Association of biogenic silica with disease

Our plain-English summary of Association of biogenic silica with disease, by R. Newman (Nutrition and Cancer, 1986).

The study

• Author: R. Newman
• Journal: Nutrition and Cancer
• Published: 1986;8(3):217-21
• Type of article: Review
• Cited by: 6 articles, as counted by NIH iCite
• Read it: PubMed · Publisher

Abstract

Certain plants contain structures consisting of biogenic silica. This form of silica has been implicated as a causative agent in the high esophageal cancer areas of southern Africa, northeast Iran, and northern China. A spicule shape of biogenic silica is known to act as a tumor promoter in the mouse skin model system. The observation that fine biogenic silica fibers are found in leaves of sugarcane may pose a hazard for cane workers; also, the discovery that bracken contains silica fibers could have implications for browsing cattle. This paper reviews and discusses the involvement of biogenic silica in disease.

In plain English

This article was a review, not a new study. The author gathered published work on biogenic silica, the silica that living plants deposit, and its possible links to disease. It summarized earlier research from high esophageal cancer areas. In the Transkei in southern Africa, commonly eaten plants contained silica. In northeast Iran, other researchers found up to 3,000 plant silica fibers per gram of flour, from the grass Phalaris minor. In northern China, esophageal tissues of cancer patients held more than 15 times as many silica fragments as tissues from London patients dying from other causes. In cited mouse-skin experiments, fibers from a related species, Phalaris canariensis, strongly promoted the action of a chemical carcinogen. The review noted that sugarcane workers can develop mesotheliomas and lung cancer. The author had earlier suggested that silica fibers released when cane leaves are burned might be involved, and described these fibers as within the size range of asbestos fibers linked to mesothelioma. Bracken, which cattle eat, also contains silica fibers. The author concluded that biogenic silica may make a previously undervalued contribution to disease.

We wrote this plain-English summary from the full article with the help of AI, and a second AI model checked each sentence against the article. It is not the authors' wording; the abstract and the article are their own account.

What the study did and found

• Design: Narrative review of published studies on biogenic (plant) silica and disease; no new data collected
• Who was studied: No study population of its own. The review discussed earlier reports on grain handlers, people in high esophageal cancer areas (Transkei in southern Africa, northeast Iran, northern China), sugarcane workers, cattle feeding on bracken in Scotland, and mouse and cell-culture experiments.
• Exposure: Biogenic silica, meaning silica deposited in living plants, in forms such as spicules, fibers and sharp-edged sheets. Sources discussed were wheat dust, Phalaris grass contaminating flour, millet bran, sugarcane leaves and bracken. No asbestos exposure was studied; asbestos fibers were used only as a size comparison.
• Main results:
  • Earlier reports from the Transkei: esophageal tumors accounted for 47% of all tumors in males and 36% of all tumors in females. Rose proposed a disease entity termed phytolithicosis.
  • O'Neill and co-workers, northeast Iran: up to 3,000 silica fibers per gram of flour, originating from weedy Phalaris contaminants of wheat.
  • O'Neill and co-workers, cell culture: similar fibers from Phalaris canariensis stimulated proliferation of mouse 3T3 fibroblast cells more than 100-fold.
  • Bhatt and co-workers, mouse skin model: fibers from Phalaris canariensis acted as a powerful promoter of the action of a chemical carcinogen. The fibers were not reported to cause tumors on their own.
  • O'Neill and others, northern China: more than 15 times as many silica fragments in esophageal tissues of cancer patients in that area as in ordinary London patients dying from other causes.
  • Cited reports show sugarcane workers can develop mesotheliomas and lung cancer. The author's own 1983 letter had postulated a role for silica fibers from mature sugarcane leaves.
  • Silica fibers were found in mature bracken fronds. The review raised this as possibly relevant to intestinal and bladder cancer in cattle feeding on bracken in Scotland.
• The authors' conclusion: The author concluded that biogenic silica, because of its size, shape and mode of presentation, may make a previously undervalued contribution to disease, especially where it may act together with a chemical carcinogen.

Topics

Medical terms in this study, explained in our Lexicon: Esophageal Cancer, Discovery.

Related studies

• Fine biogenic silica fibres in sugar cane: a possible hazard — R.H. Newman (1986)
• Exposure to biogenic silica fibers and respiratory health in Hawaii sugarcane workers — T. Sinks, R. Hartle, et al. (1994)
• DNA double-strand breaks by asbestos, silica, and titanium dioxide: possible biomarker of carcinogenic potential? — Z. Msiska, M. Pacurari, et al. (2010)
• One agent, many diseases: exposure-response data and comparative risks of different outcomes following silica exposure — K. Steenland (2005)
• Dose-response associations of silica with nonmalignant respiratory disease and lung cancer mortality in the diatomaceous earth industry — H. Checkoway, N.J. Heyer, et al. (1997)
• Mortality from lung cancer and respiratory disease among pottery workers exposed to silica and talc — T.L. Thomas, P.A. Stewart (1987)

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