Some of you may find this interesting:
In a study funded by the environmental group Oceana, University of North Carolina scientists collected samples of tuna and swordfish from more than 20 states and a variety of national supermarket chains, including Safeway, Albertsons, and Whole Foods.
50 Percent Above the Action Limit
50 percent of the swordfish samples tested by researchers exceeded the FDA's action limit of mercury 1 parts per million (ppm). Swordfish bought in Maine and Rhode Island contained more than twice as much mercury than the FDA allows. The samples ranged from 0.41 ppm to 2.33 ppm, with an average mercury concentration of 1.11 ppm.
Tuna is Dangerous for Children
Tuna fared somewhat better; overall, tuna samples averaged 0.33 ppm of mercury and those analyzed from Maine, Washington, D.C., Maryland, and Montana exceeded .50 ppm. However, although this is below the action limit, it is comparable to the levels found in canned albacore tuna that led the FDA and EPA to warn children and women of childbearing age to limit their consumption of it.
The study notes that a 44 pound child consuming 6 ounces of tuna a week at this mercury concentration would be exposed to 4 times the EPA reference dose for mercury, and an 120 pound woman consuming the same amount would be exposed to one and one half times the EPA reference dose.