Pollution arises from all human activity and the provision of oral healthcare using resin-based composite restorative materials (RBCs) should be considered. This paper aims to provide a comprehensive review of the potential pollutant risk to the environment from the chemical compounds found in resin-based restorative materials, by including: 1) the principal pollutant compounds present in the resin matrix; 2) the degradation process of RBCs and its consequences; 3) the methods used for the detection and quantification of monomer elution and RBC microparticles; and 4) a review of the release mechanisms of eluates and RBC microparticles into the environment.RBCs are pollutants by virtue of the compounds created during the degradation processes. These are in the form of the constituent eluted monomers and microparticles. Their impact on the environment and biodiversity is unknown. These materials are currently one of the main direct-placement restorative materials and their success is unquestionable when used and maintained correctly. Mitigation strategies for reducing the impact of pollution on the environment should be considered and implemented by all stakeholders and processes in the supply chain, from manufacturing, clinical use and waste management. All the constituent components of resin-based composites have the potential to act as environmental pollutants as a consequence of their breakdown and subsequent elution.Microparticles have a pollution potential as they are easily dispersed in solution and have an increased surface area that potentiates the elution of monomers.Strategies to reduce their pollution impact should include: a) development of innovative direct-placement restorative materials; b) minimising waste; and c) providing good-quality preventive dentistry that minimises restoration failure and requirement for replacement. Historically, environmental pollution has started with the release of a seemingly innocuous pollutant that over time builds to a point where a critical threshold is exceeded, causing unforeseen consequences. Within dentistry, much of the pollution discussion has focused upon amalgam by virtue of its mercury content; currently, the focus of the United Nations Minamata Convention Mercury Treaty of January 2013. This legally binding treaty has advised nations to phase down the use of dental amalgam on the basis of environmental pollution from its constituent mercury.4Pollution can be defined as the presence in or introduction into the environment of a substance which has harmful or poisonous effects.5 This category of materials includes dentine adhesives, composites, resin-modified glass ionomers and resin-based luting agents, where most of which share a common organic polymer matrix (monomer before polymerisation) and a silane coupling agent. It is expected that RBC usage will increase in line with the mandates set by the Minamata Convention and the changes in treatment ethos.6,7Resin-based restorative materials, which are perceived to be either inert or have a reduced pollutant impact, are increasingly replacing the use of amalgam.4 Equally, there is no evidence of an environmental impact arising from this. It should be noted that the major environmental impacts from the use of these materials arises from the carbon footprint associated with manufacturing, distribution and disposal and use of auxiliary items , in addition to the plastic burden associated with packaging . Primary packaging acts as a container and delivery vehicle ; secondary packaging is often found in the form of polythene or aluminium/polyvinyl chloride laminate foils to protect the RBC from atmospheric humidity and light; and tertiary packaging takes the form of trays, boxes, cellophane and polythene wrapping. These all add a considerable environmental impact that should not be ignored but is outside the scope of this paper.8,9As per any manufactured item, all dental restorative materials have a potential pollutant effect on the environment. This will be associated with the manufacturing process, transportation, clinical use, disposal of waste material, human excretion and end-of-life of the person with the restorations. While there is some limited evidence of the harmful effect to health from constituents found in RBCs, such as bisphenol A (BPA) and methacrylate-based monomers, there is a lack of evidence that addresses the environmental pollutant potential of the plastic constituents of dental composite resin-based materials.The aim of this report is to provide a comprehensive review of the potential pollutant risk to the environment from the chemical compounds found in resin-based restorative materials, by considering: 1) the principal pollutant compounds present in the resin matrix; 2) the degradation process of RBCs and its consequences; 3) the methods used for the detection and quantification of monomer eluants and microparticles; and 4) a review of the release mechanisms of eluants and microparticles into the environment.10 The range of applications of RBC extends to other disciplines of dentistry for use as a cement and as an indirect restorative material.11RBC materials are used to restore the structural integrity, form and aesthetics of anterior and posterior teeth, enabling conservative cavity preparations on account of their adhesive properties.RBC consists two phases: an inorganic filler dispersed within an organic methacrylate resin-based matrix phase. Other components key to controlling the polymerisation reaction include initiators, accelerators, inhibitors and photo-stabilisers .Table 1 12 In comparison to previously used RBC monomers, BisGMA exhibits reduced toxicity, shrinkage and volatility while maintaining a high modulusBisGMA is the reaction product of bisphenol A and glycidyl ester methacrylate and contains pendant hydroxyl groups within its molecular backbone.13UDMA was developed as an alternative monomer as it has the advantages of reduced viscosity, increased filler loading and greater toughness when compared to BisGMA. UDMA is the product of 2,4,4-trimethylhexamethylene diisocyanate and 2-hydroxyethyl14,15Hydroxyethyl methacrylate (HEMA) is chemically synthesised from the reaction of methacrylic acid and ethylene oxide. HEMA is used in dental adhesives and is also used in photosensitive chemicals, adhesives, coating additives, thermosetting paints, sealants and personal care products. HEMA is also an intermediate in the production of other methacrylate esters16TEGDMA is a dimethacrylate monomer used mainly in dentistry; however, it is also used in industrial sealants, photopolymers, anaerobic adhesives, ultraviolent-cured coatings and fuel-resistant metal parts. TEGDMA is also an intermediate compound in the synthesis of other chemicals17BPA, while not a constituent of dental composites, is a degradation product of BisGMA and can be classed as a monomer of interest associated with RBCs and is recognised in the literature that it is present within dental composite.Common constituent monomers that form the matrix include bisphenol A-glycidyl methacrylate (BisGMA), urethane dimethacrylate (UDMA) and triethylene glycol dimethacrylate (TEGDMA). Various proprietary modified versions of these monomers also exist but are based around this set of methacrylate monomers. A brief description of each follows to aid with the understanding of the potential pollution mechanisms and pathways:18,19 These particles are embedded within the resin matrix and are chemically united to the resin phase via a silane-coupling process.20,21,22 Filler particles are included to improve the physical properties of hardness, flexural strength, wear resistance, radiopacity and optical characteristics.23RBC filler particles are generally inorganic silica and quartz and range in size from nanometers to hundreds of micrometers, making up 45-75% of the composite volume.24 Camphoroquinone is commonly used and is activated by blue light from a light-curing unit to start the polymerisation process. Alternative initiators include phenyl-propanedione (PPD), diphenyl , phosphine oxide (TPO) and recently, ivocerine, a germanium-based initiator.25 These initiators require different activation wavelengths; PPD is below 350-490 nm and TPO is 380-425 nm.26RBCs are used either in a paste form as a direct-placement restorative material, or in a pre-polymerised state for machining in computer-aided design and computer-aided manufacturing (CAD/CAM) applications. RBC used as a direct-placement restorative is cured to a hard state via free-radical polymerisation during chemical or light activation or a combination of the two. Chemical activation requires the mixing of an activator such as benzoyl peroxide with an organic aromatic amine in a two-paste composite system. Light activation requires the use of a high intensity light of a blue wavelength (420-540 nanometres) and is more commonly used than chemical activated systems.27Stabilisers are used to help prolong the shelf life of RBC and prevent spontaneous polymerisation in ambient light when being used. Common stabilisers include monomethylhydroquinone, butylated hydroxytoludene and triphenyl antimony. The latter of these stabilisers has been identified as an eluate.Inorganic colour pigments allow RBC to have varying shades to allow matching to tooth colour. These inorganic pigments range from grey to red to yellow.All of these chemicals described (and associated non-disclosed proprietary constituent organic and inorganic components) have the potential to be released as pollutants into the environment.et al., 2011) and a number of subsequent studies that satisfied the inclusion criteria for this review.28 Included studies considered the release of monomers and microparticles from resin-based composite restorative materials, the elution mechanisms, mechanisms of detection and the potential pathways to the environment.A comprehensive review of the literature identified one key meta-analysis that provides a thorough review of the topic up to 2011  or particles, in the micron or nanoscale.29,30,31 and as low as around 30% at the base of a restoration.32 Conversely, 'factory' polymerised RBCs, typically used as blocs or ingots for machined CAD/CAM restorations, have a much higher degree of conversion.33 The mechanical properties of RBCs and therefore clinical durability and longevity are dependent on the degree of conversion of monomers to polymer. Thus, the concentration of released components from RBCs is dependent upon the degree of polymerisation with an inverse relationship between the leaching of resin components from RBC and monomer conversion.34Free or partly-linked monomers elute from the restorations and by extension, also from microparticulate waste.32 Therefore, incomplete polymerisation of direct-placement RBCs has the potential for leaching unpolymerised chemicals.35,36 The opposite is true; that the greater the degree of polymerisation of the material, the less elution of monomers occurs, with less potential biocompatibility or environmental pollution concerns. The ester bonds of common dental resin monomers, such as BisGMA, TEGDMA and UDMA, are susceptible to hydrolysis via host salivary hydrolases and esterases and cariogenic bacterial virulence upregulation, accelerating the biodegradation of RBCs.37 The resultant degradation of the resin matrix increases water sorption of the material, resulting in further hydrolysis, degradation and monomer release.The direct placement of RBC restoratives and subsequent activation only achieves partial monomer conversion resulting in incomplete polymerisation. A maximum level of 60-75% monomer to polymer conversion is commonin situ dental RBC restoration will consistently elute a small concentration of constituent monomers over a prolonged period of time; however, particulate RBC generated through milling, preparing, removing, finishing and polishing RBC has a more pronounced monomer release. The recognised elution of monomers from RBC over the short and longer-term, with further elution caused by bacterial degradation mechanisms, coupled with the large surface area of microparticulate waste, are contributory to increasing the pollution potential of RBC waste particulates.38,39 In summary, elution of the constituent monomers of RBC results from diffusion of unpolymerised monomers out of the material and also via hydrolytic or enzymatic degradation of the resin matrix.40An RBC materials can find their way into the environment following chemical release (dissolution and elution of monomers), mechanical release (grinding into particles); or more commonly, a combination of the two degradation processes.28,41,42,43 at different time points, both directly after placement44 and over longer periods of time.38,45,46The release of monomers from RBCs into solution is termed elution. Eluent refers to the solution or solvent used to extract the monomer . Eluate is the combined extraction solvent (eluent) and the RBC monomers. When elution occurs, the chemical durability of the restoration is compromised, with subsequent biocompatibility and environmental pollution considerations. The dynamics of eluted monomers from RBC are the focus of current studies that seek to quantify this monomer release47 dental cements,48 CAD/CAM blocks,16 endodontic sealers,49,50,51 bonding systems52 and occlusal splint materials,53 again with the focus on potential biocompatibility issues without consideration of environmental pollution.The elution of monomers from other RBC applications has also been investigated. These include intermediate restorative dental materials,in vitro methods employed to extract, analyse and quantify RBC monomers include high performance liquid chromatography (HPLC),54 gas chromatography coupled to HPLC42 and solid phase micro-extraction (SPME).55 An effective methodology that meets these criteria utilises HPLC coupled with SPME.46Standard laboratory Methodological approaches can affect the nature of the results from a qualitative and quantitative perspective, that is, the type of monomers detected and their concentrations. To detect the monomers eluted from RBC, the chosen method needs to fulfil the following requirements: 1) be cost-effective, accurately quantitative and versatile enough to be used for a variety of solvents, namely urine, saliva, groundwater and landfill leachate; 2) should not alter the sample, 3) detect and quantify the eluted monomers in very low concentrations; and 4) reduce interferences or 'background noise' in complex environmental sample solutions.45,56,57,58,59,60Microorganisms capable of facilitating biodegradation of plastic materials can readily be isolated from the environment; therefore, disposed RBC will biodegrade and release monomers.61,62Furthermore, the mechanisms and nature of elution is influenced by a number of factors that are detailed in 63,64 An early study by Spahl et al. (1998) identified small amounts of BisGMA and UDMA but high concentrations of TEGDMA released from all RBC samples in water.65 Ortengren et al. (2001) investigated the water sorption and the elution of monomers from six different composite materials during water storage.66 Hydrolysis and oxidation of RBC in the presence of water has an important role in the degradation of RBC. Diffusion of water into the resin matrix of RBC promotes chemical degradation. TEGDMA was identified as the dominant monomer released from the RBC materials. UDMA and BisGMA release was noted from the RBC materials, albeit in much smaller concentrations. From elution kinetics studies, it is recognised that elution of the surface monomers occurs at approximately 100 times greater a rate than elution from the bulk of RBCs.67 Moharamzadeh et al. (2007) confirmed these findings in a study that investigated the release of the monomers BisGMA, UDMA and TEGDMA from three types of light-cured dental composite materials using HPLC.54 The study also identified TEGDMA in high concentrations in most but not all of the media samples. The high concentration of eluted TEGDMA found in these two studies is due to the increased relative hydrophilicity and lower molecular weight compared to BisGMA and UDMA, which impacts elution.The actual degradation of eluted monomers from RBC poses a significant analytical challenge. This degradation process results in further fragmentation of large molecular weight monomers to smaller compounds.Box 1 Factors that influence the elution of monomers from resin-based dental composite restorations120The composition of the monomer mixture and distribution of activators/inhibitors will affect polymerisation121 In light-polymerised RBC experiments, this is further influenced by light-curing unit factors, such as quality of light source, wavelengths of light omitted, distance to RBC and depth of light penetration122The extent of the polymerisation reaction and double-bond conversion will impact the amount of unpolymerised monomer within the resin matrix.28The solvent in which the experimental RBC resides impacts elution, with some organic solvents like ethanol or methanol resulting in greater elution rates than aqueous solvents like artificial salivaThe size and chemical nature, such as hydrophilicity of the monomers, would affect elution as, for example, a relatively large molecule such as BisGMA would not elute from the resin matrix as quickly as a small molecule such as TEGDMA123 The elution of monomers and oligomers from RBC impacts the biocompatibility and environmental impact of the material.The filler component influences elution, as the higher the load of filler materials within RBC, the volume of resin phase is reduced, with resultant reduced elution observed.in situ RBC restorations with high-speed rotary and abrasive burs/discs. This process commonly takes place during the removal of failed or aged RBC dental restorations and during the shaping, finishing and polishing of a directly placed restoration. Microparticles of RBC are also created from the subtractive milling and grinding of pre-polymerised RBC blocks to fabricate inlays, onlays, crowns, bridges and implant abutments , recommended a need for effective detection of microplastic particles and a better understanding of transport pathways, including wastewater.68 The analysis of elution from microparticulate RBC and its potential environmental impact is the focus of recent increased research attention.69,70,71,72,73The effect of waste microparticles in the environment needs to be considered in terms of the actual nature and size of the microparticles and as a function of the release of monomers through elution and subsequent degradation processes. A review of freshwater microplastic pollution studies by Eerkas-Medrano 32,74Beyond the potential pollutant effect of the actual microparticles, it is important to acknowledge the increased potential for elution of monomers from these particles. Free or partly-linked monomers elute from the resin matrix of direct-placement restorations and by extension, also from microparticulate waste.38,75The recognised short- and long-term elution of monomers from RBC, the further elution caused by bacterial degradation mechanisms and the large surface area of microparticulate waste, are contributory to increasing the pollution potential of RBC waste particulates.76,77 FTIR spectroscopy is a reliable, cost-efficient and relatively simple technique for the identification of microplastics. An additional advantage is that this method is non-destructive and FT-IR spectroscopy analyses have been successfully used for identifying microplastics in both sediment and water samples if the functional groups of the plastic have been pre-established.78,79 This method can be applied to samples from a dental origin in order to characterise microparticulates that are released from common dental applications into the environment, as the functional groups are known. Alternative techniques for analysis include Raman spectroscopy, sequential pyrolysis-gas chromatography coupled to mass spectrometry, infrared spectroscopy and combined FT-IR spectroscopy with microscopy.80,81,82,83In order to consider the environmental impact of these particles, it is necessary to analyse the composition, size and behaviour. A range of techniques have been used for this purpose, of which, fourier transform infrared (FTIR) spectroscopy is the most widely used technique for the characterisation, identification and quantification of microplastics in wastewater samples.84,85Disposal of RBC to landfill burial sites and incinerationHuman waste  into wastewater and sewerageCAD/CAM milling and release of particulates into wastewater and sewerageParticulate release from clinical procedures Cremation of cadavers containing RBC into the atmospheric airInterment of cadavers containing RBC into groundwater.A number of plausible release mechanisms are considered:86 In the UK, MSW is recycled or sent to landfill; however, in many other countries, uncontrolled disposal of hazardous waste occurs, with potential for environmental harm.87 Adverse effects include leachate and gas emissions, fires and explosions, unpleasant odours, vegetation damage, ground water pollution, landfill settlement, climate change and air pollution; all concerns associated with landfill.88The majority of the waste produced in the dental industry is classified as municipal solid waste (MSW). MSW is a generic term that can also be applied to all residential, commercial and industrial waste.89 Notwithstanding, the evidence supporting this release method is not clear. A laboratory microcosm study examining the reactiveness of RBC materials in landfill leachate concluded that the microbial activities and the increase of pH of this leachate environment may potentiate the release of TEGDMA, UDMA and BPA. However, these conditions do not affect the rate of release of Bis-GMA from dental composite materials.90 It should be considered that a breach of a landfill site through floods or coastal erosion has the potential to allow environmental pollution from RBCs.91RBC from dental surgeries that has expired its usage date and excess unused composite within discarded compules and syringes is considered as municipal solid waste and consequently disposed of in landfill sites. When disposed in this manner, landfill leachate can react with RBC allowing the release of its components. Landfill leachate is formed when precipitation percolates through the contents of a landfill site, promoting and assisting decomposition processes facilitated by bacteria and fungi. The temperature, pH and oxygen content of the landfill leachate solution change over time, affecting the reactivity of the solution. In a landfill site that receives a mixture of commercial, municipal and mixed industrial waste, a leachate composed of organic matter, inorganic ions and cations, heavy metal ions and xenobiotic compounds including persistent organic pollutants (POPs), will arise. This reactive leachate has the potential to allow breakdown and release of RBC into constituent components, including monomers, oligomers and BPA.89The potential of incineration as a suitable alternative to landfill has been investigated. A comparative study between the two methods concluded that bacteria-mediated degradation of RBC in landfill leachate with resultant increased release of BPA. Monomers are released from polymerised and unpolymerised RBC into landfill leachate over a prolonged period of time. Incineration of RBC results in the environmental release of significantly lower concentrations of monomers, elements and ions. Incineration is considered a viable alternative waste RBC disposal route, with a potentially lower environmental impact.29,30,31 Thus, unpolymerised RBC components are excreted in human waste after placement into the environment. A key large-scale study by Kingman et al. (2012) provides a very valuable insight into this pollution stream, identifying that monomer eluates  found in urine and saliva can be released into the environment up to 30 hours after the placement of a RBC restoration. The application of dental dam reduced the quantities of monomers detected in saliva significantly (by four for BisGMA).92As highlighted earlier, during normal clinical use of RBC, elution of the constituent monomers and oligomers occurs, as complete polymerisation is not possible.93 Microplastics act as direct pollutants and can attract and bind to biotoxins known as POPs, such as polychlorinated biphenyl (PCB).94 There is speculation that adsorption of POPs to microplastics increases the possibility of access to the food chain via the process of bioaccumulation.95 Ingestion of microplastics has been documented in plankton, barnacles, mussels, fish and seabirds.96 Microplastic particles are found in many species of North Sea fish, including popular edible species such as haddock, cod and herring.97 RBC microparticulates are reactive (they elute the monomer constituents) and are charged and can therefore potentially attract and bind other compounds in the same manner as microplastics can.98 Methods of detection and quantification of microplastics are improving to help better understand this phenomenon.99RBC microparticulates are distinct from microplastics, as they are a heterogenous combination of polymer and glass filler, whereas microplastics are generally homogenous and made of one polymer, such as polypropylene. Microplastics are defined as plastic particles smaller than 5 mm and represent an increasing proportion of plastic debris released into the environment.100 This waste material is removed from the oral cavity by the use of an aspirator and is disposed to wastewater, which proceeds to the environment via municipal sewerage. The size of these particulates ranges from nanoscale to around 10 μm.The clinical process of polishing, replacement or adjustment of a RBC restoration generates particulate waste.The CAD/CAM subtractive  manufacturing process of grinding pre-polymerised RBC ingots generates significant volumes of microparticulate powder that is often disposed into landfill or via wastewater discharge into municipal sewerage.29,30,31Beyond the actual impact of the microparticles, the actual pollutant potential associated with monomeric elution from these microparticles is unknown. The pollutant potential is determined by the monomeric composition, the age of the restoration (and therefore how much previous elution of monomer has occurred), the size and surface area of the microparticles released and the extent of polymerisation . In this context, it is important to note that the breakdown and potential elution of monomers from the two processes  is likely to differ on account that the CAD/CAM blocks are highly polymerised RBC, compared to the direct-placement materials, with a range of 50-70% conversion rate.85,98 The direct-placement commercial RBC microparticles were clearly discernible after this time, with consistent alteration of the outermost surfaces of particles, suggesting particle breakdown and monomer elution. The previously reported study by Polydorou (2020) evaluated the release of BPA in wastewater after grinding of resin composites and tested three filtration materials.70 BPA was detected in all solutions of ground microparticulate commercial resin-based composites, highlighting that BPA can be released in wastewater during dental procedures. The charged nature of microparticulate RBC and experiments involving catalytic carbon filtration have been suggested for RBC microparticulate and BPA reduction in wastewater when considering remediation strategies.70,71,72,85The characterisation of microparticles arising from either grinding direct placement restorations or CAD/CAM RBC ingots after 12 months ageing in water has been investigated.Interment and cremation are the most common approaches to the management of human remains, which include a high volume of dental restorations and prostheses. Given the high number of resin-based composite restorations, this potential environmental pollution pathway also merits attention.As life expectancy increases in line with the number of dentate patients containing restorations, future repair and replacement of restorations with RBC means the amount of RBC that will be placed in patients for future release into the environment will increase.in situ; and treatment-dependent factors, such as how well polymerised the material was. This is then further compounded by interment site and method-related factors:101Geological and hydrogeological characteristics of the soil, including soil type, permeability and porosity, pH and ability of groundwater to diffuse, would impact the release of eluted monomers89Microbiological characteristics of the soil and groundwaterMechanical, structural and resistance parameters of the soilCoffin or other container construction used. The less permeable or biodegradable, the less release into groundwaterLand cover and topography will affect infiltration and water permeationClimate: degradation of RBC and elution rate are temperature dependent with positive correlation between increased temperature and elution of monomersDepth of the unsaturated zone of the soil has an impact because as well as acting as a barrier to contamination of an underlying aquifer, this can also present a means for infiltration of oxygen that may aid decomposition and the elution process.The environmental impact associated with the burial of cadavers containing RBC has the potential for the release of eluates into the environment via percolation of groundwater. Understanding the extent and rate of elution of materials into groundwater is complicated by material-based factors, such as: the type of dental RBC and its composition at burial; how long it has been in vitro investigation into the elution of monomers from RBCs into groundwater identified that low concentrations of monomers are released into groundwater over a prolonged time from RBC.102 It is clear from these statistics and the highlighted trend of increasingly higher RBC use in the future, that understanding the consequences of elution of monomers from RBC into the environment from cadavers requires further investigation.An 103 Temperatures of 800 °C or higher are required over a time period of between 1-2 hours. During the cremation process of human cadavers, a number of emissions are released into the environment.104 These pollutants include mercury compounds , dioxins, furans, hydrogen chloride, nitrogen oxides, carbon monoxide and volatile organic compounds. Through the use of established combustion methods, secondary combustion chambers and filters, the majority of pollutants released can be maintained below regulation limits. In addition, concentrations of mercury, hydrogen chloride, dioxins and furans can be monitored in additional arrestment chambers.105Cremation is the process of combustion, vaporisation and oxidation of human remains. In Europe, over 150,000 cremations occur each year in the 1,000+ crematories in operation.There is no published data that characterises the pollution potential from this pathway.The oral healthcare community recognises that we have a joint responsibility to deliver products and interventions that improves oral health and does so in an environmentally sustainable manner.2e emissions and environmental pollution as much as possible. In the future, with further understanding, it is hoped that oral healthcare provision becomes carbon-neutral and pollution-free.In the last decades, the combined efforts of the oral health industry, researchers, governing bodies and the oral healthcare profession have been hugely successful in the delivery of a sophisticated understanding and knowledge of oral and dental diseases, treatment strategies and modalities. This includes the innovation and development of excellent technologies, materials and products to provide this care, including state-of-the-art RBC restoratives. These combined efforts have, to date, been largely focused on the prevention and management of oral diseases. Today, we have a further understanding of the need to ensure that optimal oral healthcare provision should also minimise unnecessary COThis article has summarised the literature regarding the release of monomers from RBC and RBC microparticles, with a focus on environmental pollution. It identifies that all the constituent components of RBCs have the potential to act as pollutants as a consequence of their breakdown. This may be in the form of eluates, microparticles, or a combination of the two. The breakdown of these materials can occur through a range of different pathways.in vitro studies, the pollution potential of these materials, we do not have, to date, any evidence that these materials have an adverse impact on the environment and biodiversity.It is important to highlight the distinction between pollution and the impact of this on the environment and biodiversity. While we recognise, from in vitro laboratory studies. The reasons for this are associated with the nature of the chemicals, their combination with other environmental substances when eluted (organic and inorganic) to form complex substances, the limitations of the analytical techniques and the interpretation of the results. Notwithstanding, the evidence to date is conclusive in that elution of monomers arising from RBCs does occur and that these are released into the environment. TEGDMA is the most dominant monomer released from RBCs but this is a function of its relatively high hydrophilicity and its lower molecular weight. It is pertinent to note that components released from RBCs into the mouth may react with other substances  and may be inactivated in the process. As such, it is difficult to study and fully understand the impact of specific constituents of RBCs.Characterisation of the pollution potential of these materials is very challenging and limited to Microparticles have a pollution potential associated with their small size that makes them easily dispersed in solution and their increased surface area that potentiates the elution of monomers. Microparticles also have a tendency to create agglomerates with other substances, creating potentially more complex polluting substances. Beyond the actual impact of the microparticles, the actual pollutant potential associated with monomeric elution from these microparticles is unknown.106 Estimates of ten-year failure rates for RBCs  range between 32 million posterior restorations  and 48 million of all restorations .107,108 Accepting an average figure of 40 million and considering the average weight of a RBC restoration to be 0.3 g, it is possible to calculate the approximate mass of particulate waste generated and released into municipal wastewater to be in the range of 12 tonnes per year. While this may be considered to be a relatively small amount of pollution compared to other industries; the oral healthcare industry has an equal level of responsibility to manage and minimise its pollution impact, regardless of the magnitude of this.A number of plausible pollution pathways are considered for RBCs, for which we have very limited knowledge. Of these, the release of microparticles and eluates during the clinical removal, finishing/polishing and CAD/CAM milling of restorations and their subsequent discharge into wastewater and landfill burial have received the greatest research attention. The relevance of these processes in generating microparticles becomes evident if we consider the number of RBC restorations that are placed and replaced/refurbished worldwide. It is estimated that in 2015, 800 million direct RBC restorations were placed; a figure based on industry sales figures.109,110111,112To promote research and development to create innovative direct-placement materials that have low technique sensitivity and are cariostatic, easily placed, durable and have a low/zero pollution impactTo adapt our processes throughout the supply chain to minimise the pollutant impact from these materials by minimising waste at all stages, through careful attention to the manufacturing processes, distribution, clinical use and associated logistics113 Ensure that procedures are executed and maintained to the very highest standards to avoid restoration removal and replacement.114 This requires the use of high-quality materials that are placed following evidence-based protocols. The repair and replacement of restorations leads to premature loss of teeth through the process known as the restorative cycle.115,116 Slowing down or stopping the restorative cycle will have a dual environmental positive effect:To suggest clinicians should engage and promote effective caries prevention regimes that will reduce the failure rate of RBCs and their need for replacement.Reduced use of materials, creating less manufacturing waste, less packaging and less clinical wasteReduced number of patient visits for routine dental care that equates to reduced travel and thus a reduced patient-based carbon footprint.With the impending demise of dental amalgam, RBCs are the only alternative direct-placement restorative materials with universal application in all the dentition. Strategies to reduce their pollution impact should be:117Further clinical strategies to reduce the generation, release and impact of microparticles are: Modify treatments by not overbuilding restorations and therefore requiring more instrumentationConsider repairing restorations rather than replacing when clinically appropriateDispose of CAD/CAM waste responsibly and not down the sinkDevelopment of RBC materials with improved degrees of monomer conversionReduce the restorative need through preventionDevelopment of adjunctive technology to capture microparticulate waste at the point of generation (clinic or laboratory).Elution of monomers can be mitigated through the use of clinical techniques and effective light curing to: maximise polymerisation conversion rates; undertake the replacement of RBC with dental dam isolation to reduce the concentration of monomer elution in saliva and; use glycerine gel on the final light-cured surface of RBC to avoid the oxygen-inhibited layer and in this way, limit the amount of unpolymerised monomer that is present and removed during finishing/polishing of the restoration :This review has identified the need for a better understanding of these pollution pathways to aid the development and implementation of restorative material technology, clinical practice protocols, technologies to mitigate the pollution impact and associated legislation and policies that support these strategies.118RBC is currently the most suitable direct aesthetic restorative dental material and its clinical success is unquestionable when used and maintained correctly. This review has identified that resin-based composites may release monomers and microparticles that are potential pollutants. We do not have, to date, any evidence that these materials have an adverse impact on the environment and biodiversity. However, these substances certainly have the potential to do harm, especially if critical thresholds are exceeded, indicating more research is required. Mitigation strategies for reducing the impact of pollution on the environment should therefore be considered and implemented by all stakeholders, from manufacturers, through clinical use or disposal and on to waste management. Recommended approaches include careful supply chain management to avoid accumulation of products beyond their use by date and delivery of high-quality clinical services to ensure that restorations deliver the greatest longevities possible. Prevention and management of oral diseases through good-quality care and treatment is key to improving sustainability by reducing the need for dental materials and associated negative environmental impacts.


Obesity and being overweight have reached incredible proportions worldwide and are one of the most common human health problems. The causes of obesity are multifactorial, including a complex interplay among genes, metabolism, diet, physical activity, and the environment. The intestinal microbiota has the ability to affect the host physiology for both benefit and damage, either directly or through microbial metabolites. The aim of this review is to discuss the mechanisms by which the intestinal microbiota could act as a key modifier of obesity and related metabolic abnormalities. The synbiotic components provide an optimal target for modulation of the intestinal microbiota and help reshape the metabolic profile in obese people. The development of novel functional foods containing synbiotic ingredients may present a support in the prevention of obesity as one of the risk factors for chronic diseases. Knowledge of the synbiotic mechanisms of action and the use of new functional foods supplemented with probiotics and prebiotics will facilitate the clinical application and development of individual health care strategies. Obesity has become one of the biggest general health challenges currently facing our society. Obesity and its complications are a significant burden. The prevalence of obesity is constantly rising worldwide, so it is considered an epidemic. Obesity and overweight, as risk factors for chronic diseases and their consequences associated with metabolic disorders and, more recently, as the factors influencing the severity of the new coronavirus disease COVID-19), and at the same time, a serious independent disease in childhood and adulthood, represent serious health problems that require a multifactorial response 9, and at,3. The pObesity is one of the controllable and “modifiable” risk factors for chronic diseases. To understand the origins and main factors supporting obesity and its physiological effects, detailed research is still needed to develop and effectively implement the potential therapeutic pathways to directly target metabolic pathology.Modern research demonstrates the central role of the human gut microbiome in modulating human health and host metabolism. The human gut microbiome can act as a key player in obesity and related metabolic changes, including type 2 diabetes.To develop strategies for the prevention of these intestinal microbiota imbalances, food companies have recently invested in finding new nutrients to manipulate and restore a healthy microbiota composition. Focusing on intestinal microbiota with synbiotics (probiotic supplements containing prebiotic components) is proving to be a promising intervention in a comprehensive nutritional approach to reduce obesity. Correction of obesity-induced disruption of the intestinal microbiota by synbiotics may be more effective than supplementation with probiotics alone because the prebiotic components of synbiotics support the growth and survival of positive bacteria in them.Obesity is now declared the current global epidemic. The pathophysiology of obesity is multifactorial. The main factors that contribute to its development are unhealthy lifestyle, neuronal and hormonal mechanisms, as well as genetic and epigenetic factors contributing to the imbalance between energy intake and expenditure . ObesityMethanobrevibacter smithii. The most numerous faecal bacterial groups of both poor and obese subjects are the Firmicutes and Bacteriodetes strains. About 90% of all intestinal bacterial phylotypes belong to either the gram-positive Firmicutes (64%) or the gram-negative Bacteroidetes (23%) [Researchers are gaining a better understanding of the “normal” bacterial communities and physiology of the current intestinal microbiota through population research, such as the Human Microbiome Project . Microbees (23%) ,13. Othe−The production of metabolites  ;−The metabolic organ  ;−The vitamin production  ;−The influence on the epithelial homeostasis  ;−The development of the immune system  ;−The impact on pathogen colonization  .The functions of microbiota are summarized as follows:Rikenellaceae (phyla Firmicutes) and Christensenellaceae (phyla Firmicutes) as well as a decrease in the abundance of the genera Bifidobacterium (phyla Actinobacteria), Oscillospira (phyla Firmicutes) and Akkermansia (phyla Verrucomicrobia) [Bifidobacterium is associated with elevated levels of short chain fatty acids (SCFAs), a decreased luminal lipoplysaccharide (LPS) and an improvement of intestinal barrier function [Akkermansia is a mucin-degrading microbe that occupies the outer mucus layer of the intestinal barrier and is connected with a healthier metabolic status in obese humans. In obese people, it could be a potential prognostic marker for predicting the outcome of dietary intervention because an increased amount of Akkermansia in the gut after embarking on weight loss leads to improvement in glucose homeostasis, blood lipids, and body composition [Faecali prausnitzii, a significant butyrate-producing microbe providing host protection against bacterial translocation, is considerably reduced in obesity, particularly in patients with diabetes mellitus [Faecali prausnitzii, Akkermansia, and Christensenellaceae [Prevotellaceae (phyla Bacteroidetes), Coriobacteriaceae (phyla Actinobacteria), Erysipelotrichaceae (phyla Firmicutes), Alcaligenaceae (phyla Proteobacteria), and genus Roseburia (phyla Firmicutes) are consistently reported in subjects with obesity and increased BMI (Body mass index) [Maintaining heterogenicity and stability within the gut microbiota community is fundamental for promoting host health. Alterations in diversity and microbiota community structure may influence host metabolism, which may contribute to the development of obesity. The first studies showing a link between the microbiome and an obese phenotype were carried out in germ-free (GF) mice, which were initially found to be sturdy against diet-induced obesity even under conditions of a high-fat diet . Moreoveicrobia) ,23,24. Mfunction . Akkermaposition ,27. Faecmellitus . Reducinellaceae ,30. Famis index) ,32. It iThe intestinal microbiota has the ability to affect host physiology for both benefit and damage, either directly or through microbial metabolites. The major microbial metabolites produced under anaerobic carbohydrate fermentation are short-chain fatty acids (SCFAs). SCFAs comprise of one to six carbons of that acetate (C2), propionate (C3), and butyrate (C4) are the most abundant (≥95%) ,33. SCFALactobacillus, Bifidobacterium, Akkermansia, Bacteroides, Prevotella, Ruminococcus, and Streptococcus [Anaerostipes, Clostridium, Coprococcus, Dorea, Eubacterium, Faecalibacterium, Roseburia, Ruminococcus, and the most plentiful producers appear to be the species Faecalibacterium prausnitzii, Eubacterium rectale, and Roseburia intestinalis. Butyrate is especially used by colonocytes as an energy source and is badly detected in the circulation. It exerts powerful anti-infective and anti-inflammatory abilities in the intestine and is able to prevent body weight gain without changing food intake and improve insulin sensitivity.Acetate, the most plentiful SCFA, is produced by gut bacteria from the genera tococcus . AcetateButyrate supports energy expenditure and possibly decreases obesity through the increase in mitochondrial efficacy (activates AMP (adenosinmonophosphate)-activated protein kinase, increasing adenosine triphosphate (ATP) consumption and the release of PGC-1 (peroxisome proliferator-activated receptor gamma coactivator one) peroxisome proliferator-activated receptor gamma coactivator one), in connection with the upgrade regulation of the expression of genes involved in lipolysis and fatty acid oxidation. Butyrate may decrease energy intake by evoking a host anorexic reaction by increasing the plasma levels of glucagon-like peptide 1 (GLP-1), glucose dependent insulinotropic polypeptide (GIP) and peptide YY (PYY) .Phascolarctobacterium, Bacteroides, Dialister, Megasphaera, Veillonella, Coprococcus, Roseburia, Ruminococcus, and Salmonella [Propionate is created by the genera lmonella . Propionlmonella ,38.Obesity in adults is caused by dysbiosis, which is also involved in the etiology of childhood obesity. Infant gut microbiota could be a biomarker to identify children who are at risk of becoming overweight or obese later in childhood. Human trials conducted to date demonstrate that obesity may be connected with a reduced bacterial diversity and shifts of gut bacteria at the phylum level; however, discrepancies exist in the directionality and suitability of the Firmicutes to Bacteroidetes ratio in obesity. It is likely that obesity-related intestinal dysbiosis has its origins in infancy, as early as 3–6 months after birth, at a time when the first colonisers of intestinal microbiota lay the basis for subsequent colonisation by anaerobes from the Bacteroidetes phylum. The structure of the gut microbiota at the age of 2 years can serve as a predictor of obesity at the age of 12 years . This fiIt is possible that the intestinal microbiota is becoming a possible tool to be used in this battle versus obesity. The common forms of obesity are multifactorial and come from a complex interplay of the environmental changes and the individual genetic predisposition. Increasing proof suggests a central role played by the alterations of intestinal microbiota that could represent the causative link between environmental factors and the onset of obesity. The useful effects of intestinal microbiota are mainly intervened by the secretion of various metabolites. In this context, host diet has a direct impact on microbiota composition and is regarded as an important way to modulate the intestinal microbiota.Gibson and Roberfroid presented the term “synbiotic” to describe a combination of synergistically acting probiotics and prebiotics, the application of which can offer more benefits than the prebiotics or probiotics individually . As the Therefore, a suitable combination of both components in a single product should ensure a better effect, compared to the activity of the probiotic or prebiotic alone ,48. With(1)synergistic synbiotics—synbiotics in which the substrate is proposed to be used selectively by the co-administered microorganism(s).(2)complementary synbiotics—synbiotics composed of a probiotic in combination with a prebiotic, that is intended for targeting the autochthonous microorganisms .The following two types of synbiotics were described:In both cases, the influence of synbiotic must be confirmed at the target host and its safety should be validated. The active components of a synbiotic must be adequately stable. Safeguarding the stability of the live microbial component of a synbiotic can be challenging. After live microorganisms are combined with a substrate(s) in a matrix , the load is on producers to ensure that the dose of the live microorganism necessary to confer the stated health advantage is delivered throughout the self-life. Live microorganism viability is highly dependent on the matrix, storage temperature, pH, and oxygen level of the product as follows: for liquid products, the self-life might be as short as 1–2 weeks, for lyophilized or encapsuled products, the self-life might be as long as 2 years. Packaging and warehousing conditions must control the critical factors, such as water activity and temperature, through the production to distribution and consumption.The choice of an appropriate probiotic and prebiotic exerting a beneficial effect on the host’s health when used separately should be the first aspect to be taken into account when forming a synbiotic formula. Considering a large number of possible combinations, the use of synbiotics for the modulation of gut microbiota in humans seems promising .Synbiotics are used not only for the improved survival of beneficial microorganisms added to diets or feed, but also for the encourage of the proliferation of specific native bacterial strains present in the gastrointestinal tract . The mosBifidobacterium or Lactobacillus with fructooligosaccharides (FOS). The most used combinations of probiotics and prebiotics are as follows: bacteria genus Lactobacillus + inulin; Lactobacillus, Streptococcus and Bifidobacterium + FOS; bacteria of the genus Lactobacillus, Bifidobacterium, Enterococcus + FOS; Lactobacillus and Bifidobacterium + oligofructose; bacteria of the genus Lactobacillus and Bifidobacterium + inulin [In synbiotic products, the most popular appears to be the combination of bacteria of the genus + inulin ,53. Preb+ inulin . This co(1)The effects through the improved viability of probiotic microorganisms.(2)The effects by providing specific actions on health.Two known modes of synbiotic effects are as follows :(1)The eThe stimulation of probiotics with prebiotics leads to a modulation of metabolic activity in the intestine with preservation of the intestinal biostructure, development of the beneficial microbiota, and the inhibition of potential pathogens present in the gastrointestinal tract. Synbiotics result in reduced concentrations of undesirable metabolites as well as the inactivation of nitrosamines and other cancerogenic substances. Their use leads to a significant increase in the levels of short-chain fatty acids, ketones, carbon disulphides, and methyl acetates, which can have a positive effect on the health of the host . In termLactobacillus in the synbiotic and placebo groups. In both groups, the mean decrease in HbA1c was accompanied by an average increase in Lactobacillus abundance. However, the decrease in body mass, BMI, waist, and body fat over time was associated with a statistically significant decrease in Bifidobacterium abundance in both placebo and synbiotic groups [Bifidobacterium animalis subsp. lactis 420+Litesse Ultra polydextrose increased the incidence of Akkermansia, Christensenellaceae, and Methanobrevibacter, while the incidence of Paraprevotella was reduced. The Christensenellaceae family is associated with a poor phenotype, as found in a negative correlation with waist-hip ratio and energy intake, and body fat and cholesterol indicators in the waist-area [Synbiotics have been shown to be highly effective in preventing osteoporosis, lowering fat and blood sugar levels, regulating the immune system and treating brain disorders associated with abnormal liver function . The conc groups . Synbiotist-area . Obesityist-area ,76,77,78ist-area , blood pist-area ,81,82. Iist-area ,84,85. Tist-area  reviewedist-area . The antist-area . The stuist-area  showed tist-area . Cardiovist-area ,90,91.Functional food products that affect many physiological functions in the body can be promising treatments for obesity and obesity-related disorders. These naturally processed foods contain bioactive compounds (probiotics and prebiotics) that have been clinically proven to provide health, well-being, and performance benefits beyond normal nutrition alone, thanks to their incorporation into the diet.The probiotics themselves have the following multiple and diverse effects on the host: (1) antagonistic effects on various microbiota and competitive adhesion to the mucosa and epithelium ; (2) causing an increase in mucus production and influencing the barrier integrity (an improved barrier function); (3) can modulate the human immune system (immunomodulation).Finally, perhaps the most promising approach to the development of effective synbiotic functional foods is the addition of supplementary prebiotic ingredients such as inulin and FOS to probiotic foods . The incAlthough the potential of these synbiotics products in the treatment of obesity is further explored, the formation of intestinal microbiota by synbiotics could be a promising new means of preventing and treating obesity and obesity-related disorders, and it can serve as an excellent alternative strategy for developing safe anti-obesity drugs. Functional foods are less likely to have side effects because they are simply common or fortified foods with bioactive compounds. In addition, the availability of functional foods can benefit many individuals of vulnerable populations, such as people from developing countries or those with lower socio-economic status. Despite the proven biological properties of synbiotics, research in this area must focus on the correct selection of probiotic strains, prebiotics, and transport systems in order to avoid suppressing their synergistic or complementary effects on human health. The future direction should lead to the development of functional food products containing stable synbiotics adapted to different age groups or specifically designed to meet the needs of adjuvant therapy. Co-encapsulated synbiotics could be one of the modern approaches currently being developed to modulate the intestinal microbiota, with an emphasis on the health benefits. However, the disadvantage of using synbiotics is that it is difficult to predict the selectivity and specificity of each component and what the resulting mechanism of action will be .The current obesity epidemic, which is afflicting a large part of society, requires sustainable, affordable, and efficient treatments to combat this public health crisis. Obesity is the result of an energy imbalance involving other factors such as an inadequate lifestyle, brain function, and hormonal mechanisms, as well as genetic and epigenetic factors. This multifactorial pathogenesis may partly explain why obesity is an important challenge for clinical treatment and health policy. Bariatric surgery that reduces weight and controls obesity-related comorbidities is a highly invasive procedure with a high risk of adverse events and poses safety issues in the paediatric population. Thus, it seems clear that the main treatment of obesity should be based on a multicomponent approach involving behaviour therapy, dietary changes, physical activity, and pharmacotherapy. However, the obese subjects expect tangible results in a very short time, which makes the long-term implementation of lifestyle changes difficult. Although the etiology of obesity is multifactorial and incredibly complex, several studies have shown the potential therapeutic effects of synbiotics on body weight, BMI, waist circumference, fat deposition, lipid profile, and chronic inflammation state. Recent research strongly implicates intestinal dysbiosis as a key contributor to the development of obesity and related metabolic abnormalities. New approaches in the treatment and prevention of obesity and related metabolic disorders are necessary. Dosage, duration of treatment, and long-term effects of the administration of different microbial strains are still under investigation; more studies are needed to rationally prescribe probiotics to prevent or treat obesity. Diet control, as well as the environmental and lifestyle factors that support the development of obesity, remains the best solution to the problems associated with weight gain. Consequently, the modulation of the intestinal microbiota to restore a stable, coherent metabolic state has become a research area of great interest in recent years. Further research, including well-controlled, randomized, and controlled clinical trials, is needed to better understand the mechanisms involved in the anti-obesogenic effects of synbiotics in order to develop safe strategies for obesity prevention and management.


This review paper discusses the importance of phenolic compounds isolated from seaweed in improving plant growth and controlling the negative effects of environmental and biological factors.Abiotic and biotic stress factors negatively influence the growth, yield, and nutritional value of economically important food and feed crops. These climate-change-induced stress factors, together with the ever-growing human population, compromise sustainable food security for all consumers across the world. Agrochemicals are widely used to increase crop yield by improving plant growth and enhancing their tolerance to stress factors; however, there has been a shift towards natural compounds in recent years due to the detrimental effect associated with these agrochemicals on crops and the ecosystem. In view of these, the use of phenolic biostimulants as opposed to artificial fertilizers has gained significant momentum in crop production. Seaweeds are marine organisms and excellent sources of natural phenolic compounds that are useful for downstream agricultural applications such as promoting plant growth and improving resilience against various stress conditions. In this review, we highlight the different phenolic compounds present in seaweed, compare their extraction methods, and describe their downstream applications in agriculture.  Seaweeds or macroalgae are photosynthetic multicellular organisms, found in the subtidal or intertidal part of the marine environment, free-floating or attached to surfaces such as rocks . These aSeaweeds, especially those in the intertidal zone, are constantly being subjected to severe stress conditions such as herbivore attack, high salinity, water loss, microbial attack, and ultraviolet rays . HoweverPhenolic compounds, one of the phytochemicals produced in seaweeds, are made up of an aromatic ring with one or more hydroxyl functional groups and their structure varies from simple molecules to high-molecular-weight molecules . The bioStress in plants can be classified into abiotic and biotic and it causes physiological, morphological, and biochemical changes such as reduced rate of photosynthesis, altered gene expression, slow growth rate, and impairment in the electron transport chain . AbioticAgrochemicals which include fungicides, herbicides, fertilizers, and pesticides are utilized for protecting plants against abiotic and biotic stress and to also increase crop yields . AlthougExogenous application of phenolic compounds can play an important role in increasing plants’ growth and mitigating the effect of abiotic and biotic stress in plants through various mechanisms such as facilitating the lignification of plant cell walls which promotes shoot length and prevents pathogens from penetrating the host plant, influencing the activity of certain enzymes such as antioxidant enzymes and the synthesis of certain compounds such as proline and phenolic compounds . Singh  reportedSeaweeds, also known as macroalgae, are multicellular organisms in the marine or coastal environment that can be found attached to rocks, logs of wood, or free-floating. they perform several functions such as food, shelter, and reproductive sites for other marine animals such as sea urchins and invertebrates . Their aUlva species (sea lettuce), Caulerpa species, and Chaetomorpha species [The Chlorophyta  are widely distributed in a variety of water bodies ranging from the Arctic region, lakes, oceans, and the Antarctic. However, about 90% are reported to inhabit freshwater bodies . Their sUndaria species, Himanthalia species, Sargassum species, and Dictyota species [The brown seaweeds  are the largest and most developed of the seaweeds. They are mostly found in the marine environment, especially in cold to temperate waters. Brown algae are affected the most by climatic conditions which influence their phytochemical content in different geographical zones. The presence of a pigment known as fucoxanthin contributes to its distinctive brownish color. Examples of common species of brown seaweeds are laminaria species, Ecklonia species,  species .Porphyra, genus Gracilaria, and genus Rhodymenia [The phylum Rhodophyta (red seaweed) is the most abundant seaweed which has adapted to living in almost all the water bodies from fresh water, tropical, temperate, and arctic water. However, they are dominant in tropical and temperate regions. Apart from chlorophyll a, they have an additional pigment known as phycoerythrin, which makes them tolerate low light intensities. As a result of this, they can survive in deep waters and absorb light when chlorophyll “a” is no longer active . Exampleodymenia .The broad bioactivity of seaweed has been linked to the presence of a plethora of inorganic compounds and organic compounds which include carbohydrates, protein, lipids, vitamins, hormones, betaines, and phytochemicals  which are more abundant than the amount found in any terrestrial plants . PhenoliSeaweed phenolics have a basic structure of a hydroxy group attached to an aromatic ring. They are categorized by the number of carbon atoms and benzene rings in a compound as well as their solubility. Phenolic compounds with a phenol ring, such as phenolic acids and phloroglucinol, are classified as simple phenolic compounds, whereas those with multiple phenols, such as phlorotannin, are classified as polyphenols ,24. The Sargassum polycystum had the highest total phenol content compared to the other drying techniques [Seaweeds are typically snap frozen in liquid nitrogen immediately after harvesting to halt all metabolic reactions that may result in the loss of phenolic compounds before the extraction process . Followichniques .Several methods can be used for extracting phenolic compounds from seaweed. However, due to their structural similarity, the extent of solubility, and the large molecular mass of some compounds, the chosen extraction technique should target the phenolic compound of interest. For instance, phlorotannin typically forms complexes with other metabolites within the seaweed cell walls. Therefore, an extraction method that would obtain extracts rich in phlorotannin should be adopted . 2 extraction. The advantages and disadvantages of each extraction method are summarized in The common methods of extracting phenolic compounds from seaweed can be classified into traditional  and non-conventional (modern) methods. The conventional extraction techniques include Soxhlet extraction, maceration, and the percolation method while the nonconventional (novel) techniques include microwave-assisted extraction, enzyme-assisted extraction, ultrasound-assisted extraction, sub-critical water extraction, and subcritical COPhenolic compounds have been used extensively to improve plant growth and increase crop yield. Data obtained from numerous studies and the literature reveal that phenolic compounds exhibit growth-promoting properties as a result of their positive impact on various phases of plant growth and developmental processes which include seed germination, shoot length, root length, plant biomass, photosynthetic pigments, and plant metabolism ,58. It hEclonia maxima were used to treat maize seeds. It was observed that there was an increased rate of germination in the treated seeds compared to the control. This was attributed to an increase in the activity of the enzyme α-amylase in the roots of eckol and phloroglucinol-treated maize seedlings, which catalyzes the breakdown of starch to simple sugars. The sugar produced was transported to the embryo to supply the needed energy for metabolism [Seed germination is a major aspect and the main determining factor of plant growth and productivity. Germinating seeds require nutrients for the growth and synthesis of the needed cellular components. These are supplied by the enzymatic hydrolysis of the food reserves such as carbohydrates, proteins, and lipids stored within the endosperm . The gertabolism .Ecklonia maxima and their effect on Eucomis autumnalis was determined. It was observed that exogenous application of the isolated polyphenols caused an increase in the auxin level, which resulted in an approximately 1.5 times increase in the root length of the treated plant.Phenolic compounds have been reported to promote the development of adventitious root and root lengthening in plants by regulating the activity of the phytohormone indole-3-acetic acid (auxin) which is the principal hormone responsible for the process. The activity of auxin is inhibited either by conjugation or decarboxylation in a reaction catalyzed by the enzyme indole-3-acetic acid oxidase (IAA oxidase). Phenolic compounds influence the root-lengthening activity of auxin by preventing the decarboxylation reaction and by acting as a cofactor that promotes the breakdown of the enzyme IAA oxidase . In a reEcklonia maxima caused an increase in shoot length, root length, and photosynthetic pigment on treated maize when compared to control plants. Briand and Salamagne [Fucus vesiculosus on soybean plants grown in the field. It was noted that it promoted the growth of vegetative  and increased pod formation, thus causing an increase in crop yield [Spinacea oleracea L.) which improved the crop yield and nutritional value.Furthermore, phenolic compounds have been shown to promote shoot lengthening by stimulating the synthesis and deposition of lignin on cell walls and cause an increase in the activity of photosynthetic pigments  in plants. In an experiment performed by Rengasamy  on maizealamagne  also evaop yield . Kulkarnop yield  reportedPlants, as sessile organisms, are constantly exposed to abiotic and biotic stress which disrupt plant metabolism, cause stunted growth, alter plant genetic composition, and cause a reduction in crop yield globally by approximately 50 percent and 30%, respectively . AbioticDrought is an environmental stress factor that occurs due to inadequate moisture in the soil as a result of dry weather or scarcity of surface and underground water. The effect of drought as evidenced in all the stages of plant growth and development includes a reduction in plant growth parameters , reduced germination rate, loss of cell turgor, accumulation of reactive oxygen species, and impairment of cell division which eventually reduce crop yield and availability to the population ,69. p-hydroxybenzoic acid via foliar application increased the total chlorophyll, total carotenoid content, and total antioxidant capacity thereby reversing the damaging effect of drought in treated rice plants [The use of phenolic acids to improve plants’ resistance to drought stress has been reported ,70. Accoe plants ,72. Salinity is abiotic stress due to the buildup of salt especially sodium chloride in the soil. The common causes of salinity are human activities , climate change, land topography, rock weathering, and seawater deposit. Salt stress causes an accumulation of sodium and chloride ions in the leaves, as well as a decrease in the concentrations of phosphate, calcium, nitrogen, potassium, and magnesium ions. This increases the production of free radicals, disrupts ion balance, causes osmotic imbalance, and alters metabolic processes, ultimately leading to stunted growth and a massive reduction in crop yield . +/K+ balance by stimulating the absorption of potassium ion and preventing the accumulation of sodium ion; and the activity of important regulatory enzymes such as proline dehydrogenase and pyrroline-5-carboxylate synthase which increases proline synthesis and the relative water content [Exogenous application of phenolic compounds has been shown to reverse the detrimental effects of salinity in plants and different types of phenolics have been quantified in seaweed. Babich  isolated content .In a study conducted by Ozfidan-Konakci , 0.75 anExtreme temperature is a significant abiotic stress factor that influences all stages of plant development  because all the metabolic processes within the plant cell are temperature-dependent. The impact of rapidly increasing temperatures on crop yields has become more frequent and intense, especially in Africa, which is expected to warm faster than the rest of the world, with an increase in the average temperature of 3–6 °C by the end of the century . AlthougPhenolic compounds have been shown to prevent the adverse effect of temperature extremities in plants and these compounds have been detected in seaweed.Agregán  identifiVaccinium corymbosum L. cv. Bluecrop) seedlings. It was observed that ferulic acid treatment enhanced the transcription of genes encoding the synthesis of the antioxidant enzymes , and increased the cellular concentration of proline and soluble sugars. The increased cellular level of antioxidant enzymes prevented the accumulation of reactive oxygen species while proline and soluble sugars increased the osmotic potential and relative water content in the cell, thus preventing the detrimental effect of heat stress in the blueberry plant [According to Cheng , exogenory plant . Exogenory plant .The effect of heavy metal stress on agricultural land due to the continuous application of fertilizers, mining, poor irrigation practices, and industrial waste is becoming a major concern globally. Recently, there has been a build-up of heavy metals such as cadmium, zinc, mercury, arsenic, lead, copper, nickel, and aluminum in the soil. Although some of these metals are needed by plants for various biochemical processes, high concentrations have the following adverse effect on plants: alteration of cell homeostasis, accumulation of reactive oxygen species, interruption of the electron transport chain, cell membrane damage, decrease in plant growth, and reduced crop yield . Turbinaria ornate and Turbinaria conoides.Phenolic compounds, known to prevent the damages caused in plants due to heavy metal stress, have been identified in different types of seaweeds. Chakraborty  detectedSeveral experimental works have been performed using phenolic compounds to mitigate the effect of heavy metal stress. For example, exogenous application of salicylic acid prevented the detrimental effect of nickel stress in mustard plants by enhancing the activities of the antioxidant enzymes and the glyoxylate enzymatic system  which improved photosynthesis and plant growth .+-ATPase, osmotic imbalance, decreased rate of photosynthesis, reduced crop yield, and plant death [Fungal diseases are more prevalent than other biotic stressors and have a greater negative impact on crop production. Fungal infections have been linked to some of the world’s greatest famines in history. An estimated 8,000 fungi species have been identified, accounting for more than 80% of post-harvest and pre-harvest infections . Fungi int death . p-hydroxybenzoic acid and protocatechuic acid in red seaweed , brown seaweed , and green seaweed ( Ulva sp.).The use of phenolics to mitigate fungal-induced physiological damages in plants has been reported. Zhong  identifiAlternaria solani by activating the enzymatic and nonenzymatic defense mechanism, which regulates cellular homeostasis, and antioxidant balance [These phenolics have been used to prevent early blight disease of tomato caused by  balance . The afo balance . Table 2Plant bacterial infections are less common than fungi infections, but they are also economically significant. There are approximately 200 pathogenic bacteria species known to cause plant diseases, and they can be classified as endogenous bacteria which infect the xylem and phloem tissues, thus interrupting the transportation of water and nutrients within the plant, or exogenous bacteria, which mainly infect the intercellular spaces (apoplast) .Phytopathogenic bacteria are transmitted to plants through a variety of means, including water, wind, insects, animals, and humans; however, they require openings such as stomata or wounds to penetrate the host plant. Once inside the plant, they cause diseases by synthesizing enzymes that degrade the host cell membrane and cell wall, and injecting toxins and proteins that lead to the death of the host cell . Phenolic compounds can be used to reverse the detrimental effect of pathogenic bacteria in plants  and thesRalstonia solanacearum infection in tobacco plants by preventing the expression of epsE and lecM genes and the formation of biofilms. In vitro, caffeic acid enhanced the activity of the enzyme phenylalanine ammonia-lyase and peroxidase, which led to the accumulation of hydroxyproline and lignin.According to Li  exogenouViral infections pose a significant challenge in agriculture due to their ability to undergo mutations and produce new variants rapidly. Furthermore, viral infections are difficult to comprehend due to the wide range of symptoms seen in host plants. Viral infections are only transmitted via vectors humans or insects, and they penetrate the host plant through wounds . Viral iGlycine soja) to soybean mosaic virus by stimulating the synthesis of antioxidant enzymes  and promoting the transcription of resistance-related genes  in the host plant. This clearly demonstrates a knowledge gap that should be addressed in future research studies.Apart from salicylic acid, the use of phenolic compounds to regulate plants’ resistance against viral infections remains scant. Zhang  showed tHerbivores and insects pose a significant threat to plant growth and development causing approximately a 15 percent loss in crop yield annually. They further create avenues for subsequent infection by phytopathogens which increases the severity of their attack .Camellia sinensis) triggered the phenyl propanoic and jasmonic acid signaling pathway which protected the plant from herbivore attack (Ectropis obliqua Caterpillars) by enhancing the synthesis of three antifeeding metabolites, namely epigallocatechin-3-gallate, naringenin, and naringenin [Exogenous application of gallic acid to tea plants (ringenin . These pringenin ,107. Exoringenin . Accordiringenin , kaempferingenin .This review illustrates the wide range of phenolic compounds present in seaweed and highlight their agricultural importance for improved plant growth and enhanced tolerance against various abiotic and biotic stress factors. The continuous use of synthetic phenolic compounds to improve plant growth whilst minimizing the negative effects of stress conditions is no longer a viable option due to its deleterious effects on human health and the environment. The use of natural phenolic compounds derived from seaweed to improve plant growth and stress tolerance could diminish the use of synthetic chemicals thus limiting the harmful impact on the environment and improve agricultural outputs in a sustainable manner.It is worth noting that although phenolic compounds have been identified in seaweed, their downstream application in agriculture remains limited. To date, most research has focused on the use of synthetic phenolic compounds instead of natural phenolic compounds to improve plant growth and enhance plant immunity/resilience. Therefore, more research on natural phenolic compounds is encouraged to obtain a holistic understanding of their modes of action for improved plant growth and enhanced stress tolerance especially in economically important food/feed crops.