The world has enjoyed picking up on plastic straws recently when it comes to ocean waste, despite them accounting for just 0.02 percent of ocean waste. But there are bigger fish to fry.

One of those appears to be cigarette butts, according to a report by NBC News. They reported it was the number one human-caused contaminant in the world’s oceans, and it has managed to avoid regulation so far.

The main issue appears to from cigarette filters, which Thomas Novotny, professor of public health at San Diego State University, told NBC News had “no health benefit”. He added that it “seems like a no-brainer to me that we can’t continue to allow this.”

The filters of the 5.6 trillion cigarettes (two-thirds of which are dumped irresponsibly) made around the world each year are composed of cellulose acetate, which can take more than a decade to decompose. Since 1986 cigarette butts have been the most collected item of ocean beaches, with about 60 million found in 32 years.

Filters were invented in the mid-1900s to alleviate health concerns from cigarettes, but have now become a major problem. A 2011 study by Professor Novotny found that getting smokers to stop flicking the ends of their cigarettes was difficult, with anti-litter campaigns and permanent ashtrays being unsuccessful.

A campaign called the Cigarette Butt Pollution Project is now hoping to change attitudes towards cigarette filters. “Cigarette butt waste has polluted our beaches, parks, and communities long enough – it’s time to take action!” they wrote on their website.

Some steps have already been taken to tackle the problem around the world. In the US, attempts have been made to pass legislation to ban filters, or raising cigarette pack costs to cover clean-up funds.

And earlier this month, we reported on a theme park in France that had trained some of its rooks to pick up litter and cigarette butts, with the goal being to show that “nature itself can teach us to take care of the environment.”

So while the war on plastic straws is undoubtedly good news – demonstrating just how easy it is to make a small change to your daily life – there is still much further to go to clean up our oceans. Cracking down on cigarette butts would be a good step.