I know that the Indian Caste system has been reviled and dehumanized for centuries. While exploitation of any kind is bad, exploiting a certain segment of society who did (still do?) the "dirty" job and treating them worse than filth needs serious review.
This article explains the ecological responsible way of dealing with human waste and composting it into rich manure. Historically, China and India separated the human solid waste from liquid (via dry toilets) and human "scavengers" took the solid out to compost and sell to the rice fields. Not only did this provide a source of income to "caste out" people, it also ensured the clean disposal of human waste that would have certainly piled up elsewhere! today this is done in smart toilets that separate the urine from the solid waste to ensure the proper composting of the waste without dehumanizing any one in some parts of the world. (check out Canadian Envirolet)
With the advent of flush toilet systems, dry toilets fell from favor. However, every metropolitan city with huge populations face heavy problems that include water shortage that indirectly leads to fewer flushes that in turn leads to improper disposal of human waste via sewage lines. Thus waste piles up in unwanted places causing epidemics to break out including cholera and other intestinal diseases. Rivers and other water ways become more polluted as humans use them as direct "dumping grounds".
The sad part is, the "untouchables" did not patent their work and today, people from other parts are doing their job in a neater way and getting paid for their patents.
Edited by blokes - 13 years ago