Johanna Marie Staples, of Toledo, Ohio, said her husband, Dennis, had been looking forward to his 60th birthday party on the last day of his life.

Contaminated heparin, a blood thinner used in dialysis and other treatments, has been connected to 81 deaths and 785 severe allergic reactions, said Rep. Bart Stupak (D., Mich.), chairman of the House Energy and Commerce subcommittee on oversight and investigations.

The heparin, made from ingredients imported from China, has been recalled by Baxter International Inc., and the Food and Drug Administration has blocked imports from the Chinese company.

Chinese officials have suggested the problem comes from manufacturing of the finished drug at a Baxter plant in Cherry Hill, N.J., which a Chinese delegation toured last week. The FDA inspected the Cherry Hill plant in February, however, and gave it a clean bill of health.

The FDA is looking at a contaminant discovered in material supplies for heparin coming from China. The agency has established, through animal tests, a biologic link between the contaminant and allergic reactions.

Colleen Hubley, a dialysis nurse whose husband, Randy, died after receiving heparin, told of a desperate struggle to save his life with cardiopulmonary resuscitation.

When her husband came home from a dialysis treatment, he suffered diarrhea and abdominal pain, and had problems breathing, she said.

At 2 a.m., she said, she awoke to find him clutching his abdomen and grabbing his chest, unable to breathe. She did CPR and called paramedics, who struggled to get a breathing tube in his throat because of swelling.

Randy Hubley's death came just a month after that of his mother, Bonnie, under the same circumstances.

Janet Woodcock, director of the FDA's Center for Drug Evaluation and Research, told the subcommittee that in recent years there had been major changes in where drugs were made.

For example, in 2007, the agency received only about 150 applications for approval to make generic drugs in the United States compared with nearly 500 from China and more than 400 from India, she said.

Baxter president Robert L. Parkinson Jr. said in testimony prepared for the subcommittee that his company was "greatly concerned that our heparin product appears to be the target of a deliberate adulteration scheme."

David Strunce, president of Scientific Protein Laboratories L.L.C., said in testimony that the worldwide problem with contaminated heparin could not be traced to processing work at the Changzhou SPL factory in China that supplied the material to Baxter. His company holds a majority interest in Changzhou SPL.

Rather, Strunce said, there appeared to be deliberate and widespread contamination of the crude heparin supply in China affecting many manufacturers.