Swimming Upstream: Toxins in Great Lakes fish (part 7)

Jul 1, 2011

Today, we wrap up our series, Swimming Upstream. Dustin Dwyer traveled all around the Lower Peninsula to gather stories for this series. And today we have a story we wish we didn't have to do. It's the story of toxins in our fish. 

Here's Dustin's story:

A few weeks ago, Joe Bohr got a surprise. He's a researcher for the Michigan Department of Environmental Quality. He was looking at some numbers for PCB contamination in carp caught in canals in St. Clair Shores.

PCBs, or polychlorinated biphenyls, are a group of chemicals that were used in all kinds of industrial products before they were banned in the 1970s. They've been found to cause cancer and other health problems.

Bohr says normally if you're looking at PCB concentrations in fish, four parts per million is pretty high.

“But I looked at those numbers, and the highest one was over 200 parts per million, and that's 50 times higher than you normally see."

It was the highest PCB concentration found in any fish ever in the state of Michigan.

The source is still a bit of a mystery. But there are ongoing tests, and health officials have gone door-to-door to warn people about eating fish from the canals.

Luckily, contamination this severe is rare. But here in Michigan we don't have the luxury to assume all our fish are safe to eat. We have a history of industrial pollution, and many harmful chemicals find their way to our water, and build up in our fish.

Kory Groetsch, is a toxicologist with the Michigan Department of Community Health. He says before you eat fish, it's a good idea to check the state's fish consumption advisory.

“If you follow the fish advisory, we can confidently say that you don't really face any increased risk. If you've been eating more than that, well, it doesn't mean you're going to actually have any negative health outcome. But what you can do is you can talk to your doctor."

But following the fish advisory is easier said than done. The current advisory is about 30 pages of charts and symbols that take you through dozens of types of fish in dozens of waterways.

We can make a couple of generalizations. Usually, smaller fish like perch are safer to eat. Bottom feeders like carp and catfish are more risky. But it can vary quite a bit depending on where the fish comes from, so again, check the advisory.

Also, the risk from these chemicals isn't the same for everyone. Women who are, or who could become pregnant are at extra risk. So are small children and people who already have health problems.

And Groetsch says how you prepare the fish can also make a big difference.

“Cutting away belly fat, back fat, taking off the skin, scraping off the grey sort of tissue on that fillet, and then cooking it on a grill or on a rack in some way that lets fat drip away will reduce significantly the amount of these chemicals in that fish."

But even that doesn't work for all of the chemicals. Mercury can't be cut away.

Mercury is also unique in another way. Most of the toxins in Michigan's fish are actually going down, and they have been for years. But mercury is slowly building up in Great Lakes fish.

Mercury can be especially harmful to brain development for babies and children.

Joe Bohr from the DEQ says most of the mercury in our fish comes from coal-burning power plants.

And while there's been a lot of talk about alternatives, the reality is coal power doesn't seem to be going away anytime soon.

So if you still hope to be eating Michigan fish 50 years from now, unless there's a dramatic change, Bohr says the mercury numbers won't be good.

“I would say it be a scary number, a number where you wouldn't want to eat the fish, right?”

Dustin: “At all.”

“Right.”

-Dustin Dwyer for The Environment Report

You can get more tips on choosing and cooking fish from the state of Michigan's Eat Safe Fish brochure.