If you’re worried you’ll wake up deathly ill after eating a fish dinner tonight, you should realize the culprit probably won’t be PCBs, dioxins, mercury, pesticides or other harmful contaminants listed in state and federal fish-consumption advisories.

Yes, you should heed the agencies’ advice, but also realize none of the 4,000 fish advisories currently circulating in the U.S. tells people to stop eating all fish now. Most such warnings conservatively counsel how much of a specific fish species you should eat weekly or monthly from individual waterways.

Therefore, unless you eat heaping daily meals of the oldest, largest, most chemically-fouled tuna, sharks, halibut, lingcod, swordfish, muskie, walleye, lake trout or other top-end predators, you’ll reap more benefit by eating fish than scorning it.

One man who understands the difficulties of offering advice to the public is Parker Hall, a wildlife biologist with the U.S. Department of Agriculture in Florida.  Previously, Hall worked in Missouri, where he loved catching flathead catfish. In fact, Hall’s family often consumed five or six deer annually until discovering the Missouri River flatheads. Their deer consumption fell to three once Hall started catching, cleaning, skinning and eating catfish. A mercury advisory suggests limiting flathead meals to one per week, which is fine by Hall.

“If I catch and eat so many big flathead catfish that it kills me, I win,” Hall said with a laugh. “I mean, it’s hard to consume so much flathead meat that it does you wrong. Until then, I plan to have lots of fun. You just pay attention and use common sense.

“The advisories say you should eat one meal a week, and advisories tend to be conservative,” Hall continued. “That means if you eat 52 meals a year, you’re still in the guidelines. I can eat a flathead or buy a cow filled with antibiotics. Flatheads are a resource I won’t pass up. They’re a great way to enjoy the outdoors and spend time with your kids. You should weigh those benefits, too.”

Rare, Sickly Exceptions
That said, a few rare individuals have trashed their health by eating too much mercury-infused fish. High mercury levels can hurt the brain, heart, kidneys, lungs and immune system. Mercury is a naturally occurring element, but scientists estimate two-thirds of what exists in our atmosphere was generated by humans, often from coal-burning power plants, often in Asian countries.

About 10 years ago, Wisconsin researcher Lynda Knobeloch identified seven cases involving 14 people whose blood had high mercury levels from eating fish. Some ate up to nine fish meals weekly, and three reported “vague symptoms” of confusion, blurry vision, sleep problems and unsteady balance. Those symptoms lessened once they quit eating so many predatory fish.

More recently, a South Carolina spearfisherman suffered from rage, mood swings, blinding headaches, irrational behavior, erratic blood pressure and long-term hearing loss after eating lots of hogfish, spiny lobster and other fish he speared on “grocery runs” in coastal waters.

In testimony to the Environmental Protection Agency, BeBe Dalton Harrison, owner of Angling Women, reported the spearer’s mercury levels were 12 times above normal. His health improved after chelation treatments, which shed mercury from his system, but he no longer dives and his hearing loss might be permanent.

Mercury poisoning from massive fish consumption can even occur fast enough to make national news. A 69-year-old Florida man ate so much mercury-tainted fish during a two-week Alaskan cruise in February that he grew confused and forgetful after returning home.

The man, who had a history of diabetes and hypertension, acted so strangely that his wife took him to the hospital. After tests showed his problem wasn’t caused by a stroke or excessive alcohol, his wife mentioned he ate halibut, lingcod and salmon shark at nearly every meal during their cruise. Further tests put his mercury level at 35ng/mL, about 3.5 times higher than normal. He returned home after four days of treatment. His mercury level a month later was normal, 9.2ng/mL.

Assessing Risks
For perspective, if you ate fish tonight and woke up in a hospital tomorrow, investigators would likely suspect that raw fish, spoiled fillets or chunked fish turned toxic on you. They’d ask if you, your Uncle Charlie or Neighbor Nell poorly canned, pickled or otherwise preserved your fateful meal.

Plain ol’ everyday botulism is more likely to put you down, much like it killed an Ohio woman and felled 28 others who ate tainted potato salad at a church potluck in April 2015. Botulism also sickened 31 Mississippi inmates who drank rancid hooch they distilled at a federal penitentiary in June 2016.

Alaskans, meanwhile, seem most prone to marine-based botulism. According to the U.S. Centers for Disease Control and Prevention, seal oil, seal blubber, fish heads, beaver tail, fermented trout and fermented seal flipper caused 10 botulism cases in 2015-2016. In addition, home-canned fish caused two botulism cases in Washington in 2016.

If not botulism, there’s salmonella poisoning, especially for sushi eaters. The CDC annually links salmonella in the U.S. to about 1.2 million illnesses, 23,000 hospitalizations and 450 deaths. Food accounts for 83 percent of those ailments.

In stark contrast, the cause-and-effects of mercury and other environmental contaminants are elusive. If you’re suffering from skin rashes, liver ailments or even cancers, doctors would struggle to link your woes to PCBs, dioxins, pesticides or other contaminants you ate in fish.

Contaminant loads vary by a fish’s age, diet, water depth and home waterway. Further, many of the same contaminants appear in other foods. A 2006 American Medical Association report, for example, showed PCBs in even higher concentrations in beef, eggs, pork, butter and chicken. PCBs were often used as coolants and in carbonless copy paper from the 1940s until they were banned in the 1970s.

Likewise, contaminants in people vary by our age, location, fish preferences, where we fish and how much fish we eat. Therefore, fish-consumption advisories urge caution and moderation to avoid potential long-term ailments, and possible lifelong harm to fetuses and children whose nervous systems are still developing.

Tainted Top-End Predators
Advisories urge anglers to target smaller and younger fish, and release larger and older top-end predators. The farther up the food chain a fish swims, the more contaminants they carry. After all, contaminants accumulate in fat and muscle over time as fish eat increasingly larger and hence, more tainted prey.

The AMA, state health departments, and the federal Food and Drug Administration agree that fish provide vital nutrients for the body and mind. That 2006 AMA clinical review, for example, found one to two weekly servings of fish with higher Omega-3 fatty acids reduce the risks of coronary death by 36% and total deaths by 17%. The report also states: “The benefits of fish intake exceed the potential risks. For women of childbearing age, benefits of modest fish intake (two seafood servings weekly), excepting a few selected species, also outweigh risks.”

Despite such assurances, when many people hear about a fish advisory they assume it’s a fish-eating ban. MeatEater TV host Steven Rinella, for instance, often met people who were aghast that he and his kids caught and ate yellow perch from Lake Washington when living in Seattle. The lake’s advisory suggests no one eat more than one weekly perch meal because these fish contain PCBs, which accumulate in fish fats. Unlike mercury—which settles throughout fish in their meat, skin and bones—PCBs can be reduced through cooking.

“People were horrified we were eating Lake Washington perch,” Rinella said. “They heard there was a fish advisory, so they thought it meant, ‘Don’t eat fish.’ We were eating a bunch of perch, but we rarely caught big perch, and we knew what the advisory actually said.

“I can’t just ignore consumption advisories,” he continued. “My wife will eventually hear about it, and she automatically knows I knew about it because I follow that stuff. So I just explain advisories, give my take, and say this is how I’d like to proceed. She’s cool with that.”

Read the Advisory
Candy Schrank, a retired fisheries toxicologist, worked over 35 years for the Wisconsin Department of Natural Resources. She urges anglers to follow consumption advisories to ensure they maximize the health benefits fish flesh provide.

“Yes, advisories can get complicated, but they’re not that complicated,” Schrank said. “Advisories offer advice. Some people don’t believe the science and they ignore the advice. Other people say they won’t eat any fish from a particular lake, but they probably weren’t eating those fish anyway. And then they’ll eat fish in a restaurant or buy it at a store, and never read any consumption advice. All agencies can do is test fish and share the information. They cannot overstate things. If they go beyond what the science finds, the public soon distrusts the science.”

Schrank said fish-consumption advisories get updated regularly to inform the public of possible risks. The tests also provide insights into water quality and pollution sources, which heighten public awareness of environmental problems. For example, industrial contaminants are generally declining and mercury levels increasing, based on recent tests of Great Lakes fishes.

Rinella respects the science and draws on it regularly. He also keeps fish advisories in the back of his mind while emphasizing fishing’s benefits, which include catching, cleaning and eating fish with his family.

“Fishing is a quality-of-life issue,” Rinella said. “The fun, joy and satisfaction of fishing today outweigh the potential of unknown problems far into a future I might never see. It would be different if fishing were bad for you now and bad for you later. I mean, look at smoking. It not only harms you now, but you pretty much know you’ll live long enough to deal with its worse consequences later.”

In stark contrast, a conscientious, twice-weekly fish-eating habit boosts health. Based on science-based advice in consumption advisories, even pregnant mothers and young children should eat two to three servings of oil-rich fish each week, according to the FDA.

And as Rinella notes, anecdotal evidence suggests few people fish themselves into early graves, or even into senselessness.

“We don’t have tens of thousands of fishermen who later died horrible deaths after first suffering horrible cognitive failures from eating fish,” Rinella said. “You just don’t see that.”