From pet hate to internationally influential research

A pet hate in life led Senior Lecturer in the School of Life Sciences, Dr Dannielle Green, to a research project which had an international impact.

"You see them everywhere," she says, looking around with a scowl. “Cigarette butts. Hundreds of them, littering the parks and lovely green spaces in Cambridge, and even in nature reserves.

“Apart from being an eyesore, I couldn’t help wondering what impact they were having on the environment.”

This irritation, and curiosity, were the catalysts for Dannielle to carry out six months of work analysing the problem in a research project which, perhaps surprisingly, had never been carried out before.

In a glasshouse, on the campus in the heart of Cambridge, working with fellow researcher and collaborator Dr Bas Boots, she set up a simple experiment. It focused on two common but important species of plant, grass and clover.

In one set of pots, seeds were allowed to grow unimpeded. In the other, they had to contend with cigarette butts littering the soil.

The results, Dannielle says, were surprising. “I didn’t expect anything like such a big impact,” she observes.

In the grass half of the experiment, the germination of seeds fell by 10 per cent. Those shoots which did grow turned out to be 13 per cent shorter.

But in clover, the results were even more pronounced.

Germination was down by 27 per cent, and shoot length reduced by 28 per cent.

That was particularly significant, as clover is an important element in a healthy environment. It fixes nitrogen in soil, helping other plants to grow.

Another unexpected finding was that even unsmoked cigarette butts had an effect in hampering both plants.

That indicated most of the impact was caused by the plastics in the filter, rather than chemicals accumulated in the butt by the act of smoking.

“That was another real surprise,” Dannielle says. “The results immediately made me want to get the word out there, about what discarded cigarette butts were doing to our environment, and how little people seemed to notice, or care.

“It’s strange, how flicking away a cigarette butt is somehow not regarded as littering. Maybe it’s because of films, where characters do it and it’s seen as cool.

“I was determined to reverse that impression and show it’s as socially unacceptable as any form of littering.”

When the research was published it had an immediate impact, with journalists across the world running stories on the findings.

“I was interviewed for radio, television, newspapers and websites,” Dannielle says. “The story also made a big impact on social media. There was a long debate about litter and smoking, which has to be a good thing. The word really got out there about what impact discarded cigarette butts can have.”

There was another positive, but unexpected side effect of the research. It resonated strongly with teachers and students.

Schools from across Europe got in touch to ask how they could replicate the experiment to help teach their pupils about science. Students from America and Canada also contacted Dannielle, wanting to try out their own versions of the research.

“It was so great, to get teenagers interested in science like that,” Dannielle says. “I had no idea it would happen, but was really pleased it did.

“I suppose it’s a good experiment to use for teaching as it’s simple, and can be carried out just about anywhere, but it has very obvious and fascinating results.”

But that’s not the end of the impact of the research. It’s now starting to influence thinking in political and policy-making circles.

The lobbying group Keep Britain Tidy are currently campaigning about the issue of cigarette litter, and invited Dannielle to talk to the All-Party Parliamentary Group meeting of MPs on the issue.

“I know it will take time to change people’s behaviour,” Dannielle says. “But I’m so pleased it looks like the decision makers are listening and we’ve got a chance of actually doing so. It’s such a small thing to remember, but it can make a big impact – not just flicking away a cigarette butt without thinking about it.

“Studies tell us that butts are the single most common type of litter. If we can start to convince more people to stop littering like that, it’s a big win for us as a society, with no more eyesore discarded butts in our beautiful public spaces, and a big win for the environment as well.”

Dr Green was a keynote speaker at the Tidy Britain All Parliamentary Party Group meeting on the issue of smoking related litter in July 2020, alongside Minister Rebecca Pow, DEFRA, Clive Betts, Chair HCLG Committee and Richard McIlwain, Deputy Chief, Keep Britain Tidy. The aim of the meeting was to discuss ways to tackle cigarette butts and smoking related litter including the possible introduction of an Extended Producer Responsibility (EPR) scheme on tobacco products. The research is being used as evidence to try to bring these measures into the UK.