Cigarette butts are the most common trash on the planet

By José Tadeu Arantes

No fewer than 4.5 trillion cigarette butts are discarded incorrectly every year, forming one of the most ubiquitous – and least noticed – faces of global environmental pollution. This means around 550 butts released annually into the environment for each inhabitant of the planet.

A broad survey compiled data from 130 scientific studies carried out in 55 countries from 2013 to 2024 and reveals that these small residues reach average densities of 0.24 butts per square meter in urban and aquatic environments. It’s like finding a cigarette butt every 4 square meters. Extreme peaks in the world exceeded 38 butts per square meter on beaches and highly frequented and populated coastal areas. The total mass of cigarette butts discarded annually into the environment is around 766.6 million kilograms.

The study also shows that environmentally protected areas – especially those with more restrictive rules – can reduce contamination by up to 10 times when compared to places without any type of legal protection. Even so, not even national parks or marine reserves are completely exempt from the problem, since sea currents can carry trash discarded very far from them to these locations, whether on beaches or in urban areas.

The review, the result of a partnership between researchers linked to Unifesp (Federal University of São Paulo), Unesp (Universidade Estadual Paulista), Inca (National Cancer Institute), Johns Hopkins University, in the United States, and Universidad San Ignacio de Loyola, in Peru, constitutes the most comprehensive synthesis ever produced on the global distribution of cigarette butts and their environmental implications. Article about this, with the environmental engineer as the 1st author, doctoral student at Unifesp’s Instituto do Mar, was published in the journal Environmental Chemistry Letters. It describes in detail spatial patterns, so-called hotspots of contamination, and the effect of the degree of environmental protection in reducing the problem.

“The chemical contaminants present in butts spread quickly, even more so when in contact with seawater. Within a few weeks, this toxic material is released into the environment, which can be lethal to several aquatic species”said Ribeiro. Cigarettes contain more than 7,000 chemical compounds, at least 150 of which are toxic. But the problem doesn’t end there: the filter core is made up of a polymer, cellulose acetate, which, like other plastics, remains in the environment for a long time, fragmenting into microplastics that contaminate marine organisms and can return to humans when these organisms are consumed.

In addition to the environmental impact, the study also speaks to the debate on public health and the role of the filter in the history of cigarettes. For , from the Inca Tobacco Control Division, who guided the review study, the existence of the filter was historically used as a marketing argument. “The idea is that, with a filter, cigarettes would be a healthier product, therefore favoring the initiation and maintenance of smoking behavior. But this is not sustainable. With the introduction of filters, a specific type of lung cancer, linked to fine particles, has even increased”he stated.

Szklo draws attention to the idea conveyed by the tobacco industry about individual responsibility for disposal in the environment. “It is important not to blame the smoker. The tobacco industry for decades spread the idea that the filter would be biodegradable. This influenced and continues to influence behavior. The truth is that butt contamination only exists because there is an industry that profits from the sale of cigarettes.”

“If people understood that they were throwing a chemical bomb when they discarded a cigarette butt, perhaps they wouldn’t act so normally.”declared Ribeiro.

The number of 4.5 trillion cigarette butts that reach urban and aquatic environments annually was not produced directly by the new review, but by a compilation made by the WHO (World Health Organization). Ribeiro recalls that, globally, around 12 trillion cigarettes are smoked per year. “A huge fraction ends up in the oceans, where almost all water converges”he stated.

Beaches concentrate large circulation of people, intense tourism and recreational consumption – factors that favor inappropriate disposal. But that’s not the only reason they appear as the most contaminated areas: they also function as true “sinks” for solid waste. Butts discarded inside cities or even in distant regions can be carried by rain and rivers to the sea. In addition to the direct environmental impact of disposing of smoked cigarettes (butts), the production and consumption of cigarettes emits 84 million tons of carbon dioxide into the atmosphere each year.

The global analysis showed a strong concentration of hotspots –critical areas that comprise the approximately 5% most contaminated among all monitored locations in the world– in 17 countries, located mainly in South America, the Middle East and Southeast Asia. On beaches in the Persian Gulf, for example, more than 38 butts per square meter have been measured. In South America, beaches in Chile, Brazil, Uruguay and Ecuador repeatedly appear among the hotspots, in some cases with more than half of all trash collected consisting of cigarette butts.

The authors of the study created the ICBC (Cigarette Butt Contamination Index), going from the “absent” to the “extremely high” classification. There is a lack of published data for most of North America, Africa, Central and East Asia, and all of Oceania, making global comparisons difficult.