A research team in Great Britain has determined that discarded cigarette butts "have adverse effects" on the initial growth of two plants studied.

The scientists from Anglia Ruskin University in Cambridge wrote in a paper published in the journal Ecotoxicology and Environmental Safety that experiments on a species of ryegrass and clover showed that after 21 days, "shoot length and germination success were significantly reduced by exposure to any type of cigarette filter for the grass and clover".

The greenhouse experiment evaluated whether or not the plastics in discarded cigarette butts—regular and menthol; smoked, unsmoked, or partially smoked—would have a detrimental effect on plants.

One of the surprising results, according to an article in the Independent newspaper, was that unsmoked filters caused almost the same amount of damage as smoked filters, indicating that the deleterious results came from the filters, not the chemicals contained in the tobacco.

Final results in the paper showed that root weight had a 57 percent reduction and that germination success and shoot length for clover went down 27 percent and 28 percent, respectively; in the ryegrass, the same factors were reduced by 10 percent and 13 percent.

Report author Dannielle S. Green told the newspaper: "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.

“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."

About five trillion cigarette butts are estimated to be discarded into the environment every year, according to the Surfrider Foundation in an article by David Suzuki. The British scientists found areas in and around Cambridge that contained as many as 128 butts per square metre.

A study reported in the Georgia Straight two years ago found genetic damage in North American songbirds that used discarded cigarette butts as nesting material.