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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

râles: See SN crepitations.
random sample: Subset of a population that is arrived at by selecting units such that each possible unit has a fixed and determinate probability of selection.
After Last, 1988.
AN biased sample.
BT sample.
rate: Measure of the frequency of a phenomenon: an expression of the frequency with which an event occurs in a defined population during a specified time interval.
Last, 1988
rate difference (RD): Absolute difference between two rates, for example, the difference in incidence rate between a population group exposed to a causal factor and a population group not exposed to the factor: in comparisons of exposed and unexposed groups, the term "excess rate" may be used as a synonym for rate difference.
Last, 1988
rate ratio (RR): In epidemiology, the value obtained by dividing the rate in an exposed population by the rate in an unexposed population.
After Last, 1988
ratticide: Substance intended to kill rats.
RT rodenticide.
readily biodegradable: Arbitrary classification of substances that have passed certain specified screening tests for ultimate biodegradability; these tests are so stringent that such compounds will be rapidly and completely biodegraded in a wide variety of aerobic environments.
reasonable maximum exposure (RME): Highest exposure that is reasonably expected to occur: typically the 95% upper confidence limit of the toxicant distribution is used: if only a few data points (6-10) are available, the maximum detected concentration is used.
USEPA, 1989
recalcitrance: Ability of a substance to remain in a particular environment in an unchanged form.
Nagel et al. (eds), 1991
RT persistence.
receptor: High affinity binding site for a particular toxicant.
BT target, target organ.
1. Process leading to partial or complete restoration of a cell, tissue, organ or organism following its damage from
   exposure to a harmful substance or agent.
2. Term used in analytical and preparative chemistry to denote the fraction of the total quantity of a substance
   recoverable following a chemical procedure.
   RT recovery factor.
recovery factor: Fraction or percentage of the total quantity of a substance extracted under specified conditions.
Gold, Loening, McNaught and Sehmi, 1987
recycling (of waste): Process or method allowing for the recovery of some value from a waste, either as re-usable material or as energy.
reference concentration: Term used for an estimate of air exposure concentration to the human population (including sensitive subgroups) that is likely to be without appreciable risk of deleterious effects during a lifetime.
USEPA, 1989
RT acceptable daily intake.
BT dose.
reference distribution: Statistical distribution of reference values.
Solberg, 1987
reference dose: Term used for an estimate (with uncertainty spanning perhaps an order of magnitude) of a daily exposure to the human population (including sensitive subgroups) that is likely to be without appreciable risk of deleterious effects during a lifetime.
Barnes and Dourson, 1988
RT acceptable daily intake.
BT dose.
reference group: See SN reference sample group.
reference individual: Person selected with the use of defined criteria for comparative purposes in a clinical study.
Solberg, 1987
reference interval: Area between and including two reference limits, for example the percentiles 2.5 and 97.5.
 Solberg, 1987
reference limit: Boundary value defined so that a stated fraction of the reference values is less than or exceeds that boundary value with a stated probability.
Solberg, 1987
reference material: Substance for which one or more properties are sufficiently well established to be used for the calibration of an apparatus, the assessment of a measurement method, or for assigning values to other substances.
SN calibration material, standard material.
Solberg, 1987
reference population: Group of all reference individuals used to establish criteria against which a population that is being studied can be compared.
Solberg, 1987
reference sample group: Selected reference individuals, statistically adequate numerically to represent the reference population.
Solberg, 1987
reference value: According to IFCC, measured value of a property in a reference individual or sample from a reference individual.
Solberg, 1987
regulatory dose: Term used by the USEPA to describe the expected dose resulting from human exposure to a substance at the level at which it is regulated in the environment.
Barnes and Dourson, 1988
relative odds: See SN odds ratio.
relative risk:
1. Ratio of the risk of disease or death among the exposed to that among the unexposed.
   SN risk ratio.
2. Ratio of the cumulative incidence rate in the exposed to the cumulative incidence rate in the unexposed; the cumulative
   incidence ratio.
Last, 1988
renal: Pertaining to the kidneys.
repellent: Substance used mainly to repel blood sucking insects in order to protect man and animals: also used to repel mammals, birds, rodents, mites, plant pests, etc.
replicate sampling: Act of taking multiple samples concurrently under comparable conditions; may be accomplished by taking samples adjacent in time or space.
PAC, 1990
1. Duplicated or repeated performance of an experiment under similar (controlled) conditions to reduce to a minimum the
   error, and to estimate the variations and thus obtain a more precise result: each determination, including the first is
   called a replicate.
2. Process whereby the genetic material is duplicated.
reproducibility: Closeness of agreement between test results obtained under reproducibility conditions (see below).
ISO 5725, 1986.
RT reproducibility conditions.
reproducibility conditions: Situation where test results are obtained with the same method on identical test material in different laboratories with different operators using different equipment.
ISO 5725, 1986.
reproductive toxicant: Substance or preparation that produces non-heritable harmful effects on the progeny and/or an impairment of male and female reproductive function or capacity.
USEPA, 1986
RT teratogen.
reproductive toxicology: Study of the adverse effects of substances on the embryo, fetus, neonate and prepubertal mammal and the adult reproductive and neuro-endocrine systems.
RT embryo, fetus, neonate.
reserve capacity: Physiological or biochemical capacity that may be available to maintain homeostasis when the body or an organism is exposed to an environmental change.
resistance (in toxicology): Ability to withstand the effect of various factors including potentially toxic substances.
resorptive effect: Action of a substance after its resorption from the gut into the blood.
IRPTC, 1982
1. Proportion of an exposed population with a defined effect or the proportion of a group of individuals that demonstrate a
   defined effect in a given time at a given dose rate.
   RT dose-response relationship.
2. Reaction of an organism or part of an organism (such as a muscle) to a stimulus.
1. Holding back within the body or within an organ, tissue or cell of matter that is normally eliminated.
   AN elimination.
2. Holding in memory of what has been learned for later use as recall, recognition or relearning.
3. Amount of a substance that is left from the total absorbed after a certain time following exposure: if the retention
   follows a course in relation to time that is a first order process, it may be described in terms of biological half-life
   RT half-life.
retrospective study: Research design used to test aetiological hypotheses in which inferences about exposure to the putative causal factor(s) are derived from data relating to characteristics of the persons or organisms under study or to events or experiences in their past: the essential feature is that some of the persons under study have the disease or other outcome condition of interest, and their characteristics and past experiences are compared with those of other, unaffected persons. Persons who differ in the severity of the disease may also be compared.
RT case control study.
Last, 1988
returned effect of poisons: Enhancement of the dose-effect relationship for a poison following repeated exposure to decreasing doses.
reverse transcription: Process by which an RNA molecule is used as a template to make a single-stranded DNA copy.
reversible alteration: Change from normal structure or function, induced by a substance or other agent(s), that returns to normal status or within normal limits after cessation of exposure.
rhabdomyolysis: Acute, fulminating, potentially lethal disease of skeletal muscle that causes disintegration of striated muscle fibres as evidenced by myoglobin in the blood and urine.
rhinitis: Inflammation of the nasal mucosa.
rhonch/us (pl -i): Harsh crepitation in the throat, often resembling snoring.
BT crepitations.
ribonucleic acid: Linear, usually single stranded, polymer of ribonucleotides, each containing the sugar ribose in association with a phosphate group and one of 4 nitrogenous bases: adenine, guanine, cytosine, or uracil: it encodes the
information for the sequence of amino-acids in proteins synthesized using it as a template.
RT deoxyribonucleic acid.
1. Possibility that a harmful event (death, injury or loss) arising from exposure to a chemical or physical agent may occur
   under specific conditions.
2. Expected frequency of occurrence of a harmful event (death, injury or loss) arising from exposure to a chemical or
   physical agent under specific conditions.
NT excess lifetime risk, extra risk.
RT hazard.
risk acceptance: Decision that the risk associated with a given chemical exposure or an event leading to such exposure is low enough to be tolerated in order to gain associated benefits.
RT acceptable risk.
risk assessment: Identification and quantification of the risk resulting from a specific use or occurrence of a chemical or physical agent, taking into account possible harmful effects on individual people or society of using the chemical or physical agent in the amount and manner proposed and all the possible routes of exposure. Quantification ideally requires the establishment of dose-effect and dose-response relationships in likely target individuals and populations.
RT exposure assessment, hazard identification, risk characterization, risk estimation, risk evaluation, risk identification, risk management, risk perception.
risk assessment management process: Global term for the whole process from hazard identification to risk management.
WHO, 1988
RT hazard identification, risk management.
risk associated with a life time exposure: Probability of the occurrence of a specified undesirable event following exposure of an individual person from a given population to a specified substance at a defined level for the expected lifetime of the average member of that population.
risk aversion: Term used to describe the tendency of an individual person to avoid risk.
risk characterization: Outcome of hazard identification and risk estimation applied to a specific use of a substance or occurrence of an environmental health hazard: the assessment requires quantitative data on the exposure of organisms or people at risk in the specific situation. The end product is a quantitative statement about the proportion of organisms or people affected in a target population.
After WHO, 1979
RT hazard identification, risk estimation.
risk communication: Interpretation and communication of risk assessments in terms that are comprehensible to the general public or to others without specialist knowledge.
risk de minimis: Risk that is negligible and too small to be of societal concern (usually assumed to be a probability below 10-5 or 10-6); can also mean 'virtually safe'. In the USA, this is a legal term used to mean "negligible risk to the individual".
SN negligible risk.
risk estimation: Assessment, with or without mathematical modelling, of the probability and nature of effects of exposure to a substance based on quantification of dose-effect and dose-response relationships for that substance and the population(s) and environmental components likely to be exposed and on assessment of the levels of potential exposure of people, organisms and environment at risk.
RT risk evaluation.
RT exposure assessment, hazard identification.
risk evaluation: Establishment of a qualitative or quantitative relationship between risks and benefits, involving the complex process of determining the significance of the identified hazards and estimated risks to those organisms
or people concerned with or affected by them.
RT exposure evaluation, hazard identification, risk assessment, risk characterization, risk estimation, risk identification, risk perception.
risk identification: Recognition of a potential hazard and definition of the factors required to assess the probability of exposure of organisms or people to that hazard and of harm resulting from such exposure.
risk indicator: See SN risk marker.
risk management: Decision-making process involving considerations of political, social, economic, and engineering factors with relevant risk assessments relating to a potential hazard so as to develop, analyse, and compare regulatory options and to select the optimal regulatory response for safety from that hazard. Essentially risk management is the combination of three steps: risk evaluation; emission and exposure control; risk monitoring.
RT emission and exposure control, risk evaluation, risk monitoring.
risk marker: Attribute that is associated with an increased probability of occurrence of a disease or other specified outcome and that can be used as an indicator of this increased risk: not necessarily a causal or pathogenic factor.
SN risk indicator.
Last, 1988
risk monitoring: Process of following up the decisions and actions within risk management in order to check whether the aims of reduced exposure and risk are achieved.
BT monitoring.
RT risk management.
WHO, 1988
risk perception: Subjective perception of the gravity or importance of the risk based on a person's knowledge of different risks and the moral, economic, and political judgement of their implications.
RT risk evaluation.
WHO, 1988
risk phrases: Word groups identifying potential health or environmental hazards required under CPL Directives (European Community); may be incorporated into Safety Data Sheets.
RT material safety data sheet, safety data sheet.
risk ratio: Value obtained by dividing the probability of occurrence of a specific effect in one group by the probability of occurrence of the same effect in another group, or the value obtained by dividing the probability of occurrence of one potentially hazardous event by the probability of occurrence of another. Calculation of such ratios is used in choosing
between options in risk management.
RT risk management.
risk-specific dose: Amount of exposure corresponding to a specified level of risk.
USEPA, 1989
rodenticide: Substance intended to kill rodents.

route of exposure: Means by which a toxic agent gains access to an organism by administration through the gastrointestinal tract (ingestion), lungs (inhalation), skin (topical), or by other routes such as intravenous, subcutaneous, intramuscular or intraperitoneal routes.


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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

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