Is Your Sushi Killing You?

Mercury. It’s poisonous, and it’s in our favorite fish. How worried should we be?

For decades now, doctors and media pundits have been warning us about the dangers of mercury in fish, particularly in larger varieties such as swordfish and tuna. Given how much ahi Hawaii eats, are we doomed to slow mercury poisoning? And how much do you have to eat, anyway, to catch a toxic dose?

The short answer: No one really knows for sure. Neither the Hawaii State Department of Health (DOH) nor the feds have an advisory on the subject for the general public. The good news: Hawaii has had no known cases of mercury poisoning stemming from fish consumption, says state toxicologist Barbara Brooks. The furthest the state will go is to warn pregnant women, nursing mothers and younger children to eat ahi only once every two weeks, and to completely avoid shark, marlin and swordfish.

That doesn’t mean the rest of us can relax. Hawaii researchers continue to study the mercury levels of ahi caught in Island waters, and while the levels don’t approach the unambiguously dangerous level found in shark, tilefish and swordfish (1 part per million, or ppm, roughly), they’re far from zero. Of 97 tuna (bigeye, yellowfin and skipjack) tested by the state DOH in 2009, bigeye ahi had the highest levels, with .542 PPM, (plus or minus 0.261 PPM). You’d have to eat a lot of ahi, for a long time, to incur much risk, but given Hawaii’s abundance of fresh fish, it’s something to keep in mind.

To further complicate matters, ahi also contains selenium, a trace element that scientists believe helps counteract the toxic effects of methylmercury. And let’s not forget that ahi is also a rich source of lean protein filled with omega-3 fatty acids ... if you need some shred of hope to cling to as you dig into yet another poke bowl.