Acknowledgment : The authors thank the members of the Shanghai field team; Professors Gu Xue-qi, Lu Pei-lian, and Ye Ting-ting from Shanghai Medical University; the Shanghai Textile Bureau; workers and staff of the First and Second Textile Mills and the First Silk Mill; Ms. Marcia Chertok, Ms.Janna Frelich, and Ms. Lucille Pothier for research assistance and computer
programming; and Mr. Michael Whitmer for assistance in endotoxin analysis.