Silicone breasts are now poised to bounce back onto U.S. markets. On Friday, the federal government gave Botox maker Allergan and Mentor the okay to sell the implants.

Cosmetic use of silicone implants were banned in 1992 due to concerns that leakage could trigger a variety of health concerns, including cancer.

But the U.S. Food and Drug Administration said it has determined the implants safe and effective.

"The FDA has reviewed an extensive amount of data from clinical trials of women studied for up to four years, as well as a wealth of other information to determine the benefits and risks of these products," said Daniel Schultz, a director for the FDA, in a statement.

And as the FDA sees it, the evidence was enough to provide reasonable assurance of the implants' benefits and risks, he said.

The news perked up both companies' shares in after-hours trading. Allergan's stock jumped $1.76 to $112.50, while Mentor's climbed $1.47 to $47.58.

Mentor

In the past decade, a number of studies have weighed in on whether the implants are associated with connective tissue disease or cancer.

Among the more recent studies was one funded by major silicone manufacturer Dow Corning. The study, which was published in an April issue of the Journal of the National Cancer Institute, found the implants did not increase the risk of breast cancer or cancer overall (see Study Clears Silicone Implants).

Study Clears Silicone Implants

Public Citizen, however, points to previous concerns over high rupture rates, lymph node infiltration, and damage by leaked silicone.

"The approval makes a mockery of the legal standard that requires 'reasonable assurance of safety,'" said Sidney Wolfe, a director at Public Citizen.

But the FDA assures the public that a number of independent studies have also examined the issue.

For example, the FDA points to a repot by the Institute of Medicine that also concludes there is no convincing evidence that breast implants are associated with either of the diseases.

Institute of Medicine

Until today, women seeking breast enhancement in the U.S. only had one option, saline implants.

U.S.

But the U.S. isn't the only country to have recently brought silicone breast implants back. In late October, Canada also gave Allergan and Mentor the green light.

U.S.Mentor

However, the U.S.'s approval will come with a few hitches. Women looking to cosmetically alter their appearance must be at least 22 to get the implants. But there is no age limit for those using the implants for breast reconstruction.

U.S.

The FDA also said they will continue to monitor the implants. To that end, the agency is requiring each company conduct a large post-market study following about 40,000 women for 10 years after receiving breast implants.

Contact the writer: RBarron@RedHering.com