What should you worry about more: Raw sushi or cooked fish?  Let’s get the bad out of the way: there’s no getting around mercury. Eat your hamachi, hirame, and hamaguri raw, cooked to shoe leather, or any way in between; mercury levels will remain the same, says Rebecca Goldburg, senior scientist for the Environmental Defense Fund. Mercury, which is linked to a host of health problems, settles in the flesh of the fish where it remains stable, cooking or no.

Now the good news: Polychlorinated biphenyls (PCBs), toxic industrial chemicals that linger in the food chain, are another story. “Cooking does actually help for PCBs because they concentrate in the fat. When you cook fish, a certain amount of the fat melts away,” says Goldburg.

That means that if you are going to indulge in fish that contain high levels—like flounder and farmed salmon—you’ll take in slightly fewer toxins if you cook them well. (Eel, another Japanese favorite that can be high in PCBs, is almost always cooked anyway.)

Of course it’s best to eat fish that are not only low in mercury and PCBs in the first place, but also sustainably fished. True, this probably knocks out some choices at your favorite Japanese restaurant, but it stills leave quite a few healthy, eco-friendly options in play.

Check out EDF’s Seafood Selector, which combines info on all three categories; you can also download it to your web-enabled PDA or cell phone, or print it out on a wallet-sized booklet. The NRDC also lists mercury levels of fish by their Japanese name.

Story by Sarah Schmidt. This article originally appeared in Plenty in April 2008.

Copyright Environ Press 2008