Repository: UIHistories Project: SWE - Proceedings of the First International Conference of Women Engineers and Scientists [PAGE 156]

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half-life has the advantage that the greater part of its radioactivity is exhausted before the fallout reaches the earth. Immediately after the first nuclear explosions, intensive research began throughout the world with the objectives of examining the effects of radioactive fallout and of protecting society from the fatal consequences. It was realized that satisfactory results could be achieved only by means of close cooperation between public health officials and farm officials, chemists and physicists. It was noted that the dangerous effects of radioactive fallout might be reduced by the use of correct methods of cultivation, feeding, storage and treatment. Regular measurements of the radioactivity in the atmospheric air and drinking water were begun in many countries, and there was initiated the control of foodstuffs with respect to its radioactivity, Radioactive residues in milk Milk and milk products constitute the main sources of calcium in the average diet of many European and North-American countries. A direct consequence of this fact was that the study of the radioactive residues in milk became the object of intense interest during the period of experimental nuclear explosions. This also applied in Finland, where according to information compiled by the Food and Agricultural Organization of the United Nations (FAO) the consumption of milk is about 0.8 litre per person per day, the highest average consumption of milk in the world. This quantity of milk contains about one gram of calcium, or an amount which is sufficient alone to cover the calcium need of man. The necessity of calcium to man, the close relationship between calcium and strontium, and the possible contamination of the most important source of calcium, milk, through the agency of feed eaten by cattle were things which alarmed the people living in the northern hemisphere. The result was a rush on the chemists' shops, calcium pills were eaten in unreasonable amounts, and calcium was even added to the baking soda in pursuance of the belief that radio-strontium cannot penetrate people saturated with calcium. However, food and milk investigations brought very reassuring information to milk drinkers. It was observed that the most important source of milk was in the happiest situation as regards the receipt of calcium; this finding was based on the cow's organs being able to remove strontium, a foreign substance to the animal, to a greater extent than calcium; consequently, the relationship of active strontium to calcium in milk becomes small. This kind of strontium-straining occurs to such an extent that 90 Sr/Ca in milk amounts to only one-tenth of the corresponding ratio in the feed. The use of milk is further facilitated in that only a small proportion of the racioactive matter in milk is in the fatty part, e.g., only two percent as regards 90 Sr. Butter prepared from contaminated milk thus contains no more than a small proportion of the fallout isotopes in contaminated milk.

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