Wool, cotton and linen are natural protein and cellulose fibres used for clothing, home textiles, packaging and bags.
They replace polyester, nylon and acrylic fabrics, fleece and synthetic fill. A PLOS One laundry study (2021) measured synthetic microfibre loss at 9.6 to 1,240 mg per kg of fabric per wash; cotton and wool also shed, at about 165 mg per kg, but natural fibres biodegrade. Wool (a protein, keratin) breaks down in weeks to months, and plant fibres such as cotton and linen (cellulose) in months to years, while polyester, nylon and acrylic persist.
The landmark caveat for bags: the Danish Environmental Protection Agency's 2018 life-cycle assessment (LCA) found a conventional cotton carrier bag must be reused 7,100 times to match a thin plastic (low-density polyethylene, LDPE) supermarket bag across all impact categories, driven by ozone depletion. An organic cotton bag needs 20,000 uses, mainly because the organic bag studied was smaller, so two were needed to carry the same shopping, and organic cotton was assumed to yield 30 percent less; on climate change alone the figures are 52 and 149 uses.
Drawbacks: cotton is water and pesticide intensive; sheep emit methane; natural fabrics can carry chemical finishes; cost varies widely. End of life is biodegradation or textile recycling.