Plastics have outgrown the majority of artificial materials and have long been scrutinized by environmentalists. However, reliable global data are scarce, notably about their end-of-life fate. We present the first global analysis of all mass-produced plastics generated by locating and synthesizing dispersed data on production, usage, and end-of-life management of polymer resins, synthetic fibers, and additives. To date, 8300 million metric tons (Mt) of virgin plastics have been created, according to our estimates. In 2015, over 6300 Mt of plastic garbage was generated, with approximately 9% was recycled, 12% was burnt, and 79% ended up in landfills or the natural environment. By 2050, over 12,000 Mt of plastic garbage will be in landfills or the natural environment if present manufacturing and waste management patterns continue.
Plastics, or synthetic organic polymers, are ubiquitous in today’s society, but their large-scale manufacturing and use date only from 1950. Although the first synthetic plastics, such as Bakelite, were developed in the early twentieth century, widespread use of plastics outside the military did not begin until after World War II. Since then, plastics production has grown at an incredible rate, outpacing most other artificial materials. Steel and cement, commonly utilized in the building industry, are notable outliers (1, 2).
Instead, the most significant market for plastics is packaging, which has accelerated due to a global move away from reusable to single-use containers. As a result, the proportion of plastics in municipal solid trash (by mass) in the middle- and high-income countries climbed from less than 1% in 1960 to more than 10% by 2005. (3). At the same time, worldwide solid waste creation has increased significantly over the last five decades (4, 5), which is highly connected with gross national income per capita.
The great majority of plastic monomers, such as ethylene and propylene, are made from fossil hydrocarbons. Biodegradability is not a feature of any of the regularly used polymers. As a result, they collect in landfills or the natural environment (6). Only destructive heat treatment, such as fire or pyrolysis, can permanently eradicate plastic trash. As a result, near-permanent plastic trash contamination of the natural environment is becoming a growing concern. Plastic debris has been discovered in all major ocean basins (6), with an estimated 4 to 12 million metric tons (Mt) of land-based plastic garbage entering the marine environment in 2010. (3). Environmental contamination with synthetic fibers and contamination of freshwater systems and terrestrial habitats is becoming more common (7–9). Plastic garbage has become so pervasive in the environment that it has been recommended as a geological indicator of the Anthropocene epoch (11).
We present the first global analysis of all mass-produced plastics ever made by generating and merging global data on the manufacture, usage, and end-of-life fate of polymer resins, synthetic fibers, and additives into a comprehensive material flow model. The study looks at thermoplastics, thermosets, polyurethanes (PURs), elastomers, coatings, and sealants. Still, it focuses on the most common resins and fibers: high-density polyethylene (PE), low-density and linear low-density PE, polypropylene (PP), polystyrene (PS), polyvinylchloride (PVC), polyethylene terephthalate (PET), and P To improve the material’s characteristics, the pure polymer is combined with additives.
RESULTS AND DISCUSSION
Global resin and fiber output increased from 2 Mt in 1950 to 380 Mt in 2015, representing an 8.4% compound annual growth rate (CAGR) (table S1), almost 2.5 times the CAGR of global gross domestic product (12, 13). From 1950 to 2015, 7800 Mt of resins and fibers were produced, half of which (3900 Mt) was created in just the last 13 years. China produces 28 percent of global resin and 68 percent of global PP&A fiber (13–15). On the other hand, bio-based or biodegradable plastics have a global production capacity of only 4 Mt. Hence they are not included in this study (16).
We gathered resin, fiber, and additive production figures from various industry sources and synthesized them by type and consuming sector (table S2 and figs. S1 and S2) (12–24). Data on the manufacture of fibers and additives is scarce and has often been ignored until recently. Nonfiber plastics have 93 percent polymer resin and 7% additives by mass on average. When additives are factored in, the amount of non-fiber plastics (hereafter defined as resins plus additives) produced since 1950 rises to 7300 Mt, with PP&A fibers accounting for another 1000 Mt. Plasticizers, fillers, and flame retardants account for around three-quarters of all additives (table S3). PE (36%) is the most common non-fiber plastic, followed by PP (21%) and PVC (12%). PET, PUR, and PS each account for 10% of total non-fiber plastics manufacturing. Polyester accounts for 70% of total PP&A fiber output, the majority of which is PET. These seven organizations are responsible for 92 percent of all polymers ever produced. Packaging has accounted for around 42% of non-fiber plastics, with PE, PP, and PET being the most common. The building and construction sector, which consumes 69 percent of all PVC, is followed by the non-fiber plastics industry, which consumes 19 percent of all non-fiber plastics (table S2).
To simulate how long plastics remain in use until they reach the end of their usable lifespan and are disposed of, we merged plastic production data with product lifetime distributions for eight major industrial use sectors or product categories (22, 25–29). For packing, we used log-normal distributions with means ranging from less than a year to decades for building and construction. This is a popular modeling technique for calculating waste generation for specific materials (22, 25, 26). Combining solid waste generation statistics with waste characterization information, as Jambeck et al. did, provides a more direct technique to measure plastic trash generation (3). However, these data are not available in the detail and quality required for the current research for many nations.
In 2015, we estimate that 407 Mt of primary plastics (plastics made from pure ingredients) went into usage, while 302 Mt went out. As a result, 105 Mt were added to the in-use stock in 2015. In contrast, we estimate that plastic garbage creation in 2010 was 274 Mt, the same as Jambeck et al. independent .’s estimate of 275 Mt. (3). Because of the varying product lifetimes, there is a significant movement in the industrial use sector and polymer type when plastics enter and leave usage (tables S4 and S5 and figs. S1 to S4). For example, most packaging plastics are no longer used the same year they are manufactured, whereas construction polymers were manufactured decades ago when production volumes were significantly smaller. In 2015, for example, 42 percent of primary non-fiber plastics produced (146 Mt) went into the packaging, and 19 percent (65 Mt) went into the building. In contrast, non-fiber plastic waste went into 54 percent packaging (141 Mt) and just 5% construction (12 Mt). Similarly, PVC was responsible for 11% of non-fiber plastics production (38 Mt) but only 6% of non-fiber plastic trash output in 2015. (16 Mt).
By the end of 2015, total plastic waste generated from primary plastics had reached 5800 Mt, with PP&A fibers accounting for 700 Mt. Plastic garbage can end up in one of three main places. First, it can be recycled or converted into a secondary substance in the first place (22, 26). Instead of avoiding eventual disposal, recycling postpones it. Only if it displaces primary plastic manufacturing (30) does it minimize future plastic trash generation; however, due to its counterfactual character, this displacement is extremely difficult to show (31). Contamination and polymer mixing also produce secondary polymers with restricted or low technical and commercial value. Second, plastics can be thermally damaged. Although new technologies are emerging, such as pyrolysis, which extracts fuel from plastic trash, practically all thermal destruction has been accomplished through incineration, with or without energy recovery. The environmental and health effects of waste incinerators are heavily influenced by emission control technology and the design and operation of the incinerator. Finally, plastics can be dumped and managed, such as in sanitary landfills or left unmanaged in open dumps or the natural environment.
We estimate that 2500 Mt of plastics is currently in use, accounting for 30% of all plastics ever created. Between 1950 and 2015, 6300 Mt of primary and secondary (recycled) plastic garbage was generated, with around 800 Mt (12%) being burnt and 600 Mt (9%) being recycled, with only 10% being recycled more than once. Thus, around 4900 Mt of plastics were thrown, accounting for 60% of all plastics ever created, and are now accumulating in landfills and the natural environment. PP&A fibers accounted for 600 Mt of this total. None of the mass-produced plastics deteriorate in any significant way; nonetheless, sunshine weakens the materials, producing fragmentation into millimeter- or micrometer-sized fragments (32). In recent years, research into the environmental implications of these “microplastics” in marine and freshwater habitats has intensified (33). Still, little is known about the impacts of plastic debris in terrestrial ecosystems.
Plastic recycling and incineration were almost non-existent before 1980. Only non-fiber plastics have been subjected to considerable recycling efforts since that time. The following findings solely pertain to non-fiber plastic trash: In 2014, global recycling and incineration rates accounted for 18 and 24 percent of non-fiber plastic waste created, respectively (figs. S5 and S6). Based on the limited data available, Europe (30%) and China (25%) had the most effective recycling rates in 2014, while plastic recycling in the United States has stayed stable at 9% since 2012 (12, 13, 34–36). Incineration rates in Europe and China have risen over time, reaching 40 and 30 percent, respectively, in 2014 (13, 35). In the United States, however, non-fiber plastics incineration peaked at 21% in 1995 before falling to 16% in 2014 as recycling rates grew, but disposal rates remained constant at 75% over that time (34). According to waste management data from 52 other nations, the remainder of the world had recycling and incineration rates equivalent to the United States in 2014. (37). End-of-life textiles (fiber products) currently have low recycling rates and are therefore burnt or disposed of with other solid trash.
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Primary plastics manufacturing data show a consistent time pattern throughout its existence. By the year 2050, humanity will have generated 26,000 Mt of resins, 6000 Mt of PP&A fibers, and 2000 Mt of additives if production continues at this rate. If present global waste management trends continue, 9000 Mt of plastic trash will be recycled, 12,000 Mt will be burnt, and 12,000 Mt will be thrown in landfills or the natural environment by 2050 (fig. S7).
Any material flow analysis of this nature necessitates several assumptions or simplifications, which are listed in Materials and Methods, and is subject to considerable uncertainty; as a result, all cumulative effects are rounded to the nearest 100 Mt. The most significant sources of uncertainty are the lifetime distributions of the product categories, as well as plastic incineration and recycling rates outside of Eurozone. By changing the mean lives of all product categories by one standard deviation, the cumulative primary plastic waste generation (from 1950 to 2015) goes from 5900 to 4600/6200 Mt, or by 4/+5%. By increasing/decreasing current worldwide incineration and recycling rates by 5% and changing time trends correspondingly, the total discarded plastic trash goes from 4900 Mt (from 1950 to 2015) to 4500/5200 Mt, or by 8%/+6%.
Plastics production has grown at a faster rate than any other industrial material in the last 65 years. Unfortunately, plastics’ durability and resistance to deterioration, which make them so valuable for many uses, make them difficult or impossible for nature to digest. As a result, without a well-designed and tailored end-of-life plastics management strategy, humans are performing a single uncontrolled experiment on a global scale, in which billions of metric tons of material will collect throughout all significant terrestrial and marine ecosystems on the world. Therefore, the relative advantages and disadvantages of dematerialization, substitution, reuse, material recycling, waste-to-energy, and conversion technologies must be designed to design the best solutions to the environmental challenges posed by the enormous and sustained global growth in plastics production and use carefully considered.
MATERIALS AND METHODS
The Plastics Europe Market Research Group published global annual pure polymer (resin) production statistics from 1950 to 2015 and yearly global fiber production data from 1970 to 2015, which were both published by The Fiber Year and Tecno OrbiChem (table S1). The resin data closely followed a second-order polynomial temporal trend, yielding an R2 = 0.9968 fit. The fiber data closely followed a third-order polynomial secular trend, delivering an R2 = 0.9934 fit. Annual market and polymer statistics for North America, Europe, China, and India (table S2) were used to generate global breakdowns of total output by polymer type and industrial use sector (12, 13, 19–24). For the years 2002 through 2014, data from the United States and Europe are available. As a result, polymer production is broken down by polymer type and industrial use industry comparable across countries and regions.
Data on global additives production, which isn’t publicly available, was obtained from market research firms and cross-checked for accuracy (table S3) (17, 18). Data on additives are available from 2000 to 2014. Polymer production and additions to polymer fraction breakdowns by polymer type and industrial use sector were both stables across the period for which data were available and assumed constant throughout the modeling period of 1950–2015. The reduced production rates in those years offset any faults made in the early decades. The polymer data was combined with the additive data classified by additive type and industrial application sector. The number of primary plastics (polymers + additives) generated in year t and utilized in the industry is denoted by Pi (t).