[[en/index|English]] · [[zh/index|中文]] · [[en/classics/oneill-silica-fibers|EN]] · [[zh/classics/oneill-silica-fibers|中文]] # O'Neill's silica fibre series — key points The key findings and graphical data from O'Neill et al.'s series of papers on silica fibre-induced carcinogenesis are summarized below. ## 1973 — Fibroblast Anchorage in Carcinogenesis by Fibres To propose the "anchorage-dependence" hypothesis for fibre-induced cancer. Mechanism: long fibres provide physical anchorage, activating sustained proliferation of mesenchymal cells (e.g., fibroblasts), leading to mesothelioma. In vitro test: ![[About O’Neill fig2.png|400]] The ability of fibres to support cell growth increases starting from a length of 40 μm. In vivo test: ![[About O‘Neill fig1.png|400]] A higher incidence of mesothelioma was associated with a higher proportion of long fibres in the sample. ## 1980 — A Fine Fibrous Silica Contaminant of Flour in the High Oesophageal Cancer Area of North-East Iran A silicon fibre contaminant was discovered in flour from a high-incidence region of esophageal cancer in Iran. This fibre originates from the inflorescence bracts of *Phalaris minor*, a weed of wheat fields. ![[About O’Neill fig3.png|500]] In vitro tests confirmed that cells attached to silica fibres from *Phalaris canariensis* proliferate significantly faster than cells suspended in gel. ![[About O’Neill fig9.png|400]] ## 1982 — Silica Fragments from Millet Bran in Mucosa Surrounding Esophageal Tumours in Patients in Northern China Mucosa adjacent to tumours from Linxian surgical cases was compared with normal mucosa from London controls. <table> <tr> <td> <img src="About O’Neill fig4.png" style="height: 200px; width: auto; display: block; margin: 0 auto;"> </td> <td> <img src="About O’Neill fig10.png" style="height: 200px; width: auto; display: block; margin: 0 auto;"> </td> </tr> <tr> <td align="center"><em>a: Surface of a 25 mm filter used to collect the residue from a sample from Lin Xian.</em></td> <td align="center"><em>b: Similar specimen at the same magnification from a London pneumonia patient.</em></td> </tr> </table> The concentration of silica particles found in the esophageal mucosa of chickens from Linxian was similar to that in patients from Linxian. ![[About O’Neill fig5.png]] ## 1984 — Biogenic Silica Fibre Promotes Carcinogenesis in Mouse Skin Dietary exposure: adding *Phalaris canariensis* seeds containing silica fibres to the feed resulted in a significant increase in skin tumour incidence around the mouth and nose of mice. ![[About O’Neill fig6.png]] Skin contact studies: 1) dorsal skin exposure to seeds via a wire gauze barrier; 2) light rubbing of dorsal skin with isolated fibres. Both methods resulted in frequent tumour development at the contact sites on the dorsal skin. <table> <tr> <td> <img src="About O’Neill fig7.png" width="100%"> </td> <td> <img src="About O’Neill fig8.png" width="100%"> </td> </tr> </table>