Diatomaceous Earth
Classification:
Diatomaceous earth is a finegrained amorphous variety of silica, produced by SiO2 concentrating animalcule. Naturally found diatomaceous earth has to be heated to 700-800°C, because it contains up to 70% water and bituminous organic materials. During the heating process, silicates with a high fibrogenic potency can be released.
Synonyms/Trade Names:
Celite, Diatomit, Diatonsit, Infusorienerde, Kieselgur, Tripel, Tripolite.
Chemistry/Composition:
SiO2+aq(< 40%) .
Natural Sources:
Denmark, Germany, the USA (Santa Babara/California), and in smaller deposits world-wide.
Medical Importance:
Key Hazards:
Fibrogenic.
Involved Organs:
Lung.
Exposure/Epidemiology:
It is used in thermic and acoustic insulation, farming, chemical industries, as filtering material and filling material in rubber industries and cosmetics. The annual world production is about 1 800 000 tons.
Thresholds:
For further information compare to silica.
Etiology/Pathophysiology:
During the heating, (“calcination”) diatomaceous earth may convert into the crystalline form (temperature 450° C). Calcinated products can contain <60% of tridymite.
Lung Diseases:
Diatomaceous earth can be fibrogenic; for further information see silica. Clinical Presentation
: Patients present with cough, shortness of breath during exercise, and dyspnea if heavily exposed.
Radiology:
Chest radiographs reveal a nodular pattern with nodular components; for details see under the heading silica.
Lung Function:
Usually mild to moderate restrictive or obstructive changes; for details see under the heading silica.
Bronchoalveolar Lavage:
The activity of the interstitial fibrosis is associated with the T4/T8 ratio of lymphocytes and the activated complement measured in the lavage fluid; for details see under the heading silica.
Pathology:
Gross:
The fibrotic and emphysematous lungs are of grayish -red color and may display several black nodules which are randomly distributed in both lungs.
Histology:
Circumscribed black, “onion-shaped” nodules with some scattered mononuclear inflammatory infiltrates and histiocytes, acellular collagenous fibers diffusely distributed in both lungs, and dust-laden macrophages are common findings. The birefringent crystal fibers are deposited in the distant airways and can be transported into the central localized lymph nodes which may be altered by dense collagenous fibers.
Prognosis:
Fair, as slowly progressive respiratory failure is the common course after heavily exposure.
Additional Diseases:
None.
References:
search Pubmed for Diatomaceous Earth
Bariums HK: Diatomaceous earths silicosis. Am J Ind Med 18 (1990) 591-597
Cooper WC, Sargent EN: A 26-year radiographic follow up of workers in a diatomite mine and mill. J Occup Med 26 (1984) 456-460
Craighead JE: Asbestos-associated diseases. Arch Pathol Lab Med Special Issue 106 (1982) 579-597
Dail DH, Hammar SP: Pulmonary Pathology. Springer, New York (1988)
Dayan AD, Morgan RJI, Trefty BT: Naturally occuring diat omaceous pn eumoconiosis in sub-human primates. J Comp Pathol Vol 88 (1978) 321-325
Elmes PC: Other isometric mineral dusts pneumoconiosis: cement. In: JK Howard, FH Tyrer (Eds): Textbook of occupational medicine. Churchill Livingstone, Edinburgh (1987)
Feigin DS: Misconceptions regarding the pathogenicity of silicas and silicates. J Thorac Imaging 1 (1989) 68-80
Kayser K: Analytical Lung Pathology. Springer, Heidelberg, New York (1992)
Maeda H, Ford J, Williams MG, Dodson RF: An ultrastructural study of acute and long-term lung response to commercial diatomaceous earth. J Comp Pathol 3 (1986) 307-317
Nakamura M, Chiyotani K, Takishima T: Pulmonary dysfunction in pneumoconiosis. Maruzen, Tokyo (1991)
Rom WN: Occupational and environmental medicine. Little, Brown & Comp, Boston (1983)
Worth G, Schiller E: Die Pneumokoniosen. Staufen, Köln (1954).
Wozniak H: (Comparative studies on fibrogenic properties of diatomes and other silica dusts.) Badania p o rownaw cze wlasciw osc i zwloknia a cych diatomitow z innymi pylami krzemionkowymi. Med Pr 34 (1983) 427-434