Document mbxoXG53yDyqaOyV8LyMXZajZ

Canad. Med. Ass. J. May 8.1986, vol. 92 Special Report: Asbestos and Cancer 1025 It is therefore recommended that: (a) Standard reference samples, of respirable size, of amosite, chrysotile, crocidolite, tremolite and anthophyllite be prepared from as pure parent ma terial as possible and held at the Pneumoconiosis Research Unit (P.R.U.) in Johannesburg for distri bution to centres requiring them. (These standards should also serve as references for comparison with larger amounts of material--such as may be required for inhalation or chemical extraction.) It is pro posed that samples of chrysotile from different countries--for example, from Arizona, Havelock (Swaziland), Quebec and Shabani (Southern Rho desia)--be included in the reference collection. (b) The standard samples be analyzed and characterized quantitatively by: Chemical and spectrographic analysis. Optical and electron microscopy, for determina tion of shape, size distribution, and optical proper ties such as refractive indices, extinction angle, etc. X-ray diffraction analysis by the powder tech nique. Specific surface measurement by low tempera ture gas adsorption. Determination of amount and type of organic matter present. (c) Oils and waxes isolated from asbestos be prepared and also distributed through the P.R.U., Johannesburg. (d) When the standards have been collected and prepared, the P.R.U., Johannesburg, will notify workers of their existence through the U.I.C.C. Bulletin and any other appropriate channels. 1. Identification and Quantitative Assessment of Asbestos in Tissues In tissue sections- it may be only possible to identify the type of asbestos present. For quanti tative studies of the amount present in any organ such as the lung, it is necessary to analyze repre sentative samples of the organs. It is recommended that: Tissue sections should be treated to remove or ganic material, for instance, by ashing or treatment with active oxygen; but this will not remove the asbestos bodies completely, and chemical treatment may be necessary to free the fibres. The best method for this is not known, but treatment with acetic acid may be useful. Identification of the type of fibre can only be made on free asbestos fibres and not on fibres inside asbestos bodies. It is recom mended that methods of distinguishing asbestos from other fibres which may be present be further investigated. This can probably best be done by phase contrast or polarized light microscopy. It is also recommended that the treated sections be ex amined by electron microscopy for recognition of submicroscopic fibres. For large samples of tissue, acetic acid, hydrogen peroxide and formamide methods be tried as they appear to be superior to ashing, but the best method of extraction of mineral matter from tissue is not yet known and needs further study. However, the quantitative determination of asbestos in the residue obtained in this way is difficult but could be based on chemical analysis, x-ray diffraction, or fibre counts. It is recommended that methods for concentrating such asbestos and separating different types of asbestos from each other be further investigated. Reprints may he obtained from the National Cancer Institute, 790 Bay St., Toronto, Ont. References 1. Miller, D. L.: Amer. Rev. Reap. Dis.. 88: 473. 1963. 2. International Labor Office: Occup. Safety Hlth., 9: 63, 1959. 3. Gloyne, S. R.: Tubercle, 14: 445, 1933. 4. Hakinoton, J. S. and Kilroe-Smitk. T. A.: Arch. Environ. Health (Chicago), 9: 395, 1964. 5. Wagner, J. C., Monday, D. E. and Harinoton, J. S.: J. Path. Bact., 84: 73. 1962. PAGES OUT OF THE PAST: FROM THE JOURNAL OF FIFTY YEARS ACO WHAT IS TO BE DONE? Nor is the death from asphyxiating gases a sudden and painless death, as hypocritical articles in German news papers will have us believe. In very small doses it first produces a temporary cessation of breathing reflexly through irritation of the nasal mucous membrane. Next, when this inhibition of necessity ceases, the gas is drawn into the other respiratory passages and, on account of its solubility in moisture, it attacks the respiratory mucous membranes, producing violent catarrh. The later sequelae are results of the disintegration of these membranes caused either by direct union of the chlorine with their proteins or by the formation of hypochlorous and hvdro-chloric acids and the evolution of nascent oxygen. There is fre quently a purulent discharge, with inflammation, bronchitis, haemorrhage, and broncho-pneumonia. All these symptoms have been observed in rescued soldiers. The sufferer may die before pneumonia ensues and, in the case of consider able concentration of the gas (over one in a thousand), dyspnoea, coma and death rapidly follow. But meanwhile what is to be done? Can we bring our selves to imitate the methods of the enemy? To blow steam or atomized water from a spray into the fumes may be effective but it is to be remembered that chlorine water blisters the skin and causes acute inflammation of the con- juctiva. A combination of wet respirators and water sprays would be useful and a means of creating a violent up draught of air some distance in front of the trenches, by means of burning gasoline or kerosene, would so dilute the cloud of vapour as to render it less noxious. Meanwhile we can take some comfort in the thought that it is but rarely that atmospheric conditions will render the use of this diabolic means of warfare possible. Already, if we can believe reports, our enemies have been caught in their own trap.--Editorial, Canad. Med. Ass. J., 5: 516, 1915.