Fabric Bleaching and Dyes

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Rebecca Spector and Sandra Marquardt

Monday, June 18, 2007

Many cotton garments are first bleached white before they are dyed another color, either with chlorine or hydrogen peroxide. And dioxin, a carcinogen and possible hormone disrupter, is produced and released into the environment during chlorine bleaching of cotton.

Chemical dyes frequently include toxic heavy metals such as chrome, copper and zinc, and sometimes contain known or suspected carcinogens. Even natural dyes, because of their poor colorfastness, are often accompanied by heavy metals in the mordant, or dyefixing, agent. Due to cotton's natural resistance to dyes, at least half of the chemicals used in the dying process end up as waste in rivers and soil.

Although currently there are inherent problems in the dying process, some companies are using low-impact or natural dyes to reduce their overall impact on the environment as much as possible. Patagonia, for example, has developed a rating system for evaluating the environmental impact of their dying process that includes an evaluation of energy and water use, dye fixation, and heavy metal and chemical use. "By using this rating system, we can look at a whole host of problems and determine what parts of the process need to be improved," says Eric Wilmanns, an environmental analyst at Patagonia.

Some companies also offer products that are made with undyed or unbleached cotton, or cotton that's been bred to grow in natural earth colors. But unless the cotton is grown organically, these are only partial solutions.

There are currently no uniform guidelines for the use of sizing agents, bleaches and dyes on organic cotton. According to Jeffrey Hollender, CEO of Seventh Generation , "There are people who dye organic cotton with what they call 'low impact' reduced heavy metal dyes. They say these heavy metals occur in nature. They're still toxic!"

Luckily, indigenous people have been growing cotton in natural colors like brown and green for years. Some companies sell unbleached, undyed, naturally-colored organic cotton fabrics. Other companies use heavy-metal-free natural dyes derived from plants and insects.