaining to or arising from chance and hence obeying the laws
of probability.
stochastic effect
stochastic process
Phenomenon pertaining to or arising from chance, and hence
obeying the laws of probability.
stochastic process
See stochastic
effect
stratification (in epidemiology)
Process of or result of separating a sample into several subsamples according to
specified criteria such as age groups, socio-economic status,
etc.
stratified sample
Subset of a population selected according to some important
characteristic.
stress proteins
See heat shock
proteins
structural alert
Chemical grouping which is known to be associated with a
particular type of toxic effect, e.g. mutagenicity.
structure activity relationship (SAR)
Association between specific aspects of molecular structure and
defined biological action.
See also quantitative
structure-activity relationship
structure-metabolism relationship
(SMR)
Association between the physicochemical and (or) the structural
properties of a substance and its metabolic behavior.
[2]
subacute
See subchronic
subchronic
Repeated over a short period, usually about 10 % of the life
span; an imprecise term used to describe exposures of intermediate
duration.
subchronic effect
Biological change resulting from an environmental alteration
lasting about 10 % of the lifetime of the test organism.
Note: In practice with experimental animals, such an effect is
usually identified as resulting from multiple or continuous
exposures occurring
over 3 months (90 days). Sometimes a subchronic effect is
distinguished from a subacute
effect on the basis of its lasting for a much longer time.
subchronic toxicity test
Animal experiment serving to study the effects produced by the
test substance when administered in repeated doses (or continually in food,
drinking-water, air) over a period of up to about 90 days.
subclinical effect
Biological change with detectable symptoms following exposure to an agent known to cause
disease either before symptoms of the disease occur or when they
are absent.
subfertility
Fertility below the normal range for a given species.
[8]
subjective environment
perceived environment
Surrounding conditions as perceived by persons living in these
conditions.
- Substance material on which an enzyme acts.
- Surface on which an organism grows or to which is attached.
subthreshold dose
See non-effective dose
sudorific
See diaphoretic
sufficient evidence
According to the USEPA's Guidelines for Carcinogen Risk
Assessment, sufficient
evidence is a collection of facts and scientific references that
is definite enough to establish that an adverse effect is caused by
the agent in question.
suggested no adverse response level
(SNARL)
Maximum dose or concentration that on current
understanding is likely to be tolerated by an exposed organism without producing
any harm.
suicide reaction
Formation of irreversible cleavage complexes (also referred to as
‘suicide complexes’) leading to cell death.
summary sheet
Two-to-four page summary of a risk assessment.
summation (in neurophysiology)
Process of addition of separate postsynaptic responses caused by
stimuli that are adjacent in time and space.
Note: Excitation of a synapse evokes a graded potential change in
the postsynaptic membrane that may be below the threshold
required to trigger an impulse. If two or more such potentials
are caused either nearly simultaneously, at different synapses on
the same neuron (spatial summation), or in rapid succession at
the same synapse (temporal summation), the summed response may be
sufficient to trigger a postsynaptic impulse. Summation may occur
between excitatory potentials, inhibitory potentials, or between
an excitatory and an inhibitory potential.
Superfund
Federal authority, established by the US Comprehensive
Environmental Response, Compensation, and Liability Act (CERCLA)
in 1980, to respond directly to releases or threatened releases
(such as from landfills or waste disposal areas) of hazardous
substances that may endanger health or welfare.
superoxide dismutase
Enzymatic antioxidant that removes the potentially toxic
superoxide ion (O2- ) by disproportionating it to
O2 and hydrogen peroxide
(H2O2).
super-threshold dose
See toxic dose
surface layer
Region of space comprising and adjoining the phase boundary
between a solid and liquid phase, between a solid and gas phase,
or between a liquid and gas phase within which properties of
matter are significantly different from the values in the
adjoining bulk phases.
surrogate
Relatively well studied toxicant whose properties are
assumed to apply to an entire chemically and toxicologically
related class; for example, benzo(a)pyrene data may be used as
toxicologically equivalent to that for all carcinogenic polynuclear aromatic
hydrocarbons.
surveillance
Systematic ongoing collection, collation, and analysis of data
and the timely dissemination of information to those who need to
know in order that action can be taken to initiate investigative
or control measures.
susceptible
vulnerable
Describing a group of organisms more vulnerable to a given
exposure than the
majority of the population to which they belong.
Note: Susceptibility may reflect gender, age, physiological
status, or genetic constitution of the organisms at risk.
[2]
susceptibility biomarker
See biomarker
of susceptibility
susceptibility
Condition of lacking the power to resist a particular disease or
infection; thus in susceptible people ‘normal
expected’ results occur but with a lower exposure (or dose) than in the rest of the
population.
- adj., Blocking transmission of impulses from the adrenergic (sympathetic) postganglionic fibers to effector organs or tissues.
- n., Agent that blocks transmission of impulses from the adrenergic (sympathetic) postganglionic fibers to effector organs or tissues.
- adj., Producing effects resembling those of impulses transmitted by the postganglionic fibers of the sympathetic nervous system.
- n., Agent that produces effects resembling those of impulses transmitted by the postganglionic fibers of the sympathetic nervous system.
symptom
Any subjective evidence of a disease or an effect induced by a
substance as perceived by the affected subject.
symptomatology
General description of all of the signs and symptoms of
exposure to a
toxicant
Note: Signs are the overt (observable) responses associated with
exposure (such as convulsions, death, etc.) whereas symptoms are
covert (subjective) responses (such as nausea, headache,
etc.).
synapse
Functional junction between two neurons, where a nerve impulse is
transmitted from one neuron to another.
synaptic transmission
See synapse
syndrome
Set of signs and symptoms occurring together and often
characterizing a particular disease-like state.
synergism (in toxicology)
synergistic effect
synergy (in toxicology
Pharmacological or toxicological interaction in which the
combined biological effect of exposure to two or more substances
is greater than expected on the basis of the simple summation of
the effects of each of the individual substances.
synergist (in toxicology)
Substance which contributes more than additively to a mutual
effect with another substance.
synergistic effect
See synergism
synergy
See synergism
synomone
Semiochemical that is
produced by one organism inducing a response in an organism of
another species that is favorable to both the emitter and the
responding organism.
See allomone,
kairomone
synteny
Property of genes which reside on the same chromosome.
systematic sample
Subset selected according to some simple rule such as specified
date or alphabetic classification.
- Relating to the body as a whole.
- Occurring at a site in the body remote from the point of
contact with a substance.
After [1]
systemic effect
Consequence that is either of a generalized nature or that occurs
at a site distant from the point of entry of a substance.
Note: A systemic effect requires absorption and distribution of
the substance in the body.
systems biology
Study of the mechanisms underlying complex biological processes
as integrated systems of many, diverse, interacting
components.
Note: It involves (1) collection of large sets of experimental
data (by high-throughput technologies and/or by mining the
literature of reductionist molecular biology and biochemistry),
(2) proposal of mathematical models that might account for at
least some significant aspects of this data set, (3) accurate
computer solution of the mathematical equations to obtain
numerical predictions, and (4) assessment of the quality of the
model by comparing numerical simulations with the experimental
data.