Plastic may not be so fantastic.

A large new analysis has found that silicone breast implants are associated with a host of serious diseases and complications, but some regulators say the findings are flawed.

The study, led by a team at the University of Texas MD Anderson Cancer Center in Houston and published two weeks ago in the Annals of Surgery, looked at data from more than 100,000 breast-implant recipients who are enrolled in a Food and Drug Administration database designed to track patient health outcomes. All patients received the implants between 2007 and 2010.

Among the troubling findings: Compared with people in the general population, those with silicone implants are eight times more likely to develop Sjogren’s syndrome, seven times more likely to develop scleroderma and six times more likely to develop rheumatoid arthritis. Melanoma is four times more common, and the likelihood of pregnancy ending in stillbirth is 4.5 times higher.

While the study authors write that their research is not conclusive and requires further investigation into potential causes, the FDA — which regulates breast implants — quickly fired back with a pointed rebuttal.

“We respectfully disagree with the authors’ conclusions,” writes Dr. Binita Ashar, director of the agency’s Division of Surgical Devices.

Ashar cited concerns such as poor study methodology and potential sources of bias.

“Because of these concerns, we urge the public and health-care community to view this external assessment’s conclusions with caution,” she writes.

The FDA plans to hold a public meeting in 2019 “to ensure that patients and health-care providers continue to have accurate, scientifically sound information about breast-implant safety and effectiveness, and to promote public dialogue on the issue.”