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Bioaccumulative & Persistent Chemicals in Fish

Michigan's fish consumption guidelines are the result of years of chemical pollution from near and far building up in our waters and in our fish.  The chemicals that cause the fish advisories to be issued, like PCBs, DDT, dioxin and mercury, are chemicals that are bioaccumulative and persistent.

The word bioaccumulative or bioaccumulation is used to describe the build up of chemicals in fish found in some of Michigan's lakes and rivers. The chemicals build up through the food chain, as shown in the picture below.

image demonstrating how chemicals bioaccumulate in fish

Unfortunately, these very same chemicals are also persistent. Persistent chemicals are very stable and don't break down over time.


image demonstrating the concept of persistent chemicals in the environment

If you eat a lot of fish that have these persistent and bioaccumulative chemicals in their bodies, these chemicals can build up and stay in your body, too. These chemicals may cause health problems for growing children and adults, alike.

So, why do we have the Eat Safe Fish Guide?

plates of fish with chemicals in them, man and children checking the Michigan Fish Advisory

After eating fish with these chemicals in them, the chemicals will build up in your body, too.

If you only eat fish every so often and the level of chemicals are low enough, your body has a chance to get rid of the some of the chemicals that build up. 

However, if you eat fish often or if you eat a fish that has a lot of chemicals in it, your body will have a harder time getting rid of the chemicals.

After years of these chemicals building up in your body, some people may develop health issues, like cancer or diabetes.  The growth and brain development of children may also be affected.

You can find out which Michigan fish are lower in chemicals by using the MDHHS Eat Safe Fish Guide (ESF Guide).  This is a guide that is published by the Michigan Department of Health and Human Services (MDHHS). 

The MDHHS ESF Guide can be used to help you choose fish that are lower in chemicals, so that you can avoid fish higher in chemicals and protect your health.

"I've been eating fish all my life, and I don't have anything wrong."

It's true that not everyone will get sick. Some people may be fine after years of eating fish with these chemicals in them. Others may have health problems. 

However, there is currently no way to know who might get sick from the chemicals found in some fish and who won't. 

Whether you get sick from the chemicals or not depends on your DNA and any other chemicals you may have been exposed to in your lifetime.  It is like a jigsaw puzzle inside your body - sometimes the pieces can fit together and cause illness, sometimes they won't fit at all and you won't get sick.

Because there is currently no way of keeping track of all the chemicals you've been exposed to during your life, and there is no way of knowing who might get sick from these chemicals, it is best for everyone to make good choices when it comes to eating fish.

How does MDHHS know what chemicals are in fish?

The Michigan Department of Natural Resources (MDNR) collects fish from waterbodies around Michigan.  These fish are fileted like they are going to be eaten, but instead those filets are sent to the lab to be tested for chemicals.  The recommendations in the MDHHS ESF Guide are based on the amount of chemicals only in the parts of fish that are eaten.

Working with the Michigan Department of Environmental Quality (MDEQ), MDHHS reviews the amount of these chemicals in fish that have been tested. 

They use this information to make the eating suggestions found in the MDHHS Eat Safe Fish Guide.  You can use the ESF Guide to choose the best fish for you.

To see technical chemical analyses for the fish found in the MDHHS ESF Guide, please visit the Michigan Department of Environmental Quality's Fish Contaminant Monitoring Program Online Database.

What is being done to fix this problem of chemicals in fish?

The MDEQ and the United States Environmental Protection Agency (EPA) oversee laws that have stopped a lot of the pollution of our waters and air. However, some chemicals are still entering our waterways from wind, rain, and ground run-off from melting snow, rain, and other sources.

The MDEQ and EPA are working to clean up some of the more heavily polluted areas in Michigan, but it can take a long time to complete the job. And until all countries of the world adopt better environmental standards, more chemicals can continue to enter our waterways.  That's why it's important that you learn how to protect yourself and make the best choices for you and your family when it comes to eating fish.

If you eat a lot of fish or always go fishing in the same lake or river, check the MDHHS Eat Safe Fish Guide, the Statewide Safe Fish Guidelines and/or the Buy Safe Fish brochure to be sure you're eating safer fish!

Click here for a definition of bioaccumulative and persistent chemicals
that you can print out or save to your computer.


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