Digesting the facts: Is fish safe?

Recent studies show that some large commercially caught finfish may have unsafe levels of mercury. This has led to worries over seafood consumption in general — and tuna consumption in particular. With the glorious abundance of seafood available in the Pacific Northwest, and conflicting information regarding its health benefits, what's a consumer to do?

Don't freak out. Fish and shellfish are good for you, and eating a variety of seafood is considered an important part of a healthy diet. Seafood contains high-quality protein; is low in saturated fat; and rich in vitamins, minerals and those necessary omega-3 fatty acids said to promote everything from a healthy heart to a better brain. Here's a conversation to help you understand this piscatorial can o' worms:

Q: What's up with these reports about mercury in tuna? Should I be alarmed?

A: Alarmed, no. Concerned, yes: sufficiently enough to make yourself aware of the risk that may apply to you.

Q: What's the risk?

A: Mercury exposure in humans here in the U.S. comes almost exclusively from eating fish, and nearly all fish and shellfish contain traces of it. Mercury is an element that occurs naturally in the environment. It is incorporated into the seafood chain through industrial-age water and air pollution and transforms to methylmercury when it enters the water.

Hey! Don't roll your eyes! Here comes the easy part: Big fish eat little fish. And since large fish typically live longer, they ingest more methylmercury, potentially accumulating concentrated levels of a toxic substance that, once ingested (by the fish or by us), isn't excreted.

Q: So, what does the U.S. government have to say about this?

A: In 2004, the FDA and EPA issued a joint advisory noting the many nutritional benefits of eating fish and shellfish — benefits that extended to everyone. But they did acknowledge there were high mercury levels in certain fish and recommended that pregnant women or those who may become pregnant, nursing women and young children specifically avoid eating swordfish, shark, tilefish and king mackerel.

They also warned that at-risk group to limit intake of certain seafood, recommending as allowable portions 12 ounces (or "two average meals") per week of low-mercury seafood, namely: shrimp, canned light tuna, salmon, pollock and catfish. Canned albacore tuna (aka "white" tuna) was limited to only six ounces per week.

Q: Why are certain groups knocking the 2004 advisory?

A: Conspicuously absent in that advisory was a direct reference to fresh or frozen tuna. Nor did it discuss the fact that the mercury count in tuna may vary widely by species ranging from the smallest (skipjack) to the largest (bluefin). Plus, much of the language in that advisory is ambiguous or doesn't go far enough, say advocacy groups like Oceana, a Washington, D.C.-based conservation group, whose recent report helped jump-start the very conversation we're having. They strongly suggest the FDA revisit their mercury "action level" of 1 ppm (parts per million) — particularly in light of the rise in tuna consumption and the growing popularity of tuna sushi, now available at stores and restaurants nationwide.

Q: What does the local government think?

A: The Washington State Department of Health (DOH) has a Fish Consumption Advisories Program and concurs with the Oceana study on several counts. They're not waiting around for the FDA to make changes. Instead, they've issued their own seafood consumption advisory, an easy-to-read "Healthy Fish Choice" guide notable for its color-coded cross-referencing of sustainable seafood. They've even got a catchy catchphrase: "Eat Fish. Be Smart. Choose Wisely." And seeing as we're seafood eaters, not seafood scientists, they suggest you not get caught up in the numbers game with the FDA "action levels" and other variable numerical indicators of mercury content, paying attention instead to what — and how much — we're eating.

Q: OK. Then what and how much seafood should we eat?

A: Most of the fish and shellfish we'll find in our stores and on restaurant menus is considered "healthy choices," according to the DOH. Only a handful of fish should be eaten "rarely, if at all" (these include king mackerel, marlin, shark, swordfish, tilefish and tuna steak). Depending on your "healthy choice," if you're looking to reduce exposure to toxins, you can safely eat anywhere from one to three seafood meals per week.

Portion-wise, an adult meal size is eight ounces (uncooked); a child's is half that. Those figures are based on a 160-pound adult and an 80-pound child. Add or subtract one ounce for every 20-pound difference in body weight. Can't do the math? Do this: remember that a seafood meal appropriate for your body size is approximately the size and thickness of your hand. So, if you've got a small hand, eat a smaller portion. Got a big mitt? Throw another shrimp — or two — on the barbie.

Q: What about mercury in canned tuna?

A: Canned light tuna (skipjack) is a "healthy choice," according to DOH guidelines, but albacore (or "white") tuna gets the nod only if it's troll-caught off the coast of Washington, Oregon or Northern California. As for the commercial brands of canned albacore? Sorry, Charlie! In 2005, the state tested 300 cans of popular tuna brands sold at stores in Washington state (including StarKist, Bumble Bee and Chicken of the Sea), and determined the mercury count too high to warrant the "healthy choice" label, says state fish toxicologist Dave McBride.

Q: Is mercury the only concern?

A: Nope. In addition to mercury, fish may harbor polychlorinated biphenyls (PCBs), polybrominated diphenyl (the flame-retardants known as PBDEs) and other toxic contaminants introduced to local waters by industrial and urban runoff. These can be passed on to developing fetuses. And children whose mothers consume contaminated fish before or during pregnancy are at greater risk for neurological problems. In adults, such contaminants can also affect the heart and the immune systems. Women beyond their childbearing years, and men, face fewer health risks than children.

Q: Is there a difference between commercially caught fish (the kind bought at the store or eaten in a restaurant) and fish caught for sport in Washington?

A: Due to industrial and urban runoff, some fish caught recreationally may contain higher levels of contaminants. In 2003, the DOH issued a statewide advisory specifically identifying smallmouth and largemouth bass as having higher levels of mercury, limiting consumption to twice monthly. In 2006, the DOH warned against overconsumption of Puget Sound chinook ("blackmouth"), noting that these "resident" salmon had increased levels of mercury and PCBs. That said, toxicologist McBride notes, "Would I feed these fish to my kid? I would. Just not every day."

To further reduce the exposure risk to PCBs, the DOH recommends removing the fat and skin from the fish, noting that it's best to grill, broil or bake the local chinook rather than fry it.

Q: Sheesh! This is enough to make me run straight to a steakhouse for some beef! Where can I turn to find out which seafood I should be eating?

A: Someday, the DOH hopes to have their guidelines posted at seafood counters throughout the state; funding is pending. Meanwhile, advocacy groups like Oceana are lobbying the FDA, recommending "point-of-purchase" postings of fish-consumption guidelines and customer advisories (like the mercury warnings found at Whole Foods Markets) at seafood counters nationwide. Until then, you'll have to read up before you eat up. Here's a Web site list for starters:

• FDA/EPA seafood consumption advice: www.cfsan.fda.gov/~dms/admehg3.html or call 888-SAFEFOOD

• Washington State Department of Health Fish Consumption Advisories: www.doh.wa.gov/ehp/oehas/fish/fishconadvice.htm

• Washington State Healthy Fish Choice Guide: www.doh.wa.gov/ehp/oehas/fish/fishchart.htm

• The Monterey Bay Aquarium's Seafood Watch: www.mbayaq.org/cr/SeafoodWatch.asp

• Oceana (a Washington DC-based environmental Advocacy group): oceana.org/north-america

Q: I'm too busy (and, OK, too lazy) to delve into the literature, science, politics and debate over what is or isn't safe. How about some quick advice?

A: Variety is not only the spice of life — it's the best way to ensure you're eating seafood healthfully. Eat across the seafood spectrum. Consume younger, smaller fish. If you eat more than the recommended amount of seafood one month, scale back the next. And if you're a sushi fan, recognize that the fattier the tuna, the more likely it may harbor methylmercury: Limit your tuna intake and lay off the "toro" (bluefin).

Q: So, what's the bottom line?

A: Truth? Most of us actually eat less seafood than we should. For the great majority of the population, the health benefits gained from eating seafood far outweigh whatever scary news about mercury and other contaminants we might be hearing. To quote the folks paid to keep us healthy: Eat Fish. Be Smart. Choose Wisely.

Nancy Leson: 206-464-8838 or nleson@seattletimes.com.

More columns at seattletimes.com/nancyleson.