In a small, damp factory here, blood-smeared men wring pulp from pig intestines, then heat it in concrete vats.
The activity at Yuan Intestine & Casing Factory is the first step in the poorly regulated process of making raw heparin, the main ingredient in a type of blood-thinning medicine that in recent days has come under suspicion in the deaths of four Americans.
More than half the world's heparin comes from China. The chemical is often extracted from pig entrails in small factories -- many as rudimentary as this one, which also manufactures sausage casings from intestines. The heparin eventually ends up in drugs used world-wide by patients having surgery or who need dialysis.