Toxicology Glossary - I
iatrogenic: Any adverse condition resulting from medical treatmentNT nosocomial
icterus: Excess of bile pigment in the blood and consequent deposition and retention of bile pigment in the skin and the sclera
RT hyperbilirubinaemia, jaundice
idiosyncrasy: Genetically based unusually high sensitivity of an organism to the effect of certain substances
RT hypersusceptibility, pharmacogenetics
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)
immune complex: Product of an antigen-antibody reaction that may also contain components of the complement system
Roitt et al 1989
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
RT antibody, autoimmune disease, cell-mediated hypersensitivity
immunochemistry: Study of biochemical and molecular aspects of immunology, especially the nature of antibodies, antigens and their interactions
immunogen: See SN antigen
immunoglobulin: Family of closely related glycoproteins capable of acting as antibodies and present in plasma and tissue fluids; immunoglobulin E is the source of antibody in many hypersensitivity (allergic) reactions
RT allergy, antibody, hypersensitivity
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
RT allergy, antibody, antigen, cell-mediated hypersensitivity, hypersensitivity, immunoglobulin
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
immunotoxic: Poisonous to the immune system
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, the denominator being the average number of persons in the specified population during a defined period or the estimated number of persons at the mid-point of that period. The basic distinction between "incidence" and "prevalence" is that whereas incidence refers only to new cases, prevalence refers to all cases, irrespective of whether they are new or old. When the terms incidence and prevalence are used, it should be stated clearly whether the data represent the numbers of instances of the disease recorded or the numbers of persons ill
WHO, 1989a
incidence rate: Measure of the frequency with which new events occur in a population. 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
After Last, 1988
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 metre (mg/m3) of the pollutant in the air they breathe
WHO, 1987
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
RT bystander exposure, para-occupational exposure
individual protective device (IPD): Device for individual use for protection of the whole body, eyes, respiratory pathways or skin of workers against hazardous and harmful production factors
SN personal protective device (PPD), personal protective equipment (PPE)
IRPTC, 1982
individual risk: Probability that an individual person will experience an adverse effect.
inducer: Substance that causes induction
RT induction
induction:Increase in the rate of synthesis of an enzyme in response to the action of an inducer or environmental conditions: often the substrate of the induced enzyme or a structurally similar substance (gratuitous inducer)that is not metabolized
After Nagel et al. (eds), 1991
induction period: Time from the onset of exposure to the appearance of signs of disease
SN latent period
inhalation:Act of drawing in of air, vapour 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
RT biodegradation
inhibitory concentration (IC): Concentration of a substance that causes a defined inhibition of a given system: IC50 is the median concentration that causes 50 % inhibition
RT effective concentration, lethal concentration
inhibitory dose (ID):Dose of a substance that causes a defined inhibition of a given system: ID50 is the median dose that causes 50 % inhibition
RT effective dose, lethal dose
initiator:
- Agent that induces a change in a chromosome or gene that leads to the induction of tumours after a second agent, called a promoter, is administered to the tissue.
RT promoter. - Substance that starts a chain reaction; an initiator is consumed in a reaction, in contrast to a catalyst
Gold, Loening, McNaught and Sehmi, 1987
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) characterising the overall changes in the general state of the organism exposed to a toxic substance
IRPTC, 1982
interfacial layer:Region of space comprising and adjoining the phase boundary within which properties of matter are significantly different from the values in the adjoining bulk phases
PS surface layer
intermittent effect: Biological change that comes and goes at intervals
SN discontinuous effect
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
IPCS, 1978
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 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 modifying a supposed causal factor in a population.
Last, 1988
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.
WHO, 1979
intoxication:
- Poisoning: pathological process with clinical signs and symptoms caused by a substance of exogenous or endogenous origin
RT exogenous, endogenous - Drunkenness following consumption of beverages containing ethanol or other compounds affecting the central nervous system
in vitro: In glass, referring to a study in the laboratory usually involving isolated organ, tissue, cell, or biochemical systems
AN in vivo
in vivo: In the living body, referring to a study performed on a living organism
AN in vitro
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
Gold, Loening, McNaught and Sehmi, 1987
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. 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
isotonic: Denoting a fluid exerting the same osmotic pressure or water potential as another fluid with which it is being compared
itai-itai disease: Illness observed in Japan possibly resulting from the ingestion of cadmium-contaminated rice: damage occurred to the renal and skeleto-articular systems, the latter being very painful ("itai" means pain in Japanese)