Plastic bags carry dangerous bacteria that are harmful to humans after just six weeks in the sea

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Bacteria that are harmful to humans can stick to plastic bags in the ocean in less than six weeks.

Scientists who cut up single use carrier bags and submerged them in the sea found thick layers of bacteria were able to cling to the plastic within 40 days.

There are growing fears the plastic choking our oceans could cause illness in humans, as the material acts as a magnet for toxins in the for toxins in the water - and waste swallowed by fish makes its way up the food chain.

Researchers at National University in California were particularly interested in floating fragments of plastic bags, which the Daily Mail has campaigned to banish.

The scientists cut plastic bags into squares and placed them into stainless steel cages 20in under the surface of the sea.

Analysing the microbes on the plastic, they found bacteria that cause serious fevers, including one similar to strains used in biological terrorism.

Study leader Dr Anna Maria Barral said: 'We were very surprised to see plastics in the water were colonised so quickly.