If you could somehow weigh all the plastic floating in the world's oceans， it would equal the mass of roughly 38 000 African elephants.

That estimate comes from a new global study of plastics floating in the oceans. After six years of research， scientists estimate the seas contain about 5.25 trillion pieces of this trash. Its combined weight： an estimated 269 000 metric tons.

"We found plastics are widely distributed across all oceans，" says Marcus Eriksen. Eriksen works with the 5 Gyres Institute in Los Angeles， Calif. This group looks for solutions to problems caused by plastic trash.

Scientists find the extent of the ocean's plastic trash problem worrying. Fish and other marine organisms can ingest tiny plastic fragments. This trash can then move up the food chain as seabirds， seals and other marine predators eat those fish.

Eriksen and his team travelled more than 50 000 nautical miles while making their measurements. They surveyed five subtropical gyres. These are large areas of rotating currents. Floating plastic accumulates in these large circular loops. The team also measured concentrations of plastic off the coast of Australia， on the Bay of Bengal and in the Mediterranean Sea.

The experts used a fine mesh net to capture plastic particles smaller than 4.75 millimeters. Later， they weighed all the tiny bits.

The researchers found that more than half of the weight of all ocean plastics is made up of such tiny pieces. This discovery concerned the team because smaller particles have a greater surface area. This allows them to absorb more pollution per unit weight than larger pieces will. But bigger pieces also are a problem. Plastic bags， six-pack rings for canned drinks and fishing nets - all can entangle seabirds， turtles and even whales.