Product Range Distribution: Sustainable alternatives?

As mentioned in the previous post about cotton manufacturing and the destructive impact it has on the environment, lots of manmade material processing and manufacture can also have a much more devastating effect. Fibers such as polyester from factories can be washed into rivers, polluting the water making it unsafe to consume or use. 

There is a more "sustainable" alternative to cotton or polyester, viscose. The sustainability of this material is called into question, however.
Made from cellulose or wood pulp from trees such as beech, pine and eucalyptus - these trees are generally quick growing. This makes the material more sustainable as it is;

1. natural 
2. replaceable

It is also cheaper and more durable, making it very popular.

The Changing Markets foundation ran a report on 10 manufacturing sites in India, China, Indonesia and found severe environmental damage. 
Viscose production is chemical heavy, using sodium hydroxide and sulphuric acid. However, the chemical central to the process is carbon disulphide. This chemical has polluted China's largest freshwater lake, Poyang, and killed aquatic life. Not only have the chemicals polluted water, the fumes have polluted the air and affected nearby communities, and most significantly the factory workers. The toxin has been linked to coronary heart disease, birth defects, skin conditions and cancer, and in the past has caused severe mental health problems in rubber factory workers.

One of the plants visited in the eastern province of Shandong was the Shandong CHTC Helon Company which the Changing Markets Foundation says supplies H&M, Inditex (Zara), and Marks & Spencer.The report alleges residential areas nearby to the factory are polluted with carbon disulphide levels three times higher than the permitted limit. According to the report, local people told investigators water from their well is now undrinkable due to pollution. - (source)

This shows that even though the sustainable alternative may be naturable and more sustainable in terms of materials, the process in which the viscose is made pollutes the environment regardless, yet in a different way.
This calls into question the concept of sustainability