The Effects of Volcanic Ash on the Organ System of the Mice (A Research) / Margarita Cristobal ; Nenel Lao ; Marwhin Molinyawe ; Mirielsa Shaharmy Nufable and Robert John Uy.

Includes bibliographical references.

Abstract: The major questions and issues relating to the physical health effects of the eruptions of Mount Pinatubo that were appropriate to answer by means of human studies were as follows: 1) What are the acute and chronic effects of exposure to volcanic ash on the upper and lower respiratory tracts? Does the ash affect the airways and/or lung parenchyma? Are these effects (if any) reversible or irreversible? 2) Is there a subset of the population which is at increased risk for the development of pulmonary-related problems? Are persons with chronic obstructive pulmonary disease at increased risk ? Are the elderly, especially those with heart and/or lung disease, at increased risk? Are asthmatics or persons with nonspecific bronchial hyperreactivity at increased risk? Are smokers at increased risk? 3)Does acute and/or Chronic exposure to inhaled volcanic ash affect the reactivity of the airways? 4) Does long-term exposure to inhaled volcanic ash cause chronic bronchitis? 5) Does long term exposure to inhaled volcanic ash cause silicosis or other fibrotic lung disease? The only real advantage that human studies have over animal studies is that the results are likely to be relevant to humans. Although this is a very important advantage, it must be weighed against the sizable disadvantages or drawing conclusions from observational studies. Specifically, 1)the generalizability of results obtained from observational studies may be limited because of the way in which the subjects were selected, the characteristics of the study population, or the inability to obtain an acceptable rate of participation; 2) they tend to be very costly; 3) they almost always take a long time; and 4) they are very difficult to control. But it has been interesting to watch the answers for the animal studies and the human studies coverage and provide more or less the same conclusions. Because of the logical and funding difficulties associated with carrying out a well-designed epidemiologic study, the amount of epidemiologic information available from human studies about the effect of the volcanic ash from Mount Pinatubo on the respiratory system in somewhat limited. Nevertheless, the most important questions have been answered and from the available information it is possible to draw conclusions, which are probably valid, about the risks for the respiratory system of short and long term exposure to low concentrations of inhaled volcanic ash. Only limited information is available about the effects of short and long term exposure to high levels of inhaled ash. However, since most exposures following a volcanic eruption, at least after the first few days, tend to be low-level exposures and since high-level exposures typically only occur among fatalities who are missed by the evacuation efforts, this piece of information is probably relatively unimportant. The studies that have involved groups exposed to varying level of airborne resuspended volcanic ash have provided some reassuring answers to the fundamental questions about the potential risks attached to living and working in an ashfall area. The answers obtained so far are reassuring because they provided evidence that the effects of low-level exposures to ash on the respiratory tract are probably temporary and probably mostly inflammatory in nature. It must be stressed, however, that these conclusions are based on subjective appreciation and reporting of respiratory symptoms and histologic findings.

Thesis - Department of Pathology & Laboratory Diagnosis