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Lake trout: What not to eat (or at least not much of it). Credit: Steve Geving, Minnesota Department of Natural Resources, via the U.S. EPA.

In the best-case scenario, we’ll be able to eat all the Lake Michigan lake trout we want without worrying about getting cancer from the PCBs — in another 20 years.

Less optimistically, we might have to wait until 2046.

Those are the predictions of U.S. Environmental Protection Agency researchers, who have modeled how long it will take for Lake Michigan to get rid of its PCBs (aka polychlorinated biphenyls) — those persistent, toxic compounds that accumulate in fish and people and, as the report says, “have been consistently identified as the contaminant of greatest concern to human and ecosystem health in the Great Lakes.”

Right now, we’re not supposed to eat more than one meal a month of lake trout — assuming we stick to the smaller fish, and trim away the PCB-laden fatty tissues and skin.

Monsanto Co. produced 700,000 tons of PCBs from 1929 until 1977, according to the EPA. They were used to insulate and cool electrical equipment. Banned in the U.S. in 1979, they’re still around: In Lake Michigan, air and watershed tributaries continue to bring PCBs into Lake Michigan, according to the EPA, and the pollutant hangs around in the lake’s sediment.

Researchers found the main way PCBs get into or leave the lake nowadays is by volatilizing, getting into the air. Once airborne, they travel downwind until they’re deposited on land or water elsewhere. (Figure at this link on page 433.)

More information:

Wisconsin Department of Natural Resources advises us which fish not to eat and where in its full Fish Consumption Guide (warning: big PDF, and potentially frightening for avid piscivores). We weren’t talking about mercury in this post — the other reason to avoid Wisconsin fish — but this guide sure does.


EPA’s PCB resources

Lake Michigan Mass Balance Study (also EPA)

More from the State of Wisconsin on fish consumption

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Kate Golden, multimedia director and reporter, specializes in environmental stories and data visualizations.

One reply on “Data for fishermen: How long until the fish are safe?”

  1. In Northeast Wisconsin, Green Bay and Lake Michigan, the main source of PCB (and mercury) pollution was the PAPER INDUSTRY along the Fox River, NOT electrical equipment.

    Starting in 1954, NCR Corporation and Appleton Paper Company produced huge amounts of PCB-coated carbonless copy paper for worldwide distribution, and sent their waste trimmings to nearby paper recyclers, who then incorporated the PCBs in their own products.

    In addition, a few large post-consumer waste paper recyclers in the Fox River valley (especially Fort Howard Corporation, now Koch’s Georgia-Pacific) were contaminated for decades (and some STILL are to some extent), because old PCB-coated documents and files have gradually been cleaned out of office file cabinets and closets, to be re-processed by paper recycling plants year after year.

    None of these self-centered corporations properly cleaned their wastewater before dumping it into the Fox River.

    As a result, at least 7 large paper companies released hundreds of thousands of pounds of PCBs into the Fox River, Green Bay and Lake Michigan. Up to 70% of the waterborne PCBs that contaminate Lake Michigan came from the Fox River in northeast Wisconsin.

    And though DNR issued its first formal report in 1972 about the severe levels of PCB contamination in the Fox River, a “CLEAN-UP” didn’t start until the last few years. Over 30 years passed before our governments finally enforced federal and state laws and began to take REAL actions to protect public health and restore the usefulness of our PUBLIC property: our river, bay and lake.

    But this happened AFTER millions of people in a 4-state region around Lake Michigan had already suffered significant PCB exposures, and AFTER a large portion of the Fox River PCBs had been given time to escape into deeper waters of the upper Bay and Lake Michigan proper, out of reach.

    (A few years ago, a Wisconsin state toxicologist remarked that roughly 1/3 of all Wisconsin residents now carry enough persistent PCBs in their bodies to be over the threshold for potential health effects. Of course, a DNR fisheries biologist immediately objected, saying “We don’t want to alarm the public!”)

    For more than 30 years, the paper industry blocked progress and dragged its feet EVERY STEP of the way, and they continue to obstruct whenever possible if it’s in their financial interest.

    Unfortunately, the final Fox River “clean-up” now underway has been badly compromised by corporate political pressure and the cowardice of our elected officials. It’s only an infuriating half-hearted effort. Roughly 50% of the PCBs still in the river are being “capped” in place, in a crazy distributed patchwork of underwater sites that cover significant portions of river bottom. The so-called “caps” are often just 6 inches of sand, or in a few cases a foot of gravel and rock. The caps are not sealed and have never been proven to work long-term in any large flowing river, particularly in a northern climate with heavy spring and fall ice shoves and erosion, or exposed (as many of these “caps” are) to powerful Great Lakes storms that surge upstream.

    The “clean fish” projections that the DNR and EPA give in this article are based on Fox River caps that stay put.

    When these fraudulent “caps” inevitably begin to leak and erode, and especially when a large flood or storm obliterates caps suddenly, the river and bay will be re-contaminated by formerly covered PCBs.

    The fishermen’s “progress clock” will RESET back to zero.

    This could occur several times over coming centuries, until all the Fox River PCBs are distributed evenly and are gradually buried under cleaner sediments in deeper parts of the Bay and Lake Michigan. Some PCBs will also break down very slowly and some will volatilize into the air and blow to other regions of the world, where NEW people can join in our fun.

    Our children and grandchildren may enjoy some years of relatively clean fish, but with such poorly designed and untested “caps,” these indefinite “clean” periods can’t be guaranteed and may not last long.

    Besides, the corporations have been required to pay for only 40 years of cap testing and fish monitoring. After that, who knows WHAT will be going on out there?

    The corporations are getting away with murder.

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