Effect of Occupational Exposure to Silica Dust on the Thyroid Gland in Ceramic Workers
Safia Beshir Ahmed, Hesham Mohamed Aziz, and Safaa Mohamed Elserougy
Department of Environmental and Occupational Medicine, National Research Center, Cairo, Egypt
Corresponding author: Safaa Mohamed Elserougy
Department of Environmental and Occupational Medicine
National Research Centre, Cairo, Egypt
Fax number: 00202-3370931
E-mail: safaaser@yahoo.com
CEJOEM 2007, Vol.13. No.1.: 33–42
Key words:
Silica dust, thyroid hormones, occupational exposure, autoimmune antibodies, ceramic industry
Abstract:
In the present study, occupational exposure to crystalline silica dust has been examined as a possible
risk factor with respect to thyroiditis as an autoimmune disease. Sixty one exposed workers from a ceramic
factory versus 68 controls of same age, socioeconomic status and habits were included. Data were collected
through a questionnaire and clinical examination. Biochemical analyses of serum thyroid stimulating hormone
(TSH), thyroid hormones [total tri-iodothyronine (T3), Free tri-iodothyronine (FT3),
total thyroxine (T4) and Free thyroxine (FT4), serum angiotensin-converting
enzyme (ACE) and some auto-antibodies (serum anti-thyroid antibodies (ATHA), anti-nuclear antibodies (ANA),
anti-smooth muscle antibodies (ASMA), anti-parietal cell antibodies (APCA), anti-mitochondrial antibodies
(AMA), and liver kidney microsomal antibodies (LKM) were done.
Results: Enlarged thyroid gland was found in only two workers (exposed for
more than 10 yrs.). Statistical analysis showed that the means of serum T3, FT3
and FT4 were significantly higher in the exposed workers than in the controls, while the mean of
T4 was significantly lower. The frequency of ATHA was significantly higher in the exposed than in
the control group (p<0.05) while other auto-antibodies showed statistically non-significant difference.
A highly significant positive correlation was found between the duration of exposure to silica dust and the
thyroid hormone serum levels. The present study concluded that occupational silica dust exposure may affect
the activity of thyroid gland hormones even in the absence of clinical features, through an autoimmune mechanism
and detection of anti-thyroid antibody (ATHA) levels in workers exposed to silica dust can be of great value as
a biomarker or a predictor factor for early thyroid gland dysfunction.
Received: 23 March 2007
Accepted: 08 June 2007
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