Sulphuric acid (SA) is used in innumerable industrial processes. In this work the
effect of exposure to SA fumes for various periods at different duration on the
larynx of the rabbits was evaluated histochemically and immunohistochemically.
This study was conducted on 50 healthy rabbits divided into control group
comprised 5 animals not exposed to SA and experimental group comprised 45
animals divided into three equal groups (15 in each) expqsed to SA fumes daily
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for 30, 60 and 120 minutes respectively. Each prouppubdivided into three equal
subgroups (5 in each) according to the period of exposure; one, two or three
weeks. The fumes were pumped through a hole in the side of glass box using an
electric nebulizer at concentration 1 mg/m3 .The larynxes of all animals were
stained histochemically by Masson trichrome, Orcein, PAS, Alcian blue and
silver stained nucleolar organizer regions (AgNORs) and
immunohistochemically by Ki-67. The results showed that after exposure to SA
especially at longer periods and long durations there was increase of the
thickness and disturbance of stratified and respiratory epithelia, ',Increase of
collagen fibers and decrease of elastic fibers. There was increase of the numbers
of glands and increase of neutral and acidic mucosubstance. There was increase
of both m AgNORs and P AgNORs >1 of both epithelia .Also, there was increase
of Ki-67 PI and the reaction was not restricted to the basal layer. This means
that SA exposure caused increase of the ploidy and proliflerative activities of the
epithelia of the larynx especially after long period and duration. From this work
it can be concluded that the exposure to sulphuric acid fumes especially at longer
periods and long durations have a carcinogenic effect on the larynx. So, it is
recommended that workers exposed to SA their larynx must be examined
periodically. |
