Bioassay-based ecotoxicological investigation on marine and freshwater impact of cigarette butt littering

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.

Emerging threat of marine microplastics: Cigarette butt contamination on Yellow Sea beaches and the potential toxicity risks to rotifer growth and reproduction

Cigarette butts have become one of the most common and persistent forms of debris in marine coastal areas, where they pose significant toxicity risks. This study investigated cigarette butt pollution along beaches of the Yellow Sea and used laboratory experiments to assess the toxicity of their leachate and fibers on the euryhaline rotifer Brachionus plicatilis. A pollution index confirmed pollution by this debris across all eight beaches surveyed, where the density of cigarette butts averaged 0.23 butts/m2. In controlled laboratory experiments, both the fibers and leachates from cigarette butts exhibited negative impacts on the development, reproduction, and population growth of rotifers. Unique abnormalities observed under different exposure treatments indicated toxicity specific to certain chemicals and particles. Continuous exposure to cigarette butts initially reduced rotifer fecundity, but this effect diminished over successive generations. However, the exposure induced transgenerational reproductive toxicity in the rotifers. Adaptive responses in rotifers after repeated exposure led to relative reduction in reproductive inhibition in the F3 and F4 generations. Furthermore, rotifers were capable of ingesting and accumulating cigarette butts, and maternal transfer emerged as an alternative pathway for uptake of this material in the offspring. These results increase our understanding of the ecological risks posed by cigarette butts in aquatic environments.

Negative effects of cigarette butt leachate on freshwater phytoplankton communities

We experimentally tested the effects of different concentrations of cigarette butt leachate on freshwater phytoplankton chlorophyll-a, species richness, cell density, and community composition. For this, we sampled the phytoplankton from a eutrophic lake and acclimated it for 24 h in microcosms. We then conducted the experiment in microcosms maintained for 96 h. The experiment consisted of four treatments: control and leachate from 1 butt L-1 (T1), 5 butts L-1 (T5), and 10 butts L-1 (T10), which were prepared by diluting a stock solution of leachate from 50 butts L-1. We found that algal chlorophyll-a content was not affected by different leachate concentrations. In contrast, phytoplankton cell density decreased in a dose-dependent manner as concentrations of the leachate increased. Similarly, the number of species was highest in the control group relative to all other treatments, with T1 and T5 showing higher species richness than T10. Additionally, the exposition to different concentrations of the leachate impacted community composition across all treatments in comparison to the control group. Our results suggest that cigarette butt leachate alters the number of cells and species, as well as the distribution of abundance, without necessarily reducing chlorophyll-a concentrations. Our findings indicate that to gain a comprehensive understanding of the effects of cigarette butt leachate on freshwater ecosystems, it is essential to evaluate more realistic scenarios that incorporate aquatic communities, rather than isolated species.

Risk assessment of cigarette butts and microplastic pollution in a drinking and irrigation water basin of West Anatolia, Türkiye

Cigarette butts (CBs) and Microplastics (MPs) have serious harmful effects on the environment and living organisms despite their small size. This research aims to investigate the abundance and pollution status of CBs and MPs in Tahtalı Dam Basin (West Anatolia, Türkiye) which is the most important drinking and irrigation water resources. Clean Environment Index (CEI) and Cigarette Butt Pollution Index (CBPI) were used to determine pollution degree of the basin. The total number of CBs were 1.478 items, the total number of MPs were 477 items/m2 in the basin. As a result of this study, MP particles weren't found in Balaban Stream. Highest number of MP particles observed in 100-250 μm (45%) size class. The most abundant MP type and colour were, fragment (54%) and white (42%), respectively. Polyethylene terephthalate (50%) was the most abundant type of polymer according to the ATR- FTIR analysis. As a result of the CEI and CBPI, the upstream stations of the stream were classified as "clean" status, while downstream sampling points of the stream and Balaban Lake coasts were classified as "extremely dirty" status. The calculated volumes of MP particulates from mining facility, agricultural and recreational activities indicate that anthropogenic factors are the most important MP source in the Tahtalı Dam Basin. This study is the first study about MP and CB pollution of the freshwater ecosystems in the region.

A review on cigarette butts: Environmental abundance, characterization, and toxic pollutants released into water from cigarette butts

Every year, trillions of cigarette butts (CBs) are discarded into the environment. CBs are frequently found on beaches and in urban areas worldwide due to their high resistance to physical and biological degradation. Components of CBs, such as heavy metals, polycyclic aromatic hydrocarbons (PAHs), cellulose acetate fibers (microplastics), nicotine, aromatic amines, and BTEX (benzene, toluene, ethylbenzene, and xylene), are released into aquatic environments. Harmful components released into water from CBs cause both water pollution and toxic effects on different aquatic organisms. In the first part of this review, studies investigating the density of CBs in different environments were reviewed. In the second part, the results of studies investigating the characteristics of cigarette filters using characterization techniques were reviewed. Then, studies on heavy metals, PAHs, microplastics (microfibers), nicotine, aromatic amines and BTEX released into water from CBs were reviewed, and factors affecting the types, amounts and release conditions of compounds (pollutants) released into water from CBs were discussed. In the last section, taking into account the studies carried out to date, deficiencies in the research on pollutants released into water from CBs were identified and recommendations were made for future studies. This review highlights the environmental abundance of CBs, the characterization results of CB filters, and the release into water of some substances in CBs that are pollutants for the aquatic environment. This review may serve as a guide to elucidate the environmental abundance of CBs, the characteristics of CBs/filters, and the concentration in water of some pollutants released into water from CBs.

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.

Toxicity of leachate from smoked cigarette butts to terrestrial animals: A case study on the earthworm Eisenia fetida

Cigarette butts, as easily overlooked littered wastes, have been evaluated for toxicity in various researches. In this study, we investigated the toxic effects of smoked cigarette butt leachate (SCBL) on the earthworm Eisenia fetida. The results showed the following: 1) E. fetida avoided SCBL in artificial soil, and the avoidance rate was positively correlated with the concentration of SCBL but negatively correlated with the exposure time; 2) the LD50 of SCBL on earthworms at 36 and 48 h of exposure were 3.71 × 10-4 and 2.67 × 10-4 butts/cm2, respectively. Moreover, both the body surface and intestinal tissues of E. fetida were damaged after exposure to SCBL; 3) the survival rates of E. fetida exposed to artificial soil with an SCBL of 3.6 butts/kg for 7 and 14 days were 80.00 ± 7.07 % and 68.00 ± 4.47 %, respectively; and 4) the mean biomass of the surviving E. fetida in all treated groups decreased with increasing SCBL concentration and exposure time. We concluded that SCBL exerted significant negative effects on soil animals, and suggested that SCBs should be collected, detoxified, and reused before entering the natural environment.

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.

Eco-toxicity assessment of industrial by-product-based alkali-activated binders using the sea urchin embryogenesis bioassay

New cement-based materials such as alkali-activated binders (AABs) or geopolymers allow the incorporation of waste or industrial by-products in their formulation, resulting an interesting valorization technique. Therefore, it is essential to inquire about the potential environmental and health impacts throughout their life cycle. In the European context, a minimum aquatic toxicity tests battery has been recommended for construction products, but their potential biological effects on marine ecosystems have not been considered. In this study, three industrial by-products, PAVAL® (PV) aluminum oxide, weathered bottom ash (WBA) resulting from incinerator bottom ash and glass cullet recycling waste (CSP), were evaluated as precursors in the AAB formulation from an environmental point of view. To determine the potential effects on marine environment caused by the leaching of contaminants from these materials into seawater, the leaching test EN-12457-2 and an ecotoxicity test using the model organism sea urchin Paracentrotus lividus were conducted. The percentage of abnormal larval development was selected as endpoint of the toxicity test. Based on the results obtained from the toxicity tests, AABs have less damaging impact (EC₅₀ values: 49.2%-51.9%) on the marine environment in general than raw materials. The results highlight the need to stablish a specific battery of toxicity tests for the environmental assessment of construction products on marine ecosystem.

Toxicological effects of cigarette butts for marine organisms

Cigarette butts (CBs), one of the most common litter items found on beaches, represent a still unexplored environmental hazard. This study aimed at a multidisciplinary characterization of their toxicological risks on marine organisms integrating chemical analyses of released compounds with a wide panel of biological responses, such as ecotoxicological bioassays on species of different trophic positions, molecular responses in an ex vivo model (Precision-Cut Tissue Slices, PCTS of mussels digestive glands), bioavailability and cellular biomarkers in mussels exposed to CBs in laboratory experiments. Trace metals, aliphatic and polycyclic aromatic hydrocarbons, nicotine and cotinine were released in artificial seawater after 24 h which determined a significant inhibition of bacterial bioluminescence, oyster embryo development and growth in different algal species. Modulation of peroxisomal proliferation and antioxidant gene expression was observed in mussels PCTS, while the in vivo exposure determined accumulation of chemicals and significant alterations of immune system, antioxidant and neurotoxic responses, peroxisomal proliferation and genotoxic damage. Using a quantitative Weight of Evidence model, the risks of CBs to the marine environment were summarized, highlighting the importance of integrating chemical analyses, batteries of ecotoxicological bioassays, molecular and cellular biomarkers to assess the impact of these hazardous materials on marine environment.

Preparation of a cellulose acetate membrane using cigarette butt recycling and investigation of its efficiency in removing heavy metals from aqueous solution

This study investigated the recycling of freshly-smoked cigarette butts (FCBs) and unsmoked cigarette filters (UCFs) into a cellulose acetate (CA) membrane. The both samples were prepared by means of a combination of seven cigarette brands, and the phase inversion method was used to recycle each sample into a membrane using N-methyl-2-pyrrolidone. The efficiency of the prepared membranes for the removal of chromium, cadmium, and lead from an aqueous solution in a forward osmosis reactor was investigated. The results showed that the both membranes had a smooth surface and macrovoids. The flux of the prepared membranes from the UCFs and FCBs recycling were 14.8 and 13.2 LMH, respectively. The porosity and reverse salt of the UCFs membrane were 61% and 3.5 gMH, while those for FCBs membrane were 58% and 3.9 gMH. The observed metal removal efficiency of the both membranes was in the range of 85 to 90%. However, increasing the concentration of metals up to five times caused a slight decrease in the removal efficiency (less than 5%).

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.

UV-B Irradiation Effect on Microalgae Performance in the Remediation of Effluent Derived from the Cigarette Butt Cleaning Process

In this study, the potential of ultraviolet B (UV-B) radiation to alleviate the effects of pollutants in cigarette butt wastewater (CBW) was investigated using different Chlorella sorokiniana strains (F4, R1 and LG1). Microalgae were treated with UV-B (1.7 W m⁻²) for 3 days prior to their exposure to CBW and then incubated for 4 days in the absence or presence of UV-B. UV-B-untreated microalgae were used as the control. Comparative physiological responses, including photosynthetic pigments and non-enzymatic antioxidants, as well as nicotine and nicotyrine removal, were evaluated in 7-day cultures. UV-B treatments did not negatively impact algal chlorophyll or carotenoid production. UV-B acclimation was strain-dependent, correlating with native environment adaptations and genetic constitutions. UV-B as a pretreatment had long-term positive effects on non-enzymatic antioxidant capacity. However, LG1 needed more time to readjust the pro-oxidant/antioxidant balance, as it was the most UV-B-sensitive. Phenolic compounds played an important role in the antioxidant system response to UV-B, while flavonoids did not contribute to the total antioxidant capacity. Although cross-resistance between UV-B and CBW was observed in F4 and R1, only R1 showed nicotine/nicotyrine catabolism induction due to UV-B. Overall, the results suggest that UV-B activates defense pathways associated with resistance or tolerance to nicotine and nicotyrine.

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.

Recycling Cigarette Filters as Plant Growing Substrate in Soilless System

Two massive wastes are cigarette butts (CB) and stone wool (SW), both representing a threat to the environment. Although the cellulose acetate filters (CAF) in CB are long-term degradable, SW soilless substrates are not. Here, a soilless substrate for growing ornamental plants was manufactured with CAF and compared to commercial SW substrate. CB treatment consisted of a washing in boiling water with a dramatic reduction of pollutants in CAF. Then, cleaned filters were separated, dried, carded to fibers, and subsequently compacted into plugs. The trace pollutants in recycled CAF substrate did not negatively affect the germination of Spartium junceum L. and Lavandula angustifolia Miller seeds as well as the root development of Salvia officinalis L. and Salvia rosmarinus Schleid. stem cuttings. Plants grown in recycled CAF showed a differential species-dependent change of pigments in comparison with those in SW, without compromising their photosynthesis performance. Overall, the results demonstrated that these plants can be well established and grow in recycled CAF, as comparable to SW substrate. This study highlights a novel and promising solution in CAF recycling by turning this litter into an efficient soilless substrate for growing ornamental plants, thus limiting the use of SW and indirectly decreasing its industrial waste flow.

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.