IUPAC Glossary of Terms Used in Toxicology – O
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objective environment
Actual physical, chemical, and social environment as described by
objective measurements, such as noise levels in decibels and
concentrations of
air pollutants.
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.
- 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.
- 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.
occupational medicine
Specialty devoted to the prevention and management of
occupational injury, illness and disability, and the promotion of
the health of workers, their families, and their communities.
occupational safety and health
See occupational
hygiene
octanol-water partition coefficient Pow, Kow
Ratio of the solubility of a chemical in octanol divided by
its solubility in water.
Note: Measure of lipophilicity, used in the assessment of both
the uptake and physiological distribution of organic chemicals
and prediction of their environmental fate.
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.
odds ratio (OR), Θ
cross-product ratio
relative odds
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 ad/bc.
Note 1: The exposure-odds ratio for a set of
case control data is the ratio of the odds in favor of exposure
among the cases (a/b) to the odds in favor of
exposure among non-cases (c/d), which is equal
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 (force
of morbidity) in the exposed and unexposed. No rarity
assumption is required for this.
Note 2: The disease-odds (rate-odds) ratio for a cohort or cross
section is the ratio of the odds in favor of disease among the
exposed population (a/c) to the odds in favor
of disease among the unexposed (b/d), which is
equal to ad/bc and hence is equal to the
exposure-odds ratio for the cohort or cross section.
Note 3: The prevalence-odds ratio
refers to an odds ratio derived cross sectionally, as, for
example, an odds ratio derived from studies of prevalent (rather
than incident) cases.
Note 4: The risk-odds ratio is the
ratio of the odds in favor of getting disease, if exposed, to the
odds in favor of getting disease if not exposed. The odds ratio derived
from a cohort study is an estimate of this.
odor threshold
odour threshold
odor detection threshold
In principle, the lowest concentration of an odorant in
the air that can be detected by a human being.
Note: In practice, a panel of “sniffers” is often
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). The odor concentration at the
detection threshold may be defined as one odor unit.
oedema
See edema
olf
unit used to measure scent emission of people and objects; one
olf is defined as the scent emission of an “average
person”, a sitting adult that takes an average of 0.7 baths
per day and whose skin has a total area of 1.8 m2; the
scent emission of an object or person is measured by specially
trained personnel comparing it to normed scents.
Note: The olf should not be confused with the of unit of scent
immission (as opposed to emission), the decipol which also takes into
account the ventilation system’s air volume flow.
olfactometer
Apparatus for testing the power of the sense of smell.
oligozoospermia
Sperm concentration less than a reference value.
[8]
oliguria
Excretion of a diminished amount of urine in relation to fluid
intake.
-omics, -omes
Neologism referring to the fields of study in biology ending in
the suffix -omics, such as genomics or proteomics: the related
neologism -omes are the objects of study of the field such as the
genome or proteome, respectively.
oncogene
Gene that can cause
neoplastic (see neoplasia) transformation of a
cell; oncogenes are slightly changed equivalents of normal
genes known as
proto-oncogenes.
oncogenesis
Production or causation of tumors.
oncogenic
Capable of producing tumors in animals, either benign
(non-cancerous) or malignant (cancerous).
[9]
one-compartment model
Kinetic model, where the whole body is thought of as a single
compartment in which
the substance distributes rapidly, achieving an equilibrium between blood and
tissue immediately.
[2]
one-hit model
Dose-response model of the form
P =1 - e-bd
where P is the probability of cancer death from a
continuous dose rate,
d, and b is a constant.
onycholysis
Loosening or detachment of the nail from the nail bed 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.
organic carbon partition coefficient, Koc
Measure of the tendency for organic substances to be adsorbed by soil or sediment, expressed as:
Koc = (mass adsorbed substance) / (mass organic carbon)____
(mass concentration of absorbed substance)
The Koc is substance-specific and is largely independent of soil properties.
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.
osteomalacia
Condition marked by softening of the bones (due to impaired
mineralization, with excess accumulation of osteoid), with pain,
tenderness, muscular weakness, anorexia and loss of weight,
resulting from deficiency of vitamin D and calcium.
osteoporosis
Significant decrease in bone mass with increased porosity and
increased tendency to fracture.
ovicide
Substance intended to kill eggs.
oxidative stress
Adverse effects occurring when the generation of reactive oxygen
species (ROS) in a system exceeds the system’s ability to
neutralize and eliminate them; excess ROS can damage a
cell’s lipids, protein or DNA.