sion: the upper incisors and canines
(front teeth) slightly overlap the lower
ones; the front two upper incisors are
aligned centrally with the front two
lower incisors;
the remaining
teeth are positioned in an alternating
pattern relative to the equivalent lower
teeth; and the outer ridges of the lower
premolars and molars (back teeth) fit
into the hollows in the corresponding
upper teeth. Very few people have an
ideal occlusion, but in the majority the
arrangement of the teeth allows effi-
cient biting and chewing of food. (See
m a l o c c l u s i o n ; r e t i n a l a r t e r y o c c l u s i o n ;
r e t i n a l v e i n o c c l u s i o n . )
o c c u lt
Hidden or obscure. For example, the
occult blood is
often used to
describe blood in a sample of faeces
that is not visible to the naked eye but
can be detected by chemical tests.
o c c u lt b lo o d , fa e c a l
The presence in the
f a e c e s
of blood that
cannot be seen by the naked eye, but
can be detected by chemical tests (see
f a e c a l o c c u l t b l o o d t e s t ) .
Faecal occult blood tests are widely
used in screening for cancer of the colon
c o l o n ,
c a n c e r o f ) .
occult blood may also be a sign of vari-
ous gastrointestinal disorders including
o e s o p h a g i t i s
(inflammation of the gul-
g a s t r i t i s
stomach lining);
s t o m a c h c a n c e r ;
of the intestine (see
i n t e s t i n e , c a n c e r o f ) ;
r e c t u m ,
c a n c e r o f ) ;
d i v e r t i c u l a r d i s e a s e
(in w hich pouches
form in the wall of the intestine);
p o l y p s
in the colon;
u l c e r a t i v e c o l i t i s
tion and ulceration of the lining of the
colon and rectum); or irritation of the
stomach or intestine by drugs such as
aspirin. (See also
r e c t a l b l e e d i n g . )
o c c u p a tio n a l d is e a s e a n d in ju ry
Illnesses, disorders, or injuries that are
the result of exposure to chemicals or
dust, or are caused by physical, psycho-
logical, or biological factors that occur
in the workplace. Serious occupational
diseases are far less common than for-
merly, but still make up an important
group of conditions. They include the
following main categories.
The term
p n e u m o c o n i o s i s
is used to refer
f i b r o s i s
(formation of scar tissue) in
the lung due to inhalation of industrial
dusts, such as coal.
A s b e s t o s i s
is a lung
condition associated with asbestos in
industry. Allergic
a l v e o l i t i s
tion of the tiny air sacs in the lungs) is
caused by inhalation of organic dusts
(often containing fungal spores)
f a r m e r ’s l u n g ) .
Industrial chemicals can damage the
lungs if they are inhaled, or other major
organs if they enter the bloodstream
through the lungs or skin. Examples
of harmful chemicals include fumes of
cadmium, beryllium, lead,
and ben-
Carbon tetrachloride and vinyl
chloride are
of liver
Many of these compounds can cause
kidney damage.
d e r m a t i t i s
(skin inflammation),
w hich results either from allergy or
from direct irritation by chemicals in
contact with the skin, and
s q u a m o u s
c e l l c a r c i n o m a ,
w hich may be caused by
exposure to tar.
Rare infectious diseases that are more
common in certain jobs include
b r u c e l -
l o s i s
Q f e v e r
(acquired from live-
p s i t t a c o s i s
(acquired from birds),
l e p t o s p i r o s i s
(caused by a bacterium
excreted in rat’s urine). People who
work with blood or blood products are
at increased risk of viral hepatitis (see
h e p a t i t i s , v i r a l )
A I D S ,
as are health-
care professionals.
The nuclear industry and some health-
care professions use measures to reduce
the danger from
r a d i a t i o n h a z a r d s .
increases the risk of cancer.
Other occupational disorders include
w r i t e r ’s c r a m p , c a r p a l t u n n e l s y n d r o m e ,
s i n g e r ’s n o d e s . R a y n a u d ’s p h e n o m e n o n
associated with the handling of vibrat-
ing tools. Deafness may be caused by
exposure to excessive noise.
A branch of medicine that deals with
the effects of various occupations on
health and with an individual’s capacity
for particular types of work. It includes
prevention of
o c c u p a t i o n a l d i s e a s e a n d
i n j u r y
and the promotion of health in
the working population.
E p i d e m i o l o g y
is used to analyse pat-
terns of sickness absence, injury, illness,
and death. Clinical techniques are used
to monitor the health of a particular
workforce. Assessment of psychological
stress and hazards of new technology
are part of the remit.
Occupational health risks are reduced
by dust control, appropriate waste dis-
posal, use of safe work stations and
practices, lim iting exposure to harmful
substances, and screening for early evi-
dence of occupational disorders.
Death due to work-related disease or
injuries. Annual death rates (deaths per
m illion at risk) vary widely between
occupations, ranging from very low lev-
els in clothing and footwear manu-
facture to very high levels in industries
such as the offshore oil and gas indus-
tries. The pattern of deaths varies over
as industrial
Certain diseases that take many years to
develop may reflect occupational prac-
tices that have since been improved.
s o m a t o s t a t i n a n a l o g u e ,
a hormone that
acts on the
p i t u i t a r y g l a n d .
Given by
injection, octreotide is used mainly in
the treatment of
a c r o m e g a l y
(a rare dis-
order that causes abnormal enlargement
of certain body parts) and hormone-
secreting intestinal tumours. Octreotide
is also used to prevent complications
following pancreatic surgery.
Side effects of octreotide may include
various gastrointestinal disturbances such
as nausea, vomiting, abdominal pain
and bloating, flatulence, and diarrhoea.
Relating to or affecting the
e y e
and its
structures; also the eyepiece of an opti-
cal device, such as a
m i c r o s c o p e
A state in w hich the eyes are fixed, usu-
ally upwards, for minutes or hours. The
crisis may occur with muscle spasm of
the tongue, mouth, and neck, and is
often triggered by stress. It may occur
e n c e p h a l i t i s
(inflammation of
o c c u p a tio n a l th e ra p y
Treatment comprising individually tail-
ored programmes of activities to help
people who have been disabled by illness
or accident to improve their function
and ability to carry out everyday tasks.
Occupational therapy also involves rec-
ommending aids and changes to the
home that help to increase an indi-
vidual’s independence.
o c tre o tid e
o c c u p a tio n a l m e d ic in e
o c u la r
o c u lo g y ric c r is is
o c c u p a tio n a l m o rta lity
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