Fine biogenic silica fibres in sugar cane: a possible hazard

Our plain-English summary of Fine biogenic silica fibres in sugar cane: a possible hazard, by R.H. Newman (The Annals of Occupational Hygiene, 1986).

The study

• Author: R.H. Newman
• Journal: The Annals of Occupational Hygiene
• Published: 1986;30(3):365-70
• Cited by: 18 articles, as counted by NIH iCite
• Read it: PubMed · Publisher
• In J-M's library: Johns-Manville's company medical library held a copy (J-M no. 004060).

Abstract

Some plants contain structures of biogenic silica which have been implicated as causes of disease in man. Following reports of mesotheliomas and lung cancers in sugar-cane workers, an examination of residues from sugar cane leaf has shown the presence of acicular biogenic silica, 0.85 µm in dia. and 10-300 µm long, which is within the carcinogenic size range for asbestos fibre. It is postulated that the release of such material during the common practice of burning off sugar-cane leaves before harvesting the stems may have health implications for sugar-cane workers.

PubMed has no abstract for this study. This is the authors' abstract, copied from the article.

In plain English

This short communication described a laboratory examination of sugar cane leaf. No workers were studied. The author cited earlier reports by other researchers of mesotheliomas and lung cancer in sugar-cane workers, and noted that cane leaves are commonly burned off before harvest. Leaf from immature and roughly one-year-old sugar cane from Trinidad was burned to ash or digested in concentrated nitric acid. The residues were then examined with a scanning electron microscope and X-ray analysis. The residue was almost entirely silicon. From 5 g of digested mature leaf, 150 needle-shaped fibres from the leaf's hypoderm layer were obtained. They were 0.85 micrometres in diameter and 10.0 to 300.0 micrometres long. Silica made up 5 to 7% of the weight of mature dried leaf. The author concluded that these dimensions were within the size range of asbestos fibres. The author stated that this was evidence for the hypothesis that such plant fibres are involved in mesothelioma and lung cancer in sugar-cane workers. The author added that the hypothesis needed testing through airborne particle monitoring, disease studies in other sugar-cane areas and animal experiments.

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: Laboratory examination of plant material (short communication), using ashing or nitric acid digestion of leaf, then scanning electron microscopy with energy dispersive X-ray analysis
• Who was studied: Leaf from immature and approximately 1-year-old sugar cane from Trinidad; no human subjects
• Exposure: Biogenic (plant-made) silica fibres in sugar cane leaf. No asbestos was examined; the fibres' dimensions were compared with those of asbestos fibres.
• Main results:
  • Silica structures in the mature leaf residue were assigned to the epidermis, stoma, mesophyl, prickle hairs and hypoderm
  • X-ray analysis showed the residue material was almost entirely silicon (a 99% silicon signal)
  • From 5 g of mature leaf nitric acid digest, a total of 150 hypoderm fibres were obtained, 0.85 micrometres in diameter and 10.0 to 300.0 micrometres long
  • In a representative histogram of hypoderm fibre lengths, the most common length was 200 micrometres
  • Biogenic silica made up 5 to 7% of the weight of mature dried leaf, determined by acid digestion
• The authors' conclusion: The author stated that the work presented evidence for the hypothesis that siliceous plant fibres, with dimensions similar to asbestos, are involved in causing mesothelioma and lung cancer in sugar-cane workers. The author said the hypothesis needs testing.
• Limitations the authors state:
  • The author stated that the hypothesis still needs testing through airborne particle monitoring, study of disease in other sugar-cane growing areas, and animal experiments
  • The author noted that the shorter fibre lengths measured may reflect damage during preparation

Topics

The National Library of Medicine indexes this study under subjects our site covers: Lung cancer, Mesothelioma.

Medical terms in this study, explained in our Lexicon: Mesothelioma, Lung Cancer, Acicular, Carcinogenic, STEM.

Related studies

• Association of biogenic silica with disease — R. 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)
• A case-control study of mesothelioma and employment in the Hawaii sugarcane industry — T. Sinks, M.T. Goodman, et al. (1994)
• Exposure to asbestos versus organic fibrous dusts — G.D. Clarke, R.H. Newman, et al. (1983)
• 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)

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