Smoking tobacco don’t stop being toxic when you put the cigarette out. Cigarette filters can contain 7,000 chemicals, as well as microplastics fibers, that risk leaking into the environment and causing harm. Credit: Bethanie Carney Almroth
Cigarette filters, or butts, are the most littered plastic item in the world. They are also toxic, as they are made of plastic fibers that break down into microplastics—but do not decompose. The butts also contain chemicals and heavy metals, such as nicotine, cadmium, lead and chromium.
A new study from researchers in Sweden shows these microfibers and toxic chemicals are making their way to waterways, where they are harming aquatic larvae.
“The filter is full of thousands of toxic chemicals and microplastic fibers, so it’s not just any piece of plastic that’s being discarded into the environment,” said study author Bethanie Carney Almroth, professor of ecotoxicology at the University of Gothenburg. “It’s hazardous waste.”
That’s why she and her team are calling for a complete ban on cigarette filters. In the EU, as of January 2023, tobacco manufacturers have to cover the cost of clean-up, collection, transport and treatment of cigarette butt waste. In November 2022, Baltimore filed a first-of-its-kind lawsuit against six major tobacco companies, seeking redress for the persistent harm resulting from the copious amounts of cigarette butt litter on city property.
Still, Carney Almroth says that’s not enough.
“They have to be taken off the market entirely,” she said. “It’s not the right approach to focus on making tobacco producers pay for cleaning up the filters. The problem should be prevented in the first place, rather than cleaned up later.”
Contaminated water
In the study, which has been published in Microplastics and Nanoplastics, the researchers tested the effects of the toxins that are found in the filter after smoking, as well as the substances that are in the filter from the start, on aquatic mosquito larvae.
The team used the freshwater invertebrate Chironomus ripariu, exposing them to toxic water for different intervals. According to the results, after 48 hours of exposure, concentrations of 2 filters/L from smoked filters caused 36 to 100% larvae immobility. Meanwhile, water contaminated by 2 filters/L of unsmoked butts caused 75 to 100% larvae immobility.
In addition to the contaminated water, the scientists also tested the effects of contaminated sediment. For this, the team set a 3-week leaching time, which was the equivalent of 1 filter/L of water. After 7 days of exposure to either water or sediment, study results showed the sediment actually caused more frequent and severe effects on the larvae than the water.
Larvae exposed to contaminated sediment (both smoked and unsmoked filters) had a 20% higher mortality rate, a 1.5-fold decrease in growth and an 80% decreased development compared with the water larvae.
Why litter?
Carney Almroth’s study also focused on the act of cigarette butt littering itself. Her team observed 597 smokers at public places, finding the vast majority—80%—littered their cigarettes.
The researchers then applied a regression model to identify predictor variables of littering. Out of seven variables, three showed strong evidence of being related to cigarette littering—age (negatively) and group setting (positively) are personal predictors, while the number of present ashtrays (negatively) is a contextual predictor of cigarette littering.
Along with other experts, Carney Almroth wrote an opinion piece in the magazine Science of the Total Environment arguing that cigarette butts are not just the most common litter in the world, but they are also just a marketing ploy that do little to protect the smoker, as many people believe.