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Pure Appl. Chem.,
Vol. 65, No. 9, pp. 2003-2122, 1993.
CLINICAL
CHEMISTRY DIVISION
COMMISSION ON TOXICOLOGY
Glossary for chemists of terms used in toxicology
(IUPAC Recommmendations 1993)
Alphabetical entries
A | B | C
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| G | H | I
| J | K | L
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| W | X | Y
| Z
haematemesis: Vomiting of blood.
haematoma: Localised accumulation of blood,
usually clotted, in an organ, space, or tissue, due to a failure
of the wall of a blood vessel.
haematuria: Presence of blood in the urine.
haemodialysis: Use of an artificial kidney
to remove toxic compounds from the blood by passing it through a
tube of semipermeable membrane. The tube is bathed in a dialysing
solution to restore the normal chemical composition of the blood
while permitting diffusion of toxic substances from the blood.
haemoglobinuria: Presence of free haemoglobin
in the urine.
haemolysin: Substance that damages the membrane
of erythrocytes causing the release of haemoglobin.
haemolysis: Release of haemoglobin from erythrocytes,
and its appearance in the plasma.
haemoperfusion:
Passing blood through a column of charcoal or adsorbent resin for
the removal of drugs or toxins.
haemosiderin: Iron-containing pigment that
is formed from haemoglobin released during the disintegration of
red blood cells and that accumulates in individuals who have ingested
excess iron.
half-life (half-time)
(t1/2): Time in which the concentration of
a substance will be reduced by half, assuming a first order elimination
process or radioactive decay.
haploid (monoploid):
State in which a cell contains only one set of chromosomes.
RT diploid, gamete,
meiosis.
hapten: Low-molecular-weight
molecule that contains an antigenic determinant (epitope) that may
bind to a specific antibody but which is not itself antigenic unless
complexed with an antigenic carrier such as a protein or cell; once
bound it can cause the sensitization of lymphocytes, possibly leading
to allergy or cell-mediated hypersensitivity.
After Nagel et al. (eds),
1991
RT allergy, antigen,
antibody, cell-mediated
hypersensitivity, epitope.
harm: Damage or adverse effect to a population,
species, individual organism, organ, tissue or cell.
SN adverse effect.
harmful occupational factor: Component of
the work environment the effect of which on a worker under certain
conditions leads to ill health or reduction of working ability.
harmful substance:
Substance that, following contact with an organism can cause ill
health or adverse effects either at the time of exposure or later
in the life of the present and future generations.
SN noxious substance.
hazard: Set of inherent
properties of a substance, mixture of substances or a process involving
substances that, under production, usage or disposal conditions,
make it capable of causing adverse effects to organisms or the environment,
depending on the degree of exposure; in other words, it is a source
of danger.
RT risk.
hazard assessment:
Determination of factors controlling the likely effects of a hazard
such as the dose-effect and dose-response relationships, variations
in target susceptibility, and mechanism of toxicity.
RT exposure assessment,
hazard evaluation, hazard
identification, risk
assessment, risk characterization,
risk estimation, risk
evaluation, risk
identification, risk perception.
hazard
communication standard: US OSHA standard requiring all employers
to inform employees of the hazard of substances in the workplace
and the steps necessary to avoid harm.
hazard identification:
Determination of substances of concern, their adverse effects, target
populations, and conditions of exposure, taking into account toxicity
data and knowledge of effects on human health, other organisms and
their environment.
WHO, 1988
hazard quotient (HQ): Ratio of toxicant exposure
(estimated or measured) to a reference value regarded as corresponding
to a threshold of toxicity: if the total hazard quotient from all
toxicants to a target exceeds unity, the combination of toxicants
may produce (will produce under assumptions of additivity) an adverse
effect.
RT hazard, pollutant,
toxic substance.
hazardous production factor: Production factor
the effect of which on a worker under certain conditions results
in injury or some impairment of health.
SN hazard at work, hazardous occupational factor.
IRPTC, 1982
health:
1. State of complete physical, mental and social
well-being, and not merely the absence of disease or infirmity.
WHO, 1978b
2. State of dynamic balance in which an individual's
or a group's capacity to cope with the circumstances of living is
at
an optimal level.
3. State characterized by anatomical, physiological and psychological
integrity, ability to perform personally valued
family, work and community roles; ability to deal with
physical, biological, psychological and social stress; a feeling
of wellbeing; and freedom from the risk of disease
and untimely death.
Last, 1988
health-based exposure limit: Maximum concentration
or intensity of exposure that can be tolerated without significant
effect (based on only scientific and not economic evidence concerning
exposure levels and associated health effects).
de Koning, 1987, ACGIH 1975
health hazard: Any factor or exposure that
may adversely affect health.
Last, 1988
healthy worker effect: Epidemiological phenomenon
observed initially in studies of occupational diseases: workers
usually exhibit lower overall disease and death rates than the general
population, due to the fact that the old, severely ill and disabled
are ordinarily excluded from employment. Death rates in the general
population may be inappropriate for comparison, if this effect is
not taken into account.
WHO, 1989a
hepatic: Pertaining to the liver.
hepatotoxic: Poisonous to liver cells.
Henry's law constant: At constant temperature
and pressure, the ratio of the partial pressure of a gas above a
liquid to its molal solubility in the liquid and therefore a measure
of its partition between the gas phase and the solute phase.
herbicide: Substance
intended to kill plants.
histogenic origin: Germ cell layer of the
embryo from which a given adult tissue develops.
histology: Study (usually microscopic) of
the anatomy of tissues and their cellular and subcellular structure.
histopathology: Microscopic pathological
study of the anatomy and cell structure of tissues in disease to
reveal abnormal or adverse structural changes.
homeostasis: Normal, internal stability in
an organism maintained by co-ordinated responses of the organ systems
that automatically compensate for environmental changes.
homology: Degree of identity existing between
the nucleotide sequences of two related but not complementary DNA
or RNA molecules; 70 % homology means that on the average 70 out
of every 100 nucleotides are identical in a given sequence. The
same term is used in comparing the amino acid sequences of related
proteins.
hormesis: Stimulatory effect of small doses
of a potentially toxic substance that is inhibitory in larger doses.
hormone: Substance formed in one organ or
part of the body and carried in the blood to another organ or part
where it selectively alters functional activity.
human ecology: Interrelationship between
humans and the entire environment - physical, biological, socio-economic,
and cultural, including the interrelationships between individual
humans or groups of humans and other human groups or groups of other
species.
human equivalent dose: Human dose of an agent
that is believed to induce the same magnitude of a toxic effect
that the known animal dose has induced.
IRIS, 1986
hydrophilic/ adj .,
-ity n.: Describing the character of a molecule or atomic group
which has an affinity for water.
hydrophobic/ adj.,
-ity n.: Describing the character of a molecule or atomic
group which is insoluble in water, or resistant to wetting or hydration.
hygiene: Science of health and its preservation.
hyper-: Prefix meaning above or excessive:
when used with the suffix "-aemia" refers to blood and with the
suffix "-uria" refers to urine, for example "hyperbilirubinaemia".
hyperaemia: Excessive amount of blood in
any part of the body.
hyperalimentation: Ingestion or administration
of nutrients in excess of optimal amounts.
hyperbilirubinaemia:
Excessive concentration of bilirubin in the blood.
hypercalcaemia: Excessive concentration of
calcium in the blood.
hyperglycaemia: Excessive concentration of
glucose in the blood.
hyperkalaemia: Excessive concentration of
potassium in the blood.
hypernatraemia: Excessive concentration of
sodium in the blood.
hyperparathyroidism: Abnormally increased
parathyroid gland activity that affects, and is affected by, plasma
calcium concentration.
hyperplasia: Abnormal
multiplication or increase in the number of normal cells in a tissue
or organ.
RT hypertrophy, neoplasia.
hyper-reactivity: Term used to describe the
responses of (effects on) an individual to (of) an agent when they
are qualitatively those expected, but quantitatively increased.
hyper-reflexia: Exaggeration of reflexes.
hypersensitivity:
State in which an individual reacts with allergic effects following
exposure to a certain substance (allergen) after having been exposed
previously to the same substance.
PS allergy.
RT cell-mediated
hypersensitivity, sensitization.
hypersusceptibility:
Excessive reaction following exposure to a given amount or concentration
of a substance as compared with the large majority of other exposed
subjects.
RT idiosyncrasy.
hypertension: Persistently high blood pressure
in the arteries or in a circuit, for example pulmonary hypertension
or hepatic portal hypertension.
hypertrophy: Excessive
growth in bulk of a tissue or organ through increase in size but
not in number of the constituent cells.
RT hyperplasia.
hypervitaminosis: Condition resulting from
the ingestion of an excess of one or more vitamins.
hypo-: Prefix meaning under, deficient: when
used with the suffix "-aemia" refers to blood and with the suffix
"-uria" refers to urine, for example "hypocalcaemia".
hypocalcaemia: Abnormally low calcium concentration
in the blood.
hypokalaemia: Abnormally low potassium concentration
in the blood.
hyponatraemia: Abnormally low sodium concentration
in the blood.
hypovolaemic: Pertaining to an abnormally
decreased volume of circulating fluid (plasma) in the body.
hypoxaemia: Deficient oxygenation of the
blood.
hypoxia:
1. Abnormally low oxygen content or tension.
2. Deficiency of oxygen in the inspired air, in blood or in tissues,
short of anoxia.
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
Page last modified 12 September 2001.
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