The news is rife with reports of high mercury levels in fish and dire warnings for women planning to breed. Lost amid these dueling studies and conflicting health requirements is a truly important question: What about sushi? Can you be healthy and still allow yourself the world's most delectable upscale treat?

Conflicting Reports:

While a certain amount of naturally-occurring mercury always showed up in fish, the 50% of American power that comes from the combustion of fossil fuels (that's coal, to you and me) has led to a sharp increase in mercury which travels from air to soil to water and finally into the biggest, bottom-feeding fish. n 2004, the FDA and EPA joined forces to recommend that women of childbearing age and young children should steer clear of Shark, Swordfish, King Mackerel and Tilefish, since they have the highest levels of mercury.

But the American Heart Association comes out strong in favor of Omega-3 Fatty Acids, which have a proven benefit in older patients prone to heart problems.

A recent study claimed to find huge, toxic levels of mercury in a random sampling of LA sushi eateries, but between the study's sponsor's blatantly partisan status and a big shout-down from the restaurant and tuna-fishing industries, confusion was the natural result.

Slate explored the depth of the confusion last year, but it's still an open question: How much sushi is good, bad, or ugly?

The Cons:

Whether you're talking about Chicken of the Sea or a Spicy Tuna Roll, mercury is mercury. Actually, methylmercury is methylmercury—that's the kind that gets into the brain and stays there. (It gets into other parts of the body, too, but it doesn't build up because it's excreted.) You can't cook it out, so the fact that you're eating it raw has no health effect, mercury-wise.

"The strictures from the FDA pertain only to women of childbearing age and to children, I don't think people understand this too well," says Dr. Robert Goyer, a pathologst and retired deputy director of the National Institute of Environmental Health Science. Women "of childbearing age" are included just in case they might get pregnant. "I'm an old retiree," says Goyer, "So I don't care how much methylmercury I get. You really shouldn't stop eating fish, but certain people shouldn't have too much." Certain people being developing fetuses, via their mothers.

So how much is too much? Depends on the fish. The aforementioned offenders are out . (When was the last time you had a tilefish handroll, anyway?) Newer FDA guidelines point out that the bigger the fish, the higher the mercury level. So those fat, buttery pieces of white tuna? Bad. The less enticing, but still acceptable, pink tuna? Slightly less bad. Salmon? Much better choice. So in terms of cans, if you're spending extra bucks to get the fancy solid white albacore tuna, don't. It's much more toxic than the proletarian chunk light.

Strictly by the numbers, this list divides fish into high- and low-mercury varieties. If you're choosing high-mercury fish like white tuna, the FDA says to only have 6 ounces per week; the average roll has 2 to 4 ounces, and the average piece has 2 ounces. Switch to a lower-mercury fish and you can have up to 12 ounces per week. So if a sushi fix is all you're after, just widen your palate.

Image originally appeared on Flickr.