The FDA Action Level

See this related seafood lobby fable:
Fable: Fish that meets the FDA Action Level for mercury poses no risk

In the 1970s, the FDA set an “Action Level” for mercury in fish. Initially, FDA set the level at 0.5 part per million, the level adopted by most other countries that have similar limits. However, the fishing industry sued FDA, arguing that the economic impacts of the standard were likely to be too severe. A court agreed, and FDA had to revise the Action Level, raising it to 1.0 ppm, the current level.

An Action Level is a legal device; it allows FDA to order fish with more than 1 ppm of mercury to be taken the market, without needing to establish that a hazard exists in each specific case, which is otherwise be required under food safety laws. An Action Level is not a safety standard. But can be confused for one, as in this popular seafood lobby fable:

Fable: Fish that meets the FDA Action Level for mercury poses no risk.

Facts: The Action Level is not a risk-based standard. Risk is determined by dose, not by the level in fish. The mercury dose a person gets depends on three factors: The mercury level in the fish; how much fish the person eats, and how much the person weighs. The definition of safe exposure is the Reference Dose.

Unfortunately, it is quite easy to exceed the Reference Dose for mercury intake by eating fish often, even if that fish contains much less than 1 ppm mercury. Five servings of different fish with an average mercury level of 0.2 ppm contain just as much mercury as one serving of fish with 1.0 ppm. The amount of fish consumed and the level of mercury in the fish are both critical.

The FDA Action Level is therefore an unreliable guide as to whether eating fish poses significant risks. The Action Level is also rarely enforced, and as a practical matter, it is unenforceable. FDA cannot monitor all the places where fish are sold, and enforcing the 1 ppm limit would essentially ban the sale of swordfish, shark and Gulf tilefish—a step FDA has long chosen to avoid for economic and pragmatic reasons.