By Michael J. Critelli | MakeUsWell Newsletter,
Seafood should be one of the healthiest and most sustainable foods on our plates. Rich in omega-3 fatty acids, lean protein, and essential micronutrients, it is often held up as a cornerstone of a heart-healthy diet.
Yet the truth is more complicated. Every bite of seafood carries a story—not just of the ocean or river it came from, but of how our industrial systems handle waste, how fisheries are managed, and how chemicals and contaminants move through our environment. To eat seafood wisely, you need to understand the invisible risks and make informed choices.
The Hidden Threat in Our Water
When most of us imagine water treatment, we assume the plants that clean our wastewater are removing everything harmful. The reality is far less reassuring. Traditional wastewater treatment facilities are excellent at breaking down organic matter and killing pathogens. What they cannot do, at least not reliably, is filter out pharmaceuticals, hormones, pesticides, PFAS, and microplastics. I saw this myself when visiting a 100-year-old waste treatment plant in Ridgefield CT some years ago. I learned that chemical wastes of all kinds would eventually end up in Long Island Sound, a tidal estuary of the Atlantic Ocean.
Around America, that means residues from birth control pills, livestock waste, and painkillers end up in the same rivers, lakes, and coastal waters where fish and shellfish live. These contaminants may be invisible, but they reshape aquatic life. Male fish exposed to trace levels of estrogen develop female traits. Populations of freshwater species have declined because their fertility has been quietly compromised. What happens under the surface of these waters eventually makes its way onto our dinner plates.
The Risks That Reach Our Tables
Mercury and heavy metals remain the most immediate concern for consumers. Large, long-lived predators such as shark, swordfish, and bigeye tuna accumulate dangerous levels of mercury. That doesn’t mean we should give up seafood altogether—far from it. Safer choices abound: wild salmon, sardines, anchovies, trout, Atlantic mackerel, and most shellfish are low in mercury and rich in nutrition. The key is restraint. Treat high-mercury fish as rare indulgences, not weekly staples.
Other contaminants are less visible but equally worrisome. PCBs and dioxins collect in the fat of fish from polluted waters or poorly regulated farms. Microplastics that strip off plastic food and beverage containers are increasingly present in mussels, oysters, and small filter-feeding fish.
No one yet knows the long-term impact of microplastic consumption, but the early signs are troubling. Choosing fish from cleaner waters, trimming skin and fat where contaminants accumulate, and rotating the types of seafood you eat are practical steps to reduce risk.
And then there is the question of estrogens in seawater. In the last several decades, the use of estrogen has increased significantly through the increased use of birth control pills and hormone replacement therapy.
Unlike mercury, estrogens don’t build up as strongly in fish tissue, so our direct exposure through seafood is relatively small. But their ecological effects are devastating. They weaken fish populations, disrupt reproduction, and erode biodiversity. For humans, the danger is not so much from eating fish as it is from losing them. When fish populations collapse, our food security and the resilience of aquatic ecosystems collapse with them.
Choosing Between Farmed and Wild
Aquaculture is sometimes presented as the answer to overfishing, but it is not without its pitfalls. In crowded pens, farmed fish, very much like cattle, may be treated with antibiotics, exposed to pollutants in feed, and stressed in ways that compromise their health and ours. Wild-caught fish avoid those conditions, but unsustainable fisheries can deplete stocks and damage marine ecosystems.
The solution is not to reject one in favor of the other, but to demand accountability. Certifications matter. The Aquaculture Stewardship Council (ASC) and Best Aquaculture Practices (BAP) labels signal that farmed fish were raised responsibly. The Marine Stewardship Council (MSC) label helps identify wild fisheries that are sustainably managed. These aren’t perfect systems, but they are our best tools for separating responsible producers from reckless ones.
Shellfish: Small but Powerful
Shellfish deserve special mention. Mussels, oysters, and clams are nutritional powerhouses, low in mercury and rich in protein and omega-3s. They also filter water as they feed, improving water quality in the process. But that same filtering makes them vulnerable to bacteria, viruses, and toxins in polluted waters. The safest approach is to buy shellfish from regulated sources and avoid eating them raw unless you are certain of the water quality.
Practical Guidelines for Smarter Choices
So what can consumers actually do? Start with the basics:
Use the Seafood Watch app from the Monterey Bay Aquarium for real-time guidance on sustainable options.
Favor low-mercury, certified seafood such as wild Alaskan salmon, sardines, trout, and mussels.
Rotate your choices—variety reduces the risk of concentrating any single contaminant.
Follow the American Heart Association’s advice: two modest (3.5–4 oz) servings of low-mercury fish per week.
Support investments in advanced wastewater treatment that can remove estrogens, PFAS, and pharmaceuticals before they enter our waterways.
The Bigger Picture
Seafood connects our health to the health of our environment more directly than almost any other food. What happens in wastewater plants, in aquaculture pens, and on fishing boats does not stay hidden; it shows up in the meals we feed our families. The good news is that we have choices. We can demand traceability. We can favor certified, sustainable options. We can treat high-risk fish as rare treats rather than weekly staples.
The message is clear: seafood is worth keeping in our diets, but only if we choose wisely. By protecting the ecosystems that produce it and holding ourselves accountable as consumers, we protect not just the oceans, but our own health and future.