PRINCIPLES OF TOXICOLOGY

GLOSSARY 559
chloracne An acne-like skin eruption caused by exposure to halogenated compounds, especially the
polyhalogenated naphthalenes, biphenyls, dibenzofurans, and dioxins.
cholestasis Stoppage or suppression of the flow of bile.
cholestatic Pertaining to or characterized by cholestasis.
cholinesterase An enzyme found chiefly at nerve terminals that inactivates the neurotransmitter
acetylcholine by hydrolyzing it to form acetic acid and choline.
chromhidrosis The secretion of colored sweat.
chromophore A chemical group capable of selective light absorption resulting in the coloration of
certain organic compounds.
chromosome aberrations Structural mutations (breaks and rearrangements of chromosomes) or
changes in number of chromosomes (additions and deletions).
chronic toxicity Adverse effects occurring after a long period of exposure to a toxic agent (with
animal testing this is considered to be the majority of the animals life). These effects may be
permanent or irreversible.
clastogenic Giving rise to or inducing a breakage or disruption of chromosomes.
cocarcinogen Any chemical capable of increasing the observed incidence of cancer if applied with
a carcinogen, but not itself carcinogenic.
collagen The fibrous protein constituent of bone, cartilage, tendon, and other connective tissue. It is
converted into gelatin by boiling.
comedo A plug in an excretory duct of the skin, containing microorganisms and desquamated keratin;
a blackhead.
competitive inhibition Inhibition of enzyme activity in which the inhibitor (substrate analog)
competes with the substrate for binding sites on the enzymes; such inhibition is reversible since it
can be overcome by increasing the substrate concentration.
complement A complex system of proteins found in normal blood serum that combines with
antibodies to destroy pathogenic bacteria and other foreign cells.
conformational change A change in the particular shape of a molecule.
conjugation The addition by drug metabolizing enzymes of hydrophilic moieties to xenobiotics to
hasten their excretion from the body.
conjunctivitis Inflammation of the conjunctiva, the delicate mucous membrane that lines the eyelids
and covers the exposed surface of the eye.
contact dermatitis See dermatitis.
contraindication Any condition, especially one of disease, that renders some particular line of
treatment improper or undesirable.
corpus luteum A yellow glandular mass in the ovary formed by an ovarian follicle that has matured
and discharged its ovum.
cryptorchism A development defect marked by the failure of the testes to descend into the scrotum.
cutaneous sensitization Immune reaction characterized by local skin rashes, urticaria (hives),
erythema, edema, and itching. Cutaneous sensitization is thought to be initiated by the release of
histamine.
cyanosis A bluish discoloration, especially of skin and mucous membranes, owing to excessive
concentration of reduced hemoglobin in the blood.
cystitis Inflammation of the urinary bladder.
cytochrome oxidase An oxidizing enzyme containing iron and a porphyrin, found in mitochondria
and important in cellular respiration as an agent of electron transfer from certain cytochrome
molecules to oxygen molecules.
cytochrome enzymes See mixed-function oxidase system (MFO).