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IUPAC Glossary of Terms Used in Toxicology, 2nd Edition
IUPAC Recommendations, 2007

IUPAC Glossary of Terms Used in Toxicology - Terms Starting with F


  1. Ability to produce offspring frequently and in large numbers.
  2. In demography, the physiological ability to reproduce.
  3. Ability to produce offspring within a given period of time.

Substance used in olfactory communication between organisms of the same species eliciting a change in sexual or social behavior.

Ability to conceive and to produce offspring: for litter-bearing species the number of offspring per litter is used as a measure of fertility.
Note: Reduced fertility is sometimes referred to as subfertility.

fertility toxicant
Produces abnormalities of male or female reproductive functions or impairs reproductive capacity.

Substance applied to soil or hydroponic systems for improving the root nutrition of plants with the aim of increasing crop yields and (or) controlling production.

fetal period
See fetus

Toxicity to the fetus.

fetus (often incorrectly foetus)
Young mammal within the uterus of the mother from the visible completion of characteristic organogenesis until birth.
Note: In humans, this period is usually defined as from the third month after fertilization until birth (prior to this, the young mammal is referred to as an embryo).

Abnormal formation of fibrous tissue.

fiducial limit
Form of confidence limit given as a stated probability, for example P = 0.95.
Note: In toxicology the terms fiducial limits and confidence limits are generally considered to be synonymous.

first-order chemical reaction
first-order reaction
  1. Chemical reaction where the initial rate is directly proportional to the concentration of one of the reactants.
  2. Any process in which a variable decreases with time at a constant fractional amount.

first-pass effect
Biotransformation and, in some cases, elimination of a substance in the liver after absorption from the intestine and before it reaches the systemic circulation.

first-pass metabolism
See first-pass effect

fixed dose procedure
Acute toxicity test in which a substance is tested initially at a small number (3 or 4) predefined doses to identify which produces evident toxicity without lethality: the test may be repeated at one or more higher or lower defined discriminating doses to satisfy the criteria.

See fluorosis

Adverse effects of fluoride, as in dental or skeletal fluorosis.

flux (of a quantity)
Flow rate of an entity through a cross-section perpendicular to the flow divided by the cross-sectional area.

foci (singular focus) in neoplasia
Small groups of cells distinguishable, in appearance or histochemically, from the surrounding tissue: indicative of an early stage of a lesion that may lead to the formation of a neoplastic nodule.

See fetus

follow-up study
See cohort study

food additive
Any substance, not normally consumed as a food by itself and not normally used as a typical ingredient of a given food, whether or not it has nutritive value, that is added intentionally to food for a technological (including organoleptic) purpose in the manufacture, processing, preparation, treatment, packing, packaging, transport or holding of the food. Addition results, or may be reasonably expected to result (directly or indirectly), in the substance or its byproducts becoming a component of, or otherwise affecting, the characteristics of the food to which it is added.
Note: The term does not include “contaminants” or substances added to food for maintaining or improving nutritional qualities.

food allergy
Hypersensitivity reaction to substances in the diet to which an individual has previously been sensitized.

food chain
Sequence of transfer of matter and energy in the form of food from organism to organism in ascending or descending trophic levels.

food intolerance
Physiologically based reproducible, unpleasant (adverse) reaction to a specific food or food ingredient that is not immunologically based.

food web
Network of food chains.

forced diuresis
Method of stimulating diuresis based on performing hydrational therapy, sometimes with parallel introduction of diuretics, with the aim of achieving increased clearance of a toxic substance in urine.

foreign substance
See xenobiotic

founder effect
Changes in allelic frequencies that occur when a small group is separated from a large population and establishes a colony in a new location.

Process of classification of an analyte or a group of analytes from a sample according to physical (e.g. size, solubility) or chemical (e.g. bonding, reactivity) properties.

frame-shift mutation
Point mutation involving either the deletion or insertion of one or two nucleotides in a gene: by the frame shift mutation, the normal reading frame used when decoding nucleotide triplets in the gene is altered.

Substance that is vaporized in order to kill or repel pests.

functional genomics
Development and implementation of technologies to characterize the mechanisms through which genes and their products function and interact with each other and with the environment.

Substance intended to kill fungi.

fungus preparation
Substance obtained from fungi that has an insecticidal effect reflecting the pathogenicity of the fungi for insects.