Are ocean plastics bioaccumulating up the food chain?

New evidence emerges that microplastics eaten by marine animals may be traveling up the food chain to our plates.

In a way, the ocean’s estimated 5.25 trillion pieces of floating plastic may not even be the worst of it. There’s plastic everywhere in the seas. Big pieces ensnare marine creatures and kill animals that attempt to ingest it. Then there are the tiny bits of plastic — microplastics of less than 5mm in size, such as microbeads in toothpaste and other household products, fibers from clothing, and the remains of degraded larger pieces of plastic.


According to a report published by the U.S. Environmental Protection Agency in 2015, “Slightly more than half of all plastic is negatively buoyant, meaning that it will sink upon reaching the ocean, either into the near-shore sediment environment or to the ocean floor."

Sources of microplastics (Amanda Montañez)

These microplastics are small enough for fish and other sea creatures to eat successfully. But they’re indigestible, and they remain in a fish’s stomach until the animal dies and decomposes, or is itself eaten. Mark Brown first documented this worrying process in 2008. Since then, scientists have wondered if such non-biodegradable bits could be traveling up the food chain, and if so, how far up could they possibly go. Now a recent study provides evidence of such “trophic transfer,” at least as far up as seals. While the study of what otherwise happens to all this microplastic is ongoing, it’s, therefore, a safe bet that humans eventually consume some of it, too. And microplastics are just one relatively trackable category of substances. Their impact on the food chain also serves as a chilling indicator of what’s likely also occurring with deadly persistent organic pollutants, such as dioxins and DDT.

Cornish seals and Atlantic mackerel

The study by a group of British scientists was published in the journal Environmental Pollution in July 2018. It describes their work with 31 captive seals at the U.K.'s Cornish Seal Sanctuary. The seals were fed Atlantic mackerel caught in the wild. When the seals’ stools were examined, half of them contained plastic fibers around a millimeter long. When researchers examined the stomach contents of other wild Atlantic mackerel, they found similar microplastics in about a third of them.

According to the scientists who conducted the study, “Our findings suggest that trophic transfer represents an indirect, yet potentially major, pathway of microplastic ingestion for any species whose feeding ecology involves the consumption of whole prey.”

(Snap2Art/browndogstudios/Big Think)

Sjúrður Hammer, who was not involved in the study, tells Gizmodo, “The study convincingly showed that plastic in mackerel fed to seals could be detected in seal scat.” But there are a couple of caveats worth noting:

  • First of all, the mackerels whose stomach contents were examined were not the same mackerel fed to the seals.
  • It’s also not clear that the mackerels’ fibers were the same type of plastic found in the seals’ feces.

Hammer continues, “It’s important to be very clear about the conclusion of this study. They have shown evidence of trophic transfer, but this is not necessarily evidence that microplastic is ‘bioaccumulating up the food chain.’” “From a human perspective,” says marine scientist and engineer Richard Thompson, also not one of the study’s authors, “at the moment I think there’s cause for concern rather than cause for alarm.”

Don’t eat fish? Great. Well, wait.

The danger of ingesting microplastics, unfortunately, extends beyond those who partake of fruits de mer. It’s in the water itself, and widespread. When scientists examined 159 samples of globally sourced tap water, 12 brands of Laurentian Great Lakes beer, and 12 brands of commercial sea salt, they found its particles basically everywhere. In the tap water, for example, 81% of the samples contained microplastics, most often fibers. Their report was published in PLOS One.

Can we safely ingest this stuff?

Short answer: Unknown. For some, it’s worth the risk in exchange for the nutritional benefits of eating fish. “To the best of my knowledge the benefits outweigh the costs,” researcher Chelsea Rochman tells Scientific American. Is there some level of microplastics we can consume that won’t hurt us, and where’s the limit? “We just need to try to understand what that threshold is,” she notes.

And it’s not that this a totally new problem. It’s just that the complexities involved have proven to be only more complicated the more scientists know about it. Innovative techniques are being deployed to try to get a better handle on what’s going on, such as those of ecotoxicologist Martin Wagner and others.

“Mesocosm” pools help Wagner simulate the ways in which microplastics affect marine animals. (Martin Wagner)

Still, all of the research into the mechanics is taking place against the background of an overarching understanding of the real problem: We have too much plastic, and we haven’t yet figured out a sustainable way to deal with it all. 

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Political division is nothing new. Throughout American history there have been numerous flare ups in which the political arena was more than just tense but incideniary. In a letter addressed to William Hamilton in 1800, Thomas Jefferson once lamented about how an emotional fervor had swept over the populace in regards to a certain political issue at the time. It disturbed him greatly to see how these political issues seemed to seep into every area of life and even affect people's interpersonal relationships. At one point in the letter he states:

"I never considered a difference of opinion in politics, in religion, in philosophy, as cause for withdrawing from a friend."

Today, we Americans find ourselves in a similar situation, with our political environment even more splintered due to a number of factors. The advent of mass digital media, siloed identity-driven political groups, and a societal lack of understanding of basic discursive fundamentals all contribute to the problem.

Civil discourse has fallen to an all time low.

The question that the American populace needs to ask itself now is: how do we fix it?


Discursive fundamentals need to be taught to preserve free expression

In a 2017 Free Speech and Tolerance Survey by Cato, it was found that 71% of Americans believe that political correctness had silenced important discussions necessary to our society. Many have pointed to draconian university policies regarding political correctness as a contributing factor to this phenomenon.

It's a great irony that, colleges, once true bastions of free-speech, counterculture and progressiveness, have now devolved into reactionary tribal politics.

Many years ago, one could count on the fact that universities would be the first places where you could espouse and debate any controversial idea without consequence. The decline of staple subjects that deal with the wisdom of the ancients, historical reference points, and civic discourse could be to blame for this exaggerated partisanship boiling on campuses.

Young people seeking an education are given a disservice when fed biased ideology, even if such ideology is presented with the best of intentions. Politics are but one small sliver for society and the human condition at large. Universities would do well to instead teach the principles of healthy discourse and engagement across the ideological spectrum.

The fundamentals of logic, debate and the rich artistic heritage of western civilization need to be the central focus of an education. They help to create a well-rounded citizen that can deal with controversial political issues.

It has been found that in the abstract, college students generally support and endorse the first amendment, but there's a catch when it comes to actually practicing it. This was explored in a Gallup survey titled: Free Expression on Campus: What college students think about First amendment issues.

In their findings the authors state:

"The vast majority say free speech is important to democracy and favor an open learning environment that promotes the airing of a wide variety of ideas. However, the actions of some students in recent years — from milder actions such as claiming to be threatened by messages written in chalk promoting Trump's candidacy to the most extreme acts of engaging in violence to stop attempted speeches — raise issues of just how committed college students are to
upholding First Amendment ideals.

Most college students do not condone more aggressive actions to squelch speech, like violence and shouting down speakers, although there are some who do. However, students do support many policies or actions that place limits on speech, including free speech zones, speech codes and campus prohibitions on hate speech, suggesting that their commitment to free speech has limits. As one example, barely a majority think handing out literature on controversial issues is "always acceptable."

With this in mind, the problems seen on college campuses are also being seen on a whole through other pockets of society and regular everyday civic discourse. Look no further than the dreaded and cliche prospect of political discussion at Thanksgiving dinner.

Talking politics at Thanksgiving dinner

As a result of this increased tribalization of views, it's becoming increasingly more difficult to engage in polite conversation with people possessing opposing viewpoints. The authors of a recent Hidden Tribes study broke down the political "tribes" in which many find themselves in:

  • Progressive Activists: younger, highly engaged, secular, cosmopolitan, angry.
  • Traditional Liberals: older, retired, open to compromise, rational, cautious.
  • Passive Liberals: unhappy, insecure, distrustful, disillusioned.
  • Politically Disengaged: young, low income, distrustful, detached, patriotic, conspiratorial
  • Moderates: engaged, civic-minded, middle-of-the-road, pessimistic, Protestant.
  • Traditional Conservatives: religious, middle class, patriotic, moralistic.
  • Devoted Conservatives: white, retired, highly engaged, uncompromising,
    Patriotic.

Understanding these different viewpoints and the hidden tribes we may belong to will be essential in having conversations with those we disagree with. This might just come to a head when it's Thanksgiving and you have a mix of many different personalities, ages, and viewpoints.

It's interesting to note the authors found that:

"Tribe membership shows strong reliability in predicting views across different political topics."

You'll find that depending on what group you identify with, that nearly 100 percent of the time you'll believe in the same way the rest of your group constituents do.

Here are some statistics on differing viewpoints according to political party:

  • 51% of staunch liberals say it's "morally acceptable" to punch Nazis.
  • 53% of Republicans favor stripping U.S. citizenship from people who burn the American flag.
  • 51% of Democrats support a law that requires Americans use transgender people's preferred gender pronouns.
  • 65% of Republicans say NFL players should be fired if they refuse to stand for the anthem.
  • 58% of Democrats say employers should punish employees for offensive Facebook posts.
  • 47% of Republicans favor bans on building new mosques.

Understanding the fact that tribal membership indicates what you believe, can help you return to the fundamentals for proper political engagement

Here are some guidelines for civic discourse that might come in handy:

  • Avoid logical fallacies. Essentially at the core, a logical fallacy is anything that detracts from the debate and seeks to attack the person rather than the idea and stray from the topic at hand.
  • Practice inclusion and listen to who you're speaking to.
  • Have the idea that there is nothing out of bounds for inquiry or conversation once you get down to an even stronger or new perspective of whatever you were discussing.
  • Keep in mind the maxim of : Do not listen with the intent to reply. But with the intent to understand.
  • We're not trying to proselytize nor shout others down with our rhetoric, but come to understand one another again.
  • If we're tied too closely to some in-group we no longer become an individual but a clone of someone else's ideology.

Civic discourse in the divisive age

Debate and civic discourse is inherently messy. Add into the mix an ignorance of history, rabid politicization and debased political discourse, you can see that it will be very difficult in mending this discursive staple of a functional civilization.

There is still hope that this great divide can be mended, because it has to be. The Hidden Tribes authors at one point state:

"In the era of social media and partisan news outlets, America's differences have become
dangerously tribal, fueled by a culture of outrage and taking offense. For the combatants,
the other side can no longer be tolerated, and no price is too high to defeat them.
These tensions are poisoning personal relationships, consuming our politics and
putting our democracy in peril.


Once a country has become tribalized, debates about contested issues from
immigration and trade to economic management, climate change and national security,
become shaped by larger tribal identities. Policy debate gives way to tribal conflicts.
Polarization and tribalism are self-reinforcing and will likely continue to accelerate.
The work of rebuilding our fragmented society needs to start now. It extends from
re-connecting people across the lines of division in local communities all the way to
building a renewed sense of national identity: a bigger story of us."

We need to start teaching people how to approach subjects from less of an emotional or baseless educational bias or identity, especially in the event that the subject matter could be construed to be controversial or uncomfortable.

This will be the beginning of a new era of understanding, inclusion and the defeat of regressive philosophies that threaten the core of our nation and civilization.