Greener Jeans

Blue jeans are some of the most popular clothing items of all time. But manufacturing them comes with a hidden cost: Many of the chemicals used to produce jeans’ characteristic blue color are toxic and can end up polluting the environment. Now scientists are working on a greener way to make jeans blue with help from an unusual source—bacteria.

Blue jeans are some of the most popular clothing items of all time. But making them has a hidden cost. Many of the chemicals that give jeans their well-known blue color are toxic. They can pollute the environment. Now scientists are working on a greener way to make jeans blue. They’re getting help from an unusual source—bacteria.

Blue jeans were originally colored with natural indigo, a blue dye derived from several tropical plants, including Indigofera tinctura. Eventually, chemists developed a synthetic, or artificial, version of indigo to keep up with the high demand for the dye. “Synthetic indigo is very useful for industry, but it’s made in an unsustainable way,” says Tammy Hsu, a biochemist at the University of California, Berkeley.

At first, blue jeans were colored with natural indigo. This blue dye comes from several tropical plants, including Indigofera tinctura. Later, chemists made a synthetic, or artificial, version of indigo. This helped to keep up with the high demand for the dye. “Synthetic indigo is very useful for industry, but it’s made in an unsustainable way,” says Tammy Hsu. She’s a biochemist at the University of California, Berkeley.

Synthetic indigo is not soluble—able to dissolve—in water. To make synthetic indigo soluble so it can attach to fabric, jean manufacturers must mix it with harsh chemicals (see Making Jeans Blue). Unfortunately, jean factories overseas sometimes release water tainted by these chemicals into lakes and streams during the dyeing process. The pollution puts people and wildlife at risk.

Synthetic indigo isn’t soluble, meaning it doesn’t dissolve in water. Jean manufacturers must mix it with harsh chemicals. This makes the dye soluble so it can attach to fabric (see Making Jeans Blue). Water that contains these chemicals is used during the dyeing process. Sadly, jean factories in other countries sometimes release this water into lakes and streams. The pollution puts people and wildlife in danger.