Plastic straws and bags have received widespread attention as pollutants. But another, even bigger, plastic problem has been slipping under the radar -- cigarette filters. Cigarette butts containing plastic filters are the most littered item in the world.

"Many smokers assume the filters are made of a biodegradable material," says Elizabeth Smith, who works on tobacco control policy at the University of California San Francisco.

In fact, filters are made of cellulose acetate -- a type of plastic that can take up to a decade to decompose.

But now the European Union is cracking down on this hidden problem. New rules will require the tobacco industry to fund the cleaning up of cigarette stubs, as part of a broader initiative to reduce single- use plastic items. About 6 trillion cigarettes are manufactured a year and over 90% of them contain plastic filters. Thats more than one million tonnes of plastic.

Tossing a cigarette butt on the ground is one of the most accepted forms of littering, according to the World Health Organization. About two-thirds of butts are dumped irresponsibly -- stubbed out on pavements or dropped into gutters, from where they are carried via storm drains to streams, rivers and oceans… (CNN)