Vietnam

The planes used to spray Agent Orange in Vietnam weren't retired from service — they were used by reservists in the U.S. for more than a decade after the war, exposing the crews to harmful chemicals.

Demand for rhino horn, used in traditional Chinese medicine, is fueling a slaughter of the animals in Africa. In Vietnam, the sought-after commodity is fetching prices as high as $1,400 an ounce, or about the price of gold. There, some believe ground horn can cure everything from hangovers to cancer.