Posted on July 17, 2014 by Gregory Bibler
On June 10, FDA issued draft updated advice on fish consumption.
The announced purpose of the new advice is to redress a health problem largely attributable to the old advice: “For years many women have limited or avoided eating fish during pregnancy or feeding fish to their young children,” FDA stated. Prominently featured in the old advice, which is still in effect, were warnings that methyl mercury may harm an unborn baby or young child’s developing nervous system, and that nearly all fish and shellfish contain traces of methyl mercury. Women, and their doctors, became so concerned about the potential for trace amounts of methyl mercury in fish to cause harm that they avoided fish entirely.
Acting on the misperception that all fish and all risk should be avoided caused more harm than good. “[P]rimary research studies with pregnant women have consistently found that the nutritional value of fish is important during growth and development before birth,” FDA now says, “even though nearly all fish contain at least traces of mercury.” Rather than trumpeting the dangers of methyl mercury in fish and shellfish, therefore, the new advice affirmatively promotes fish consumption (including shellfish).
There is no indication in the advice that the data on methyl mercury have changed. Both the old and new advisory, in fact, target the same four “bad” fish to be avoided: shark, tilefish, swordfish, and king mackerel. What has changed is a realization that, absent appropriately worded warnings, the public inevitably will conclude that there is no level of acceptable risk.
The essential premise of FDA’s new advice, in short, is that it is not possible to eliminate all risk without unacceptable cost. Implicit in FDA’s justification, in fact, is the realization that warning the public that trace levels of chemicals may cause harm, without making clear either the relative magnitude of the risk or the countervailing benefits that may be sacrificed in eliminating such risk, may itself cause harm. This is not a new lesson. Unfortunately, it is an historical lesson that we appear doomed to repeat.