Cigarette filters, the main component of cigarette butts, are a persistent source of harmful plastic pollution. When discarded, they don’t biodegrade. Instead, they gradually release a mixture of hazardous and cancer-causing chemicals into the environment. Now, a study has estimated how much this environmental damage costs.

Debora Sy, a researcher at the Global Center for Good Governance in Tobacco Control in Thailand, found that plastic in cigarette butts and packaging costs around US$26 billion every year or $186 billion every 10 years in waste management and ecosystem damage. They are costs that have been largely overlooked and can be prevented, Sy explained.

For her study, the researcher drew on currently available public data sources for cigarette sales, clean-up costs and plastic waste on land and sea. These include the World Bank, the World Wildlife Fund (WWF), the Organization for Economic Cooperation and Development and the Tobacco Atlas, a resource for tobacco data.

Each plastic filter weighs 3.4 grams. As they are often littered along with plastic packaging, which weighs an average of 19 grams for a standard pack of 20 cigarettes, this was also included in the calculations. Sy estimated the annual and 10-year projections of tobacco plastic’s environmental and economic cost based on tonnage.

Of the annual $25.7 billion, $20.7 billion is the cost of marine ecosystem damage and the remaining costs are waste management — adding to $186 billion over 10 years — the period it takes for cigarette butts to degrade. Countries with the most cigarette waste are low and middle-income, especially China, Indonesia, Japan and Bangladesh.

“Although this amount is small compared with the annual economic losses from tobacco ($1.4 trillion per year) and may appear insignificant compared with the 8 million deaths attributable to tobacco each year, these environmental costs should not be downplayed as these are accumulating and are preventable,” Sy said in a news release.

While she acknowledges that the figures are only estimates, Sy believes they are likely conservative, as they don’t account for the toxic metals and chemicals in cigarette butts that accrue over time. A 2011 study found that the quantity of chemicals released by a single cigarette butt was capable of killing fish in a one-liter bucket of water.

Policies to shift the responsibility for the clean-up costs to the tobacco industry are under consideration in many countries such as Spain, the UK, the European Union and the US. However, Sy believes that the best solution is to ban the sale of plastic cigarette butts as part of the global effort to eliminate single-use plastics, something currently being discussed as part of a global treaty.

The study was published in the journal BMJ.