Cotton

Cotton fiber is inert against skin and does not leach. Every real question is about what was applied to it. Start with the claim you have probably read: that cotton consumes 25 percent of the world's insecticides. That number traces to a 1995 industry marketing report and is not current - ICAC data for 2019 puts cotton at 10.24 percent of global insecticide sales and 4.71 percent of all pesticide sales, and those are sales figures rather than measured farm use. Organic cotton is still worth choosing, but for accurate reasons. The residue that actually reaches your skin is finishing chemistry. Formaldehyde resins have been used since the mid-1920s to give cotton durable-press and wrinkle-free performance, and here too the honest story is improvement: CPSC testing in 1985 found 67 percent of items above 100 ppm, while studies since 2003 have found 2 percent or less above that level. The United States still sets no legal limit on formaldehyde in clothing, and for people with formaldehyde-sensitive skin it remains a genuine cause of allergic contact dermatitis. PFAS stain and water repellents are the newer concern and are now being legislated: California AB 1817 bars PFAS in textile articles sold in the state from 1 January 2025 at 100 ppm total organic fluorine, dropping to 50 ppm in 2027. Two labels do different jobs. GOTS requires at least 95 percent certified organic fiber for its Organic grade and 70 percent for Made with Organic Materials, and governs inputs through every processing stage. OEKO-TEX STANDARD 100 says nothing about organic farming - it certifies that every thread, button and accessory was tested against a list of over 1,000 harmful substances, graded by how much skin contact the product has. For a finish question, OEKO-TEX is the more directly relevant mark.

Heat is a non-issue for cotton in the sense this site usually means: nothing softens and nothing migrates. It shrinks on the first hot wash, scorches under an iron, and burns rather than melting. The heat that matters in a cotton garment belongs to whatever was blended into it - elastane is what degrades in a hot dryer, and why a stretch waistband goes slack years before the cotton around it wears out.

Read the fiber content label, then look past it. A garment sold as cotton is frequently 95 percent cotton with 5 percent elastane, and that elastane is the plastic in your contact path. Check the waistband, cuffs and gusset separately - they are commonly a different blend from the body, and on underwear the waistband is the part in constant contact. A rubbery, slightly shiny printed graphic that sits on top of the fabric rather than in it is plastisol, a PVC-based screen ink; a print that has sunk into the weave and feels like nothing is water-based or discharge. Burn-testing a snipped thread is the field test: cotton burns to soft grey ash smelling of paper, while synthetics shrink from the flame and leave a hard bead. If a brand advertises wrinkle-free, easy-care, stain-release or durable press, ask what the finish is - those are the categories where formaldehyde and PFAS chemistry lives.

Cotton takes hot water, real detergent and sunlight better than almost any synthetic, which is why it survives laundering that kills performance fabric. It shrinks on the first wash unless pre-shrunk, wrinkles freely without a finish, and wears thin at friction points rather than pilling into plastic lint. A cotton tee worn weekly is a three-to-five-year garment, and the seams and any elastane trim usually give out before the fabric does.

Pure cotton genuinely biodegrades. Tested in coastal seawater against synthetics, cellulose fibers including both organic and conventional cotton disappeared completely in roughly 35 days and reached 76 to 82 percent biodegradation in a 28-day bioreactor, while PET and PP showed no visible breakdown past 231 days. That result only holds for the pure fiber: in a cellulose-synthetic blend only the cotton goes and the synthetic stays. Textile-to-textile cotton recycling exists but is small and mostly downcycles into wiping rags and insulation, with blends and finishes the main blocker.