By Dr. Mercola
Fish was once one of the healthiest food sources on the planet, but as waterways have become increasingly polluted by industry and pharmaceuticals, so, too, have the creatures that live in them.
Discharge from wastewater treatment plants is turning out to be an alarming source of this pollution, particularly since the plants are not always designed to remove pharmaceuticals and chemicals in personal care products.
The result is that once they get flushed down the drain (or toilet), they end up in local waterways.
Puget Sound Fish at Risk From Wastewater Contaminants
A study by the National Oceanic and Atmospheric Administration (NOAA) Northwest Fisheries Science Center analyzed wastewater effluent for 150 contaminants and found 81 present in the samples.1
Pharmaceuticals, including the antidepressant Prozac, the diabetes medication metformin, cholesterol-lowering statin drugs and triclosan, an antibacterial compound found in soap and personal care products, were found in the wastewater flowing into Washington's Puget Sound, as well as in the Sound's water and fish.
According to the researchers:2
"Collectively, we detected 81 analytes in effluent, 25 analytes in estuary water, and 42 analytes in fish tissue.
A number of compounds, including sertraline, triclosan, estrone, fluoxetine, metformin, and nonylphenol were detected in water and tissue at concentrations that may cause adverse effects in fish."
Nearly 30 of the contaminants were detected in fish but not in surrounding waters, which suggests the toxins are bioaccumulating in their flesh.
Salmon on Drugs
Salmon are regarded as an indicator species, which means they serve as a measure of environmental conditions. The researchers examined juvenile Chinook salmon and Pacific staghorn sculpin, both of which are native to Puget Sound.
More than 40 contaminants were detected in their tissues and some, namely Prozac, metformin and triclosan, were found at levels that could harm their growth, reproduction and behavior.
No one knows how this chemical cocktail will affect fish, especially since they're being exposed to a mixture of drugs at once, but it may mean adverse effects will occur at even lower concentrations.
The study did not look into the health effects to humans of eating these contaminated fish, but the fish themselves could likely show some issues. Past research has found, for instance, that dilute concentrations of psychiatric drugs alter the behavior of fish.
Exposure to Pharmaceuticals Disrupts Wild Fish Behavior
Wild perch exposed to anxiety drugs displayed increased activity, reduced sociality and higher feeding rates,3 which could disrupt the natural balance of their surrounding ecosystem.
The featured study researchers further explained that while the contaminants may not kill fish outright, they're likely to have serious, lasting consequences:4
"A noteworthy outcome of the present study is the occurrence of several compounds in water and tissue that have the potential to affect fish growth, behavior, reproduction, immune function, and antibiotic resistance.
One recent review provides a summary of studies on the effects of endocrine disruptors on immune system in fish (Milla et al., 2011). Many of these agents, such as metformin [a diabetes drug], may impact multiple systems such as growth and reproductive pathways.
It is unlikely that the level of exposure for these compounds would result in direct mortality to estuarine organisms; however, all of the above mentioned responses could lead to indirect mortality or reduced population fitness.
As noted by Spromberg and Meador (2005) and Meador (2014) even a minor inhibition in juvenile salmonid immune function or growth likely results in a major impact on survivability during their first year in marine waters."
Kentucky Warns Residents Not to Eat Too Much Locally Caught Fish
Unfortunately, the contamination in Puget Sound is not unique. Fish across the U.S. are simply too contaminated to eat.
Kentucky is one state that has a fish-consumption warning in place for women of childbearing age and children aged 6 years and younger, as these are the populations most at risk from eating mercury-contaminated fish.
But the state's waterways are so contaminated with mercury that state officials have since expanded the warning. Now, everyone is warned not to consume much of the fish caught in local rivers, streams and lakes. Kathy Fowler, director of the Division of Public Health Safety, said:5
"Contaminants, like mercury, can be harmful to the brain and nervous system if a person is exposed to too much of them …
We ask that Kentuckians be mindful of the kinds and amounts of fish they consume, particularly more sensitive populations such as infants, young children and pregnant women."
The waterways are still clearly contaminated, despite the Clean Water Act, which was enacted more than 40 years ago. It's crucial to heed such warnings, as the effects of mercury poisoning are slow; you likely won't realize you're being poisoned until months or years down the road.
Why Mercury-Contaminated Fish Must Not Be Eaten
Pollution has rendered many sources of seafood unsafe to eat, and a major problem is the combustion in power plants of coal containing mercury.
Mercury pollution from coal-fired power plants and other sources moves through the air and is deposited in water and finds its way into fish, accumulating especially in fish that are higher up the food chain.
Fish like tuna, marlin, shark, barracuda, and swordfish have some of the highest levels of contamination. Further, according to a U.S. Geological Survey study, mercury contamination was detected in EVERY fish sampled in nearly 300 streams across the U.S.
More than one-quarter of these fish contained mercury at levels exceeding the EPA criterion for the protection of human health. Up to 90 percent of the organic mercury in fish and shellfish is methylmercury, which is the most dangerous form.6
Methylmercury harms your nervous system to differing degrees depending on how much mercury you've accumulated.
At above average doses, brain functions such as reaction time, judgment, and language can be impaired. At very high exposures, mercury can affect your ability to walk, speak, think, and see clearly.
A 2012 study that evaluated the effects of mercury on cognition in otherwise healthy adults found that those with blood mercury levels below 5 µg/L had the best cognitive functions.7 Mild impairment was evident at blood mercury levels of 5 to 15 µg/L and above 15 µg/L, cognition was significantly impaired.
The risks are even steeper for children and pregnant women, the latter of whom suffer higher rates of miscarriage and birth defects if they eat mercury-contaminated seafood, even if the woman does not appear to be poisoned. Eating mercury-contaminated food may even alter human chromosomes.8,9
Philippines' Fish Distorted by Endocrine-Disrupting Toxins
The problem also extends beyond U.S. borders. Laguna de Bay is the largest lake in the Philippines. Untreated wastes dumped into the bay are being blamed for reproductive system abnormalities in male common carp, including testicular degeneration that could lead to infertility and ultimately threaten the sustainability of the species.
Among the pollutants are xenoestrogens, which are capable of disrupting the endocrine system. Study author Michelle Grace Paraso, PhD an associate professor at the University of the Philippines Los Baños, College of Veterinary Medicine, told SciDev:10
" … [I]n humans, xenoestrogen exposure has been linked to low sperm count, precocious puberty and increased incidence of cancer in estrogen-sensitive tissues [such as in the breast]. In wildlife, exposure has been linked to reproductive abnormalities and population decline."
Moss in Portland, Oregon Contaminated With Toxic Heavy Metals
Even Portland, Oregon, a city known for its "green" initiatives, is not immune from the assaults of environmental pollution. Researchers from the U.S. Forest Service revealed that moss taken from the city's tree trunks and branches contains high levels of heavy metals, including cancer-causing, kidney-damaging cadmium.
Nearby glass factories, which use metals for coloring, are the suggested culprits, although other industry, including a railroad yard, a cement plant and a metal-casting company, are also in the area. The city and its residents were left reeling over the news and puzzled over what to do next.
City officials are now testing soil and air samples and have warned residents living near the glass factories to hold off on backyard gardening until further notice, a warning that, according to The New York Times, "sent another shiver through a city where 'eat local' is almost a mantra." The Times continued:11
"Oregon's state epidemiologist and medical director of public health, Dr. Paul R. Cieslak, called the Forest Service study 'genius' in looking where no one had ever thought to look. But the puzzle of science, anxiety and uncertainty that has resulted, he said, is messy.
… 'From a doctor's standpoint, they always tell us, 'Never order a test unless you know what you're going to do with the result,' Dr. Cieslak said. 'Now we're in this situation where we have all this data from the moss, and we're left struggling to figure out what does it all mean.'"
Are Any Fish Safe to Eat?
Among the safest in terms of contamination, and the highest in healthy omega-3 fat, is wild-caught Alaskan and sockeye salmon. Neither is allowed to be farmed, so each is always wild-caught.
The risk of sockeye accumulating high amounts of mercury and other toxins is reduced because of its short life cycle, which is only about three years. Additionally, bioaccumulation of toxins is also reduced by the fact that it doesn't feed on other already contaminated fish. The two designations you want to look for on the label are: "Alaskan salmon" (or wild Alaskan salmon) and "Sockeye salmon."
Canned salmon labeled "Alaskan salmon" is also a good choice and offers a less expensive alternative to salmon fillets. A general guideline is that the closer to the bottom of the food chain the fish is, the less contamination it will have accumulated, so other safer choices include smaller fish like sardines, anchovies, and herring.
Sardines, in particular, are one of the most concentrated sources of omega-3 fats, with one serving containing more than 50 percent of your recommended daily value.12 They also contain a wealth of other nutrients, from vitamin B12 and selenium to protein, calcium, and choline, making them one of the best dietary sources of animal-based omega-3s.
If you enjoy catching your own fish, you'll want to pay attention to local fish advisories and avoid eating fish from contaminated waters. The U.S. Environmental Protection Agency (EPA) maintains a searchable map to find fish advisories where you live.13
Finding Sustainable Seafood Is Important Too
In addition to finding non-polluted fish, you'll also want to look for fish that are being harvested responsibly. From a sustainability perspective, you'll want to avoid Atlantic sardines that come from the Mediterranean in favor of Pacific sardines. According to the Seafood Watch program:14
"As a result of ineffective management and overfishing, consumers should 'Avoid' Atlantic sardines from the Mediterranean. Instead, choose the relatively abundant and well-managed Pacific sardines from U.S. waters — a Seafood Watch 'Best Choice.'
Also, look for varieties that have received the Marine Stewardship Council (MSC) certification. This certification assures that every component of the manufacturing process — from how the raw materials are harvested to how the product is manufactured — has been scrutinized by MSC and has been independently audited to ensure it meets sustainable standards.
Seafood Watch can also guide you in the direction of more sustainable seafood choices. They have a searchable database to find more sustainable seafood options, and they even offer a Sustainable Seafood app for your smartphone. Other labels that signify more sustainable products include:
- Whole Foods Market Responsibly Farmed 3rd Party certification
- Fishwise: The Fishwise label identifies how the fish was caught, where it came from, and whether the fish is sustainable (or environmentally threatened).
- Seafood Safe: The Seafood Safe label involves independent testing of fish for contaminants, including mercury and PCBs, and recommendations for consumption based upon the findings.