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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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| T | U | V
| W | X | Y
| Z
objective environment: Actual physical, chemical,
and social environment as described by objective measurements, such
as noise levels in decibels and concentrations of air pollutants.
WHO, 1979
occupational environment: Surrounding conditions
at a workplace.
occupational exposure: Experience of substances,
intensities of radiation etc. or other conditions while at work.
occupational exposure limit (OEL): Regulatory
level of exposure to substances, intensities of radiation etc. or
other conditions , specified appropriately in relevant government
legislation or related codes of practice.
occupational exposure standard (OES):
1. Level of exposure to substances, intensities of radiation etc.
or other conditions considered to represent specified
good practice and a realistic criterion for the control
of exposure by appropriate plant design, engineering controls,
and, if necessary, the addition and use of personal
protective clothing.
2. In GBR, health-based exposure limit defined under COSHH Regulations
as the concentration of any airborne substance,
averaged over a reference period, at which, according
to current knowledge, there is no evidence that it is likely to
be
injurious to employees, if they are exposed by inhalation,
day after day, to that concentration, and set on the advice
of the HSE Advisory Committee on
Toxic Substances.
occupational
hygiene: Identification, assessment and control of physicochemical
and biological factors in the workplace that may affect the health
or well-being of those at work and in the surrounding community.
octanol-water
partition coefficient (POW, K OW): Measure
of lipophilicity by determination of the equilibrium distribution
between octan-1-ol and water, as used in pharmacological studies
and in the assessment of environmental fate and transport of organic
chemicals.
RT lipophilicity, lgKOW,
lgPOW.
ocular: Pertaining to the eye.
odds: Ratio of the probability of occurrence
of an event to that of non-occurrence, or the ratio of the probability
that something is so, to the probability that it is not so.
Last, 1988
odds ratio: Quotient
obtained by dividing one set of odds by another. The term "odds"
or "odds ratio" is defined differently according to the situation
under discussion. Consider the following notation for the distribution
of a binary exposure and a disease in a population or a sample.
Exposed Nonexposed
Disease a
b
No disease c
d
The odds ratio (cross-product ratio) is ad/(bc).
Notes:
1. The exposure-odds ratio for a set of case control data is the
ratio of the odds in favour of exposure among the cases
( a/b) to the odds in favour of exposure among
non-cases ( c/d). This reduces to ad/(bc). With incident
cases, unbiased
subject selection, and a "rare" disease (say, under
2 % cumulative incidence rate over the study period), ad/(bc
) is
an approximate estimate of the risk
ratio. With incident cases, unbiased subject selection, and density
sampling of
controls, ad/(bc ) is an estimate of the ratio
of the person-time incidence rates (forces of morbidity) in the
exposed
and unexposed. No rarity assumption is required.
2. The disease-odds (rate-odds) ratio for a cohort or cross section
is the ratio of the odds in favour of disease among the
exposed population (a/c) to the odds in favour
of disease among the unexposed (b/d). This reduces to ad/(bc)
and hence
is equal to the exposure-odds ratio for the cohort
or cross section.
3. The prevalence-odds refers to an odds ratio derived cross sectionally,
as, for example, an odds ratio derived from
studies of prevalent (rather than incident) cases.
4. The risk-odds ratio is the ratio of the odds in favour of getting
disease, if exposed, to the odds in favour of getting
disease if not exposed. The odds ratio derived from
a cohort study is an estimate.
SN cross-product ratio,
relative odds.
Last, 1988
odour threshold:
In principle, the lowest concentration of an odorant that can be
detected by a human being: in practice, a panel of "sniffers" is
used, and the threshold taken as the concentration at which 50 %
of the panel can detect the odorant (although some workers have
also used 100 % thresholds).
oedema: Presence of
abnormally large amounts of fluid in intercellular spaces of body
tissues.
olfactometer: Apparatus for testing the power
of the sense of smell.
oliguria: Excretion of a diminished amount
of urine in relation to fluid intake.
oncogene: Gene that can cause neoplastic
transformation of a cell; oncogenes are slightly changed equivalents
of normal genes known as proto-oncogenes.
RT transformation.
oncogenesis: Production or causation of tumours.
one-hit model: Dose-response model of the
form
P(d) = 1 - exp(- bd)
where P(d) is the probability of cancer death from a continuous
dose rate (d) and b is a constant. The one-hit model
is based on the concept that a tumour can be induced after a single
susceptible target or receptor has been exposed to a single effective
dose unit of an agent.
IRIS, 1986
onycholysis: Loosening or detachment of the
nail from the nailbed following some destructive process.
oogenesis: Process of formation of the ovum
(plural ova), the female gamete.
operon: Complete unit of gene expression
and regulation, including structural genes, regulator gene(s) and
control elements in DNA recognized by regulator gene product(s).
ophthalmic: Pertaining to the eye.
organ dose: Amount
of a substance or physical agent (radiation) absorbed by an organ.
organelle: Microstructure or separated compartment
within a cell that has a specialized function, for example ribosome,
peroxisome, lysosome, Golgi apparatus, mitochondrion, nucleolus,
nucleus.
After Nagel et al. (eds),
1991
organic carbon partition coefficient (KOC)
Measure of the tendency for organic substances to be adsorbed by
soil and sediment, expressed as:
(mg substance adsorbed)/(kg organic carbon)
KOC = --------------------------------------------
(mg substance
dissolved)/(litre of solution)
The K OC is substance-specific
and is largely independent of soil properties.
USEPA, 1986
organoleptic: Involving an organ, especially
a sense organ as of taste, smell or sight.
osteo-: Prefix meaning pertaining to bone.
osteodystrophy: Abnormal development of bone.
osteogenesis: Formation or development of
bone.
osteoporosis: Significant decrease in bone
mass with increased porosity and increased tendency to fracture.
ovicide: Substance intended to kill eggs.
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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