Animals and the Atom

Radioactive isotopes are revealing new facts about animals, too. Scientists can follow changes which occur in various chemicals from the instant they enter an animal's body until they leave it. To determine how a cow manufactures milk, radioactive isotopes were added to the animal's food and injected into various parts of its body. Tracer elements are also used to study how hens make eggs. Scientists are using tracers to follow the activities and processes of mice, fish, flies, and other animals.

"Tagged" atoms are widely used in medicine. The discovery that iodine always collects in the thyroid gland led to the development of a new method of treating cancer of that organ. Radioactive iodine taken by a patient accumulates in the thyroid and its radiations kill the cancer cells.

Scientists are now searching for chemicals that accumulate selectively, in other organs of the body. When a harmless radioactive gas is taken into the lungs of a patient it is carried to the left side of the heart. If radioactivity is detected immediately in blood samples drawn from an artery supplied by the right side of the heart, surgeons know that there is a leak between the two chambers of the heart.

Research workers are also studying the harmful effect of radiation on the human body. Experiments which may cause malformations cannot be performed on humans. Much data valuable to medicine is therefore obtained by studying the effect of radiation upon animals.

Задание 2. Заполните таблицу, опираясь на тексты

Ученые, связанные с открытием радиоактивности
Названия химических радиоактивных элементов
Основные химические и физические свойства радиоактивных элементов
Сферы использования радиоактивных элементов

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