Pollution in Hawaii is giving turtles deadly tumors, a new study found.

Researchers at Duke University, the University of Hawaii and the National Oceanic and Atmospheric Administration have determined that nitrogen runoff is polluting the algae that turtles eat, causing them to develop tumors in their eyes, flippers and internal organs.

Nitrogen is a critical component of fertilizers used by farms and golf courses, but it’s proving deadly for Hawaii’s green sea turtles, which NOAA already considers threatened.

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