Epidemiology - The Method
Epidemiology is based on comparisons: researchers obtain clues by comparing disease rates in groups with differing levels of exposure to the factor under investigation. For instance, studies of a rubella outbreak in Australia during 1941 revealed more cases of congenital cataract in infants whose mothers had been exposed to the virus during pregnancy. This was the first evidence that rubella causes birth defects.2
Some population studies, where one community is compared to another, involve huge numbers of people. A recent survey of eating habits in China, referred to as the “Grand Prix” of epidemiology, compared people from 65 counties. The findings indict fat and meat as major causes of chronic disease and point to a vegetarian diet as most likely to promote health.3,4
© Hulton-Deutsch Collection
(4)Epidemiological studies In China have shown the simple, traditional, largely vegetarian diet to be healthiest.
A recent survey of eating habits in China, referred to as the “Grand Prix” of epidemiology, compared people from 65 countries. The findings indict fat and meat as major causes of chronic disease and point to a vegetarian diet as most likely to promote health.3,4
On the other hand, vital clues also come from tiny “clusters” of very unusual disease. One of the first reports of radiation- induced cancer came from an epidemiological study in New Jersey where young women were employed to paint the luminous faces on wrist watches with radium. The survey found more cases of the normally rare cancer, osteosarcoma, than would have been expected among the general population. The victims had all been swallowing the substance when moistening the paint brushes between their lips.5
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