The Widespread Environmental Footprint of Indigo Denim Microfibers from Blue Jeans

At any moment, approximately half of the world’s population is wearing blue jeans and other denim garments. We examine the footprint of our modern blue jean society by investigating the environmental distribution, pathways, and sources of indigo denim microfibers shed by denim clothing. Microfibers comprised 87–90% of the anthropogenic particles found in sediments from the Canadian Arctic Archipelago, Laurentian Great Lakes, and shallow suburban lakes in southern Ontario. Twenty-one to fifty-one percent of all microfibers in sediments were anthropogenically modified cellulose (AC), of which 40–57% were indigo denim microfibers (12–23% of all microfibers analyzed). AC microfibers were also found in rainbow smelt from the Great Lakes. Wastewater treatment plant effluent collected in southern Ontario contained 22 ± 18 microfibers L–1, 13% of which were dyed with indigo, characteristic of denim fabrics. Finally, as a source for introduction into wastewater, we found that one pair of used jeans can release 56000 ± 4100 microfibers per wash. Microfibers from jean laundering were consistent in chemical composition and morphology with those found in the environment. We conclude that blue jeans, the world’s single most popular garment, are an indicator of the widespread burden of anthropogenic pollution by adding significantly to the environmental accumulation of microfibers from temperate to Arctic regions.