What happens to a cigarette butt after 10 years - scientists' answer
A discarded cigarette butt doesn't disappear after a few months, as many people think. A new study shows that even after 10 years, it remains in the environment - and becomes a source of microplastics.
Cigarette butts are the most common type of litter in the world. Trillions of them end up in nature every year.
The main problem is that cigarette filters are not made of paper, but of cellulose acetate, a type of plastic that is resistant to decomposition.
Scientists conducted a long-term study and tracked what happens to cigarette butts in different environments - from urban surfaces to soil - over 10 years.
The details
In the first few weeks after being exposed to the environment, the cigarette butt really starts to break down:
some of the substances are leached out, the outer layer is damaged.
But then the process slows down dramatically.
In unfavourable conditions - e.g. in the city or poor soils - filters practically stop decomposing and can remain almost unchanged even after years.
Even in more "living" soils with active microflora, decomposition is very slow.
After 10 years:
- in the best case, about 80 per cent of the mass disappears
- in urban areas, only about 50 per cent
That is, a significant part of the material still remains in the soil.
What does a cigarette butt turn into?
Over time, the filter does not disappear, but changes shape.
Microscopic fibres:
- break down
- mix with the soil
- form dense particles
In effect, the cigarette butt becomes a microplastic that becomes part of the soil.
Fresh cigarette butts are particularly dangerous - they release nicotine, heavy metals and other toxic substances.
Over time, the toxicity decreases, but it doesn't disappear completely.
Scientists have found that even years later, cigarette butt residue still has a noticeable biological impact on the environment.
Why it matters
The study shows: cigarette butts don't behave like ordinary rubbish that decomposes over time.
They:
- persist for a long time
- turn into microplastics
- continue to affect the ecosystem
Given the scale of pollution, this makes cigarette butts one of the most underestimated environmental problems.
A discarded cigarette butt doesn't disappear - it stays in nature for years, gradually turning into microplastics and continuing to pollute the environment.
Who conducted the research
The work was coordinated by Professor Giuliano Bonanomi of the Frederick II University of Naples, a specialist in plant pathology.
He studies how microorganisms in soil affect plant health and the resilience of ecosystems. His research also focuses on the role of soil bacteria and fungi in the development of plant diseases and on ways to improve soil health, including through compost and biochar.
In recent years, he has been developing models to help predict soil health and manage risks to agriculture.