Ecotoxicity and social factors of cigarette butts thrown into the environment

A Swedish study looked at discarded cigarette butts, trying to identify some factors associated with the throwing of cigarette butts, but also analyzing the consequences on aquatic life of this phenomenon. It concludes that strong measures and educational campaigns are needed, based on ecotoxicity data.

Cigarette butts are the most frequently found waste in the natural or urban environment, and the consequences of their release into soil, sea and water ecosystems are increasingly highlighted. Composed of cellulose acetate – a semi-synthetic polymer – cigarette filters have been considered single-use plastic waste for several years. Once the cigarette is smoked, the butts are also loaded with thousands of toxic particles.

In order to assess as closely as possible the determinants and consequences of cigarette butts being thrown into the environment, a team of Swedish and French researchers developed a two-part study: one systematically observed the behavior of smokers in real-life situations, with the aim of identifying the predictors of cigarette butts being thrown on the ground; a second part examined the toxicity of cigarette butts and filters on invertebrate aquatic fauna.[1].

Cigarette butts are more common among young people and smokers in groups

Systematic observations were conducted in four public gardens and busy places of passage in the city of Gothenburg. 597 smokers were observed, two thirds of whom were alone when throwing their cigarette butts. 80% of these smokers threw their cigarette butts on the ground, corresponding to the rate assessed by a recent study (77% of smokers).[2]. This rate was 74 % among single people, and rose to 91 % when people were in a group, suggesting a group effect. Age differences played a role: the rate of cigarette butts thrown on the ground was 93 % among 15-25 year-olds compared to 65 % among those over 56. The group effect also seemed to be less present with increasing age. The influence of the number of ashtrays present was finally more debated, but it appeared that the number of cigarette butts thrown on the ground was lower when the number of public ashtrays present was greater. The presence or absence of cigarette butts on the ground – highlighted by other studies –, the sex of the smokers and the time of day did not seem to play a role in whether or not cigarette butts were thrown on the ground.

Impact of filters and cigarette butts on the development and mortality of invertebrates

The other part of the study consisted of placing freshwater invertebrates (Chironomus riparius) in water solutions where either cigarette butts or empty cigarette filters had been mixed. The results indicate a 20 % increase in mortality, a 1.5-fold decrease in growth and an 80 % decrease in development capacity. A teratogenic effect was also observed, with deformations of the mouths of invertebrates. The impact of cigarette butts and empty filters was demonstrated with both acute and chronic exposure; however, it is more difficult to reproducibly assess exposure to cigarette butts, as the toxic substance levels and age of these butts remain undetermined.

Banning filters and educating the population are the recommended avenues

Confirming that filters and cigarette butts pose a threat to aquatic ecosystems, the authors question the different ways to stem the flow of cigarette butts onto the ground. Among the solutions considered to remedy the problem of cigarette filters, they believe that the most consistent would be to simply remove them. by banning themThis track was notably carried by 130 associations environmental and health issues at the second round of negotiations of the plastic pollution treaty, which was held in Paris from May 29 to June 2, 2023.

The authors of the study recommend combining this ban with public information and education campaigns on the need to avoid throwing cigarette butts into the environment. These campaigns could be based on the ecotoxicity data on cigarette butts highlighted in particular by this study. The posting of signs alerting the public and reminding them of the ban on leaving any waste on the ground would support these educational campaigns, as would the application of fines in the event of throwing cigarette butts or waste on the ground.

Keywords: Cigarette butts, filters, environment, ecotoxicity.

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[1] Nitschke, T., Bour, A., Bergquist, M. et al. Smokers' behavior and the toxicity of cigarette filters to aquatic life: a multidisciplinary study. Microplastics and Nanoplastics. 3, 1 (2023).

[2] Patel V, Thomson GW, Wilson N. Cigarette butt littering in city streets: a new methodology for studying and results. Tob Control. 2013;22(1):59–62.