Blood and Treasure: Free Trade Human Plasma Across the US Mexican Border?

From The National, a strange phenomenon I just wrote about: impoverished Mexican residents trek across the border to sell the plasma in their veins to multinational corporations. The companies set up operations literally within sight of the border crossings:

The United States is the world's leading exporter of human plasma - providing about 70 per cent of global supplies, the biggest player in what is now a multibillion dollar business. In recent years, nondescript plasma collection centres have sprung up in dusty towns all along the US-Mexico border: in Laredo, Texas, across the border from the drug-war battlefield of Nuevo Laredo; in Eagle Pass, Texas; in Yuma, Arizona. Here, giant for-profit companies pump blood plasma from the veins of paid donors - many of them poor Mexicans with nothing left to sell but their blood."