There is tremendous controversy about a surgical device implanted in more than two million American women. It's a strip of plastic called gynecological mesh. The manufacturers and several medical societies say the implant is safe. But more than 100,000 women are suing. And together, they make up the largest multi-district litigation since asbestos. One of the largest manufacturers of gynecological mesh is Boston Scientific, a medical device maker with $9 billion in sales. Millions of patients benefit from its pacemakers, stents and other devices. But Boston Scientific has attracted 48,000 lawsuits which claim that its mesh can inflict life-altering pain and injury.

Surgeons use Boston Scientific's gynecological mesh like a sling to relieve urinary incontinence and to lift organs that shift after pregnancy. Gwyn Madsen had a Boston Scientific implant in 2012.

Gwyn Madsen: It felt like a cheese grater inside of me.

Like thousands of others who have filed suit, she says she suffered pain, which in her case, left her hardly able to sit or play with her children.

Gwyn Madsen: It felt like the material was pulling on the muscles and I'd get shooting pains you almost felt like there was something inside of you that was like sandpaper back and forth, every time you'd walk.

Boston Scientific has fought allegations like Gwyn Madsen's for years. They declined an interview for our story but the company told us, "Nearly one million women have been successfully treated… We have extensively tested the [plastic] resin to confirm its composition, safety and performance." The American Urogynecological Society has also said that plastic mesh is "safe and effective." But that's not what many doctors are finding.

Dr. Michael Margolis: The mesh causes a chronic inflammatory reaction.

Dr. Michael Margolis is a surgeon who has removed 350 mesh implants. He's been a witness in lawsuits against Boston Scientific.

Dr. Michael Margolis: The slings I've removed are substantially altered in their architecture. They are shrunk by at least 50% in width; they are encased in scar tissue. The pores here, these openings here are shrunk substantially.

Dr. Margolis recently removed this type of Boston Scientific mesh. It had been implanted in his patient for life, but after two years, it looked like this.

Dr. Michael Margolis: It was folded, it was contracted, it was embedded in scar tissue, it was choking off the urethra. It was 50% the size of its original implant. I measured it, as I always do.

Scott Pelley: These are things that are not supposed to happen?

Dr. Michael Margolis: Of course not. This implant is not supposed to change.

The mesh is made of a plastic called polypropylene, a common material in packaging. Boston Scientific had clearance from the FDA to use a brand of polypropylene called "Marlex" made in Texas by a subsidiary of Chevron Phillips. But in 2004, Chevron Phillips became concerned about medical use of Marlex. It issued a warning that it must not be used for "permanent implantation in the human body." Duane Priddy is a leading plastics engineer and a fellow of the American Chemical Society.

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