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Pure Appl. Chem., Vol. 65, No. 9, pp. 2003-2122, 1993.



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 



abiological: See SN abiotic

abiotic: Not associated with living organisms.
SN abiological.

abiotic transformation: Process in which a substance in the environment is modified by non-biological mechanisms.
RT biotransformation.
IPCS, 1987

absolute lethal concentration (LC100): Lowest concentration of a substance in an environmental medium which kills 100 % of test organisms or species under defined conditions. This value is dependent on the number of organisms used in its assessment.
WHO, 1979

absolute lethal dose (LD100): Lowest amount of a substance which kills 100 % of test animals under defined conditions. This value is dependent on the number of organisms used in its assessment.

absorbed dose (of a substance): Amount of a substance absorbed into an organism or into organs and tissues of interest.

absorbed dose (of radiation): Energy imparted to matter in a suitably small element of volume by ionizing radiation divided by the mass of that element of volume. The SI unit for absorbed dose is joule per kilogram (J kg-1) and its special name is gray (Gy).
ISO, 1972
RT ionizing radiation.

absorption (biological): Process of active or passive transport of a substance into an organism: in the case of a mammal or human being, this is usually through the lungs, gastrointestinal tract, or skin.

absorption (in colloid and surface chemistry): Process whereby, when two phases are brought into contact, a particular component is transferred from one phase to the other.
PAC, 1972

absorption (of radiation): Phenomenon in which radiation transfers some or all of its energy to matter which it traverses.
ISO, 1972

absorption coefficient (in biology): Ratio of the absorbed amount (uptake)of a substance to the administered amount (intake): for exposure by way of the respiratory tract, the coefficient is the ratio of the absorbed amount to the amount of the substance (usually particles) deposited (adsorbed) in the lungs.
RT absorbed dose.
SN absorption factor.
IRPTC, 1982

abuse (of drugs, substances, solvents etc.): Improper use of drugs or other substances.
RT "glue sniffing", solvent abuse, "solvent sniffing".

acaricide: Substance intended to kill mites, ticks or other Acaridae.

acceptable daily intake (ADI): Estimate of the amount of a substance in food or drinking water, expressed on a body mass basis (usually mg/kg body weight), which can be ingested daily over a lifetime by humans without appreciable health risk. For calculation of the daily intake per person, a standard body mass of 60 kg is used. ADI is normally used for food additives (tolerable daily intake is used for contaminants).
WHO, 1991
RT tolerable daily intake.

acceptable daily intake (ADI) not allocated: See SN no acceptable daily intake allocated.

acceptable residue level of an antibiotic: Acceptable concentration of a residue which has been established for an antibiotic found in human or animal foods.

acceptable risk: Probability of suffering disease or injury which is considered to be sufficiently small to be "negligible".
PS tolerable risk.
RT accepted risk, negligible risk, risk de minimis.

accepted risk: Probability of suffering disease or injury which is accepted by an individual.

accidental exposure: Unintended contact with a substance or change in the physical environment (including for example radiation) resulting from an accident.

acclimatization (biological):
1. Processes, including selection and adaptation, by which a population of micro-organisms
   develops the ability to degrade a substance, or develops a tolerance to it.
2. In animal tests - allowing an animal to adjust to its environment prior to undertaking a

accumulation: Successive additions of a substance to a target organism, or organ, or to part of the environment, resulting in an increasing amount or concentration of the substance in the organism, organ, or environment.
WHO, 1989a

accuracy: Quantity referring to the differences between the mean of a set of results or an individual result and the value which is accepted as the true or correct value for the quantity measured.
Gold, Loening, McNaught and Sehmi, 1987
RT precision.

acidosis: Pathological condition in which the hydrogen ion substance concentration of body fluids is above normal and hence the pH of blood falls below the reference interval.
AN alkalosis.

action level:
1. Concentration of a substance in air, soil, water or other defined medium at which specified
   emergency counter-measures, such as the seizure and destruction of contaminated materials,
   evacuation of the local population or closing down the sources of pollution, are to be
2. Concentration of a pollutant in air, soil, water or other defined medium at which some kind
   of preventive action (not necessarily of an emergency nature) is to be taken.

activation: See NT bioactivation.

1. Short-term, in relation to exposure or effect. In experimental toxicology, "acute" refers
   to studies of two weeks or less in duration (often less than 24 h).
   AN chronic
2. In clinical medicine, sudden and severe, having a rapid onset.

acute effect: Effect of short duration and occurring rapidly (usually in the first 24 h or up to 14 d) following a single dose or short exposure to a substance or radiation.

acute toxicity:
1. Adverse effects occurring within a short time (usually up to 14 d) after administration of
   a single dose (or exposure to a given concentration)of a test substance or after multiple
   doses (exposures), usually within 24 h.
2. Ability of a substance to cause adverse effects within a short time of dosing or exposure.
AN chronic toxicity.

acute toxicity test: Experimental animal study to determine what adverse effects occur in a short time (usually up to 14 d) after a single dose of a substance or after multiple doses given in up to 24h.
RT limit test, median lethal dose (LD50).

1. Change in an organism, in response to changing conditions of the environment (specifically
   chemical), which takes place without any irreversible disruptions of the given biological
   system and without exceeding normal (homeostatic) capacities of its response.
2. Process by which an organism stabilizes its physiological condition after an environmental
RT acclimatization.

added risk: Difference between the incidence of an adverse effect in a treated group (of organisms or a group of exposed humans) and a control group (of the same organisms or the spontaneous incidence in humans).
IRIS, 1986

addiction: Surrender and devotion to the regular use of a medicinal or pleasurable substance for the sake of relief, comfort, stimulation, or exhilaration which it affords; often with craving when the drug is absent.
PS dependence.

additive effect: Consequence which follows exposure to two or more physico-chemical agents which act jointly but do not interact: commonly, the total effect is the simple sum of the effects of separate exposure to the agents under the same conditions. Substances of simple similar action may show dose or concentration addition.
RT antagonism, combined effect of poisons, potentiation, synergism.

adduct: New chemical species AB, each molecular entity of which is formed by direct combination of two separate molecular entities A and B in such a way that there is no change in connectivity of atoms within their moieties A and B. Stoichiometries other than 1:1 are also possible.  An intramolecular adduct can be formed when A and B are groups contained
within the same molecular entity.
Gold, Loening, McNaught and Sehmi, 1987

adenocarcinoma: Malignant tumour originating in glandular epithelium or forming recognizable glandular structures.
RT adenoma.

adenoma: Benign tumour occurring in glandular epithelium or forming recognizable glandular structures.
RT adenocarcinoma.

1. In pharmacology, a substance added to a drug to speed or increase the action of the main
2. In immunology, a substance (such as aluminium hydroxide) or an organism (such as bovine
   tuberculosis bacillus) which increases the response to an antigen.

administration (of a substance): Application of a known amount of a substance to an organism in a reproducible manner and by a defined route.

adrenergic: See SN sympathomimetic

adsorption: Enrichment (positive adsorption, or briefly adsorption) of one or more components in an interfacial layer.
Gold, Loening, McNaught and Sehmi, 1987

adverse effect: Change in morphology, physiology, growth, development or lifespan of an organism which results in impairment of functional capacity or impairment of capacity to compensate for additional stress or increase in susceptibility to the harmful effects of other environmental influences.
After IPCS, 1978

adverse event: Occurrence which causes an adverse effect.

aerobe: Organism which needs molecular oxygen for respiration and hence for growth and life.
After Nagel et al. (eds), 1991

aerobic: Requiring molecular oxygen.

aerodynamic diameter (of a particle): Diameter of a spherical particle of unit density which has the same settling velocity in air as the particle in question.
IPCS, 1987

aerosol: Dispersion of liquid or solid material in a gas.
Gold, Loening, McNaught and Sehmi, 1987

1. Science dealing with the cause or origin of disease.
2. In individuals, the cause or origin of disease.
RT epidemiology.

after-effect of a poison: Ability of a poison to produce a change in an organism after cessation of contact.

age sensitivity: Quantitative and qualitative age dependence of an effect.
IRPTC, 1982

agonist: Substance which binds to cell receptors normally responding to naturally occurring substances and which produces a response of its own.
AN antagonist.

air pollution: Presence of substances in the atmosphere resulting either from human activity or natural processes, in sufficient concentration, for a sufficient time and under circumstances such as to interfere with comfort, health or welfare of persons or to harm the environment.
ISO, 1980
BT pollution.

air pollution control system:
1. Network of organizations which monitor air pollution.
2. Group of measures or processes used to minimize or prevent air pollution.
RT air pollution, pollution.

albuminuria: Presence of albumin, derived from plasma, in the urine.
RT microalbuminuria, proteinuria.

algicide: Substance intended to kill algae.

alkalosis: Pathological condition in which the hydrogen ion substance concentration of body fluids is below normal and hence the pH of blood rises above the reference interval.
AN acidosis.

alkylating agent: Substance which introduces an alkyl substituent into a compound.

allele: One of several alternate forms of a gene which occur at the same relative position (locus) on homologous chromosomes and which become separated during meiosis and can be recombined following fusion of gametes.
RT gametes, meiosis.
Nagel et al. (eds), 1991

allergen: Antigenic substance capable of producing immediate hypersensitivity.
RT allergy, antigen, hypersensitivity.

allergy: Symptoms or signs occurring in sensitized individuals following exposure to a previously encountered substance (allergen) which would otherwise not cause such symptoms or signs in non-sensitized individuals.  The most common forms of allergy are rhinitis, urticaria, asthma, and contact dermatitis.
RT immune response, hypersensitivity.

all-or-none effect: See SN quantal effect.
RT stochastic effect.

alopecia: Baldness; absence or thinning of hair from areas of skin where it is usually present.

alveol/us (pulmonary), -i pl., -ar adj.: Terminal air sac of the lung where gas exchange occurs.

ambient: Surrounding (applied to environmental media such as air, water, sediment or soil).

ambient monitoring: Continuous or repeated measurement of agents in the environment to evaluate ambient exposure and health risk by comparison with appropriate reference values based on knowledge of the probable relationship between exposure and resultant adverse health effects.
After Berlin, Yodaiken, and Henman, 1984
RT biological monitoring, environmental monitoring, monitoring.

ambient standard: See SN environmental quality standard.

Ames test: In vitro test for mutagenicity using mutant strains of the bacterium Salmonella typhimurium which cannot grow in a given histidine-deficient medium: mutagens can cause reverse mutations which enable the bacterium to grow on the medium. The test can be carried
out in the presence of a given microsomal fraction (S-9) from rat liver to allow metabolic transformation of mutagen precursors to active derivatives.

amplification (of genes): See gene amplification.

anabolism: Biochemical processes by which smaller molecules are joined to make larger molecules.
AN catabolism.

anaemia: Condition in which there is a reduction in the number of red blood cells or amount of haemoglobin per unit volume of blood below the reference interval for a similar individual of the species under consideration, often causing pallor and fatigue.

anaerobe: Organism which does not need molecular oxygen for life. Obligate (strict) anaerobes grow only in the absence of oxygen.  Facultative anaerobes can grow either in the presence or in the absence of molecular oxygen.
Nagel et al. (eds), 1991
AN aerobe.

anaerobic: Not requiring molecular oxygen.

anaesthetic: Substance which produces loss of feeling or sensation: general anaesthetic produces loss of consciousness; local or regional anaesthetic renders a specific area insensible to pain.

analgesic: Substance which relieves pain, without causing loss of consciousness.

analogue metabolism: Process by which a normally non-biodegradable compound is biodegraded in the presence of a structurally similar compound which can induce the necessary enzymes.

analytic study (in epidemiology): Hypothesis-testing method of investigating the association between a given disease or health state or other dependent variable and possible causative factors. In an analytic study, individuals in the study population are classified according to
absence or presence (or future development) of specific disease and according to attributes which may influence disease occurrence. Attributes may include age, race, sex, other disease(s), genetic, biochemical, and physiological characteristics, economic status, occupation, residence, and various aspects of the environment or personal behaviour.
Three types of analytic study are: cross-sectional (prevalence), cohort (prospective), and case control (retrospective).
Last, 1988

anaphylaxis: Severe allergic reaction occurring in a person or animal exposed to an antigen or hapten to which they have previously been sensitized.
RT antigen, hapten.

anaplasia: Loss of normal cell differentiation, a feature characteristic of most malignancies.
RT malignancy.

anemia: See anaemia.

aneuploid: Cell or organism with missing or extra chromosomes or parts of chromosomes.

anoxia: Strictly total absence of oxygen but sometimes used to mean decreased oxygen supply in tissues.

antagonism: Combined effect of two or more factors which is smaller than the solitary effect of any one of those factors. In bioassays, the term may be used when a specified response is produced by exposure to either of two factors but not by exposure to both together.
RT synergism.

1. Substance that reverses or reduces the effect induced by an agonist.
2. Substance that attaches to and blocks cell receptors that normally bind naturally occurring
AN agonist.

anthelmint(h)ic: Substance intended to kill parasitic intestinal worms, such as helminths.
SN antihelminth.

anthracosis (coal miners' pneumoconiosis): Form of pneumoconiosis caused by accumulation of carbon deposits in the lungs due to inhalation of smoke or coal dust.

anthropogenic: Caused by or influenced by human activities.

anti-adrenergic: See SN sympatholytic.

antibiotic: Substance produced by, and obtained from, certain living cells (especially bacteria, yeasts and moulds), or an equivalent synthetic substance, which is biostatic or biocidal at low concentrations to some other form of life, especially pathogenic or noxious organisms.

antibody: Protein molecule produced by the immune system (an immunoglobulin molecule) which can bind specifically to the molecule (antigen or hapten) which induced its synthesis.
RT antigen, hapten, immunoglobulin.

1. adj., Preventing transmission of parasympathetic nerve impulses.
2. n., Substance which prevents transmission of parasympathetic nerve impulses.

anticholinesterase: See SN cholinesterase inhibitor.

anticoagulant: Substance which prevents clotting.

antidote: Substance capable of specifically counteracting or reducing the effect of a potentially toxic substance in an organism by a relatively specific chemical or pharmacological action.

antigen: Substance or a structural part of a substance which causes the immune system to produce specific antibody or specific cells and which combines with specific binding sites (epitopes) on the antibody or cells.
After Nagel et al. (eds), 1991
RT antibody, epitope.

antihelminth: See SN anthelmint(h)ic.

antimetabolite: Substance, structurally similar to a metabolite, which competes with it or replaces it, and so prevents or reduces its normal utilization.

antimycotic: Substance used to kill a fungus or to inhibit its growth.
SN fungicide.

antipyretic: Substance which relieves or reduces fever.

antiresistant: Substance used as an additive to a pesticide formulation in order to reduce the resistance of insects to the pesticide.
IRPTC, 1982

antiserum: Serum containing antibodies to a particular antigen either because of immunization or after an infectious disease.

aphasia: Loss or impairment of the power of speech or writing, or of the ability to understand written or spoken language or signs, due to a brain injury or disease.

aphicide: Substance intended to kill aphids.
BT insecticide.

aphid: Common name for a harmful plant parasite in the family Aphididae: some species are vectors of plant virus diseases.

aplasia: Lack of development of an organ or tissue, or of the cellular products from an organ or tissue.

apoptosis: Physiological process of programmed tissue death (and disintegration) associated with normal development in animals.
RT necrosis.

arboricide: Substance intended to kill trees and shrubs.

area source: Widespread origin of emissions.
RT point source.

argyria: Pathological condition characterized by grey-bluish or black pigmentation of tissues (such as skin, retina, mucous membranes, internal organs) caused by the accumulation of metallic silver, due to reduction of a silver compound which has entered the organism during (prolonged) administration or exposure.
SN argyrosis.

argyrosis: See SN argyria.

arrhythmia: Any variation from the normal rhythm of the heartbeat.

artefact: Finding or product of experimental or observational techniques that is not properly associated with the system being studied.

arteriosclerosis: Hardening and thickening of the walls of the arteries.

arthralgia: Pain in a joint.

arthralgia saturnia: Pain in a joint resulting from lead poisoning.

arthritis: Inflammation of a joint, usually accompanied by pain and often by changes in structure.

asbestosis: Form of pneumoconiosis caused by inhalation of asbestos fibres.
BT pneumoconiosis.

ascaricide: Substance intended to kill roundworms (Ascaridae).

asphyxia: Condition resulting from insufficient intake of oxygen: symptoms include breathing difficulty, impairment of senses, and, in extreme, convulsions, unconsciousness and death.

asphyxiant: Substance that blocks the transport or use of oxygen by living organisms.

1. Process of quantitative or qualitative analysis of a component of a sample.
2. Results of a quantitative or qualitative analysis of a component of a sample.

assessment of exposure: See NT biological assessment of exposure.

asthenia: Weakness; lack or loss of strength.

asthma: Chronic respiratory disease characterised by bronchoconstriction, excessive mucus secretion and oedema of the pulmonary alveoli, resulting in difficulty in breathing out, wheezing, and cough.

1. Adj. Causing contraction, usually locally after topical application.
2. N. Substance causing cells to shrink, thus causing tissue contraction or stoppage of secretions and discharges; such
   substances may be applied to skin to harden and protect it.

ataxia: Unsteady or irregular manner of walking or movement caused by loss or failure of muscular coordination.

atherosclerosis: Pathological condition in which there is thickening, hardening, and loss of elasticity of the walls of blood vessels, characterized by a variable combination of changes of the innermost layer consisting of local accumulation of lipids, complex carbohydrates, blood and blood components, fibrous tissue and calcium deposits. In addition, the outer layer becomes thickened and there is fatty degeneration of the middle layer.

atrophy: Wasting away of the body or of an organ or tissue.

attenuation (in genetics): Regulation of gene expression in bacteria by premature termination of transcription of a biosynthetic operon.

attractant: Substance used to attract animals with the aim of killing or sterilizing them.
BT pheromone.

attributable risk: Difference between the risk of exhibiting a certain adverse effect in the presence of a substance and the same risk in the absence of the substance.
BT risk.
Last, 1988

autoimmune disease: Pathological condition resulting when an organism produces antibodies or specific cells which bind to constituents of its own tissues (autoantigens) and cause tissue injury: examples of such disease may include rheumatoid arthritis, myasthenia gravis, and scleroderma.
RT allergy, antibody, antigen, hypersensitivity, immune response.

autophagosome: Membrane-bound body (secondary lysosome) in which parts of the cell are digested.

autopsy: Post-mortem examination of the organs and body tissue to determine cause of death or pathological condition.
RT biopsy.
SN necropsy.

auxotroph: Organism unable to synthesize an organic molecule which is required for its growth: when the compound is given to the organism with the other nutrients it requires, growth of the organism may occur.

auxotrophy: Inability of a micro-organism to synthesize a particular organic compound required for its growth.
Nagel et al. (eds), 1989

avicide: Substance intended to kill birds.

axenic animal: See SN germ free animal


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