More than 8,000 synthetic chemicals are used across the apparel industry. Many are applied after a garment is constructed - to make fabric wrinkle-resistant, stain-resistant, waterproof, flame-retardant, or antimicrobial. Others are introduced during fibre production, dyeing, and finishing.

The result is that most conventionally produced clothing contains residual chemical compounds that remain on the fabric during wear, transfer to skin through contact and perspiration, and in some cases off-gas into the air. The skin is the body's largest organ and a permeable barrier - not an impermeable one. Compounds that contact skin are absorbed, particularly under conditions of heat, sweat, and prolonged exposure.

This guide covers the specific chemicals of greatest concern, the health conditions they are associated with, and how to identify clothing that is genuinely free from them.

Why Chemicals Are Used in Clothing

Synthetic chemicals entered textile production primarily to solve real problems: fire safety, mildew during shipping, wrinkle resistance, and the durability demands of mass production. The chemicals that addressed those problems worked - and became standard practice before their health and environmental consequences were understood.

Today, chemicals are used to produce garments that are:

- Wrinkle and shrink resistant

- Flame retardant

- Waterproof or water-repellent

- Stain resistant

- Mildew resistant

- Antimicrobial or odour-resistant

- Colourfast through synthetic dyes

A 2016 Greenpeace study testing products from major global brands found that 63% of items tested contained hazardous chemicals at detectable levels. The fashion industry's chemical use accounts for approximately 20% of global industrial water pollution through dyeing and finishing discharge. 

The Six Most Concerning Chemical Categories in Clothing

1. Pesticides and Insecticides — Primarily in Conventional Cotton

Cotton is one of the most pesticide-intensive crops in the world. The global cotton industry accounts for approximately 10% of all pesticides used worldwide and 25% of all insecticides - applied at volumes that leave detectable residues in finished garments.

The herbicide glyphosate (Roundup) is used extensively on conventionally grown cotton. Pesticide exposure through skin contact and ingestion has been linked in published research to:

- Leukaemia and non-Hodgkin lymphoma

- Increased autism risk in infants with prenatal exposure

- ADHD in children and adolescents

What to look for: GOTS-certified organic cotton is grown without synthetic pesticides, fungicides, or GMO seed. It also requires 71% less water and 62% less energy to produce than conventional cotton.

2. PFAS (Per- and Polyfluoroalkyl Substances) - in Waterproof and Stain-Resistant Finishes

PFAS are a class of synthetic chemicals used to create water-repellent and stain-resistant finishes on outdoor gear, rainwear, and performance clothing. They are known as "forever chemicals" because their carbon-fluorine bond is one of the strongest in chemistry - they do not break down in the environment or in the human body.

PFAS accumulate in human tissue over time. Health associations documented in peer-reviewed research include:

- Kidney and testicular cancer

- Liver damage and disrupted liver enzyme production

- Thyroid disease

- Immune system suppression

- Developmental issues in children with prenatal exposure

PFAS are present in products labelled with GoreTex, Teflon, or similar branded waterproofing technologies. They are also used in many "moisture-wicking" performance fabrics.

What to look for: brands explicitly advertising PFAS-free manufacturing. Outdoor brands including Patagonia and others have committed to PFAS elimination - verify with current published commitments rather than general brand reputation, as standards vary by product line.

3. Formaldehyde - in Wrinkle-Resistant and Easy-Care Finishes

Formaldehyde is used in textile finishing to create wrinkle-resistant, shrink-resistant, and mildew-resistant properties. It is also used as a preservative during shipping. It is the compound primarily responsible for the "new clothing smell" most people recognise.

Formaldehyde is classified as a known human carcinogen by the International Agency for Research on Cancer (IARC). Dermal exposure is associated with contact dermatitis; longer-term exposure is linked to nasopharyngeal cancer and leukaemia. It is banned or tightly restricted in clothing in the European Union, Australia, and Japan - but has no equivalent federal restriction in the United States.

What to look for: OEKO-TEX Standard 100 certification tests specifically for formaldehyde residue in finished garments, including at levels appropriate for products worn next to skin and by infants. GOTS certification restricts formaldehyde use in processing.

4. Flame Retardants - in Children's Sleepwear and Treated Fabrics

Organohalogen flame retardants - the primary class used in textile applications - have been linked in published research to:

- Thyroid cancer and thyroid hormone disruption

- ADHD and slowed neurological development in children

- Decreased IQ in children with prenatal exposure

An estimated 90% of Americans have detectable levels of flame retardant chemicals in their bloodstream. Despite documented health effects, usage is currently regulated in only a minority of US states.

The critical alternative: merino wool is naturally flame resistant without chemical treatment. Its high nitrogen and moisture content means it requires significantly higher oxygen concentration to ignite than most synthetic fibres, and it self-extinguishes rather than melting or dripping. Wool children's sleepwear meets fire safety standards without any chemical flame retardant application.

5. Phthalates - in Dyed, Printed, and Flexible Synthetic Garments

Phthalates are plasticising chemicals used to make synthetic materials more flexible and durable, and are present in the inks and dyes used for printed designs on clothing. They were banned from children's toys and products in the US in 2008 - but remain largely unregulated in clothing and textiles.

Phthalates are found at detectable levels in jeans, rainwear, synthetic leather, and printed activewear. Health associations include:

- ADHD and asthma

- Breast cancer and endometriosis

- Lowered testosterone in men

- Obesity and type 2 diabetes

- Reproductive development issues

Phthalates are not listed on clothing labels. The most reliable avoidance strategy is choosing certified organic and natural fibre garments from brands with third-party chemical testing.

6. Synthetic Dyes and Azo Compounds - in Dark and Brightly Coloured Garments

Azo dyes are the most widely used class of synthetic dyes in textiles, responsible for approximately 60–70% of all textile dyeing globally. Certain azo dyes break down to release aromatic amines - compounds classified as carcinogens, with documented links to bladder cancer.

Despite this, there are no federal restrictions on azo dyes in the United States. The European Union's REACH regulation restricts specific aromatic amine-releasing azo dyes, but enforcement varies.

Dark colours - particularly black - and synthetic indigo (used in denim) are most commonly produced using azo compounds. Dyeing and finishing processes account for an estimated 20% of global industrial water pollution.

What to look for: brands using plant-based or azo-free dyes, and OEKO-TEX certification which tests for restricted azo dye residues in finished products. 

A Note on Antimicrobial Treatments and Performance Fabrics

Two categories that are increasingly common in activewear and athleisure warrant specific attention.

Antimicrobial chemical treatments - including triclosan and nanoparticle silver - are applied to fabrics marketed as odour-resistant or antibacterial. Triclosan has been shown to cause liver cancer in mice with chronic exposure and is classified as an endocrine disruptor. Nanoparticle silver has been linked to hormone disruption and DNA damage in cell studies.

Synthetic performance fabrics - polyester, nylon, acrylic marketed as "moisture-wicking" - are petroleum-derived fibres coated with additional chemical treatments to produce performance claims. They also block the skin's natural toxin-release function and shed approximately 700,000 microplastic fibres per wash cycle into wastewater.

Merino wool and TENCEL (lyocell from sustainably sourced eucalyptus) provide genuine moisture management, odour resistance, and breathability through fibre structure rather than chemical treatment.

How to Identify Genuinely Chemical-Free Clothing

Third-party certification is the only reliable verification method. Brand claims about being "natural," "clean," or "non-toxic" are self-reported and unverified. The following certifications involve independent third-party auditing:

GOTS (Global Organic Textile Standard)

The most comprehensive certification covering the full textile supply chain - from organic fibre harvesting through spinning, dyeing, finishing, and labelling. GOTS prohibits a defined list of harmful inputs including heavy metals, formaldehyde, aromatic solvents, and specific azo dyes. It also covers social standards in manufacturing. This is the standard Nui uses across most of our range.

OEKO-TEX Standard 100

Tests finished products - every component including threads, buttons, and accessories - for over 100 harmful substances at levels calibrated to intended use. Product Class I (for babies and items with direct skin contact) applies the most stringent limits. OEKO-TEX tests for formaldehyde, pesticide residues, heavy metals, phthalates, and restricted azo dyes.

RWS (Responsible Wool Standard)

For wool specifically - covers animal welfare and land management on farms, ensuring the fibre itself is produced without chemical dipping practices that leave residues on fibre.

What certification does not cover: a GOTS or OEKO-TEX certification applies to the certified product at the time of testing. It does not guarantee that every product from a certified brand meets the standard - check that the specific garment carries the certification, not just the brand.

Chemical-Free Clothing: Practical Summary

Most Nui garments are GOTS, OEKO or RWS certified. Our merino is RWS certified and tested to OEKO-TEX Standard 100. Explore the collection.