Long associated with pool decks and beach days, flip flops have re-emerged as fashion’s most unlikely It-shoe. From The Row’s headline-grabbing £600 pair to more affordable Havaianas, the divisive style has strutted its way onto runways, into cities and across social media feeds this summer.
Flip flops’ explosion in popularity is partly due to their democratised appeal. “There’s little difference — at first glance — between a £20 pair and a £600 version from The Row,” says Molly Rooyakkers, founder of data-driven fashion forecasting account Style Analytics. “It gives everyone a way to feel like they’re participating in a ‘luxury’ trend, especially at a time when many people have limited disposable incomes and luxury feels increasingly out of reach.” Searches on Pinterest for “flip flops” grew 21 per cent year-on-year in the US and 51 per cent year-on-year in the UK, per Style Analytics.
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While the average flip flop may be lightweight, its environmental footprint is anything but. Often destined for just a single summer’s use, roughly three billion pairs of flip flops are produced each year.
Most mainstream flip flops are made with some kind of plastic — whether in the form of EVA (ethylene vinyl acetate), polyurethane or PVC (polyvinyl chloride). While most shoes feature some form of plastic, flip flops are made almost entirely of these materials (like jelly shoes and other slides), upping associated risks. These materials are petroleum-based, difficult to recycle and often leach chemicals as they degrade.
“Flip flops might look simple, but the materials used can carry a surprising number of risks if they aren’t carefully managed,” says Inga Bleyer of Oeko-Tex, an independent certification system that tests textiles and materials for harmful substances.
A harmful footprint
Base materials for flip flops can include rubber, foam, plastic, even leather, but the chemicals used to treat them are just as worthy of scrutiny, if not more so. These treatments, known as plasticisers, are added to plastics like PVC to make them less brittle, creating the bendable soles and straps that are so essential to flip flops.
Safer plasticisers like citrates and castor oil derivatives exist, however, they’re costlier and less tested at scale. True material innovation — whether through plant-based foams, algae polymers or advanced rubber blends — offers the most promise, with companies like Sea Sense and Nae embracing natural rubber, cork, cotton or algae-based polymers, effectively bypassing the need for traditional additives. However, it requires coordinated investment across the supply chain to ensure no nefarious practices — such as labour exploitation, deforestation or greenwashing — occur at any stage of sourcing or production.
Foam, widely used in footwear for comfort and shock absorption, is another under-scrutinised culprit. Most flip flops use conventional EVA or polyurethane-based foams — petrochemical products with energy-intensive manufacturing, two qualities that pose a risk to brands’ decarbonisation strategies as well as planetary and human health. “These foams are typically made with toxic chemicals that pose both environmental and health risks,” says Bleyer. “During production, they can release VOCs [volatile organic compounds], among other hazardous compounds, while post-use they’re difficult to recycle and prone to fragmenting into microplastics.”
Then, there’s the issue of durability — or lack thereof. While you’ll most likely hold onto a premium pair from The Row, most flip flops are bought for as little as £2 on the high street and treated as seasonal throwaway items. Cheap versions made from low-grade plastics or foams are prone to snapping, tearing or warping after just a few outings. And when they inevitably break, they’re rarely recycled — either because the mixed materials are too difficult to separate, or because municipal systems don’t accept them. “From an environmental standpoint, many flip flops are made from synthetic materials that don’t break down easily,” Bleyer reiterates, “and may contribute to microplastic pollution once they’re discarded.”
Not all ‘green’ flip flops are created equal
The conversation around sustainable alternatives is growing, but so-called ‘green’ solutions aren’t always as ethical or eco-friendly as they seem, and many come with unintended consequences.
“Some ‘sustainable’ flip flops have soles made of recycled tires, which contain many toxic chemicals,” says Sara Brosché, science advisor at the International Pollutants Elimination Network (IPEN). Tires are engineered to withstand extreme conditions and are full of synthetic additives, some of which are highly harmful to water systems and toxic to aquatic organisms.
While materials like cork and natural rubber may sound greener, scaling them to industrial levels can lead to issues like deforestation, biodiversity loss and exploitation of land and labour.
It’s why the word ‘natural’ itself can be misleading. “Natural doesn’t always mean ethical,” says Nick Savaidis, founder of Australian footwear brand Etiko. “What a lot of people don’t realise is that roughly 85 per cent of the world’s natural rubber is produced by smallholders, often in countries with weak labour protections and little transparency. Without proper oversight, that supply chain can be questionable.” Rubber extraction has also been closely linked to deforestation.
By paying a premium for wild rubber, Veja hopes to incentivise producers to keep the forest standing. But money alone doesn’t solve the problem.
A growing number of brands are working to reduce harm through more thoughtful materials sourcing and supply chain transparency. Paula Pérez, co-founder of Nae Vegan Shoes, says this requires both innovation and rigorous supplier vetting. Nae exclusively works with partners that carry certifications like Oeko-Tex for non-toxic textiles and REACH (registration, evaluation, authorisation and restriction) compliance for chemical safety. “Our goal is to eliminate animal-derived materials entirely, avoid virgin plastics wherever possible, and prioritise renewable, recycled, or responsibly sourced alternatives,” Pérez says.
Nae uses cork that is harvested by stripping bark from cork oak trees without cutting them down, allowing the trees to regenerate and be harvested again every nine to 11 years. Piñatex, meanwhile, is a leather alternative made from the cellulose fibres of pineapple leaves — a byproduct of existing agriculture — which would otherwise be burnt.
Etiko uses rubber certified by the Forest Stewardship Council (FSC), inputs certified under the EU’s 2006 REACH regulations, and manufactures in a Fairtrade-certified factory. While certifications can’t fix everything, they offer a starting point. “These certifications help cut through the greenwashing — holding brands accountable to real social and environmental benchmarks,” Savaidis says. “At the end of the day, it’s not just about what something’s made from, it’s about how and by whom it’s made.”
Certification schemes are meant to verify claims and accelerate progress. Critics say they may do more harm than good. The current spotlight is on Better Cotton, but the problem is far bigger.
Standards are evolving in parallel. Bleyer says Oeko-Tex updates its specific thresholds for substances commonly found in foam and rubber — including bisphenols, PAHs, phthalates, VOCs and heavy metals — annually, in line with global research and regulations, so brands have a “clear, trusted framework” to follow.
Durability is also a focus, especially as flip flops work to shed their disposable image. “We engineer our flip flops and sandals with ergonomic footbeds, arch support and cushioned soles made from natural or recycled components like cork and EVA blends with bio-based content,” says Pérez. “Our designers work closely with local shoemakers in Portugal to test fit and comfort, ensuring our shoes feel as good after 10 wears as they do after one. We believe that if a sustainable shoe isn’t comfortable, it won’t be worn – and that’s the ultimate waste.”
NAE is also building circular systems. “Right now, we run a pre-loved program — customers can send back their worn shoes (only available in Europe ), and we either refurbish and donate them or dismantle them to recover parts where possible,” says Nae’s Pérez. But true circularity remains a major hurdle. “Recycling shoes is still a massive industry challenge, because they’re made of multiple components. We’re actively exploring next-generation materials and construction methods that make disassembly easier — the ultimate goal is that one day, every flip flop could be fully broken down and fed back into the system, instead of ending up in landfill.”
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