Impact statement
This article presents a new theory for addressing the wicked problem of plastic pollution. We frame this theory as an archaeological conundrum whereby plastics represent a significant threat to environmental and planetary health, while constituting a potentially important archive of the contemporary world, representing a period of significant social and environmental change. Archaeology involves the study and interpretation of material as evidence of past human behaviours. Yet until recently, plastics have not been subject to archaeological investigation, even though archaeologists recognised the existence of a Plastic Age. This article promotes a theoretical framework for investigating plastics as archaeological remains, and highlights the benefits of incorporating archaeological approaches and methods into the wider and already interdisciplinary field of plastic pollution research.
Introduction
While plastics have been studied using the methods and perspectives of many disciplines, gaps remain in our knowledge of how they form an archaeological record of the Plastic Age. For example, while many studies have investigated the distribution of plastics by cultural behaviours in a global environment increasingly driven by anthropogenic factors (e.g., Evans et al., Reference Evans, Parsons, Jackson, Greenwood and Ryan2020; Kedzierski et al., Reference Kedzierski, Frère, Le Maguer and Bruzaud2020; Abrahms-Kavunenko, Reference Abrahms-Kavunenko2023; Voronkova et al., Reference Voronkova, Richter, Henderson, Aruta, Dumbili, Wyles, Pahl, Fleming, Alcantara Creencia, Gerwick, Goh, Gribble, Maycock and Solo-Gabriele2023), the emphasis of these studies is nearly always on the environmental problems that plastics create. Yet, few attempts have been made to explore how plastics, and the behaviours responsible for their distribution, produce an archive that may hold some historical and evidential value for society. Equally, there is, as yet, no overarching theory that encompasses how plastics enter the geosphere, the biosphere (after Vernadsky, in Samson and Pitt, Reference Samson and Pitt2012) and the cosmosphere. In our view, this lack of an overarching theory is an impediment to devising effective methods for managing the many impacts of the Plastic Age. Such an overarching theory is presented here, recognising plastics as resilient, toxic and ubiquitous. The theory applies an archaeological lens, viewing plastics from a landscape perspective (in the broadest sense, to include, e.g., space and the deep oceans) and through time, incorporating past (from 1950, at the start of the Plastic Age), present and future, including the deep future. Such a theory also ensures that plastics are not viewed in isolation but rather as being entangled with other materialities and contexts, including consumerism, fossil fuel extraction, climate change and waste. To investigate plastics in any environment is effectively to view an archaeological record already in existence, but also one in the making, given that all plastics fall out of use eventually, with most becoming incorporated into geological and biological systems.
To initiate the building of this theory, we revisit an influential concept from the ‘New Archaeology’ of the 1960s and 1970s and demonstrate how it can be used to study the Plastic Age. Specifically, we frame this study around Schiffer’s behavioural archaeology (e.g., and notably, Schiffer, Reference Schiffer1976), which challenged the prevailing view of the time that the archaeological record was a transparent and literal ‘fossil record’, which archaeologists could ‘read off’ to understand the worldview of the people whose artefacts they were studying. As is now widely accepted, archaeological sites and artefacts of any period undergo post-use modification through diverse cultural and natural processes. Schiffer called these c-transforms and n-transforms, respectively. These modifications break the one-to-one relationship between material remains and human behaviours. Schiffer argued that the archaeological record does reflect past human behaviours, but also everything that has happened to the site or landscape since humans of one era abandoned it to those who came after them. Therefore, these transformational processes are also a vital part of the archaeological record.
As with artefacts of any period, the moment a plastic object ceases to be used and is discarded, it enters the archaeological record, comprising material culture that represents human activities occurring at any time in the past. Schiffer called the circumstances of an artefact’s use ‘the systemic context’, and its fate after discard ‘the archaeological context’. However, the dividing line between them is not always clear. Discarded plastics are sometimes collected and reused—for example, to create packaging, fabrics, artworks, jewellery and other everyday items. Reuse in the ‘afterlife’, therefore, becomes a part of the object’s story, or itinerary (after Joyce and Gillespie, Reference Joyce and Gillespie2015). Degradation is also part of this story and can occur in the systemic context through wear-and-tear, but more commonly in the archaeological context (through various c- and n-transforms). In the case of plastics, this ultimately leads to the proliferation of micro and nanoparticles of plastic, just as, for early human societies, flaked stone tools or ceramic sherds will gradually fragment, albeit at variable rates depending on how robust and resilient the materials are and on the transforms that are impacting them.
Using an interdisciplinary approach and emphasising plastics as ‘type fossils’, this article will review the evidence for the formation processes that are creating and reconfiguring the archaeology of the Plastic Age (see Godin et al., Reference Godin, Pétursdóttir, Praet and Schofield2025; Praet et al., Reference Praet, Schofield and Tamoria2024, and see also Gabbott and Zalasiewicz, Reference Gabbott and Zalasiewicz2025, on other types of technofossil that are being created in the Plastic Age). In so doing, we also address the archaeology of the future (e.g., Holtorf and Högberg, Reference Holtorf and Högberg2021a).
In summary, while knowledge exists of how much plastic survives in the environment (see below), a deeper understanding is needed of how human behaviours create this archaeological record (e.g., Mytum and Meek, Reference Mytum and Meek2021), and then transform it, with a view to mitigating the impacts of the Plastic Age on the environmental systems that sustain earthly life. Establishing the foundations of a new overarching theory seems like a necessary and arguably critical intervention.
What is the archaeological record?
Archaeology is typically defined as the study of how people in the past engaged with their world, through the scientific investigation of what they left behind (Schofield, Reference Schofield2024, 4), or, as Olivier (Reference Olivier2011), xv) describes it, the ‘imprint of the past inscribed in matter’. ‘The past’ is defined by archaeologists as the entire period during which people have existed, from circa 2.8 million years ago until the present moment. That said, archaeologists are also now reflecting on the future (e.g., Holtorf and Högberg, Reference Holtorf, Högberg, Holtorf and Högberg2021b). The imprint of the past survives mostly as artefacts that form assemblages of associated material culture, often existing within an archaeological context of additional evidence, such as palaeoenvironmental remains, that indicate the local environment at the time of occupation. Some artefacts can be directly dated, by methods such as radiocarbon or other isotope dating (known as ‘absolute dating’), while others are dateable by association (‘relative dating’) because a similar artefact type, or key information about the artefact type, is already known and dated from elsewhere, or because another dateable artefact type was found in the same context. With plastics as a category of contemporary material culture, larger items (macroplastics) can often be dated directly according to dates printed on the item if these survive, while relative dating may use distinct morphological characteristics or a design element or logo that has a very specific date range. Equally, for these and for smaller items, there are plastics with distinct morphological characteristics, polymer chemistry and design that can render them reliable stratigraphic indicators (e.g., Zalasiewicz et al., Reference Zalasiewicz, Waters, Ivar do Sul, Corcoran, Barnosky, Cearreta, Edgeworth, Gałuszka, Jeandel, Leinfelder, McNeill, Steffen, Summerhayes, Wagreich, Williams, Wolfe and Yonan2016; Bancone et al., Reference Bancone, Turner, Ivar do Sul and Rose2020).
Returning to the origins of a more contemporary archaeology, in recent years, and arguably since the 1970s, when a turn towards a more scientific (‘New’) archaeology first drew archaeologists towards investigating the contemporary world (e.g., Rathje, Reference Rathje1979), most archaeologists have extended their definition of archaeology to the study of how all people across the full period of human history engage with their world, and how to investigate these complex and multifaceted relationships through studying material culture (e.g., Graves-Brown, Reference Graves-Brown2000; Buchli and Lucas, Reference Buchli and Lucas2001; Harrison and Schofield, Reference Harrison and Schofield2010; Gorman and O’Leary, Reference Gorman, O’Leary, Graves-Brown, Harrison and Piccini2013). As a result, archaeology has quickly and inevitably become more activist, interdisciplinary and socially relevant than it was before. For example, archaeologists now engage routinely with Indigenous land claims (Smith et al., Reference Smith, Burke, Ralph, Pollard, Gorman, Wilson, Hemming, Rigney, Wesley, Morrison, McNaughton, Domingo, Moffat, Roberts, Koolmatrie, Willika, Pamkal and Jackson2019), and issues such as climate change discourse (e.g., Schofield, Reference Schofield2024), while archaeologists and cultural heritage scholars have increasingly turned their attention towards various forms of toxic heritage (e.g., Kryder-Reid and May, Reference Kryder-Reid and May2024).
Archaeologists have traditionally characterised earlier periods of human cultural evolution according to the dominant materials used in technology, such as stone or metals. The dates and distributions of these ‘Ages’ have varied widely across the world. For example, the so-called ‘Stone Age’, while used to describe the material culture of the earliest hominin sites on the African continent, has not ended everywhere, as flaked stone is still the most efficient technology in some contexts. Similarly, the Iron Age has significant chronological and geographical variation. However, the current Plastic Age is effectively universal, beginning almost everywhere in the 1950s when single-use plastics came into common usage. This ubiquity, as well as the toxicity of plastics alongside other contaminants, invites a reappraisal of traditional perspectives on the archaeological record. To reflect on the theory, before introducing some examples and instances of these developments, we return to some of the ideas that dominated archaeological theory in the 1970s and 1980s, noting that the sources selected here form part of a much wider and often contested literature.
Schiffer’s (Reference Schiffer1972) Archaeological Context and Systemic Context offered a flow model by which to view the life history or processes of any material elements that characterise a society. The processes he suggested were: procurement, manufacture, use, maintenance and discard. The model was created with artefacts such as stone tools and ceramic pottery sherds in mind. However, we can apply it equally well to plastics.
One of the key purposes of Schiffer’s model was to challenge the view that the spatial patterning of archaeological remains represents patterning of past activities, which in turn reflect human behaviours (e.g., Binford, Reference Binford1964, 425; see also Binford Reference Binford1981). Rather, as Schiffer (Reference Schiffer1972, 156) states: ‘Clearly this is not always the case’. In fact, this is often not the case with plastics, especially when it comes to the influence of ocean currents or orbital dynamics in redistributing materials around the world. Such discrepancies between the distribution of artefacts and the activities that those artefacts represent always present an interpretive challenge to archaeologists. Much of what archaeologists do is to address this discrepancy. Schiffer (Reference Schiffer1972) describes his model as providing the conceptual system that explains how the archaeological record is formed, highlighting that it has both cultural and non-cultural (later defined as natural) components. Stating the model in its simplest form:
Between the time artefacts were manufactured and used … and the time these same objects are unearthed by the archaeologist, they have been subjected to a series of cultural and noncultural processes which have transformed them spatially, quantitatively, formally and relationally … If we desire to reconstruct the past from archaeological remains, these processes must be taken into account (Schiffer, Reference Schiffer1976, 11–12).
Again, this is as true for plastics as for earlier archaeological remains.
Schiffer developed these ideas into the concepts of c- and n-transforms, being the cultural and natural processes that give shape to the archaeological record (Schiffer, Reference Schiffer1976, Reference Schiffer1983). This middle-range theory bridged the gap between past activities and interpretation in the present. An example of a c-transform is agricultural ploughing, which might result in disturbing a buried land surface and distributing its artefacts across the field. An n-transform might be the action of water in transporting artefacts away from their original location. Collectively, the transforms are the taphonomy of the site, sometimes defined in geological terms as decay from the biosphere into the lithosphere (after Vernadsky, in Sansom and Pitt, 2012).
These ideas around formation processes have become highly influential in archaeological research into the deeper past (e.g., Shahack-Gross, Reference Shahack-Gross2017). They apply equally to archaeological records of the contemporary past, as well as to anticipated future behaviours and their material traces. Much of the contemporary archaeological record remains as yet unburied, as ‘surface assemblages’ (Harrison, Reference Harrison2011), while everything we do every day that involves materials (using objects and shaping places) is creating new surface assemblages as archaeological records.
In the following sections, we explore the processes that shape plastics as contemporary and future archaeological records. These include contexts as diverse as outer space, the remote oceans, the terrestrial atmosphere and living bodies. In this diverse set of contexts, the archaeological record of plastics is entirely without precedent.
Understanding how this archaeological record is formed can inform actions (in terms of both behaviours but also policy interventions) that can be taken to mitigate the impacts on the health of biological and environmental systems. We might say that, as a taphonomy, plastics are decaying from the technosphere into the biosphere and the geosphere, and it is this pathway that should be of interest across disciplines.
Plastics as an archaeological record
What are plastics?
The modern word ‘plastics’ refers to human-made materials, primarily composed of large organic molecules called polymers, which can be moulded into shape. Plastics are generally either thermoplastics, which are made of linear polymeric chains, or thermosets, which are made of cross-linked polymer networks. Only thermoplastics can be melted and remoulded. Thermosets are much harder to recycle, though innovation in this field is emerging (Wu et al., Reference Wu, Hartmann, Berne, De Bruyn, Cuminet, Wang, Zechner, Boese, Placet, Caillol and Barta2024). Plastics also typically contain chemical additives to enhance their properties, such as flexibility, heat and light resistance (Hahladakis et al., Reference Hahladakis, Velis, Weber, Iacovidou and Purnell2018).
While there are hundreds of different types of plastics, mass production is dominated by just eight kinds, which together account for more than 90% of the global plastic waste generation (after OECD, 2022). These are polypropylene, low- and high-density polyethylene, polyethylene terephthalate, polystyrene, polyvinyl chloride, polyurethane, and the synthetic fibre class mainly constituted of polyesters, polyamides, and polyacrylates. Other important plastics are polymethyl methacrylate (PMMA), a lightweight transparent thermoplastic often used to replace glass, and polytetraflouroethylene (PTFE or Teflon), often used for seals and non-stick coatings. Waste mismanagement leads to these materials reaching the environment (via the atmosphere, land, oceans and rivers) where they accumulate and degrade.
How much plastic is there, and how much of it becomes waste?
The global production of plastics is estimated by the UN Environmental Program to have increased exponentially over the past few decades to 400 million tons per year. Geyer et al. (Reference Geyer, Jambeck and Law2017) identify packaging as the largest use of plastics. About 85% of plastic ends up in landfills or is released to the environment. Annually, nearly 8 million tons of plastic waste end up in the marine environment through rivers. Some 5.25 trillion microplastic particles are estimated to be currently floating in the global ocean (Harris et al., Reference Harris, Maes, Raubenheimer and Walsh2023). The weight of plastic products will increase to 1,100 million tonnes by 2050 if the growth trend continues, although an increasing proportion is biodegradable. Approximately 1.14 million tons of biodegradable plastics were produced in 2022 (Omura et al., Reference Omura, Isobe, Miura, Ishii, Mori, Ishitami, Kimura, Hidaki, Komiyama, Suzuki, Kasuya, Nomaki, Nakajima, Tsuchiya, Kawagucci, Mori, Nakayama, Kunioki, Kamino and Iwata2024). All of this material constitutes part of the archaeological record, an archive characterising the Plastic Age (see Godin et al., Reference Godin, Pétursdóttir, Praet and Schofield2025).
Does size matter?
In the plastic pollution field, large items, that is anything bigger than 25 mm, are referred to as macroplastic, anything between 5 and 25 mm are mesoplastics, debris between 5 mm and 1 μm are called microplastics (Thompson, Reference Thompson, Bergmann, Gutow and Klages2015) and the smallest size range, below 1 μm, are typically referred to as nanoplastics. These definitions and size thresholds remain a subject of debate between different branches of science (including colloid science, environmental science, oceanography, chemistry and nanotechnology; e.g., Song et al., Reference Song, Wang and Li2024; see also Gigault et al., Reference Gigault, ter Halle, Baudrimont, Pascal, Gauffre, Phi, El Hadri, Grassl and Reynaud2018, Gigault et al., Reference Gigault, El Hadri, Nguyen, Grassl, Rowenczyk, Tufenkji, Feng and Wiesner2021, Lassen et al., Reference Lassen, Foss Hansen, Magnusson, Noren, Bloch Hartmann, Rehne Jensen, Gisel Nielsen and Brinch2015, Rani-Borges and Ando, Reference Rani-Borges and Ando2024, 4).
Microplastics are categorised as either primary or secondary. Primary microplastics include any plastic fragments or particles that are already 5 mm in size or less before entering the environment (Boucher and Friot, Reference Boucher and Friot2017). These include microfibres from clothing, microbeads, plastic pellets, powders and cosmetic products. Secondary microplastics arise from the degradation of larger plastic products through natural weathering processes after entering the environment. These processes, which include ultraviolet (UV) light, heat, winds and waves (Galgani et al., Reference Galgani, Hanke, Maes, Bergmann, Gutow and Klages2015), are the n-transforms that accompany the path of plastics from the systemic to the archaeological context. Such sources of secondary microplastics include water and soda bottles, fishing nets, plastic bags, microwave containers, tea bags and tyre wear.
The size of plastics is important because it dictates the kind of impact they can have, notably on living beings. For example: (i) macroplastics can have lethal consequences for animals as a result of entanglement, lacerations, lesions or blockades (Vanavermaete et al., Reference Vanavermaete, Lusher, Strand, Abad, Farré, Kallenbach, Dekimpe, Verlé, Primpke, Aliani and De Witte2024); (ii) mesoplastics are ingested by birds; (iii) microplastics are reportedly accumulating inside organs; and (iv) nanoplastics can cross cell membranes. The size of objects also partly determines how they respond to c- and n-transforms and their visibility and accessibility as an archaeological record.
How do plastics enter the archaeological record?
Harrison and Schofield (Reference Harrison and Schofield2010) describe how post-1950 discard differs from the prior archaeological record, listing a number of key new contributors. In addition to the introduction of new human-made materials (such as plastics), these new contributors include, for example, mass manufacture, mass discard, single-use objects, the growth of landfills, the wholesale demolition of buildings and infrastructure and an exponential increase in the mass of material use due to population growth.
Given this diversity, there are inevitably multiple pathways into the archaeological record. Edgeworth’s (Reference Edgeworth, Godin, Pétursdóttir, Praet and Schofield2025) overview of ‘how plastics get into the ground’, distinguished plastics deliberately buried as infrastructure (e.g., pipes and cables), plastics as litter, those incorporated into the agricultural treatment of soils, landfill and pollution (e.g., tyre and brake-pad degradation). Once in the archaeological record (i.e., post discard, whether deliberate or accidental), c- and n-transforms come into play.
Fishing provides a good example of an industrial pathway and the impact of c- and n-transforms on shaping the archaeological record. In terms of c-transforms, fishing fleets create plastic waste through lost or discarded fishing gear, ghost nets and the domestic waste thrown overboard due to the lack of storage space on board vessels (see Finska et al., Reference Finska, Ivanova, Jakobsen, Rapp Nilsen, Normann and Solski2022 for data related to waste management practices on fishing boats and legislative frameworks). In terms of scale, this is significant as fishing gear is estimated to contribute over 50% of plastic waste in some parts of the ocean (Apete et al., Reference Apete, Martin and Iacovidou2024; see also Li et al., Reference Li, Tse and Fok2016). This fishing waste is then distributed by n-transforms in the form of ocean currents.
Building on Edgeworth’s (Reference Edgeworth, Godin, Pétursdóttir, Praet and Schofield2025) observations, and characteristic of archaeologies of earlier periods, the subsurface (or pedosphere) provides an important context for plastics, where c- and n-transforms include agricultural activities (fertiliser applications, irrigation and ploughing), landfilling and water and wastewater treatment plant discharge. Secondary microplastics proliferate in the subsurface, resulting from the decomposition and weathering of macroplastics, car-tyre wear, degradation of furniture, washing of clothes (which leaks microfibres into wastewater), breakdown of litter and airborne dust (after Dong et al., Reference Dong, Yu, Huang, Gao and Gao2022; Guo et al., Reference Guo, Huang, Xiang, Wang, Li, Li, Cai, Mo and Wong2020; Haque and Fan, Reference Haque and Fan2023). Within the subsurface, plastics can move both horizontally and vertically, the transforms disrupting neat stratigraphic sequencing. For example, recent work in York has demonstrated the presence of microplastics in deeply buried archaeological deposits, likely to be the result of water discharge (Rotchell et al., Reference Rotchell, Mendrik, Chapman, Flintoft, Panter, Gallio, McDonnell, Liddle and Schofield2024a).
Archaeologists often distinguish human activities that occur ‘on-site’ from those occurring ‘off-site’ (after Foley, Reference Foley1981). On-site refers to key locations where people lived and worked, and where much of the archaeological evidence has therefore accumulated (Wagstaff, Reference Wagstaff and Schofield1991). Off-site is characterised by a low-density background scatter of human debris, representing more dispersed and less intensive activities. For the Plastic Age, on-site activities will include places where rubbish has accumulated through domestic use (e.g., in cities) and places of mass disposal (e.g., landfill). However, unusually, plastic waste also accumulates off-site. For example, vast accumulations of human waste from multiple locations mass in oceanic locations known as garbage patches (Lebreton et al., Reference Lebreton, Slat, Ferrari, Sainte-Rose, Aitken, Marthouse, Hajbane, Cunsolo, Schwartz, Levivier and Noble2018).
Waste is also accumulating both on- and off-site in extremely remote areas, such as in the cryosphere. There has been an awareness of fishing marine debris in Antarctica since the 1980s, and active monitoring since the early 1990s (Convey et al., Reference Convey, Barnes and Morton2002). Plastic equipment used at scientific stations, the clothing of scientists and support staff, wastewater treatment systems and polyethylene terephthalate (or PET)-based- wayfinding flags (an essential element of Antarctic establishments) all produce microplastics that are distributed in the Antarctic environment (Aves et al., Reference Aves, Revell, Gaw, Ruffell, Schuddeboom, Wotherspoon, LaRue and McDonald2022). This often involves deposition onto snow, which forms the ice sheet and ice shelves of Antarctica—the ultimate fates of which are either calving into the ocean or melting. Within this extreme environment, some studies suggest that plastics emerge from sea spray and are driven by wind to on-shore freshwater environments or onto glacier surfaces (González-Pleiter et al., Reference González-Pleiter, Edo, Velázquez, Casero-Chamorro, Leganés, Quesada, Fernández-Piñas and Rosal2020; González-Pleiter et al., Reference González-Pleiter, Lacerot, Edo, Pablo Lozoya, Leganés, Fernández-Piñas, Rosal and Teixeira-de-Mello2021).
Plastic is also a component of debris in Earth orbit, deep space and on planetary surfaces (Gorman, Reference Gorman, Godin, Pétursdóttir, Praet and Schofield2024; Olatunji, Reference Olatunji2024), meaning that the outer limit of the technosphere is coterminous with the furthest human spacecraft (Voyager 1). Plastics sent to space are designed to be robust in local conditions, such as temperature extremes and radiation exposure. They are widely used on spacecraft as internal insulation for delicate electronics and as external insulation in the form of aluminised Kapton polyimide blankets (Gorman, Reference Gorman, Godin, Pétursdóttir, Praet and Schofield2024). However, once discarded in space, these plastics rarely re-enter terrestrial systems of use and discard. In Earth’s orbit, there are an estimated 36,000 pieces of space junk over 10 cm in size, including defunct satellites, fragments of exploded spacecraft and mission-related debris (Cacioni, Reference Cacioni2022). Space junk weighs ~9,000 tons, but the proportion of plastic in this mass is unknown (NASA Orbital Debris Program Office, n.d., FAQ #3). The amount of plastic in Earth’s orbit has radically increased with the launch of thousands of satellites in mega constellations, such as Starlink. Debris under about 2,000 km in altitude is eventually drawn back towards Earth by atmospheric drag, where it incinerates in the atmosphere.
Finally, it is not just the plastics themselves that can be incorporated into the archaeological record. Plastics in the environment interact with their surroundings and are known to act as vectors for biota (Naik et al., Reference Naik, Naik, D’Costa and Shaikh2019), metals (Brennecke et al., Reference Brennecke, Duarte, Paiva, Caçador and Canning-Clode2016) and chemicals (Rodrigues et al., Reference Rodrigues, Duarte, Santos-Echeandía and Rocha-Santos2019). Although part of a broader concern for planetary mixing (e.g., water vectors, neobiota and industrial emissions), floating plastics can also act as a transport pathway for rafting marine species (González-Ortegón et al., Reference González-Ortegón, Demmer, Robins and Jenkins2024). This can change the species’ dispersal, allowing them to travel to new locations and extending their spatial distribution.
Redefining biota as an archaeological context
As well as being in the air, clouds, soil and rainwater, micro- and nanoplastics are also found in human and non-human biota (e.g., Leonard et al., Reference Leonard, Liddle, Atherall, Chapman, Watkins, Calaminus and Rotchell2024) and in the waste that bodies create (Rotchell et al., Reference Rotchell, Austin, Chapman, Atherall, Liddle, Dunstan, Blackburn, Mead, Filart, Beeby, Cunningham, Allen, Draper and Guinn2024b). Plastic particles routinely infiltrate biological bodies, meaning that components of all biota now contain a plastic decay product. This archaeological record exists inside the bodies of plants and animals, as no other artefact type has done before (unless we define geochemical traces as artefacts, in which case radiocarbon, strontium, lead, mercury, etc., will have preceded plastics as examples).
Plants and animals ingest plastics, some of which make their way out of the body during their lifetime, and others of which remain until the entity’s death, sometimes being the cause of it. Thus, animal and plant bodies bearing assemblages of plastics become archaeological sites in themselves, with archaeological ‘depth’ as a reflection of how far plastic particles have penetrated the different levels of the body. Living bodies size-sort plastics as efficiently as a river current, with layers of barriers sieving the particles to the point where nanoparticles pass through the cell membranes. While these plastics may or may not be attributable to a specific source, they will likely map onto the broader distribution of plastic producers and consumers.
The interaction of plastics with biota attracts significant research interest. However, there is insufficient evidence regarding long-term accumulation in the tissues or cells and the specific type of effects they may have on humans. Micro- and nanoplastics in aquatic environments integrate with biota and move through the food webs to accumulate in seafood organisms (Smith et al., Reference Smith, Love, Rochman and Neff2018), which are available for humans through their diet. Additionally, the localization of plastics in soil and potential accumulation in fruits and vegetables (Aydın et al., Reference Aydın, Yozukmaz, Şener, Temiz and Giannetto2023) represent another vector of micro- and nanoplastics distribution. The health effects on humans can vary depending on the size of the plastic particles. The potential risk increases with smaller particles <1 μm, which affect various organs, tissues and cells of human bodies. Studies have documented accumulation in fat tissue (Abbasi et al., Reference Abbasi, Soltani, Keshavarzi, Moore, Turner and Hassanaghaei2018), penetration through blood barriers (Leonard et al., Reference Leonard, Liddle, Atherall, Chapman, Watkins, Calaminus and Rotchell2024) and cell membranes (Järvenpää et al., Reference Järvenpää, Perkkiö, Laitinen and Lahtela-Kakkonen2022). The presence of microplastics in human faeces (Yan et al., Reference Yan, Liu, Zhang, Zhang, Ren and Zhang2021) can give an idea of further potential pathways. In summary, the main consequences of plastic and biota interaction include physical damage, chronic toxicity, cell damage and inflammation, inducing oxidative stress, among others (Wright et al., Reference Wright, Thompson and Galloway2013; Eltemsah and Bøhn, Reference Eltemsah and Bøhn2019).
How (and how far) do plastics degrade? How long will they last?
Plastics have only been around for seven to eight decades. Despite extravagant claims about their longevity, it is difficult to know exactly how long their degradation process will take and what their final form will be in archaeological records in the distant future. Once reduced to nanoplastics, will they forever stay in that form or decompose back to their monomer of origin or into even smaller molecules like CO2 and water? To start answering these questions, and replicate the long time frames present in archaeological contexts, scientists are using accelerated weathering experiments aiming to predict how long the degradation processes may take in different environmental matrices (e.g., under the sun, in seawater and in soil), with reported estimates spanning from decades to more than a thousand years (e.g., Chamas et al., Reference Chamas, Moon, Zheng, Qiu, Tabassum, Jang, Abu-Omar, Scott and Suh2020). The large variations seen in these forecasts are at least in part due to the fact that many variables, beyond the plastic type itself, influence degradation. For instance, one of the reported ways that plastics become integrated with the natural environment is through the genesis of plastiglomerates (Corcoran et al., Reference Corcoran, Moore and Jazvac2014), a new type of geological formation, such as pyroplastics, plasticrusts and plastitars, which represent the combination of plastics and solid particles (gravel, sand, silt and clay) under the influence of mechanical and chemical weathering. Resulting from n-transforms, plastiglomerates were recently found in the Canary Islands (Domínguez-Hernández et al., Reference Domínguez-Hernández, Villanova-Solano, Sevillano-González, Hernández-Sánchez, González-Sálamo, Ortega-Zamora, Díaz-Peña and Hernández-Borges2022) and in various locations in the Mediterranean (Saliu et al., Reference Saliu, Compa, Becchi, Lasagni, Collina, Liconti, Suma, Deudero, Grech and Suaria2023).
As we have seen, once they have entered the archaeological record, plastics break down into smaller debris under the action of mechanical friction, UV, temperature, in association with prolonged exposure to oxygen and water, and with the help of microorganisms, such as hydrocarbon-eating bacteria (Valenzuela-Ortega et al., Reference Valenzuela-Ortega, Suitor, White, Hinchcliffe and Wallace2023). These external factors challenge the integrity of plastics via both physical and chemical processes. In the former, plastics are cracked, chipped or abraded, while the latter refers to the breaking of chemical bonds via oxidation and hydrolysis reactions typically initiated by light or temperature. Entire scientific journals are dedicated to advancing our understanding of plastic degradation (e.g., Polymer Degradation and Stability), including in the context of recycling (e.g., Progress in Rubber, Plastics and Recycling Technology).
The decay of plastics in the archaeological record in space has not previously been specifically considered beyond the life of individual spacecraft, but is important for the sustainable use of space environments (e.g., Gorman, Reference Gorman2023, Reference Gorman, Godin, Pétursdóttir, Praet and Schofield2024). The plastics in Elon Musk’s red Tesla sports car, launched into solar orbit in 2018 and unshielded from radiation, will likely already be heavily degraded through radiation and interplanetary dust impacts (Gorman, Reference Gorman, Godin, Pétursdóttir, Praet and Schofield2024). On the Moon, it is expected that the famous nylon US flags at the six Apollo sites will have broken down under UV radiation. The Apollo landing vehicles were encased in aluminised Kapton blankets, which have been subjected to micrometeorite bombardment and dust abrasion (Gorman, Reference Gorman, Godin, Pétursdóttir, Praet and Schofield2024). This creates microplastics, which are now incorporated into the regolith of the sites. It is not known how long such plastics can be expected to survive on an airless world or in what ways they will have been broken into smaller particles, but they may now have a widespread distribution across the Moon.
What variables can influence degradation?
Most plastics are considered non-biodegradable because they can persist in the environment for many years; however, this could be a perception created by the short time span that we have available for observation. What is clear is that plastics, in terrestrial, extra-terrestrial and marine environments, break down into smaller particles through photo-, thermo- and/or biodegradation (Andrady, Reference Andrady2011) and through mechanical stress (e.g., wave action). Plastic formulations often include plasticisers (e.g., diethylhexylphthalate and bisphenol A) to increase flexibility and tensile strength. Under exposure to UV radiation, temperature changes and mechanical stress or when microorganisms attach to the plastic objects and fragments, these additives can leach out, weakening the plastic and leaving a distinct chemical signature (Rochman et al., Reference Rochman, Hoh, Kurobe and Teh2013; Magnusson and Norén, Reference Magnusson and Norén2014).
In the aquatic environment, plastics are often colonised by microorganisms (bacteria, microalgae, fungi and viruses), forming novel ecological habitats known as plastispheres (Zettler et al., Reference Zettler, Mincer and Amaral-Zettler2013). This phenomenon is considered to be a planetary-scale consequence of the Anthropocene. The algal bacterial biofilm that forms on the plastic surfaces attracts bigger organisms (such as Protista and invertebrates), leading to the establishment of multilayered biological deposits, which can affect the buoyancy of the plastics. As a result, plastic particles start to submerge and move from the surface to deeper water columns.
In the ocean water column, some bacteria secrete enzymes that can degrade polymers into monomers and oligomers. These marine processes are similar to those occurring in rivers or terrestrial environments (e.g., Yoshida et al., Reference Yoshida, Hiraga, Takehana, Taniguchi, Yamaji, Maeda, Toyohara, Miyamoto, Kimura and Oda2016). It has also been reported that some fungal species can degrade plastics, particularly polypropylene (Samat et al., Reference Samat, Carter and Abbas2023). Interestingly, recent studies suggest that newly developed biodegradable plastics (e.g., polylactic acid, or PLA) can be degraded by microorganisms in the deeper layers of the ocean, but with less efficiency compared to the coastal environment (Omura et al., Reference Omura, Isobe, Miura, Ishii, Mori, Ishitami, Kimura, Hidaki, Komiyama, Suzuki, Kasuya, Nomaki, Nakajima, Tsuchiya, Kawagucci, Mori, Nakayama, Kunioki, Kamino and Iwata2024).
In open space, plastics break down much more quickly. Atomic oxygen, common in Earth’s ionosphere, is highly damaging, as the single O atom bonds easily with the organics in plastic, breaking the chemical bonds. Ionising radiation breaks polymers up into intermediate products, such as free radicals and atomic elements (Aldas et al., Reference Aldas, Valle, Aguilar, Pavon, Santos and Luna2020, 2). In Low Earth Orbit, where the majority of spacecraft and space junk circulates, the synergistic effect of atomic oxygen corrosion and exposure to vacuum UV radiation has been described as having an ‘aggressive’ effect on polymers (Shuvalov et al., Reference Shuvalov, Tokmak and Reznichecnko2016, 442; see also Zhao et al., Reference Zhao, Shen, Xing and Ma2005). This deleterious effect, however, is utilised in additives to make plastics biodegradable by simulating the effects of atomic oxygen (Aldas et al., Reference Aldas, Valle, Aguilar, Pavon, Santos and Luna2020).
Planetary environments have specific factors that contribute to plastic degradation. On airless bodies, such as the Moon, Mercury, asteroids and comets, there is radiation exposure and impact gardening, creating an electrostatic charge and causing a constant turnover of the surface. External plastics, such as thermal insulation, would eventually break down under this bombardment. Mars is a high radiation environment as it has no magnetic field to protect it; it also has mechanical factors such as constant dust storms. On Venus, several USSR spacecraft successfully navigated the sulphuric acid-rich cloud decks to land on the surface with their internal plastics intact. If there are external plastics, slow dust abrasion may contribute to their degradation.
How do plastics move within the archaeological record?
As previously discussed, plastics enter the environment from terrestrial and aquatic pathways, including sewage and wastewater systems, riverine inputs, aquaculture and fishing activities. However, some of these pathways are poorly understood. In broad terms, the study of plastics has, to date, focused mostly on the hydrosphere, with far fewer analyses of the role of the subsurface (Haque and Fan, Reference Haque and Fan2023).
Within the marine environment, plastics, especially micro- and nanoplastics, behave as any other inert particle with specific buoyancy properties, depending on the currents and turbulence they are subjected to. Depending on hydrodynamic conditions in coastal areas, debris can be washed ashore, or it can sink to the seafloor in deeper ocean layers, as free-floating particles or embedded within dejections from aquatic organisms that have consumed them with their natural food. The fate of plastics in the abyssal environment, below 4,000 m, is unknown.
The transport and persistence of microplastics in the subsurface (the traditional domain for archaeological investigation) is influenced by a wide range of factors that need to be considered in interpreting their concentrations in soils and groundwater samples. These particular n-transforms are less well understood but include (after Dong et al., Reference Dong, Yu, Huang, Gao and Gao2022; Guo et al., Reference Guo, Huang, Xiang, Wang, Li, Li, Cai, Mo and Wong2020; Haque and Fan, Reference Haque and Fan2023) the following: (i) particle size, morphology, density and concentration; (ii) fauna and flora, including the presence of microorganisms; (iii) porous media and fluid properties; and (iv) aggregation, recognising that many of these factors are interrelated.
Contreras–Llin and Diaz-Cruz (Reference Contreras–Llin and Diaz-Cruz2024) found that microplastics are retained to different degrees within different mixtures of sand, compost, wood chips and clay, concluding that sand was the least effective in retaining them. This manifested in the distribution of microplastics (along the flow path) within reactive barriers, whereby upstream sediment contained the highest microplastic concentrations, except in barriers containing only sand, in which the most upstream sediments had the lowest concentrations. The microbial activity within porous materials with higher organic proportions, such as compost, was thought to add to the retention capacity and foster favourable conditions for microplastic breakdown. Whether or not microbes transform or degrade, the microplastic signature over time remains unclear. Sands and other highly permeable porous media are unlikely to retain an archaeological record of microplastics, whereas other porous media types may be more likely to. Some porous media likely provide a stronger record of load where microplastics change the properties of the media (e.g., Li et al., Reference Li, Wang, Zhu, Zhu, Yi and Fu2024b), such that an accumulation is encountered in horizons within the soil where the pore space (or void) has been interrupted through microplastic aggregation and clogging. Although this process has yet to be encountered in published field studies of groundwater systems, Li et al. (Reference Li, Huang, Wang, Cheng, Chen, Zhou, Xiao, Li, Du and Xu2024a) describe the types of controlling factors that are likely to affect microplastic transport and accumulation in porous media.
Progress on links between microplastic characteristics and causes, pathways and residence times is summarised by Lee et al. (Reference Lee, Cha, Ha and Viaroli2024) and Li et al., Reference Li, Huang, Wang, Cheng, Chen, Zhou, Xiao, Li, Du and Xu2024a. They report a lack of research into the pathways through which microplastics travel within groundwater systems, including the many mechanisms affecting their transport that differ from other groundwater-borne contaminants, including other colloids. He et al. (Reference He, McDonald, Zainab, Guo, Chen and Xu2024) analysed reports of microplastics within aquifers at various sites across the globe, finding that open groundwater sites (springs and karst systems) produced microplastics of higher abundance, larger particles and greater colour diversity relative to closed groundwater sites (other aquifer types). They also noted that microplastics in agricultural areas are more likely to be transparent, probably due to the mulches used. The lack of standardised detection protocols for assessing microplastic pollution of groundwater inhibits the current understanding of their characteristics attributable to specific causes (He et al., Reference He, McDonald, Zainab, Guo, Chen and Xu2024). This could also limit the utility of microplastic analyses in archaeological investigations.
An unresolved question is at what point microplastics become non-diagnostic. The composition of microplastics varies depending on the source and pathway through the subsurface (Li et al., Reference Li, Wang, Zhu, Zhu, Yi and Fu2024b). Given this, it is likely that the compositional signature of a sample can be traced to its origins, as is standard practice in modern environmental tracer studies (e.g., Cartwright et al., Reference Cartwright, Werner and Woods2019). An assessment by Lee et al. (Reference Lee, Cha, Ha and Viaroli2024) of polymer types encountered at field sites from across the globe showed that polypropylene and polyethylene were the most common. The composition of polymers showed wide variation between sites. The assessment of eight different polymers demonstrated specific signatures, although the list of polymer types found in groundwater is much larger. Lee et al. (Reference Lee, Cha, Ha and Viaroli2024) found that the variability in polymer types was likely related to the degree of contamination exposure, whereby sites of greater contamination tended to have a wider variability. More generally, the breadth of polymer types appears to be relatable to the land use, even if signatures specific to certain land-use types have not been defined in a systematic way.
Plastics move through sea ice in the Arctic and Antarctic regions, which are perhaps only a ‘temporary sink’ (Peeken et al., Reference Peeken, Primpke, Beyer, Gutermann, Katlein, Krumpen, Bergmann, Hehemann and Gerdts2018). Sea ice takes in microplastics present in the seawater, and the vertical composition then reflects microplastic concentrations in different locations as the sea ice forms during its drift. One study suggests long-range oceanic transport into the Arctic Ocean from the Atlantic and Pacific Oceans, and perhaps rivers, as well as localised inputs from increasing Arctic shipping traffic (Peeken et al., Reference Peeken, Primpke, Beyer, Gutermann, Katlein, Krumpen, Bergmann, Hehemann and Gerdts2018). Other studies suggest that sea ice contains higher concentrations of microplastics than the underlying seawater (Kanhai et al., Reference Kanhai, Gardfeldt, Krumpen, Thompson and O’Connor2020).
Plastics in space form their own ecosystem, with limited points of contact to the atmosphere and hydrosphere. These points of contact are objects, including trash, returned from crewed missions, reusable launch vehicles and space junk, which are robust enough to survive the re-entry process. Plastics in satellites or rocket stages in Low Earth Orbit, up to ~1,000 km above Earth, are eventually pulled back into the thermosphere to burn up. This process may take hundreds of years. Byproducts of atmospheric incineration are mostly soot and alumina. Burning plastics releases toxins, but their contribution to atmospheric pollution is likely to be negligible compared to the metal alloys that form the bodies of most rockets and satellites. The demise of the International Space Station will be a single event that will leave plastics scattered between space, the atmosphere and the ocean floor at Point Nemo. Point Nemo is a location in the South Pacific Ocean that is furthest from land in all directions. It has become a ‘spacecraft graveyard’ where space stations and other spacecraft are sent in controlled re-entries, where possible, to minimise environmental impacts.
Discussion: Plastics, archaeology and the noösphere
Our overarching theory of the contribution of plastics to a distinct archaeological record of the Plastic Age involves movement along two axes. Along a horizontal axis is the manufacture of plastics from raw materials to form objects and structures used by humans in industrial and domestic settings. At any moment in time, a portion of these plastics is in use in the systemic context, undergoing degradation from the wear and tear of daily use, and spatially concentrated at the ‘site’. Another portion is discarded, entering the archaeological context where both c-transforms (involving human behaviours around discard and waste) and n-transforms (the natural chemical and mechanical factors acting on the plastics) break them into ever smaller particles, which water, wind and other processes then transport ‘off-site’.
Along the vertical axis is the movement of plastic fragments and particles between the geosphere, hydrosphere, atmosphere and cosmosphere, the result of both c- and n-transforms. One could argue that other human-manufactured materials of the contemporary world are agents that are acted upon in the same way. Anthropocene theorists also recognise a technosphere: a system comprising all the objects manufactured by humans, calculated by geologist Jan Zalasiewicz (Reference Zalasiewicz2018) to weigh 30 trillion tons. Zalasiewicz calls it a system akin to biological systems, because it is in constant interaction with all human systems.
The unprecedented global distribution of plastic, coupled with its distinct material properties, creates a plastisphere that is deeply entangled with other threats to planetary health, such as the combustion of fossil fuels, consumerism and habitat destruction. We have identified the biota as a particular locus where plastics turn bodies into archaeological repositories. This could be called ‘a new state of the biosphere’, or the noösphere, as envisioned by Vladimir Vernadsky (Reference Vernadsky1938, 7).
The noösphere (Svoboda and Nabert, Reference Svoboda and Nabert1999; Vidal, Reference Vidal2024) represents an evolutionary stage where human cognition and technological progress align with the natural systems of the biosphere. It is ‘the reconstruction of the biosphere in the interests of freely thinking humanity as a single totality’ (Vernadsky, Reference Vernadsky1945, 9). The noösphere is driven by human labour and scientific thought, the reach of which spacecraft have now extended to the entire solar system. Plastics, more than any other material, represent this extension of human intentionality. Designed for convenience but with long-term environmental impacts, plastics have become omnipresent, embedding themselves into every layer of the biosphere. This has introduced a form of artificial, non-degradable material that fundamentally alters natural cycles, creating the plastisphere.
While examples of human efforts to align the noösphere with the biosphere can be seen in rewilding and nature restoration initiatives (e.g., Schmitz et al., Reference Schmitz, Sylvén, Atwood, Bakker, Berzaghi, Brodie, Cromsigt, Davies, Leroux, Schepers, Smith, Stark, Svenning, Tilker and Ylänne2023), where ecosystems or separate species are being rehabilitated and allowed to flourish, the plastisphere represents the darker side of human ingenuity. While positive environmental actions bring us closer to harmonising with the biosphere, the persistence of plastic in the environment challenges the notion of progress. It reflects the failure of the human species to fully grasp the long-term consequences of its innovations, stalling the attainment of the noösphere. As Zalasiewicz (Reference Zalasiewicz2018) points out, the biosphere is very good at recycling its materials, but not the technosphere, and plastics form a significant part of this non-renewal.
Conclusion
We argue that for plastics, as for other more recently introduced toxic contaminants, the environment is an archaeological record, existing as a vital archive of the Plastic Age. Equally, archaeological perspectives provide the foundation for an overarching theory incorporating novel and cross-disciplinary approaches to this Plastic Age. We have demonstrated this by highlighting a key theory in archaeological research: Schiffer’s (Reference Schiffer1972, Reference Schiffer1976, Reference Schiffer1983) notion of c- and n-transforms, which together define systemic and archaeological context and the vectors that move materials between and within them.
To arrest the negative impacts of plastics, the archaeological perspective suggests the need to focus interventions at the moment where plastics move from systemic to archaeological contexts. Interventions will inevitably be local, dependent on local behaviours and generating small wins (Schofield, Reference Schofield2024), but set within the global context of ‘spheres’—geo, bio, pedo, hydro, cosmo, techno and noö. On both of these levels, local and global, it is critical to ascertain whether the dominant influences are c- or n-transforms, in order to determine where mitigation efforts and archaeological research priorities are best placed.
This leads us to conclude with an ethical question, which we have not attempted to resolve with this study: that plastics represent a major challenge to environmental health; yet, they also provide an invaluable archive (an archaeological record, by our definition) comprising significant data on human behaviours throughout and of the Plastic Age (but see Shashoua, Reference Shashoua2024 for another perspective on this). With earlier archaeological remains, there is a presumption against their needless destruction, to ensure that valuable information about human agency is not lost without record. We, therefore, raise that same principle for plastics of the Plastic Age. As Shashoua (Reference Shashoua2024) also suggests, there is a need for a more nuanced approach that recognises the value of plastics in archaeological contexts while addressing the challenges they pose. Certainly, plastics represent waste that threatens environmental health, but they are also evidence of human activities and impacts at what is likely to prove a critical stage in human history. That does not mean that the types of plastics we describe in this article should necessarily be preserved. However, perhaps they should be treated more as an archive, and recorded in ways that allow for the analysis and interpretation of those human behaviours responsible for creating them. Plastics are an ‘archaeology of us’ (Gould and Schiffer, Reference Gould and Schiffer1981). Creating an archive of our impacts on this and other planets, and understanding how that archive relates to human behaviours, may prove critical to achieving planetary health in the future and to our aspirations for a noösphere that works towards the interests of humanity rather than against them.
Open peer review
To view the open peer review materials for this article, please visit http://doi.org/10.1017/plc.2025.10028.
Acknowledgements
This article is a Flinders University collaboration, and as such, we acknowledge the Kaurna people on whose land much of this research was undertaken. All of the authors are (or were at that time) based at Flinders, except for John Schofield and Fay Couceiro, both of whom (separately) received funding from the university to undertake visiting fellowships there in May/June 2024 on the subject of plastics. John and Fay are both grateful to Flinders University for this support. It was during the time of these fellowships that meetings involving all of the authors created the opportunity for and shaped this collaborative research. The authors are grateful to Rhiannon Van Eck (Marine Research Assistant in the Gillanders Aquatic Ecology Laboratory, School of Biological Sciences at The University of Adelaide) for designing and producing the graphical abstract.
Author contribution
JS and AG conceived the presented idea and devised the structure of the article. JS and AG led the writing of the paper, with specific thematic contributions from AA, FC, SL, MM, AS and AW. All authors contributed to the theory and the final manuscript.
Financial support
JS and FC both (separately) received funding from Flinders University to undertake visiting fellowships in May/June 2024 on the subject of plastics, contributing to the research that resulted in this study. Both are grateful to Flinders University for this support.
Competing interests
The authors declare none.
Open access
Comments
I am pleased to now be able to submit this paper for review. This contribution was commissioned (as one of two contributions on archaeology and plastics) on the recommendation of Professor Joanna Vince. I hope it meets with your expectations.