DTPA is a chelate which bonds to heavy metals and elements. In agriculture, it is used when soils with high pH levels (alkaline) prevent plants from absorbing micronutrients necessary from growth and production.
It is also used as a detoxification agent on humans and animals when they have been exposed to plutonium or other dangerous elements. The chelate bonds with the elements and allows them to be washed off. It is also used internally, to bond with these elements and flush them out of the digestive tracts or the kidneys.