IUPAC Glossary of Terms Used in Toxicology – I
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iatrogenic
Any adverse condition resulting from medical treatment.
icterus
Excess of bile pigment in the blood and consequent deposition and
retention of bile pigment in the skin and the sclera.
idiopathic environmental intolerance
See multiple chemical sensitivity
idiosyncrasy
Genetically based unusually high sensitivity of an organism to
the effect of certain substances.
immediately-dangerous-to-life-or-health-concentration
(IDLHC)
According to the US NIOSH, the maximum exposure concentration from which one
could escape within thirty minutes without any escape-impairing
symptoms or any irreversible health effects.
immission
Environmental concentration of a
pollutant resulting from a
combination of emissions and dispersals (often synonymous with
exposure).
immuno-assay
Ligand-binding assay that uses a specific antigen or antibody,
capable of binding to the analyte, to identify and quantify
substances. The antibody can be linked to a radioisotope
(radioimmunoassay, RIA) or to an enzyme which catalyses an easily
monitored reaction (enzyme-linked immunosorbent assay, ELISA), or
to a highly fluorescent compound by which the location of an
antigen can be visualized (immunofluorescence).
[3]
immune complex
Product of an antigen-antibody reaction that may also contain
components of the complement system.
immune response
Selective reaction of the body to substances that are foreign to
it, or that the immune
system identifies as foreign, shown by the production of
antibodies and antibody-bearing cells or by a
cell-mediated hypersensitivity
reaction.
Integrated network of organs, glands, and tissues that has evolved to protect the body from foreign substances, including bacteria, viruses, and other infection-causing parasites and pathogens.
Note: The immune system may produce hypersensitivity reactions reactions which, in the extreme, can be fatal. If the immune system misidentifies normal body components as foreign, this leads to autoimmune disorders, such as lupus, in which the body destroys its own constituents.
immunochemistry
Study of biochemical and molecular aspects of immunology,
especially the nature of antibodies, antigens and their interactions.
immunogen
See antigen
immunoglobulin
Family of closely related glycoproteins capable of acting as
antibodies and present in plasma and tissue fluids; immunoglobulin E (IgE) is the source
of antibody in Type I
hypersensitivity
(allergic)
reactions.
immunoglobulin E-mediated
hypersensitivity
State in which an individual reacts with allergic effects caused
fundamentally by the reaction of antigen-specific immunoglobulin E following
exposure to a certain substance (allergen) after having been
exposed previously to
the same substance.
immunomodulation
Modification of the functioning of the immune system by the
action of a substance that increases or reduces the ability to
produce antibodies.
immunopotentiation
Enhancement of the capacity of the immune system to produce an
effective response.
immunosuppression
Reduction in the functional capacity of the immune response; may be due to:
- Inhibition of the normal response of the immune system to an antigen.
- Prevention, by chemical or biological means, of the production of an antibody to an antigen by inhibition of the processes of transcription, translation or formation of tertiary structure.
Mechanisms by which the immune system is able to recognize and destroy malignant cells before the formation of an overt tumor.
immunotoxic
Harmful to the immune system.
Of a membrane, not allowing a given substance to pass through. When applied to nonbiological membranes with no qualification, the term normally refers to water.
implantation
Attachment of the fertilized ovum (blastocyst) to the endometrium
and its subsequent embedding in the compact layer, occurring 6 or
7 days after fertilization of the ovum.
[8]
insilico
Phrase applied to data generated and analysed using computer
modeling and information technology.
invitro
antonym in vivo
In glass, referring to a study in the laboratory usually
involving isolated organ, tissue, cell, or biochemical
systems.
invivo
antonym in vitro
In the living body, referring to a study performed on a living
organism.
incidence
Number of occurrences of illness commencing, or of persons
falling ill, during a given period in a specific population:
usually expressed as a rate.
Note: When expressed as a rate, it is the number of ill persons
divided by the average number of persons in the specified
population during a defined period, or alternatively divided by
the estimated number of persons at the mid-point of that
period.
[2]
incidence rate (epidemiology)
Measure of the frequency at which new events occur in a
population.
Note: This is the value obtained by dividing the number of new
events that occur in a defined period by the population at
risk of experiencing the
event during this period, sometimes expressed as person-time.
incremental unit risk
estimate
For an air pollutant, this is the additional lifetime
cancer risk occurring in a hypothetical
population in which all individuals are exposed continuously from birth
throughout their lifetimes to a concentration of 1 microgram
per cubic meter (μg m-3) of the pollutant in the
air they breathe.
indication
Quantity value provided by a measuring instrument or a measuring
system.
[7]
indirect exposure
- Exposure to a substance in a medium or vehicle other than the one originally receiving the substance.
- Exposure of people to a substance by contact with a person directly exposed.
individual monitor
See personal sampler
individual protective device
(IPD)
personal protective device (PPD)
See personal protective
equipment
individual risk
Probability that an individual person will experience an
adverse
effect.
inducer
Substance that causes induction.
induction
Increase in the rate of synthesis of an enzyme in response to the
action of an inducer or environmental conditions.
Note: Often the inducer is the substrate of the induced enzyme or
a structurally similar substance (gratuitous inducer) that is not
metabolized.
induction period
latent period
Time from the onset of exposure to the appearance of signs
of disease.
industrial hygiene
See occupational hygiene
inert chemical
Substance that is not generally reactive.
inert ingredient
Any intentionally added ingredient of a mixture which does not
contribute to the desired biological effect: this definition does
not include impurities and does not imply that the inert
ingredient has no biological effects.
Related term: active
ingredient
infertility (in human
medicine)
Inability to become pregnant within 1 year of unprotected
intercourse.
[8]
inflammation
Reaction of the body to injury or to infectious, allergic, or
chemical irritation; characterized by redness, swelling, heat,
and pain resulting from dilation of the blood vessels accompanied
by loss of plasma and leucocytes (white blood cells) into the
tissues.
infusion (in physiology)
Therapeutic introduction of a fluid other than blood, as a
(usually saline) solution, into a vein.
[2]
- Process of taking food and drink into the body by mouth.
- Process of taking in particles by a phagocytic cell.
inhalation
Act of drawing in of air, vapor or gas and any suspended
particulates into the
lung.
inherently biodegradable
Class of compounds for which there is unequivocal evidence of
biodegradation
(primary or ultimate) in any test of biodegradability.
inhibitory concentration
(IC)
Concentration of a
substance that causes a defined inhibition of a given system.
Note: IC50 is the median concentration that causes 50%
inhibition.
inhibitory dose
(ID)
Dose of a substance that causes a defined inhibition of a given
system.
Note: ID50 is the median dose that causes 50%
inhibition.
- Agent that induces a change in a chromosome or gene that leads to the induction of tumors after a second agent, called a promoter, is administered to the tissue.
- Substance that starts a chain reaction
Note: An initiator is consumed in a chain reaction, in contrast to a catalyst.
insecticide
Substance intended to kill insects.
intake
Amount of a substance that is taken into the body, regardless of
whether or not it is absorbed: the total daily intake is the sum
of the daily intake by an individual from food, drinking-water,
and inhaled air.
integral indicator of toxic
effect
Parameter (such as body weight or temperature) characterizing the
overall changes in the general state of the organism exposed to a toxic substance.
interactome
Large scale protein–protein interaction map.
Inhomogeneous space region intermediate between two bulk phases in contact, and where properties are significantly different from, but related to, the properties of the bulk phases.
[2]
intermittent effect
discontinuous effect
Biological change that comes and goes at intervals.
internal dose
See absorbed dose
internal validity
Selection and comparison of index and comparison groups in such a
manner that, apart from sampling error, the observed differences
between these groups with respect to dependent variables under
study may be attributed only to the hypothesized effect under
investigation.
interpolation
Estimation of a value between two known data points.
interpretation (of data or findings)
Evaluation of the observations from an investigation or study in
order to determine their significance for human health, for the environment or for
both.
interspecies dose
conversion
Process of extrapolating from the doses of one animal species to
another, for example from rodent dose to human equivalent.
interstitial fluid
Aqueous solution filling the narrow spaces between cells.
[2]
interstitial pneumonia
Chronic form of pneumonia involving increase of the interstitial
tissue and decrease of the functional lung tissue.
intervention study
Epidemiological investigation designed to test a hypothesized
cause-effect relationship by intentional change of a supposed
causal factor in a population.
intestinal reabsorption
Absorption further down the intestinal tract of a substance or
substances that have been absorbed before and subsequently
excreted into the intestinal tract, usually through the bile.
- Poisoning: pathological process with clinical signs and symptoms caused by a substance of exogenous or endogenous origin.
- Drunkenness following consumption of beverages containing ethanol or other compounds affecting the central nervous system.
intrinsic activity
Maximal stimulatory effect induced by a compound in relation to
that of a given reference compound.
[2]
intrinsic clearance
Volume of plasma or blood
from which a substance is completely removed in a period of time
under unstressed conditions.
[2]
intrinsic factor (in
biochemistry)
Specific protein required for the absorption of vitamin
B12 and secreted by cells in the gastric glands of the
stomach.
[2]
intron
Non-coding sequence within genes which separates the exons (coding
regions).
Note: Introns are spliced out of the messenger RNA molecule
created from a gene after
transcription and prior to translation.
After [9]
in vitro
antonym in
vivo
In glass, referring to a study in the laboratory usually
involving isolated organ, tissue, cell, or biochemical
systems.
in vivo
antonym in vitro
In the living body, referring to a study performed on a living
organism.
ionizing radiation
Any radiation consisting of directly or indirectly ionizing
particles or a mixture of both or photons with energy higher than
the energy of photons of ultraviolet light or a mixture of both
such particles and photons.
irreversible alteration
Change from normal structure or function that persists or
progresses after cessation of exposure of the organism.
irritant
- n., Substance that causes inflammation following immediate,
prolonged or repeated contact with skin, mucous membrane, or
other biological material.
Note: A substance capable of causing inflammation on first contact is called a primary irritant. - adj., Causing inflammation following immediate, prolonged or repeated contact with skin, mucous membrane or other tissues.
ischemia
Local deficiency of blood supply and hence oxygen to an organ or
tissue owing to constriction of the blood vessels or to
obstruction.
isotonic
Denoting a liquid exerting the same osmotic pressure or chemical
potential of water (water
potential) as another liquid with which it is being
compared.
itai-itai disease
Illness (renal osteomalacia) observed in the Toyama prefecture of
Japan, resulting from the ingestion of cadmium-contaminated
rice.
Note: Damage occurred to the renal and skeleto-articular systems, the
latter being very painful (“itai” means
“ouch” in Japanese and refers to the intense pain
caused by the condition).