Nothing can be made without some environmental impact, everything comes at a price.
Clothes will last longer if they are of good quality to begin with, less frequently laundered and mended as required. Responsible consumers will want to be aware of the provenance of the materials when selecting clothing. Choosing natural materials over synthetics is a good beginning. Consider redeployed materials where possible.
Organically grown cotton certainly saves on agricultural chemicals but is no less thirsty than the other sort, requiring just as much irrigation water.
Hemp is rather more durable than cotton and is considered to have less environmental impact but still requires a ploughed field, weed control and a lot of water in the retting process which is used to extract the fibre. On the other hand hemp can produce valuable by-products such as oil from the seeds (which are also delicious to eat as a paste) and excellent green manure.
SIlk production involves considerable manual labour but is a beautifully comfortable fibre that requires a reasonably clean production environment. The mulberry saplings needed to feed the silkworms won't flourish in dirty air. Yes, silkworms do perish in order for the cocoons to be unreeled however their little bodies are considered a valuable source of edible protein in Asia.Their bodies are not designed for longevity (having neither mouth nor anus) nor would it be practical to allow exponentially expanding numbers of flying insects out into the world.
Wool is a renewable resource which must be clipped from the sheep in order to maintain the animal's health and well-being. When sheep are managed properly by responsible farmers their environmental impact is reduced. Scouring the wool requires similar volumes of water to that required for processing hemp or cotton. Dyeing wool is much simpler though, and beautiful colours can be achieved by simple immersion in a warm brew made from water and eucalyptus leaves.
Cotton, hemp, ramie, linen, banana and other cellulose-based fibres require pre-mordant processes using protein substances in order to encourage good take up of plant dyes. Wool and silk, both protein fibres, have a natural affinity for plant dyes.
It is up to the consumer to make their own informed choice.
GreenBlue - a nonprofit institute that stimulates the creative redesign of industry by focusing the expertise of professional communities to create practical solutions, resources, and opportunities for implementing sustainability.
http://www.greenblue.org/
The Permacouture Institute - fashion and textiles from the ground up
http://www.permacouture.org/
