Genetically Engineered Salmon: FAQ

Sept. 22, 2010 - Is genetically engineered salmon safe to eat? What effects will the altered fish have on the environment? What the heck is a genetically engineered salmon, anyway?

The FDA's pending decision on whether to approve genetically engineered salmon -- and whether it should be labeled -- has spawned many questions. WebMD provides answers.

What Is Genetically Engineered Salmon?

Genetic engineering isn't new. For thousands of years, humans have used selective breeding to raise crops and livestock with desirable traits.

Modern technology now gives scientists -- and the industries that employ them -- the ability to directly alter the genetic structure of plants and animals.? This is done by inserting desirable DNA sequences directly into the genome.

This already is done in a large number of vegetable crops. But now a company called AquAdvantage wants to do it in salmon. If the FDA gives the green light, it will be the first genetically engineered animal sold as food.

The Atlantic salmon that AquAdvantage would produce are exactly the same as other farmed Atlantic salmon except for one thing. They carry a DNA switch that freezes a growth-hormone gene in the "on" position. This causes overproduction of growth hormone, making the fish grow much faster than normal farmed salmon.

How Do Genetically Engineered Salmon Differ From Normal Farmed Salmon?

They are almost exactly the same.

AquAdvantage genetically engineered salmon differ from normal farmed salmon only in their speed of growth -- and in how much growth hormone they produce. But they are not like wild salmon.

Both "normal" farmed salmon and genetically engineered salmon are manipulated in a number of ways that improve farming yield but which make them very different from wild salmon.

Are Genetically Engineered Salmon Safe to Eat?

Probably. An FDA analysis concludes that genetically engineered salmon is just as safe as normal farmed salmon. But nagging questions remain. An analysis by a Consumer Union scientist, for example, concludes that far more information is needed.

There are two basic differences between normal farmed salmon and genetically engineered salmon: The altered salmon grow much faster, and they make more growth hormone.

As long as the genetically engineered fish are raised in a healthy manner, their speed of growth does not appear to be a problem in and of itself.

But safety data analyzed by the FDA looked only at AquAdvantage salmon grown at a Canada facility. Critics say there is no data from the Panama facility at which the firm intends to produce most of its fish.

Different questions are whether the insertion of the DNA switch causes a safety problem -- and whether the extra growth hormone in the genetically engineered fish will cause problems.

The FDA analysis suggests that the DNA switch itself doesn't make the fish unsafe. And it concludes that the level of growth hormone in the altered fish is not especially worrisome.