Diatomaceous earth, or diatomite, quarried from the remains of aquatic plants deposited millions of years ago, continues to be a very important raw material with many industrial uses. In its natural state, diatomaceous earth is an amorphous
silica
with
no crystalline pattern. For many uses, however, it is calcined and calcination converts a portion of the amorphous silica to a crystalline form cristobalite which is far more fibrogenic.
In the factory which calcination was done with diatomeceous earth seven workers were proved as pneumoconiosis on June 15th 1990. Afterthen thirty five male subjects from the entire factory were examined by questionnaire, physical examination,
spirometry
and chest radiography, etc. on January 22th 1991. The radiographs were doubly read by two chest disease specialist and their findings were classified by International Classification of Radiographys of Pneumoconiosis (ILO, 1980).
@ES The results were as follows:
@EN 1. Seven workers (20.0%) were diagnosed as pneumoconiosis among male employee. There was an increasing tendency in prevalence of pneumoconiosis as the age is older and the duration of dust exas the age is older and the duration of dust
exposure
is
longer.
2. Their major complaint was extional dyspnea or dyspnea, and significant difference was observed than now cases among exposed and nonexposed group.
3. The results of spirometric test showed the forced expiratory volume at 1 second (FEV1.0) was decreased significantly in the cases than nonexposed.
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