Treehugger Tuesday

From New Atlas:

Study shows that dropped cigarette butts harm plants
Ben Coxworth
July 19th, 2019

Pots of white clover, seven days after a butt-shaped piece of wood was added (left) and an actual cigarette butt (right)(Credit: Jaime Da Silva Carvalho, Anglia Ruskin University)

Although many smokers apparently don't realize it (or just don't care), cigarette butts are very much a form of litter – in fact, they're the world's most common type of litter. And they're not just an eyesore, as new research now indicates that they also dramatically reduce plant growth.

In a study led by researchers from Britain's Anglia Ruskin University, butts from regular and menthol cigarettes (both smoked and unsmoked) were placed on soil in which either ryegrass or white clover plants were being grown – both are important forage crops for livestock, and also make up much of the ground cover in urban parks. The clover in particular is claimed to be "ecologically important for pollinators and nitrogen fixation."

Regardless of the type of butt, after 21 days it was found that their presence reduced the germination success and shoot length of the clover by an average of 27 and 28 percent respectively, and the root biomass by 57 percent. In the case of the grass, the germination success was reduced by 10 percent, and the shoot length by 13 percent. A separate group of plants, which had butt-shaped pieces of wood added to their soil over the same period, served as a control.

Given that there was little difference between the effect of butts from smoked and unsmoked cigarettes, it was determined that the problem likely lies in the cellulose acetate fiber used in the filters. More specifically, plasticizer chemicals which are used to make that material more flexible may be leaching into the soil.

"In some parks, particularly surrounding benches and bins, we found over 100 cigarette butts per square meter," says lead scientist Dr. Dannielle Green. "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."