The Lab Coat Is on the Hook in the Fight Against Germs - The New York Times
This change took place in part because doctors wanted to spruce up their dubious reputation. Until the advent of such medical reformers as Abraham Flexner and Sir William Osler about 100 years ago, medical training in the United States was notoriously lax. Lectures, not clinical experience, were the norm. It was the age of horse sense and the quack.
So to more closely associate themselves in the public mind with sound science, physicians began donning the lab coats that were being worn by chemists and other laboratory types. These coats were generally beige. But white soon became the standard.
“Our notion since the 1880s, when the germ theory of disease began to take hold, is that microbes hide in dark, dirty places, and that white stands for purity, both material and moral,” said Guenter Risse, a physician and author of “Mending Bodies, Saving Souls: A History of Hospitals” (Oxford, 1999). “Wearing white coats was a symbol that you were clean.”