ananyo writes "Toxic chemicals are accumulating in the ecosystems of the Himalayas and the Tibetan plateau, researchers warn in the first comprehensive study to assess levels of organic pollutants in that part of the world. Persistent organic pollutants (POPs) are carbon-based compounds that are resistant to break-down. Some originate from the burning of fuel or the processing of electronic waste, and others are widely used as pesticides or herbicides or in the manufacture of solvents, plastics and pharmaceuticals. Some POPs, such as the pesticide dichlorodiphenyltrichloroethane (DDT) and the herbicide Agent Orange, can cause diseases such as cancers, neurological disorders, reproductive dysfunction and birth defects. The researchers found large amounts of POPs (including DDT) in various components of the ecosystems such as soil, grass, trees and fish in the Himalayas and in the Tibetan plateau, especially at the highest elevations."