As they walk the sands of Orange Beach, Alabama, T. Prabhakar Clement and Joel Hayworth have no difficulty finding traces of the Deepwater Horizon disaster—in fact, the Auburn University researchers have a harder time making sure those traces don't stick to their feet.

On a mid-February weekend, oil—in the form of hundreds of sticky tar balls—had washed up all over the beach following a storm the night before.

"We could have collected as many tar balls as we wanted to, from less than 1 centimeter up to 4 centimeters (.4 to 1.6 inches) in diameter," Clement said. "And these are really soft tar balls that are decaying, so there are probably also millions of tiny fragments that we can't even see. I collected over 1,000 tar balls within [an area of] about 10 miles (16 kilometers) in five hours. What does that mean? I don't know. What are the health ramifications? I don't know. But this clearly demonstrates the magnitude of the [ongoing] problem attributable to Deepwater Horizon."