Prevention: Environmental and Behavioral Modification
Before the Industrial Revolution, the average life expectancy was in the twenties; the preindustrial environment was deadly. Industrial civilization, although it has created new risks, has attained life expectancy in the upper seventies. Health and life have been improved in three ways: by altering the environment to reduce its threats; by protecting individuals and populations from environmental threats; and by learning to treat illness and injury.
In some instances, there are tradeoffs: prevention versus protection versus treatment. In other cases, we have no choice: we lack treatment for most viruses, but we can vaccinate or quarantine; we cannot protect individuals from polluted outdoor air, but we can reduce pollution. How do we allocate resources between public health prevention (environment), individual prevention (behavior), and treatment? Is prevention just an added cost of health care, or is it a means of reducing medical care needs and spending?
If we measure the conquest of disease in terms of mortality and life expectancy, the first great step forward was the dramatic fall in infant and child mortality in the late nineteenth and early twentieth centuries, almost entirely the result of improvements in prevention via public health measures: safe drinking water, sewage disposal, reduction in disease vectors. The second great advance, in the first half of the twentieth century, was a combination of prevention and treatment: new vaccines, further improvements in public health, food inspection, culminating in the antibiotic revolution of the 1940s. The third advance, in which we find ourselves, is defensive as well as preventive: staving off, slowing down the killers of middle and old age, prolonging the lives of the elderly instead of saving the lives of the young. It involves new medical technology, modification of lifestyles, and new measures for environmental modification, in particular the elimination or reduction of harmful chemicals rather than microorganisms.