Cigarette butts, the most common form of litter on the planet, are a big but often overlooked problem. Cigarette butts consist mostly of cigarette filters called cellulose acetate that can take 18 months to 10 years to decompose.
Harming our plants
But that isn't the worst of it. New research out of Anglia Ruskin University (ARU) is revealing that cigarette butts cause damage to our plants.
"Despite being a common sight littering streets and parks worldwide, our study is the first to show the impact of cigarette butts on plants. We found they had a detrimental effect on the germination success and shoot length of both grass and clover, and reduced the root weight of clover by over half," said lead author Dr Dannielle Green, Senior Lecturer in Biology at Anglia Ruskin University (ARU).
The new study found that the presence of cigarette butts in the soil reduces the germination success and shoot length (the length of the stem) of clover by 27% and 28% respectively, while root biomass (root weight) reduced by 57%. And that's not even taking into account the additional toxins released from the burning of the tobacco.
ARU revealed that it is estimated that around 4.5 trillion cigarette butts are littered every year. This would make cigarette butts the most pervasive form of plastic pollution on the planet.
Forage crops for livestock
The problem affects more than just local plants. "Ryegrass and white clover, the two species we tested, are important forage crops for livestock as well as being commonly found in urban green spaces. These plants support a wealth of biodiversity, even in city parks, and white clover is ecologically important for pollinators and nitrogen fixation," said Green.
So why is this form of pollution so rampant? Well, the study's authors argue that people are simply unaware of the dangers of cigarette butts.
"Many smokers think cigarette butts quickly biodegrade and therefore don't really consider them as litter. In reality, the filter is made out of a type of bioplastic that can take years, if not decades, to break down," Green added.
"In some parks, particularly surrounding benches and bins, we found over 100 cigarette butts per square metre. Dropping cigarette butts seems to be a socially acceptable form of littering and we need to raise awareness that the filters do not disappear and instead can cause serious damage to the environment."
One key step in affecting change is raising awareness on the many dangers of improperly discarded cigarette butts.
"Although further work is needed, we believe it is the chemical composition of the filter that is causing the damage to plants. Most are made from cellulose acetate fibers, and added chemicals which make the plastic more flexible, called plasticizers, may also be leaching out and adversely affecting the early stages of plant development," said co-author Dr Bas Boots, Lecturer in Biology at Anglia Ruskin University (ARU).
The study is published in the journal Ecotoxicology and Environmental Safety.