Passage one 

The most serious health problem in the world used to be infectious diseases such as typhoid fever, influenza (flu), and plague. In the 14 century for example, an epidemic of plague killed roughly one-third of the population of Asia and about half of the population of Europe. A flu epidemic in 1918 killed millions of people around the world. Today, however, vaccines and antibiotics have prevented the spread of many serious diseases. In fact, in many parts of the world today, infectious diseases are no longer considered to be the most serious health problem. However, today the number-one health problem in most countries is a new epidemic: the obesity.

Two major reasons may be conceived for obesity. An obvious contributing factor is the sedentary lifestyle that many people in the 21" century are leading: getting around by car and working at a desk do not demand much physical activity, which is what people had to do to survive in the past. Now, however, we have to artificially add it to our life. A second cause of the obesity epidemic is an increase in the availability and consumption of junk food, defined as "foods which provide calories primarily through fats or added sugars and have minimum amounts of vitamins and minerals". Studies have shown that people are consuming substantially more calories daily than they used to, and they are consuming many of those calories outside of regular meals.

Passage two

It is paradoxical that despite extensive advances in literacy and education as well as vastly improved methods of communication, there still exists a great gap between the existing medical and health protective knowledge and the public's acceptance and use of it. Professional journals are replete with reports, surveys of school children, college students and the adult public that present discouraging and embarrassing evidence of failure in this field. Many parents, for instance, still do not obtain immunization for their children and many drivers still invite injury and death by drinking and driving, and not using belts. The use of cigarettes and patent medicines is still widespread. One of the handicaps of public health work, of course, is the absence of pain and urgency.

Passage 3

No material used in industry has been the object of more epidemiological research than asbestos, a name given to describe any fibrous material silicate used commercially. The main stimulus for this research was conference held in New York in November 1964 where it became evident that the magic mineral, with all its innumerable and invaluable uses , was a potent cause of lung cancer and perhaps some other malignancies. It was recognized that asbestos comprised at least five distinct types of mineral fibers, which might well differ in their biological properties, but that what constituted a hazardous exposure was quite unclear. At the close of the conference, an expert working group identified priorities for epidemiological research as fiber type differences, exposure-response in various industries, comprehensive studies on lung cancer and other related malignancies, and effects of removal from further exposure.

Passage 4

On the subject of physical health and medical research, there are thousands of amazing websites on the World Wide Web where people can get information. However, when does the amount of available information affect its validity and health benefit? The internet is greatly influencing people's attitudes about their own healthcare; probably, this worldwide cultural trend improves global health. Because computer users can look up almost any topic of interest to them, they become their own researchers. in the busy modern world, doctors don't always take the time to explain illnesses and possible remedies to their patients' they may not give scientific details in words that are easy to understand, either for this reason, many hopeful people take advantage of Web resources to find the facts they need for good medical decisions. But are the beliefs of "exports" always completely accurate or real? Are they helpful to everyone that needs advice on a specific medical condition? To sell health books or products might the claims that seem the most wonderful even be fraudulent - that is, dishonest or false? Do sick or worried people expect too much when they look for clear, easy answers to difficult health questions or problems on the computer