Bioplastics are a broad category of materials encompassing bio-based, biodegradable, or both bio-based and biodegradable plastics. They can be manufactured from diverse sources, including crops (e.g., corn, sugar cane, and, historically, cotton), wood pulp, fungi, and other bio-based feedstocks produced with the help of algae or microbes. Some bio-based plastics, such as polyhydroxyalkanoates (PHAs) and polylactic acid (PLA), are biodegradable under specific environmental conditions. Others, such as bio-polypropylene (bio-PP) and bio–polyethylene terephthalate (bio-PET), are also bio-based but are chemically equivalent to their conventional counterparts and do not biodegrade. Bioplastics can also include materials designed for biodegradation that are derived from fossil fuel–based rather than bio-based sources ([ 1 ]). Although bioplastics represent a small and growing segment within the industry, they are not a new idea and have a long history that is often overlooked or misunderstood.
The earliest iterations of industrial-scale molding materials date to the mid-1800s and were sourced from trees (e.g., resins, gums, and latex). Hard rubber and gutta-percha are two early examples. Later bio-based plastics were made using cellulose, including celluloid and viscose rayon (fiber) and cellophane (film). Despite their biological origins, these materials had consequences for human health and the environment, leading to displacement, deforestation, environmental degradation, and workplace hazards.
Popular accounts and even corporate advertisements from this era portray early-generation plastics relieving pressure on natural resources such as tortoise shell or ivory because they could imitate their appearance. For instance, celluloid, a nitrocellulose plastic industrialized in the 1870s, purportedly spared the elephant, especially from the billiard ball industry; however, market data show that celluloid did not decrease ivory demand, which grew in the years after celluloid's introduction. Less well known is how celluloid accelerated the demand for camphor, a tree product used as a solvent and plasticizer. The camphor market intensified as celluloid production expanded toward the end of the 19th century, when the burgeoning photography and cinematography industries required celluloid for film ([ 2 ]).
Camphor was distilled from the camphor laurel tree, a species of evergreen especially prevalent in Taiwan, where the imperial regimes of China, Britain, and Japan vied for control over its production. The camphor trade decimated Taiwan's forests and displaced its Indigenous communities—most notably the Atayal peoples, who resisted the commodification of their homelands ([ 3 ]).
Likewise, gutta-percha, a rubberlike tree resin harvested across the latter half of the 19th century in the Malay archipelago and throughout Southeast Asia, was used to insulate the growing network of undersea copper telegraphy cables so instrumental in administering the British empire. On average, a single tree would produce less than a pound of gum. In a matter of decades, the region's gutta-bearing trees were harvested to near-extinction ([ 4 ]).
Rayon fibers are another 19th-century technology based on chemically regenerated cellulose sourced from cotton, cotton linters (remnants of cotton production), or wood pulp. Multiple rayon processes were developed first in the UK and then elsewhere. In the US, the viscose process (also used to manufacture cellophane) was dominant by the Second World War, the era in which annual global rayon production exceeded 2 billion pounds ([ 5 ]).
The pursuit of rayon as a forest product, for example, resulted in clear-cut sections of the Tongass National Forest, a temperate rainforest in southeastern Alaska. After passage of the 1947 Tongass Timber Act, the US Forest Service offered 50-year timber contracts and subsidized the construction of two mills on the unceded lands of the Tlingit, Haida, and Tsimshian peoples. The first mill, built in Ketchikan, went online in 1952. The largest US rayon producer, American Viscose, had a considerable stake in the venture. Major Japanese manufacturers such as Mitsubishi Rayon, Kokoku Rayon, and Teikoku Rayon invested in the second mill built in Sitka.
But deforestation and displacement were not the only consequences. Early bio-based plastics were also as hazardous to harvest as they were to transform into moldable materials, going back to hard rubber (e.g., vulcanite or ebonite). Industrialized in the 1840s after the development of vulcanization, hard rubber was made from caoutchouc (natural latex) extracted from multiple species found in the rainforests of South America and Southeast Asia. These were later husbanded through plantation economies, often violent and exploitative, as exemplified by the rubber plantations overseen by the regime of Belgium's King Leopold II in Congo ([ 6 ]). But whether wild or domesticated, harvesting latex was dangerous work.
The hours were equally long in low-wage rubber factories. Poor ventilation exacerbated workers' exposure to a steady stream of toxic feed materials, including naphtha and carbon disulfide. From the outset, vulcanized rubber production caused a range of acute and chronic neurological issues, including mental health effects so severe that in extreme cases, workers were institutionalized. The idiom "to be gassed" originates from early rubber factories ([ 7 ]). Despite substantial evidence of its toxicity, carbon disulfide became instrumental to viscose rayon and cellophane production, too. As a result, successive generations of viscose workers into and across the 20th century also experienced neurological as well as cardiovascular effects ([ 8 ]).
Occupational hazards extended to other classes of early bio-based plastics as well. Nineteenth-century celluloid factories were notoriously prone to explosion, conflagration, and worker injury ([ 9 ]). Pulp mills, such as the Ketchikan mill built in the Tongass, used a noxious sulfite process to convert chipped spruce and hemlock into dissolving pulp. Over its lifetime, the mill racked up hundreds of environmental violations before closing in the 1990s. By then, area health professionals had appealed to state epidemiologists to investigate possible links between mill pollution and conditions prevalent among their patients. Eventually, the mill was subject to both civil and criminal investigations. Further, the environmental legacy of rayon-grade pulp in the Tongass includes dioxins, heavy metals, and polychlorinated biphenyls (PCBs) ([ 10 ]).
Natural and semisynthetic plastics were followed by a generation of fossil fuel–derived synthetics. Bakelite, invented in 1907, marked this passage and eventually replaced ivory in pool halls. Bakelite was made from the reaction of coal tar–derived phenol with formaldehyde synthesized via methanol. By the 1920s and early 1930s, a new class of vinyl plastics was also in development. One among several progenitor vinyls was Union Carbide's Vinylite, a copolymer of polyvinyl chloride and polyvinyl acetate, based on mixed feedstocks, notably ethane (a natural gas liquid). Further, Carbide's development of the then-new field of ethylene derivatives, which later capitalized on the hydrocarbon by-products of petroleum production, coupled with the rapid expansion of refinery and plastics manufacturing capacity catalyzed by the Second World War, helped facilitate the industry-wide transition toward the petrochemical-dominant plastics of today ([ 11 ]).
But the advent of these fossil fuel feedstocks did not immediately eliminate prior biomass sources. Viscose is one example. Leading into the war, plastics were also an agricultural product, making use of farm waste or farmed products, a field called chemurgy ([ 12 ]). Early proponents included George Washington Carver and Henry Ford, who envisioned an integrated forest-farm-factory system. Ford purchased not only a rubber plantation in South America but also large tracts of farmland and timber stands in Michigan's Upper Peninsula, where wood pulp was converted in the chemical distilleries at Iron Mountain into automotive paints and artificial leather.
In general, 20th-century plastics tended to follow available raw materials, both geographically and across time. As nations shifted their energy and industrial systems, plastics manufacturers diversified feed material to make use of systemic by-products or waste products. One recent example is how some US plastics producers converted from crude oil or naphtha-based feedstocks to ethane, a by-product of natural gas production through hydraulic fracturing.
The transition to renewable energy opens the question of which substrates will be used for future plastics. Understanding plastics' early industrial history is important because these bio-based products established the political-economic relations of modern, conventional plastics and portended problems to come. This history also points to the insufficiency of an ahistorical technological fix, such as swapping in alternative carbon sources, which may not improve plastics' ethics, safety, or sustainability. This is especially true if the same problematic chemistry is used to modify the base plastics' performance characteristics ([ 13 ]). For example, even if viscose/rayon is sourced from Forest Stewardship Council (FSC)–certified forests, its production may still rely on carbon disulfide.
To avoid such problems, it is necessary to rethink the premises on which plastics technologies have been developed and produced. Critical adjuncts include reengineering plastics for recovery and reuse, augmenting recycling infrastructure ([ 14 ]), and source reduction and dematerialization. This means making fewer plastics by developing alternatives to their short-term, disposable uses, which presumes land access for landfills (i.e., long-term storage of solid waste or ash) ([ 15 ]). The challenge for bio-based plastics research is to account for this history and to think critically about the supply chains required by plastics currently in development, including a focus on ethical, sustainable feedstocks; toxics reduction and safer materials; and worker and community health and safety.
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