Testing and verifying sustainability credentials

Providing an overview of how to ensure that a product’s environmental impact can be reduced.

by Nicola Pichel-Juan

It is becoming increasingly important for organisations to be able to substantiate any sustainability-related claims made about their products. Legislation now governs how information relating to sustainability should be communicated and, in some cases, requires companies to make certain information available to the public. This may include details about product supply chains or specific product attributes.

Sometimes effective and clear communication supported by due diligence is enough to support a claim. However, there are times where further verification may be required. This article introduces several testing and verification approaches that can be used as evidence relating to the environmental performance of footwear and materials.

Environmental impacts

Product carbon footprints and lifecycle assessments (LCAs) are used to measure the potential environmental impacts of a product. For organisations which have completed their own studies, an independent verification of the findings can help to strengthen any claims as it can:

• give the company confidence in the findings of the study
• create trust with customers and consumers
• avoid accusations of ‘greenwashing’
• build credibility in the marketplace
• improve the overall quality of the study by taking any feedback received into account.

Table 1 provides further information on the relevant standards for product carbon footprint verification and LCA critical review.

Table 1: Standards for product carbon footprint verification and LCA critical review
Type of study	Methodology used to conduct the study	Standard for verification
Product carbon footprint.	ISO 14067:2018 Greenhouse gases. Carbon footprint of products. Requirements and guidelines for quantification.	ISO 14604-3:2019 Greenhouse gases. Specification with guidance for the verification and validation of greenhouse gas statements.
Lifecycle assessment.	ISO 14040:2006 Environmental Management. Lifecycle assessment. Principles and framework. ISO 14044:2006 Environmental management. Lifecycle assessment. Requirements and guidelines.	ISO 14071:2024 Environmental management. Lifecycle assessment. Critical review processes and reviewer competencies. Additional requirements and guidelines to ISO 14044:2006.

Restricted substances

The footwear industry has been working to comply with restricted substances legislation from around the world for many years. However, the list of restricted substances continues to increase and the thresholds that must be achieved are becoming ever more challenging. Legislation in this area intends to protect human health and the environment by restricting or eliminating substances that are i) persistent, bioaccumulative and toxic, ii) carcinogenic, iii) mutagenic or iv) toxic for reproduction.

Laboratory testing can confirm the presence or absence of a substance, and if it is present, at what level. SATRA has an extensive library of Bulletin articles and webinars produced by its chemistry team that go into more detail about various aspects of chemical compliance.

As well as focusing on particular substances, we also publish footwear-specific Restricted Substances Lists (RSLs) twice each year and have recently launched an additional documents detailing substances relevant to footwear that are restricted by California’s proposition 65 Regulation. A similar list is also available for REACH Substances of Very High Concern (SVHCs) that are relevant to footwear.

One group of chemicals currently receiving significant attention is per- and polyfluoroalkyl substances (PFAS), often referred to as ‘forever chemicals’. These substances were first developed in the 1940s and provide useful properties such as stain resistance and water repellence. However, they are extremely persistent in the environment and do not readily break down. As a result, they accumulate in living organisms (including humans), and contaminate water, soil and food chains. Exposure to PFAS has been linked to health concerns including liver damage, thyroid disease, fertility issues, and cancer. Existing legislation already restricts certain PFAS in various parts of the world and further restrictions are expected.

Recycled polyester

Recycled polyester has been a popular ‘sustainable’ material choice across the footwear and apparel sectors in recent years. There are well-established supply chain verification schemes that are used to certify that polyester has been made from recycled rather than virgin raw material inputs. The verification process involves document checks and, in certain cases, site visits and audits to answer the following questions:

1. How was the waste generated?
2. Is the waste percentage in line with industry norms?
3. What process is the waste going into – for example, fibre production?
4. How was the waste converted into a usable input?

Laboratory test methods are now available that claim to be able to identify if a polyester has been made from recycled inputs derived from polyethylene terephthalate (PET) plastic bottles.

One such approach is by measuring the concentration of isophthalic acid. This is a compound typically added during the PET bottle manufacturing process which, in turn, can be used as a ‘marker’ in recycled polyester. From SATRA’s research into this testing, using isophthalic acid as a marker for recycled polyester has its limitations, as isophthalic acid could also potentially be present in virgin polyester. SATRA therefore recommends that this test is only carried out in conjunction with supply chain verification.

End of life impacts

There is also increasing interested in understanding the environmental impacts associated with a product at the end of its life. This could consider environments where an item is intended to be disposed of – for example, a landfill site or an incinerator, as well as ecosystems where an item is not intended to be disposed of such as the sea, a river or a field.

Some materials and products are now being developed to break down or biodegrade in a specific environment. Laboratory testing can be used to assess the rate and extent of this biodegradation under controlled conditions.

In recent years, SATRA has been focusing on compostability testing. Compostable items are now commonplace in the packaging industry – such as single-use coffee cups. Materials marketed as compostable have now started to make their way into the fashion industry. As an example, innovative tanning systems can support the production of compostable leather. A material must meet the following requirements to be certified as ‘compostable’:

1. Characterisation – the material itself cannot contain any harmful substances, typically heavy metals, and fluorine.
2. Biodegradability – the material must biodegrade and release CO_2.
3. Disintegration – the material must break down into smaller pieces.
4. Compost quality – this can be verified by exposing plants, and in some cases also earthworms, to compost containing the material to see if it causes any adverse effects.
5. Recognisability – does the resulting compost look, smell and feel like compost?

Carbon content testing

A reduction in carbon emissions is crucial to the mitigation of the worst effects of climate change, and it is increasingly being recognised that not all carbon is equal.

Bio-based carbon (also known as ‘modern’ or ‘recent’ carbon) is derived from biomass such as plants and animals. Plants absorb carbon dioxide from the atmosphere and use it to make many compounds through the process of photosynthesis. The plant compounds are consumed by animals and humans who then respire (breathe out) the bio-based carbon dioxide. Eventually, plants and animals die and decompose, releasing further bio-based carbon back into the atmosphere. This is a natural cycle that occurs relatively quickly over a period of years or decades.

‘Fossil carbon’ is carbon that has been formed over a much longer period of time. Living organisms (plants and animals) die, their remains become buried and through heat and pressure over countless years, fossil fuels such as oil and coal are created. Extracting and burning these fuels releases vast amounts of additional fossil carbon into the atmosphere, which means that more heat is trapped, and the planet gets warmer.

Although the warming effect from bio-based and fossil carbon is the same, bio-based carbon does not result in additional carbon being added into the atmosphere and so it can therefore be viewed as ‘better’ for the environment.

It is possible to analyse materials to measure their bio-based and fossil-based carbon content using test methods such as ASTM D6866-22 – ‘Standard test methods for determining the bio-based content of solid, liquid and gaseous samples using radiocarbon analysis’ and BS ISO 16620-2:2019 – ‘Plastics. Bio-based content. Determination of biobased carbon content’. SATRA explains this testing in more detail in the article ‘Bio-based carbon in footwear production’.

Microplastics and microfibres

Microplastics and microfibres ‘shedding’ from items during use (and during washing in the case of garments) is a significant cause of concern. Microfibres and microplastics have been found everywhere – from the Arctic to the peak of Mount Everest, and have even been detected in human blood and heart tissue. The impact that these tiny fragments have on ecosystems and organisms is only just starting to be understood.

There are well-established tests for measuring microfibres shedding from garments during washing, but so far there has been less focus on the potential for microplastics to shed from outsoles in wear. However, SATRA believes that this is something that will come under further scrutiny in future.

Durability

Durability is increasingly being recognised as a crucial factor in making sustainable products. A well-made, long-lasting product will have a much lower impact in use than an item that may be disposed of after only a few wears. There are existing durability protocols for footwear that form part of different frameworks or programmes, as follows.

The European Product Environmental Footprint Category Rules (PEFCR) set out detailed guidance for calculating the environmental impacts of a product. This includes physical testing criteria for several types of footwear to determine its durability level. The testing focuses on identifying and eliminating causes of premature failure in wear. The durability testing ‘score’ is then used as a factor in determining the product’s overall environmental impact score.

The European Union ‘ecolabel’ for footwear sets out various criteria for sustainable footwear, including durability Again, there are different physical tests and thresholds for distinct types of footwear.

The French Extended Producer Responsibility (EPR) scheme for apparel, footwear and household textiles includes ‘eco modulations’. Organisations receive a rebate on EPR fees for products meeting any of the requirements. The eco modulations for footwear are i) recycled content, ii) certification to certain environmental labels, and iii) durability. For footwear, the durability testing focuses on outsole abrasion and sole bonds (with some additional requirements for children’s and babies’ shoes).

Other schemes

There are many other certification schemes that have relevance for the fashion and footwear sectors. A good example is the Leather Working Group (LWG), which works to raise standards in tanneries and leather supply chains. In fact, brands and retailers will often opt to only source leather from tanneries with LWG medal status. Schemes also exist for the sustainable and ethical sourcing and production of other raw materials, including cotton and wool. Other standards may focus on areas such as chemicals used in the production of raw materials, or even the management of water throughout a material’s supply chain.

With so many different ecolabels, schemes and protocols on offer, it can be challenging for companies to choose where to focus their efforts, as well as confusing for the consumer. The European Union as part of its directive on Empowering Consumers for the Green Transition (ECGT) intends to set more stringent criteria for the introduction of new ecolabels.

In conclusion

As this article highlights, many options are available to organisations looking to back up sustainability-related claims, whether that is through laboratory-based testing or verification schemes. SATRA recommends that organisations determine which claims are the most important and relevant to a specific product and its consumer base, and then focus on demonstrating that those claims are valid.

Publishing Data

This article was originally published on page 14 of the May 2026 issue of SATRA Bulletin.

Other articles from this issue »

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