Nearly half of the world’s clothing is made of polyester and Greenpeace forecasts this amount to nearly double by 2030. Why? The athleisure trend if one of the main reasons behind it: an increasing number of consumers are look for stretchier, more resistant garments. The problem is, polyester is not a sustainable textile option, as it is made from polyethylene terephthalate (PET), the most common type of plastic in the world. In short, the majority of our clothes come from crude oil, while the Intergovernmental Panel on Climate Change (IPCC) is calling for drastic actions to keep the world’s temperature to a maximum of 1.5 °C above pre-industrial levels.

Three years ago, the non-profit organization Textile Exchange challenged over 50 textile, apparel and retail companies (including giants like Adidas, H&M, Gap and Ikea) to increase their use of recycled polyester by 25 percent by 2020. It worked: last month, the organization issued a statement celebrating that signatories have not only met the goal two years before the deadline, they have actually exceeded it by upping their use of recycled polyester by 36 percent. In addition, twelve more companies have pledged to join the challenge this year. The organization forecasts 20 percent of all polyester to be recycled by 2030.

Recycled polyester, also known as rPET, is obtained by melting down existing plastic and re-spinning it into new polyester fiber. While much attention is given to rPET made from plastic bottles and containers thrown away by consumers, in reality polyethylene terephthalate can be recycled from both post-industrial and post-consumer input materials. But, just to give an example, five soda bottles yield enough fiber for one extra large T-shirt.

Although recycling plastic sounds like an indisputable good idea, rPET’s celebration is far from being a unanimity in the sustainable fashion community. FashionUnited has gathered the main arguments from both sides.

Recycled polyester: the pros

1. Keeping plastics from going to landfill and the ocean - Recycled polyester gives a second life to a material that’s not biodegradable and would otherwise end up in landfill or the ocean. According to the NGO Ocean Conservancy, 8 million metric tons of plastic enter the ocean every year, on top of the estimated 150 million metric tons that currently circulate in marine environments. If we keep this pace, by 2050 there will be more plastic in the ocean than fish. Plastic has been found in 60 percent of all seabirds and 100 percent of all sea turtle species, because they mistake plastic for food.

As for landfill, the United States Environmental Protection Agency reported that the country’s landfills received 26 million tons of plastic in 2015 alone. The EU estimates the same amount to be generated yearly by its members. Clothes are undoubtedly a big part of the problem: in the UK, a report by the Waste and Resources Action Programme (WRAP) estimated that about 140 million pounds worth of clothes end up in landfills each year. “Taking plastic waste and turning it into a useful material is very important for humans and our environment,” said Karla Magruder, Board Member of Textile Exchange, in an email to FashionUnited.

2. rPET is just as good as virgin polyester, but takes less resources to make - Recycled polyester is almost the same as virgin polyester in terms of quality, but its production requires 59 percent less energy compared to virgin polyester, according to a 2017 study by the Swiss Federal Office for the Environment. WRAP estimates rPET’s production to reduce CO2 emissions by 32 percent in comparison to regular polyester. “If you look at life cycle assessments, rPET scores significantly better than virgin PET,” adds Magruder.

In addition, recycled polyester can contribute to reduce the extraction of crude oil and natural gas from the Earth to make more plastic. “Using recycled polyester lessens our dependence on petroleum as a source of raw materials,” says the website of outdoor brand Patagonia, best known for making fleece from used soda bottles, unusable manufacturing waste and worn-out garments. “It curbs discards, thereby prolonging landfill life and reducing toxic emissions from incinerators. It also helps to promote new recycling streams for polyester clothing that is no longer wearable,” adds the label.

“Because polyester accounts for approximately 60 percent of the world’s production of PET — about twice what’s used in plastic bottles — developing a non-virgin supply chain for polyester fiber has the potential to massively impact global energy and resource requirements,” argues American apparel brand Nau, also known for prioritizing sustainable fabric options.

Recycled polyester: the cons

1. Recycling has its limitations - Many garments are not made from polyester alone, but rather from a blend of polyester and other materials. In that case, it is more difficult, if not impossible, to recycle them. “In some cases, it is technically possible, for example blends with polyester and cotton. But it is still at the pilot level. The challenge is to find processes that can be scaled up properly and we’re not there yet,” said Magruder to Suston Magazine in 2017. Certain laminations and finishings applied to the fabrics can also render them unrecyclable.

Even clothes that are 100 percent polyester can’t be recycled forever. There are two ways to recycle PET: mechanically and chemically. “Mechanical recycling is taking a plastic bottle, washing it, shredding it and then turning it back into a polyester chip, which then goes through the traditional fiber making process. Chemical recycling is taking a waste plastic product and returning it to its original monomers, which are indistinguishable from virgin polyester. Those can then go back into the regular polyester manufacturing system,” explained Magruder to FashionUnited. Most rPET is obtained through mechanical recycling, as it is the cheapest of the two processes and requires no chemicals other than the detergents needed to clean the input materials. However, “through this process, the fibre can lose its strength and thus needs to be mixed with virgin fibre,” notes the Swiss Federal Office for the Environment.

“Most people believe that plastics can be infinitely recycled, but each time plastic is heated it degenerates, so the subsequent iteration of the polymer is degraded and the plastic must be used to make lower quality products,” said Patty Grossman, co-founder of Two Sisters Ecotextiles, in an email to FashionUnited. Textile Exchange, however, states on its website that rPET can be recycled for many years: “garments from recycled polyester aim to be continuously recycled without degradation of quality”, wrote the organization, adding that the polyester garment cycle has the potential to become “a closed loop system” someday.

Those following Grossman’s line of thought argue that the world should produce and consume less plastic in general. If the public believes everything they throw away can be recycled, they will probably see no problem in continuing to consume disposable plastic goods. Unfortunately, only a small portion of the plastic we use gets recycled. In the United States, a mere 9 percent of all plastics were recycled in 2015, according to the US Environmental Protection Agency.

Those calling for a less celebratory view of rPET defend that fashion brands and shoppers should be encouraged to favor natural fibers as much as possible. After all, even though rPET takes 59 percent less energy to produce than virgin polyester, it still requires more energy than hemp, wool and both organic and regular cotton, according to a 2010 report from the Stockholm Environment Institute.