Further back in the chain, these production processes require incredibly cheap cotton, leading to the use of some truly toxic industrial chemicals, including pesticides so strong that a teaspoon can kill an adult human. The vast use of water, particularly around the Aral Sea in Uzbekistan, creates ecological problems too - droughts, increasing salinity of water, and pollution of drinking supplies.
More info can be found at http://peopleandplanet.org/tradejustice/highcost
To repeat: today (Saturday 10th March), 11AM onwards, New Street branch of Primark. Dress in your finest hippy rags, 'cause ITV News might be coming down...