Xylene—Dangers of Its Use in the Histology
and Cytology Laboratory
by Conrad L. Bush, Capt., USAF, and George E. Nelson,
The primary reason for this
requirement is the use of the
aromatic hydrocarbon w e call
xylene (C 6 H 4 (CH 3 ) 2 in the final
processing step before coverslipping. Xylene exists in three
isometric forms, 0-, m-, and p-,
d i - m e t h y l h e n z e n e s ; all t h r e e
forms are f o u n d in commercial
xylene.
The toxicologic studies conducted on the xylenes are far
fewer in number and less complete than those reported on
benzene and toluene. There is
evidence to suggest that the acute
toxicity of the xylenes is greater
than the acute toxicity of toluene
or benzene.
Chronic poisoning brought
about by daily contact with xylene
funes may produce headache,
dizziness, malaise, loss of appetite, ready fatigue, shortness of
breath, irritability, nausea, and
burning of the eyes, throat and
respiratory membranes. Although
Conrad L. Bush, Capt., USAF, is
Chief of Laboratory Service and
George E. Nelson, Capt. USAF,
is Chief of Environmental
Health,
Patrick Air Force Base, Florida.
16
an increase in the number of
white blood cells is often reported,
the overall b l o o d picture does not
s h o w any m a r k e d a l t e r a t i o n .
There have been reports of gastrointestinal as well as neurological
disturbances, and injury to heart,
liver, kidneys, and the nervous
system among workers with xylene
exposure. There have been a
number of blood dyscrasias, some
fatal, associated with xylene exposure. I might point out that
because contamination of the
xylene by benzene cannot be
ruled out, this may have been a
major contributing factor in the
development of blood dyscrasias.
Absorption of xylene takes place
chiefly through the lungs even
though it has a relatively low vapor
pressure.
Xylene may cause skin defatting
with erythema, dry scaling, and
even secondary infections. Skin
irritation is more serious than that
f r o m exposure to benzene or
touene.
In the p u b l i c a t i o n , " D o c u mentation of the Threshold Limit
Values for Substances in Workroom Air, American Conference
of Government Industrial Hygienists," it has been concluded
that 100 ppm be established as the
maximum allowable concentration (MAC) in the air.
It must be pointed out that their
value is for a normal, healthy male
and that anyone suffering from
respiratory problems could not
tolerate that high a concentration.
It is interesting to note that the
Russian standards set a MAC of
only 11 p p m . In most new hos-
LABORATORY MEDICINE • VOL. 8, NO. 4, APRIL 1977
pitals, and even in some older
ones, we find the staining procedure set up under a hood or
close to an exhause system venting to the outside. We also find
that in these laboratories (perhaps
in more than 90% of other laboratories), the system of venting the
xylene fumes is circumvented.
This occurs when the technologist
removes the xylene dish containing the slides to be coverslipped
to another area of the laboratory
where she can complete the
processing while sitting. Of
course, in so doing she leaves the
exhaust h o o d and sits there
breathing in toxic fumes for the
rest of the processing time.
Tests were conducted in this
laboratory using MSA Detector
Tubes No. 93074 for aromatic
hydrocarbons w h i c h have the
ability to measure xylene in concentrations of 10-8000 p p m . W i t h
one staining dish of xylene at desk
height left open for three minutes
during which time six slides were
normally coverslipped, the concentration at nose level was just
over 100 p p m .
In order to conform to the
OSHA standards and protect yourself, the final step in the processing (coverslipping) must be
carried out under the h o o d , or an
auxiliary exhause system must be
placed close enough to the xylene
dish t o draw off, and dispose to
the outside, all harmful vapors.
Circumventing this vital step in
your H-E or Pap staining will not
alter the quality of your slides, but
could surely lead to altering your
health.
[Q]
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OSHA, the Occupational Safety
and Health Administration, established safety standards for all
types of industries, including
hospitals. Especially important to
the histology and cytology technologists is the requirement to
have a hood or some type of
exhaust system over the area
where staining is performed.
Capt., USAF