Scientists Want to Know How Much Fish You Ate Last Night


Fish Marquee Image
How much is safe to eat? Image courtesy of Heather Joan.

Reported by Robert McClure, InvestigateWest

The science of setting water-pollution limits for factories, sewage plants, and other facilities that dump into waterways can be tricky, especially when people catch fish for dinner from those waters. It’s a big health dilemma for some subsets of the American population who eat a lot of seafood, including sport fishers, people on low incomes, Asian immigrants, and members of coastal Indian tribes.

The current estimate of how much fish people eat, a key criterion for setting water quality standards, is in some states less than one-twentieth the figure used by Oregon.* Image courtesy of Jason Alcorn and InvestigateWest.

The federal Clean Water Act is supposed to protect the rivers, lakes, and bays where we glean our fish and other seafood, but that isn’t always the case. Fish living in polluted waters can contain toxic chemicals that, if eaten, lead to cancer and other health problems.

It may be surprising to learn that the way the U.S. Environmental Protection Agency has told states to set the pollution limits is to first find out how much fish people are eating, and then set stricter pollution restrictions if people are eating lots of fish and less strict ones if they’re eating less fish. To do this, the state determines a “fish-consumption rate,” a figure that gets cranked into a complicated health-based formula that is supposed to protect the well-being of people who eat fish and other kinds of seafood.


“Seafood is a staple of a lot of people here in the Pacific Northwest, as well as freshwater fish, and it’s supposed to be a healthy alternative to other food sources,” says Shawn Yanity, chair of the Stillaguamish tribe in Washington State. “But how healthy is it when you’re only allowed to consume so much before you start taking on a risk of cancer and other sicknesses?”
Groups that want a lower fish-consumption rate in Washington State have started a campaign on YouTube, including videos of people who eat more than the state average of fish.

The trouble is that limiting and cleaning up water pollution can have big financial consequences for industry and others regulated under the Clean Water Act. Another problem is that seafood-consumption data are not always accurate.

In some states, this crucial variable has recently been shown to fall far short of what people are actually eating. Part of the problem is that many states set their fish consumption rate years ago, when Americans ate less seafood. The American Heart Association recommends eating fish twice a week, which would greatly exceed most states’ estimates of how much people eat if all that fish came out of local lakes and rivers.

WA and OR fish rate comparison
Oregon increased its fish consumption rate to 175 grams per day in 2011, nearly 30 times that of Washington State.

For example, the state of Washington bases its water-quality standards on an estimate of just 6.5 grams per day, not even enough salmon to cover a big cracker. Where did that number come from? It turns out that it traces back to three-day food diaries filled out in the 1970s.

Washington environmentalists and Indian tribes are battling to boost the fish-eating estimate, citing studies of fish-consumption rates among tribal members and others dating to the mid-1990s. But business interests are pushing back. They want additional studies to clarify just how much of the fish people eat is actually coming from the waterways that are being polluted. After all, the current law stipulates that if people eat less seafood, more pollution can be allowed.

Meanwhile, Oregon increased its fish consumption rate to 175 grams per day in 2011, nearly 30 times that of Washington.

And in September 2013, under orders from the EPA, Idaho officials assigned a contractor to survey state residents about the amount of fish they eat.

Changes may be afoot in other states, too, as awareness of the low fish-consumption estimates garner more attention and more scientists want to know how much fish you ate last night.


* Fish-consumption estimates in selected states around the country:

Ohio: 17.5 grams per day
California: Varies depending on the pollutant and other factors. For mercury, historically 16.5 grams per day (but 32 grams per day in the San Francisco Bay and Bay Delta regions); EPA promulgated a 6.5 grams per day estimate for polychlorinated biphenyls.
Nebraska: 32 grams per day
Wisconsin: 20 grams per day
North Carolina: 17.5 grams per day