Effects of cigarette butts on marine keystone species (Ulva lactuca L. and Mytilus edulis L.) and sediment microphytobenthos

The impacts of smoked cigarette butt leachate on a common freshwater gastropod, Lymnaea stagnalis

Cigarette butts (CBs) are one of the most littered items worldwide. As litter they present physical (plastic fibres and burnt tobacco) and chemical (compounds retained on the filter and in the tobacco) contamination with detrimental effects on the receiving ecosystem. There is however a dearth of research on their effects and on the ability of organisms to recover from exposure. Here, the effects of CBs on mortality, growth, feeding, egg production and hatching success of the great pond snail (Lymnaea stagnalis), were investigated, but also their recovery post-exposure. Individuals were exposed to CB leachate at either 0 (control), 0.25, 0.5 or 1 CB L-1 for four weeks and subsequently they were allowed to recover for a further three weeks without contamination. The presence of CB leachate increased mortality and decreased egg production, egg viability, and growth of snails. Feeding rate was not affected by the presence of CB during exposure phase. All variables showed evidence of recovery once not exposed to the contaminant. Mortality decreased, growth in shell length and biomass increased whilst egg production and viability increased to the same level as controls. This study found that even environmentally realistic concentrations of CB leachate (0.25 CB L-1) can cause mortality and decreased reproductive success of aquatic snails. The improvement of these responses after removal of the leachate indicates that preventing or removing CBs could restore affected ecosystems.

Microplastics from cigarette filters: Comparative effects on selected terrestrial and aquatic invertebrates

Cigarette filters comprise plasticised cellulose acetate, a synthetic polymer categorized as bioplastic. They represent a significant source of microplastics (MPs), in particular microfibers, and associated chemicals, yet their impact on organisms, especially soil invertebrates, is not well-studied. This research examines the effects of MPs milled from smoked (SCF-MPs) and unsmoked cigarette filters (UCF-MPs) on terrestrial invertebrates (Porcellio scaber, Tenebrio molitor) and aquatic invertebrates (Daphnia magna, Brachionus calyciflorus). SCF-MPs and UCF-MPs were found to be 9.06 ± 4.1 μm and 12.71 ± 6.82 μm in size, respectively. Both samples contained triacetin and potentially toxic metals, while SCF-MPs also contained nicotine and a larger number of trace organic compounds. While exposure to SCF-MPs or UCF-MPs (up to 1.5 % MPs, w/w in soil) did not affect the survival of either terrestrial invertebrate, several physiological responses were observed. These included changes in immune parameters, energy-related biomarker levels, and altered glutathione S-transferase and acetylcholinesterase activities. Both types of MPs were acutely toxic to aquatic invertebrates, reducing the survival rates of B. calyciflorus (10 mg L-1 of either particle after 48h exposure) and D. magna (100 mg L-1 of SCF-MPs after 48h exposure). SCF-MPs generally caused more pronounced effects than UCF-MPs. This study highlights the need for effective environmental management to address both smoked and unsmoked cigarette filters.

Investigating the inflammatory effect of microplastics in cigarette butts on peripheral blood mononuclear cells

Cigarette filter microplastics are composed of cellulose acetate that does not undergo biological or photo-degradation. These microplastics are readily dispersed and can be found abundantly in water, soil, and air. These fibers possess high absorption capabilities, allowing them to collect and retain pollutants such as toxic elements. As a result, they are regarded as potential dangers to living organisms. The purpose of this study was to analyze the immune response of human peripheral blood mononuclear cells (PBMCs) when exposed to cigarette filter microfibers, measuring the secretion of the inflammatory cytokines TNFα (tumor necrosis factor-alpha) and IL-6 (interleukin-6). In this study, we examined how used cigarette cellulose acetate microfibers affect the viability of peripheral blood mononuclear cells in an appropriate culture medium at three concentrations: 50, 100, and 200 µg/ml. In addition, this study investigated the release of inflammatory cytokines TNFα and IL6 from PBMCs exposed to 200 µg/ml cigarette filter cellulose acetate. The results showed that increasing the concentration of cellulose acetate fibers of one of the brands in the culture medium has a significant effect on reducing cell viability. The 200 µg/ml in DW is more effective than 50 and 100 µg/ml in reducing cell viability. Peripheral blood mononuclear cells showed an inflammatory immune response when exposed to 200 µg/ml cellulose acetate from cigarette filters. They produced inflammatory cytokines that showed a significant increase compared to the control sample. In general, it can be concluded that cellulose acetate fibers in contact with body cells stimulate them and cause an inflammatory response.

Rapid, detrimental response of estuarine benthic macrofauna communities to pollution by littered cigarette filters and e-liquid

Cigarette butts are amongst the most littered single-use plastics on coasts, yet their impacts on marine ecosystems, especially on a community level, are not well understood. Recently, e-cigarettes have become popular and are a novel litter item in marine habitats. Preliminary research indicates that e-liquid can harm individual organisms, but few studies have been done and none on a community level. In a mesocosm experiment, we tested the impacts of cigarette butts (0.25, 1 butt L-1) or e-liquid (1 mL L-1) on infaunal invertebrate communities using intact sediment cores. After two weeks, the abundance of polychaetes, bivalves, and gastropods was significantly reduced in mesocosms with 1 cigarette butt L-1 compared with controls. Exposure to e-liquid resulted in severe oxygen depletion (<1 mg L-1) and almost complete mortality of sediment infauna after just four days. As litter, cigarette butts and disposable e-cigarettes both pose a threat to estuarine biodiversity.

Cigarette butts enable toxigenic cyanobacteria growth by inhibiting their lethal fungal infections

Cigarette butts (CBs), of which around 4.5 trillion are discarded annually, are one of the most common types of litter worldwide. CBs contain various chemicals, including metals, nicotine, and polycyclic aromatic hydrocarbons, which can leach into water and pose a threat to aquatic organisms such as cyanobacteria and chytrid fungi. Chytrids, zoosporic fungi that parasitize cyanobacteria lethally, play a crucial role in regulating cyanobacteria blooms by delaying or suppressing bloom formation. Despite the prevalence of CBs in the environment, the impact of their leachates on cyanobacteria-chytrid interactions is not well understood. We assessed the effects of CB leachate on the interaction between the toxigenic cyanobacterium Planktothrix agardhii and its chytrid parasite Rhizophydium megarrhizum. CB leachate inhibited cyanobacterial growth in uninfected cultures. Infection prevalence decreased at 0.2, 2, and 10 CB L-1, with the two highest concentrations completely suppressing infection. Interestingly, at the highest CB concentration, cyanobacterial biomass in infected cultures was comparable to that of uninfected cultures not exposed to CB leachate, suggesting that the presence of chytrids mitigates the impact of the leachate. This study demonstrates that CB leachates are a potential environmental hazard that can enable cyanobacterial growth by inhibiting chytrid infections during epidemics. In addition, our research highlights the importance of assessing the effects of chemical mixtures, such as those leached from CBs, on multi-species interactions, such as host-parasite dynamics. These assessments are crucial to better understand the impact of pollutants on aquatic ecosystems.

Cellulose acetate cigarette filter is hazardous to human health

The World No Tobacco Day 2022 theme emphasised tobacco's adverse environmental effects, including through agriculture, manufacturing, distribution, use and the disposal of tobacco product waste. A main concern regarding this toxic waste is the cigarette filter, which is attached to nearly all commercial cigarettes and is predominantly made from a plant-based plastic (cellulose acetate). Laboratory studies have demonstrated the chemical toxicity of discarded cigarette butts, and there is growing public concern regarding environmental plastic pollution resulting from single-use cellulose acetate filters. Important considerations are whether the filter has any protective role against the harms of smoking and whether it should be regulated as a plastic environmental pollutant. There is persistent misunderstanding among smokers and policy makers about the implied value of the cigarette filter. The cellulose acetate filter is simply a marketing tool that encourages smoking initiation and reduces intentions to quit smoking. This is because it makes smoking easier and implies added safety through the presumed filtration of inhaled smoke. The sale of filtered cigarettes should be prohibited to protect public health and the environment.

Exploring cigarette butts pollution in Saint Martin Island: A marine protected area

Saint Martin Island (SMI), the only coral island in Bangladesh, is located in the Bay of Bengal and has been identified as a marine protected area (MPA). Littering cigarette butts (CBs) waste in an ecologically sensitive environment can have numerous adverse effects. The purpose of this research is to investigate the abundance and density of CBs in SMI and to assess the pollution status using the Cigarette Butt Pollution Index (CBPI). This study is conducted based on the visual survey method in the three types of land use zones of SMI. During the peak season, the investigation was carried out from 9 a.m. to 5 p.m. in December 2023. A total of 4481 CBs item were counted, and the density ranged from 0.37 to 1.76 m-2 with an average value of 0.99 m-2 across 12 sampling campaigns. The highest density was observed at service zones, and the fishing zones had the lowest density. The calculated CBPI values revealed that 75 % of the sampling stations were in the "severe pollution" while 25 % were classified as "high pollution" status, underscoring the prevalence of hazardous CBs across most areas of SMI. To tackle these issues requires regulatory measures, public awareness initiatives, and community involvement. Effective waste management and eco-friendly product promotion can help reduce CBs pollution risks in marine protected islands.

Microfibers from cigarette butts can induce exoskeletal alteration in whiteleg shrimp (Penaeus vannamei)

Cigarette butts (CB) are a source of microfibers (MFs) in aquatic environments, posing a risk to the health of aquatic organisms. Research has been focused on examining the toxicity of CBs on ecological receptors, including invertebrates. More focus has been on death, growth, or movement inhibition of but less on exoskeletal effects in malacostracans. We evaluated the alteration in the carapace structure of whiteleg shrimp (Penaeus vannamei Boone, 1931) caused by MFs derived from CBs (CB-MF). Exposure to CB-MF damaged the gills, the main organs adsorbing calcium in shrimps to generate a hard carapace, disturbing calcium uptake via respiration. Rapid ecdysis caused on CB-MF exposure reduced the environmental adaptation capacity of crustaceans in the absence of normal pigments in the chromatophore of the carapace. These findings indicate that MFs released from CBs released into the aquatic environment can adversely affect exoskeletal alteration within the overall ecosystem.

Cigarette butt pollution in popular beaches of Morocco: Abundance, distribution, and mitigation measures

Cigarette butts pose a significant challenge in managing solid litter, with an estimated 4.5 trillion of them being discarded into the environment annually. This study investigated the pollution of eleven beaches along the Moroccan Mediterranean by cigarette butts compared to other types of marine litter between 2018 and 2023. Sampling was conducted using the visual survey technique according to a standardized protocol. A total of 50, 575 items were collected with cigarette butts (14.62 %) and plastic caps/lids drinks (10.93 %) being the most common. Our survey of eleven beaches revealed 7395 cigarette butts, giving an average density of 0.06/m2 comparable to other countries in the Mediterranean. The analysis of the results shows significant differences in the abundance cigarette butts according to the beach typology, seasonality, sediment type, and number of beach users. Moreover, the study discovered a decrease in beach pollution during the COVID-19 pandemic lockdown, resulting in less litter collected compared to pre- and post-pandemic periods. The Cigarette Butt Pollution Index was categorized as very low pollution in M'diq and Kaa Asrass, low pollution in Ksar Sghir, Fnideq, Amsa, Oued Laou, significant pollution in Martil and Nador and sever pollution in Saidia and Sababia. The CBPI was higher during summer and winter, significantly associated with the density levels of beach users. The study recommends immediate action by the local administration to prevent the potential pollution of groundwater and sand by toxic substances leached from cigarette butts.

Time to kick the butt of the most common litter item in the world: Ban cigarette filters

Cigarette filters offer no public health benefits, are single-use plastics (cellulose acetate) and are routinely littered. Filters account for a significant proportion of plastic litter worldwide, requiring considerable public funds to remove, and are a source of microplastics. Used cigarette filters can leech toxic chemicals and pose an ecological risk to both terrestrial and aquatic ecosystems. Bottom-up measures, such as focusing on consumer behaviour, are ineffective and we need to impose top-down solutions (i.e., bans) if we are to reduce the prevalence of this number one litter item. Banning filters offers numerous ecological, socioeconomic, and public health benefits.

Toward a sustainable circular economy for cigarette butts, the most common waste worldwide on the coast

The circular economy is based on the maximum use of resources by reducing, reusing, and recycling the elements used. Currently, the items littered most frequently in the world are cigarettes butts (CB) as these debris are freely disseminated in the marine habitat, they are generally difficult to collect and very complex to recycle. Litter CB is a great social problem that generates excessive economic costs and serious environmental problems. CB is also not biodegradable and highly toxic to marine organisms and presents a distinctive mixture of physical and chemical contamination. However, little research has been done on the management and recycling of this dangerous waste. Several proposals have been made to incorporate this waste into high-volume articles of direct production or recycling, but collection logistics are lacking since the current system is inefficient, in addition to the poor environmental behaviour of citizens. This work presents a current synthesis of the CB problem from all its possible aspects in order to have a global vision of the life cycle of the CB, indicating both the known and the gaps in the knowledge of each of them, and intends to give a general outline of the steps to follow to try to end such a worrying problem at the global level.

Remediation Capacity of Different Microalgae in Effluents Derived from the Cigarette Butt Cleaning Process

Microalgal-based remediation is an ecofriendly and cost-effective system for wastewater treatment. This study evaluated the capacity of microalgae in the remediation of wastewater from cleaning process of smoked cigarette butts (CB). At laboratory scale, six strains (one from the family Scenedesmaceae, two Chlamydomonas debaryana and three Chlorella sorokiniana) were exposed to different CB wastewater dilutions to identify toxicity levels reflected in the alteration of microalgal physiological status and to determine the optimal conditions for an effective removal of contaminants. CB wastewater could impact on microalgal chlorophyll and carotenoid production in a concentration-dependent manner. Moreover, the resistance and remediation capacity did not only depend on the microalgal strain, but also on the chemical characteristics of the organic pollutants. In detail, nicotine was the most resistant pollutant to removal by the microalgae tested and its low removal correlated with the inhibition of photosynthetic pigments affecting microalgal growth. Concerning the optimal conditions for an effective bioremediation, this study demonstrated that the Chlamydomonas strain named F2 showed the best removal capacity to organic pollutants at 5% CB wastewater (corresponding to 25 butts L−1 or 5 g CB L−1) maintaining its growth and photosynthetic pigments at control levels.

Attitudes, Beliefs, and Behaviors about Cigarette-Butt Littering among College-Aged Adults in the United States

This study reports attitudes, beliefs, and littering behaviors of 7532 college-aged cigarette smokers from across the United States. Four behavioral variables were measured: littering of last cigarette butt, number of butts littered in past 24 h, littering in past month, and ever having littered. Questions about beliefs centered on whether cigarette butts are biodegradable, if butts were harmful to the environment, and if butts are considered to be litter. One attitudinal question focused on whether seeing butts on the ground was bothersome. Littering was most likely among people who believed butts were biodegradable, believed they are not harmful to the environment, do not believe butts are litter, and among those with the attitude that littered butts are not bothersome. Logistic regression analyses found that the strongest influence on littering behavior was the attitude that seeing butts was bothersome. The second-strongest driver was the belief that butts are litter.

The ecological impacts of discarded cigarette butts

Cigarette butts, one of the most littered items globally, present a unique challenge to ecosystems due to their ubiquity, persistence, and potential for harm. Over 35 studies have examined the toxicity of cigarette butts in biota from aquatic and terrestrial habitats from microbes to mice, but many organisms and habitats have not been tested. Two-thirds of studies are on aquatic organisms, and lethal effects were common. Research on the impacts on terrestrial life is lagging behind. Cigarette butts can affect the growth, behaviour, and reproductive output of individual organisms in all three habitats, but research on wider effects on biodiversity and ecosystem functioning is lacking. Here, we summarise the ecotoxicological concerns and identify important knowledge gaps for future research.

Animal contests and microplastics: evidence of disrupted behaviour in hermit crabs Pagurus bernhardus

Microplastics are ubiquitous in global marine systems and may have negative impacts on a vast range of species. Recently, microplastics were shown to impair shell selection assessments in hermit crabs, an essential behaviour for their survival. Hermit crabs also engage in 'rapping' contests over shells, based on cognitive assessments of shell quality and opponent fighting ability and, hence, are a useful model species for examining the effects of microplastics on fitness-relevant behaviour in marine systems. Here, we investigated how a 5-day microplastic exposure (25 microplastics/litre) affected the dynamics and outcome of 120 staged hermit crab contests. Using a 2 × 2 factorial design, we examined how microplastics (i.e. presence or absence) and contestant role (i.e. attacker or defender) affected various behavioural variables. Significantly higher raps per bout were needed to evict microplastic-treated defenders when attackers were pre-exposed to control conditions (i.e. no plastic). Also, significantly longer durations of rapping bouts were needed to evict control-treated defenders when attackers were pre-exposed to microplastics. We suggest that microplastics impaired defenders' ability to identify resource holding potential and also affected attackers' rapping strength and intensity during contests. These impacts on animal contests indicate that microplastics have broader deleterious effects on marine biota than currently recognized.