IUPAC Glossary of Terms Used in Toxicology – P
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palpitation
- Unduly rapid or throbbing heartbeat that is noted by a patient; it may be regular or irregular.
- Undue awareness by a patient of a heartbeat that is otherwise normal.
paralysis
Loss or impairment of motor function.
paralytic shellfish poisoning (PSP)
Serious illness which is a consequence of consumption of toxic
bivalve shellfish (mollusks) such as mussels, oysters and clams
that have ingested, by filter feeding, large quantities of
micro-algae containing saxitoxin or its derivatives.
Note: Initially there is tingling, numbness and burning of the
tongue and lips, which spreads to the face, neck, arms,
fingertips, legs and toes and this is followed by weakness of the
upper and lower limbs, loss of motor coordination and, in severe
cases, paralysis.
- Exposure of a worker’s family to substances carried from the workplace to the home.
- Exposure of visitors to substances in the workplace.
parasympathetic
Of, relating to, or affecting the parasympathetic nervous system
which stimulates digestive secretions, slows the heart,
constricts the pupils of the eyes, and dilates blood vessels
parasympatholytic
Producing effects resembling those caused by interruption of the
parasympathetic nerve; also called anticholinergic.
parasympathomimetic
cholinomimetic
Producing effects resembling those caused by stimulation of the
parasympathetic nervous system.
parenteral dosage
Method of introducing substances into an organism avoiding the
gastrointestinal tract (subcutaneously, intravenously,
intramuscularly etc.).
paresis
Slight or incomplete paralysis.
paresthesia
paraesthesia
Abnormal or unexplained tingling, pricking, or burning sensation
on the skin.
- General term used to describe airborne solid or liquid
particles of all sizes.
Note: The term aerosol is recommended to describe airborne particulate matter. - Particlesin air, usually of a defined size and specified as
PMn where n is the maximum aerodynamic
diameter
(usually expressed in μm) of at least 50% of the
particles.
[2]
partition coefficient
Concentration
of a substance in one phase divided by the concentration of the
substance in the other phase when the heterogeneous system of two
phases is in equilibrium.
Note 1: The ratio of concentrations (or, strictly speaking,
activities) of the same molecular species in the two phases is
constant at constant temperature.
Note 2: The octanol/water partition coefficient is often used as
a measure of the bioconcentration
factor for modeling purposes.
[2]
Note 3: This term is in common usage in toxicology but is not
recommended by IUPAC for use in chemistry and should not be used
as a synonym for partition constant, partition ratio or
distribution ratio.
partition
ratio,KD
Ratio of the concentration
of a substance in a single definite form, A, in the extract to
its concentration
in the same form in the other phase at equilibrium, e.g. for an
aqueous/organic system:
KD(A) =
[A]orgc/[A]caq
[2]
Device for taking samples of environmental media following diffusional contact with a suitable collecting material.
See personal sampler
passive smoking
Inhalation of sidestream smoke by people who do not smoke
themselves.
See also sidestream
smoke
patch test
Test for allergic sensitivity in which a suspected allergen is
applied to the skin on a small surgical pad.
Note: Patch tests may be used to detect exposure to
pesticides.
peak daily average concentration of an air
pollutant
See
maximum average daily concentration of an atmospheric
pollutant
- Action of entering or passing through a cell membrane.
- Ability or power to enter or pass through a cell membrane.
perceived environment
perceived risk
See subjective
environment
percutaneous
Through the skin following application on the skin.
- Act of pouring over or through, especially the passage of a fluid through the vessels of a specific organ.
- Liquid poured over or through an organ or tissue.
[2]
perinatal
Relating to the period shortly before and after birth, usually
from the twentieth to the twenty-ninth week of gestation to one
to four weeks after birth.
peritoneal dialysis
Method of artificial detoxication
in which a toxic
substance from the body is transferred into liquid that is
instilled into the peritoneum.
Note: Effectively this represents the employment of the
peritoneum surrounding the abdominal cavity as a dialysing
membrane for the purpose of removing waste
products or toxins accumulated as a result of renal
failure.
permeability
Ability or power to enter or pass through a cell membrane.
permeability coefficient,P
Quantity defining the permeability of molecules across a cell
membrane and expressed as:
where K is the partition coefficient, D is
the diffusion coefficient, and Δx is the thickness
of the cell membrane.
Note: SI units m s-1; frequently-used units cm
s-1, with units cm2 s-1 for
D, cm for Δx.
permeable
Of a membrane, allowing a given substance to pass through.
Note: When applied to nonbiological membranes with no
qualification, the term normally refers to water.
permeation
Action of entering or passing through a cell membrane.
permissible-exposure-limit (PEL)
Recommendation by US OSHA for a TWA
concentration
that must not be exceeded during any 8-hour work shift of a 40h
working week.
peroxisome
Organelle, similar to a lysosome, characterized by its content of
catalase (EC 1.11.1.6), peroxidase (EC 1.11.1.7) and other
oxidative enzymes.
persistence
Attribute of a substance that describes the length of time that
the substance remains in a particular environment before it is
physically removed or chemically or biologically transformed.
persistent inorganic pollutant (PIP)
Inorganic substance that is stable in the environment, is liable
to long-range transport, may bio-accumulate in human and animal
tissue, and may have significant impacts on human health and the
environment.
Note 1: Examples are arsenides, fluorides, cadmium salts and lead
salts.
Note 2: Some inorganic chemicals, like crocidolite asbestos, are
persistent in almost all circumstances, but others, like metal
sulfides, are persistent only in unreactive environments;
sulfides can generate hydrogen sulfide in a reducing environment
or sulfates and sulfuric acid in oxidizing environments. As with
organic substances, persistence is often a function of
environmental properties.
persistent organic pollutant (POP)
Organic chemical that is stable in the environment, is liable to
long-range transport, may bio-accumulate in human and animal
tissue, and may have significant impacts on human health and the
environment.
Examples: dioxin, PCBs, DDT, tributyltin oxide (TBTO).
Note: The Stockholm Convention on Persistent Organic Pollutants
was adopted at a Conference of Plenipotentiaries held from 22 to
23 May 2001 in Stockholm, Sweden; by signing this convention,
governments have agreed to take measures to eliminate or reduce
the release of POPs into the environment.
personal monitoring
Type of environmental monitoring in which an individual's
exposure
to a substance is measured and evaluated.
Note: This is normally carried out using a personal sampler.
personal protective device (PPD)
See personal protective
equipment
personal protective equipment (PPE)
individual protective device (IPD)
personal protective device (PPD)
Equipment (clothing, gloves, hard hat, respirator and so on) worn
by an individual to prevent exposure
to a potentially toxic
substance
personal sampler
individual sampler
Compact, portable instrument for individual air sampling,
measuring, or both, the content of a harmful substance in the
respiration zone of a working person.
See also passive
sampler
pest
Organism that may harm public health,
that attacks food and other materials essential to mankind, or
otherwise affects human beings adversely.
pesticide
A substance intended to kill pests.
Note: In common usage, any substance used for controlling,
preventing, or destroying animal, microbiological or plant
pests.
pesticide residue
Any substance or mixture of substances found in man or animals or
in food and water following use of a pesticide: the term includes
any specified derivatives, such as degradation and conversion
products, metabolites, reaction products and impurities
considered to be of toxicological significance.
phagocytosis
Process by which particulate material is endocytosed by a
cell.
[2]
See also endocytosis,
pinocytosis
pharmaceutical
Medicinal drug.
pharmacodynamics
Process of interaction of pharmacologically active substances
with target
sites in living systems, and the biochemical and physiological
consequences leading to therapeutic or adverse
effects.
[2]
pharmacogenetics
Study of the influence of genetic factors on the effects of
drugs on
individual organisms.
[2]
pharmacogenomics
Methods and science permitting identification of the genes which
influence individual variation in the efficacy or toxicity of
therapeutic agents, and the application of this information in
clinical practice.
[2]
- Process of the uptake of drugs by the body, the biotransformation they undergo, the distribution of the drugs and their metabolites in the tissues, and the elimination of the drugs and their metabolites from the body.
- Study of such processes.
[2]
Science of the use and effects of drugs: may be subdivided into pharmacokinetics and pharmacodynamics defined above.
[2]
pharynx
Throat, the part of the digestive tract between the esophagus
below and the mouth and nasal cavities above and in front.
phase I reaction of biotransformation
Enzymic modification of a substance by oxidation, reduction,
hydrolysis, hydration, dehydrochlorination or other reactions
catalysed by enzymes of the cytosol, of the endoplasmic reticulum
(microsomal enzymes) or of other cell organelles.
See also cytochrome
P450
phase II reaction of biotransformation
Binding of a substance, or its metabolites
from a phase I reaction, with endogenous
molecules (conjugation),
making more water-soluble derivatives that may be excreted in the
urine or bile.
Note: Phase II reactions include glucuronidation, sulfation,
acetylation, amino acid (e.g., glycine) and glutathione
conjugation.
phase III reaction of
biotransformation
Further metabolism
of conjugated
metabolites
produced by phase II
reactions.
[2]
Complete phenotypic description of an organism (by analogy with genome).
phenotype
Observable structural and functional characteristics of an
organism determined by its genotype
and modulated by its environment.
photo-irritation
Inflammation of the skin caused by exposure
to light, especially that due to metabolites
formed in the skin by photolysis.
photolysis
Cleavage of one or more covalent bonds in a
molecular
entity resulting from absorption of light, or a photochemical
process in which such cleavage is an essential part.
Note: Term often used incorrectly to describe irradiation of a
sample, although in the combination flash photolysis
this usage is accepted.
[3]
photo-oxidation
Oxidation reactions induced by light. Common processes are:
(1) Loss of one or more electrons from a chemical species as a
result of photoexcitation of that species;
(2) Reaction of a substance with oxygen under the influence of
ultraviolet, visible, or infrared light. When oxygen remains in
the product this latter process is also called photooxygenation.
Reactions in which neither the substrate nor the oxygen are
electronically excited (i.e., photosensitized oxidations) are
sometimes called photoinitiated oxidations.
[3]
Abnormal visual intolerance of light.
photosensitization of skin
Allergic reaction (see allergy)
due to a metabolite formed by the influence of light.
phototoxicity
Adverse
effects produced by exposure
to light energy, especially those produced in the skin.
physical map (in genetics)
Map showing how much DNA, measured in base pairs, separates two
genes.
Note: Not to be confused with a genetic map which shows the
position of genes in relation to each other, based on the
frequency of crossing overs.
physiological availability
See bioavailability
physiological pharmacokinetic model
See physiologically-based pharmacokinetic
modeling
physiologically based pharmacokinetic modeling
(PBPK)
toxicologically based pharmacokinetic modeling (TBPK)
Mathematical modeling of kinetic behavior of a substance, based
on measured physiological parameters.
[2]
Type of endocytosis in which soluble materials are taken up by the cell and incorporated into vesicles for digestion.
[2]
piscicide
Substance intended to kill fish.
pivotal study
See critical
study
- Formation of a placenta in the uterus.
- Type or structure of a placenta.
- In botany, arrangement of placentas within the plant ovary.
- Fluid component of blood in which the blood cells and platelets are suspended.
- Fluid component of semen produced by the accessory glands, the seminal vesicles, the prostate, and the bulbo-urethral glands.
- Cell substance outside the nucleus, i.e. the cytoplasm.
plasma half-life
See elimination
half-life
plasmapheresis
Removal of blood from the body and centrifuging it to obtain
plasma and packed red blood cells:
the blood cells are resuspended in a physiologically compatible
solution (usually type-specific fresh frozen plasma or albumin)
and returned to the donor or injected into a patient who requires
blood cells rather than whole blood.
plasmid
Autonomous self-replicating extra-chromosomal circular
DNA molecule
present in bacteria and yeast.
Note 1: Plasmids replicate autonomously each time a bacterium
divides and are transmitted to the daughter cells.
Note 2: DNA segments are commonly cloned using plasmid
vectors.
After [9]
pleura
Lining of the lung.
ploidy
Term indicating the number of sets of chromosomes
present in an organism.
plumbism
saturnism
Chronic poisoning caused by absorption of lead or lead salts.
pneumoconiosis
Usually fibrosis of the lungs that develops owing to (prolonged)
inhalation of inorganic or organic dusts.
Note: Cause-specific types of pneumoconiosis are:
- anthracosis: from coal dust.
- asbestosis: from asbestos dust.
- byssinosis: from cotton dust.
- siderosis: from iron dust.
- silicosis: from silica dust.
- stannosis: from tin dust.
pneumonitis
Inflammation
of the lung.
point mutation
Reaction that changes a single base pair in DNA.
point source
Single emission
source in a defined location.
poison (in toxicology)
Substance that, taken into or formed within the organism, impairs
the health of
the organism and may kill it.
poison-bearing
Containing a poison.
poisoning
intoxication
Morbid condition produced by a poison.
pollutant
Any undesirable solid, liquid or gaseous matter in a solid,
liquid or gaseous environmental medium.
Note 1: ‘Undesirability’ is often concentration-dependent,
low concentrations of most substances being tolerable or even
essential in many cases.
Note 2: A primary pollutant is one emitted into the atmosphere,
water, sediments or soil from an identifiable source.
Note 3: A secondary pollutant is a pollutant formed by chemical
reaction in the atmosphere, water, sediments, or soil.
pollution
Introduction of pollutants into
a solid, liquid, or gaseous environmental medium, the presence of
pollutants in a solid, liquid, or gaseous environmental medium,
or any undesirable modification of the composition of a solid,
liquid or gaseous environmental medium.
polyclonal antibody
Antibody
produced by a number of different cell types.
polydipsia
Chronic excessive thirst.
polymerase chain reaction(PCR)
Technique by which specific DNA segments are amplified
selectively using cycles of annealing, chain extension, and
thermal dissociation.
After [9]
polymorphism (polymorphia) in
metabolism
Interindividual variations in metabolism
of endogenous and exogenous
compounds due to genetic influences, leading to enhanced side
effects or toxicity of drugs (for
example, poor versus fast metabolizers) or to different clinical
effects (metabolism of steroid hormones).
polyuria
Excessive production and discharge of urine.
population (in statistics)
Totality of related items under consideration.
Note 1: A clearly defined part of a population is called a
subpopulation. The term ‘population segment’ is
sometimes used as a synonym for subpopulation.
Note 2: In the case of a random variable, the probability
distribution is considered as defining the population of that
variable.
population (in epidemiology)
Assemblage of individuals with defined characteristics.
population-at-risk
Persons who can and may develop an adverse health
effect and who are potentially exposed
to a substance under study. People already having chronic disease
are excluded from the population at risk in
studies of the incidence
of the adverse
effect.
[2]
Concentration of a substance in the critical organ at which a specified percentage of the exposed population has reached the individual critical organ concentration.
Note: The percentage is indicated by PCC-10 for 10%, PCC-50 for 50% etc. (similar to the use of the term LD50).
population effect
Absolute number or incidence
rate of cases occurring in a group of people.
population risk
See societal
risk
porphyria
Disturbance of porphyrin metabolism
characterized by increased formation, accumulation, and excretion
of porphyrins and their precursors.
porphyrin
Natural pigment containing a fundamental skeleton of four pyrrole
nuclei united through the α-positions by four methine
groups to form a macrocyclic structure (porphyrin is designated
porphine in Chemical Abstracts indexes).
posology
Pharmacological study of the choice of appropriate dose
of a drug in relation to the physiological factors, such as age,
that may influence its effect.
post-translational modification
Processes by which proteins are biochemically modified within a
cell following their synthesis in the ribosomes.
potency (in toxicology)
Expression of relative toxicity
of an agent as compared to a given or implied standard or
reference.
potentiation
Dependent action in which a substance or physical agent at a
concentration
or dose that
does not itself have an adverse
effect enhances the harm done by another substance or
physical agent.
See also synergism
practical certainty (of safety)
Numerically specified low risk of
exposure
to a potentially toxic
substance (for example, 1 in 1000) or socially acceptable low
risk of adverse
effects from such an exposure applied to decision making
in regard to chemical safety.
precautionary principle
Approach to risk management that can be applied in circumstances
of scientific uncertainty, reflecting a perceived need to take
action in the face of a potentially serious risk without waiting
for definitive results of scientific research.
Note: The 1992 Rio Declaration on Environment and Development
says: “In order to protect the environment, the
precautionary approach shall be widely applied by states
according to their capabilities. Where there are threats of
serious or irreversible damage, lack of full scientific certainty
shall not be used as a reason for postponing cost-effective
measures to prevent environmental degradation.”
precision (in metrology)
Closeness of agreement between indications
obtained by replicate measurements on the same or similar objects
under specified conditions.
Note: Measurement precision is usually expressed numerically by
measures of imprecision, such as standard deviation, variance, or
coefficient of variation under the specified conditions of
measurement.
[7]
Pertaining to the region over the heart and lower thorax.
precursor
Substance from which another, usually more biologically active,
substance is formed.
predicted environmental concentration
(PEC)
predicted exposure concentration
See estimated
environmental concentration
predicted no effect concentration
(PNEC)
Concentration that is expected to cause no adverse effect to any
naturally occurring population in an environment at risk from
exposure to a given substance.
predictive validity
Reliability of a measurement expressed in terms of its ability to
predict the criterion: an example would be an academic aptitude
test that was validated against subsequent academic
performance.
predictive value
Percentage of positive results that are true positives or of
negative results that are true negatives.
premature ovarian failure
Follicular depletion by the age of 35 years.
[8]
preneoplastic
Before the formation of a tumor.
prevalence
Number of instances of existing cases of a given disease or other
condition in a given population at a designated time; sometimes
used to mean prevalence
rate.
Note: When used without qualification, refers usually to the
situation at a specified time (point prevalence).
prevalence rate (ratio)
Total number of individuals who have an attribute or disease at a
particular time (or during a particular period) divided by the
population at risk of
having the attribute or disease at this point in time or midway
through the period.
primary pollutant
See pollutant
prior informed consent (PIC)
Concept in law and medicine which states that before one is
subjected to a risk, especially a risk of bodily harm, one is
entitled to be fully informed well in advance of the nature of
that risk in order to make an informed decision about whether to
accept it or not.
primary protection standard
Accepted maximum level of a pollutant (or its indicator) in the
target
organism, or some part thereof, or an accepted maximum intake of
a pollutant or nuisance into the target under specified
circumstances.
probit
Probability unit obtained by adding 5 to the normal deviates of a
standardized normal distribution of results from a dose response
study.
Note 1: Addition of 5 removes the complication of handling
negative values.
Note 2: A plot of probit against the logarithm of dose or
concentration
gives a linear plot if the response follows a logarithmic normal
distribution. Estimates of the LD50 and
ED50 (or LC50 and
EC50) can be obtained from this plot.
procarcinogen
Substance that has to be metabolized before it becomes a
carcinogen.
[2]
prodrug
Precursor converted to an active form of a drug within
the body.
[2]
progression (in oncology)
Increase in the size of a tumor or spread of cancer in the
body.
prokaryote
Unicellular organism, characterized by the absence of a
membrane-enclosed nucleus.
Note: Prokaryotes include bacteria, blue-green algae and
mycoplasmas.
promoter (in molecular genetics)
Sequence of nucleotides in a DNA molecule to which RNA polymerase
binds so as to start transcription.
promoter (in oncology)
Agent that induces cancer
when administered to an animal or human being who has been
exposed
to a cancer initiator.
promotor
Erroneous spelling of promoter
(in molecular genetics), found in some literature.
pro-pesticide
Substance applied in a form that is not active as a pesticide and
which becomes active once it enters an organism and undergoes
chemical modification.
prophage
Latent state of a phage genome in
a lysogenic bacterium.
proportional mortality rate (ratio)
Proportion of observed deaths from a specified condition in a
defined population divided by the proportion of deaths expected
from this condition in a standard population, expressed
either
prosthetic group
Nonprotein entity essential for an enzyme’s activity and
tightly bound to the enzyme molecule in its active form.
[2]
proteinuria
Excretion of excessive amounts of protein (derived from blood
plasma or kidney tubules) in the
urine.
proteome
Description of the complete set of proteins encoded by the
genome.
[2]
Global analysis of gene expression using a variety of techniques to identify and characterize proteins.
Note: It can be used to study changes caused by exposure to chemicals and to determine if changes in mRNA expression correlate with changes in protein expression: the analysis may also show changes in post-translational modification, which cannot be distinguished by mRNA analysis alone.
[2]
provisional tolerable weekly intake
(PTWI)
See tolerable weekly
intake
pseudo-acceptable daily intake (PADI)
Intake for a substance derived by applying a thousandfold
uncertainty factor to the lowest low-effect level for
noncarcinogenic endpoints.
pseudoadaptation
Apparent adaptation of an organism to changing conditions of the
environment (especially chemical) associated with stresses in
biochemical systems that exceed the limits of normal
(homeostatic) mechanisms.
Note: Essentially there is a temporary concealed pathology that
later on can be manifested in the form of explicit pathological
changes sometimes referred to as
‘decompensation’.
psychosis
Any major mental disorder characterized by derangement of the
personality and loss of contact with reality.
psychotropic
Exerting an effect upon the mind and capable of modifying mental
activity.
public health impact assessment
Applying risk
assessment to a specific target population of known size, giving
as the end product a quantitative statement about the number of
people likely to be affected in a particular population.
pulmonary
Pertaining to the lung(s).
[2]
purgative
See laxative
pyrexia
Condition in which the temperature of a human being or mammal is
above normal.
pyrogen
Any substance that produces fever.