Dinitrophenol (2, 4-DPN), a yellow food dye, was once
routinely added to commercial baked goods to make them appear "egg
rich". In 1933, this manufactured chemical was introduced as a treatment
for obesity. DPN helped patients loose weight by uncoupling oxidative phosphorylation.
This proved to be very dangerous; many users suffered injury and death
due to elevated body temperature. Over one hundred thousand people took
these "anti-fat medicines" before they were abandoned in 1937.
DPN was used as a herbicide and insecticide until it was
banned by the US EPA in the early 1990's.