A new study from Boston College and the Woods Hole Oceanographic Institution draws some jarring conclusions on the link between ocean pollution and human health. Lead researcher Dr. Philip Landrigan discussed the study with GBH All Things Considered Host Arun Rath. This transcript has been edited for clarity.

Arun Rath: I think people probably aren't surprised to hear that our oceans are polluted. But how polluted are they? And was this a surprise?

Dr. Philip Landrigan: Yeah, I agree. It's not news that the oceans are polluted. But what we learned through this two-year study that we took in collaboration with the government of Monaco is that ocean pollution is much more extensive than previously realized, and also that it has many more effects — direct effects and indirect effects — on human health than we had previously understood. I think those are the two big messages here.

Rath: We want to talk about the effects in detail. First though, do we have a clear understanding of the various sources of the pollution that is in the oceans?

Landrigan: Mostly. Not entirely, but mostly. So to run down the numbers, mercury is one of the big pollutants in the ocean. Coal combustion is the major source of that mercury. All coal contains a certain amount of mercury, and when you burn thousands of tons of coal, the mercury vaporizes, it goes up into the atmosphere, and it comes down into the oceans. In the ocean, it accumulates in fish, especially in predator species like tuna, like striped bass, like bluefish, like swordfish, and that's how humans can be exposed. If a pregnant mom eats fish that's contaminated with mercury that originated in a coal-fired power plant, that mercury goes into her body, goes through to her baby, and it can cause brain damage in the baby, loss of I.Q., increased risk of attention deficit disorder, increased risk of autism spectrum disorder.

Rath: Do we have a sense of how extensive ocean pollution is across the world? Are there places that are notably worse than others?

Landrigan: I would say it's definitely worse along the coast of developing countries. Unfortunately, low-income and middle-income countries don't have sophisticated waste collection systems. A lot of waste gets dumped there and washes into the sea. But pollution originates in every country, and every country that still uses plastic bags — every country that still extensively uses one-shot plastic that's one and done and gets tossed out — those countries, including our country, the United States, contribute to ocean pollution.

Rath: We'll talk in more detail about how pollution affects humans through food. Are there other ways that ocean pollution is a factor in human health?

Landrigan: Food consumption, consumption of contaminated seafood, is the main route of consumption. So the mercury that comes from coal reaches us through food. Plastic waste in the ocean breaks down and forms what are called microplastic particles, microscopic particles that harbor a whole slew of toxic chemicals — carcinogens, neurotoxins, endocrine disruptors. Those little plastic particles get into fish, get into shellfish, we eat them, and the plastic comes into our body. Another route of exposure is inhalation. When the oceans get polluted with chemical waste, animal waste, human waste, we have these algal blooms that we have along the coast every summer, what we call mung down on Cape Cod — red tides, green tides, brown tides. Some of those algal blooms release these very potent natural toxins, and when we eat them in contaminated shellfish or inhale them, they can cause asthma if we inhale them. If we eat them in contaminated shellfish, they can cause acute neurologic disease, paralysis, amnesia, even rapid death. So there's a whole series of different pollutants and a whole range of different ways in which these pollutions can come back and bite us.

Rath: At the consumer level, at the individual level, obviously we are in a place where people love seafood. It's also part of culture and commerce. How concerned should people be, and what should they be concerned about specifically when it comes to consuming seafood?

Landrigan: Sure, there's always a risk vs. benefit here. Clearly seafood has enormous benefits for health here in New England, and it's part of our culture. We all grew up on it. And we know that people who eat seafood have reduced risk of heart disease, reduced risk of stroke, reduced risk of dementia. But still, if the seafood is contaminated, those benefits are not obliterated, of course, but they're eroded. The balance becomes particularly difficult when you're dealing with vulnerable populations like pregnant women. That's why pediatricians and obstetricians advise pregnant women to stay away from those species of fish, like tuna, like swordfish, like striped bass, that are high in mercury during pregnancy.

But what can people do? Well, I think another message that came through in this analysis we did is that pollution of the oceans is highly preventable. Even though it's a big problem, even though it's a growing problem, it is not inevitable. It's not unavoidable. Eighty percent of ocean pollution arises on the land. What that means is that we can use exactly the same toolkit that we have used so successfully over the past half century in this country to control other forms of pollution — laws, policies, monitoring, regulation and ultimately strong and visionary leadership by government.

Rath: Dr. Landrigan, you actually wear a number of hats, and one of them is pediatrician. You mentioned concern about mothers and pregnant mothers. Knowing that environmental issues are especially concerning during times of development, are there special concerns we should have for young kids with this?

Landrigan: The same concerns that apply to pregnant women certainly apply to young children, because all the organ systems in a child are developing, which means that even small doses of toxic chemicals can cause more harm in in a little kid than in a grownup.

Rath: There's obviously the bigger context here, beyond what we can do individually to protect ourselves. What kind of interventions and what size interventions are we talking about that would be needed to really clean up the oceans and cut down on these negative health consequences?

Landrigan: We recommended four actions that governments around the world can take. When we released the report, we also at the same time released a declaration calling on governments around the world to take these four actions. The first is to end all combustion of coal. Coal is such a dirty fuel. It's a major contributor to global climate change. It's a major generator of particulate air pollution that causes so many adverse health effects, and it's a major source of the mercury that gets into the oceans. Our second recommendation is to ban the production and use of single-use plastics. The production of single-use plastics has just skyrocketed in the last decade.

In countries around the world, so much more stuff is wrapped in plastic, wrapped in so many more layers of plastic than was the case even ten or fifteen years ago. This is a very deliberate marketing strategy by the plastic industry, in the fossil fuel industry, to push more plastic upon us. We have to take actions like the action that New York state took last week to ban all use of plastic bags in stores.

A third need is to control coastal pollution, which comes from industrial sources, agricultural sources, uncontrolled sewage releases. We know that control of coastal pollution can be highly successful. One of the best examples in the world is the Boston Harbor cleanup, which has been a wild success. It cost $4-5 billion to accomplish, but the estimated economic benefit from cleaning up Boston Harbor has been in excess of $100 billion, in the form of increased tourism, restored fisheries, and even improved human health.

A fourth recommendation that we made is that countries around the world seek to create new marine protected areas and to expand existing marine protected areas. I think of these marine protected areas as the the national parks of the ocean, like the big one that was established a few years ago north of Hawaii. Marine protected areas, just like national parks, have such benefits for human health and well-being. They preserve vital ecosystems.