Boston Scientific Corp. is under investigation for allegedly using defective material in surgical mesh implants, and the Houston-based law firm that originally raised the case is pushing for the FDA to double its efforts.

The controversy is based around raw material which may have been used in vaginal mesh implants, causing patient discomfort and complications. Boston Scientific has rejected the claim, saying that they had used “a new supplier” of Marlex resin, a type of polypropylene resin, for several years and found the product to be sound.

“Upon doing so, we put samples of the resin through a rigorous battery of tests to demonstrate equivalency. In addition, we conducted extensive mechanical tests to ensure that our mesh products manufactured with the newly sourced material met product specifications,” Boston Scientific said in a press release.

Mostyn Law, which brought the allegations forward in January in a federal racketeering suit and again in a citizen petition on behalf of a West Virginia patient, said that they do not feel the internal tests are sufficient.

“The FDA’s investigation should not be into the quality of the raw material, but rather the source of the raw material,” Amber Mostyn said in a letter sent to several FDA executives. “The FDA’s proposal to allow BSC to test its own product for equivalency is flawed at its core and stands in stark contrast to statements by the FDA, statutes enacted by Congress, and the public policies behind them.”

Mostyn further alleges that Boston Scientific was aware that the material was counterfeit when they received it from China in 2011 and 2012, and that it did not pass FDA approval at the time.

The mesh is currently undergoing studies by the FDA, which are expected to take several months to complete. The FDA does not recommend that patients who have received the surgical mesh have it removed, since the risks of removal are greater than those presented by the material itself.