If you've ever looked at the label of a major sportswear brand and seen "anti-odour" or "antimicrobial", the technology behind it is almost certainly silver ions, zinc compounds, or — until recently — PFAS chemicals. These are the industry standard approaches to the persistent problem of gym clothes smell.

But there's a growing body of evidence — and increasing regulatory pressure — suggesting these approaches come with costs that most brands don't advertise. Here's what you should know before you buy.

Silver Ions in Sportswear

Silver has been used as an antimicrobial agent for thousands of years. Silver ions kill bacteria by binding to proteins and disrupting cellular metabolism. Applied to textiles, silver-ion treatments were adopted by activewear brands from the early 2000s as a solution to the odour problem in synthetic fabrics.

They do work — initially. But they come with significant problems.

Silver Washes Out

Silver-ion treatments aren't permanently bonded to textile fibres. They leach out progressively with each wash cycle. Research consistently shows significant reduction in antimicrobial effectiveness within 10–30 wash cycles depending on water temperature, hardness, and detergent type. A garment advertised as "anti-odour" when new may offer minimal protection after a few months of regular use.

Silver Pollutes Waterways

The silver that washes out doesn't disappear. Multiple peer-reviewed studies have found that silver nanoparticles and ions from textile washing pass through wastewater treatment systems and enter rivers and coastal waters, where they are toxic to aquatic organisms at the concentrations found in treatment plant effluent. Silver-contaminated sewage sludge used as agricultural fertiliser has also been identified as a contamination pathway.

Regulatory Direction

The EU's REACH regulation (enforced by the European Chemicals Agency) already restricts certain silver compounds in textiles. The trajectory of EU chemical regulation in clothing is consistently toward tighter restrictions on heavy metals — including silver and zinc.

Zinc in Sportswear

Zinc-based antimicrobial treatments operate on similar principles to silver. They're common in both anti-odour activewear and footwear — zinc oxide in shoe liners, for example, is widespread. The same washout and aquatic toxicity concerns apply. Zinc is an essential nutrient at low concentrations but is toxic to aquatic organisms when present in elevated concentrations in waterways, and household laundry is a documented source of zinc in urban water systems.

PFAS: The "Forever Chemical" Problem

PFAS (per- and polyfluoroalkyl substances) are a broad class of synthetic chemicals used in sportswear and outdoor apparel for water resistance, stain resistance, and — in some applications — antimicrobial finishes. They're called "forever chemicals" because their carbon-fluorine bonds are among the strongest in chemistry: they don't break down in the environment, in wastewater treatment, or in the human body.

PFAS accumulate. In ecosystems, in wildlife, and in human tissue. They've been found in the blood of people living far from any industrial source, in Arctic wildlife, and in rainwater samples across the planet. Studies have linked PFAS exposure to endocrine disruption, immune system effects, thyroid disorders, and elevated cancer risk.

Regulatory action has accelerated significantly:

• France: Adopted legislation in 2025 banning PFAS in textile products from January 1, 2026, extending to all textiles by 2030.
• EU-wide: PFAS restrictions under REACH are actively expanding. The French ban is widely expected to become the template for EU-level legislation within this decade.
• United States: California, New York, Washington, and several other states have passed or are advancing bans on PFAS in textiles.

If you're buying activewear from brands that haven't publicly committed to PFAS-free manufacturing, there's a reasonable probability those garments contain PFAS compounds — at least until regulatory bans take effect.

How to Evaluate a Brand's Approach

Garment labels rarely disclose "contains silver ions" or "treated with PFAS". Here's how to assess what you're actually getting:

• Look for what they explicitly don't use. Brands committed to avoiding heavy metals and PFAS will typically say so — "free from silver and zinc" or "PFAS-free" — because it's a genuine market differentiator worth highlighting.
• Check for OEKO-TEX Standard 100 certification. OEKO-TEX independently tests garments for a range of harmful substances including heavy metals and certain PFAS compounds. Certification confirms they meet defined limits.
• Look for Bluesign certification. Bluesign approval for chemical treatments confirms responsible chemistry standards in manufacturing.
• GOTS certification (Global Organic Textile Standard) restricts the use of toxic substances in both fibre production and processing.
• Ask the brand directly. A brand confident in their approach should be able to answer: "What antimicrobial technology do you use, and does it contain silver, zinc, or PFAS?"

The Alternative: Plant-Based Anti-Odour Technology

The reason these heavy metal and synthetic approaches became industry standard is that, until recently, there wasn't a durable plant-based alternative that could perform comparably across many wash cycles.

That's changed. The two technologies APRÍ uses — HeiQ Mint (derived from peppermint) and NordShield (derived from wood extractives) — were developed specifically to address the sustainability and durability limitations of conventional antimicrobial textile treatments:

• Free from silver, zinc, and all heavy metals
• No PFAS or synthetic biocides
• OEKO-TEX Standard 100 certified — independently verified safe for skin contact
• 94%+ anti-odour effectiveness retained after 20 wash cycles at 30°C
• Biodegradable — the compounds that eventually do wash out break down naturally

The plant-based approach isn't a performance compromise. The same antibacterial function is achieved using materials whose environmental footprint is fundamentally different from heavy metals or synthetic chemicals.

The Bottom Line

Most mainstream anti-odour activewear relies on silver, zinc, or PFAS. The environmental concerns around these substances are well-documented, and the regulatory pressure to restrict or ban them from textiles is accelerating — particularly in Europe.

If you care about what your sportswear does to the environment when it's washed, these questions are worth asking before you buy. The information isn't always on the label — but the certifications and brand commitments that signal a genuinely different approach do exist.

Learn about APRÍ's plant-based alternatives to silver and zinc →