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.