Toxicology Glossary - A
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, 1978
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
- 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.
- In animal tests - allowing an animal to adjust to its environment prior to undertaking a study
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:
- 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 taken.
- 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.
acute:
- 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 - In clinical medicine, sudden and severe, having a rapid onset
acute toxicity:
- 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
- Ability of a substance to cause adverse effects within a short time of dosing or exposure.
AN chronic toxicity.
RT limit test, median lethal dose (LD50)
adaptation:
- 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
- Process by which an organism stabilizes its physiological condition after an environmental change
RT acclimatization
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
adjuvant:
- In pharmacology, a substance added to a drug to speed or increase the action of the main component
- In immunology, a substance (such as aluminium hydroxide) or an organism (such as bovine tuberculosis bacillus) which increases the response to an antigen
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, 1978
aerosol: Dispersion of liquid or solid material in a gas
Gold, Loening, McNaught and Sehmi, 1987
aetiology:
- Science dealing with the cause or origin of disease
- In individuals, the cause or origin of disease
RT epidemiology
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:
- Network of organizations which monitor air pollution
- Group of measures or processes used to minimize or prevent air pollution
RT air pollution,pollution
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
antagonist:
- Substance that reverses or reduces the effect induced by an agonist
- Substance that attaches to and blocks cell receptors that normally bind naturally occurring substances
AN agonist
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
anticholinergic:
- adj., Preventing transmission of parasympathetic nerve impulses
- n., Substance which prevents transmission of parasympathetic nerve impulses
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
assay:
- Process of quantitative or qualitative analysis of a component of a sample
- Results of a quantitative or qualitative analysis of a component of a sample
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
astringent:
- Adj. Causing contraction, usually locally after topical application
- 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
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