Federal health regulators say a genetically modified salmon that grows twice as fast as normal is unlikely to harm the environment, clearing the way for the first approval of a scientifically engineered animal for human consumption.

The Food and Drug Administration on Friday released its environmental assessment of the AquaAdvantage salmon, a faster-growing fish which has been subject to a contentious, yearslong debate at the agency. The document concludes that the fish "will not have any significant impacts on the quality of the human environment of the United States." Regulators also said that the fish is unlikely to harm populations of natural salmon, a key concern for environmental activists.

The company behind the fish, AquaBounty Technologies, has run a gamut of regulatory hurdles since the fish critics have dubbed "frankenfish" was created in 1989 by scientists at Memorial University in Newfoundland and Labrador. The Waltham, Mass.-based company acquired the licence for the fish in 1994 and began the regulatory approval process in 1996.

If the company is successful in gaining approval, the salmon would be the first genetically modified food animal on the market.

The FDA will take comments from the public on its report for 60 days before making it final.

The FDA said more than two years ago that the fish appears to be safe to eat, but the agency had taken no public action since then. Executives for Aquabounty, speculated that the government was delaying action on their application due to push-back from groups who oppose genetically modified food animals.

Experts view the release of the environmental report as the final step before approval.

If FDA regulators clear the salmon, as expected, it would be the first scientifically altered animal approved for food anywhere in the world.

Critics worry that it could cause human allergies and the eventual decimation of the natural salmon population if it escapes and breeds in the wild.

AquaBounty has maintained that the fish is safe and that there are several safeguards against environmental problems. The fish would be bred female and sterile, though a very small percentage might still be able to breed. The company said the potential for escape is low. The FDA backed these assertions in documents released in 2010.

Since its founding in 1991, Aquabounty has burned through more than $67 million US developing the fast-growing fish. According to its midyear financial report, the company had less than $1.5 million US in cash and stock left. It has no other products in development.

Genetically engineered animals contain DNA that has been altered to produce a desirable trait.

The AquaAdvantage salmon has an added growth hormone from the Pacific Chinook salmon that allows the fish to produce growth hormone all year long. The engineers were able to keep the hormone active by using another gene from an eel-like fish called an ocean pout that acts like an "on" switch for the hormone. Typical Atlantic salmon produce the growth hormone for only part of the year.