Are the Oceans Plagued by Plastic?

Agresti, J. D. (2015, February 28). Are the Oceans Plagued by Plastic? Retrieved from
Agresti, James D. “Are the Oceans Plagued by Plastic?” Just Facts. 28 February 2015. Web. 14 July 2024.<>.
Chicago (for footnotes)
James D. Agresti, “Are the Oceans Plagued by Plastic?” Just Facts. February 28, 2015.
Chicago (for bibliographies)
Agresti, James D. “Are the Oceans Plagued by Plastic?” Just Facts. February 28, 2015.

By James D. Agresti
February 28, 2015

Based upon two new papers in academic journals, media outlets have been reporting that the world’s oceans are overwhelmed with plastic waste. However, as detailed below, the documented amount of plastic in the world’s oceans is the equivalent of placing a microscopic speck of plastic weighing less than one-thousandth of an ounce into this Olympic-sized swimming pool containing 660,000 gallons of water:

Creative Commons |
Creative Commons |

The papers in question were published in the journals PLoS ONE and Science. Numerous media outlets and organizations reported on these papers with cataclysmic headlines, such as:

“Plastic, plastic everywhere: World’s oceans plagued by waste.”
– Traci Watson of USA Today

“World’s oceans clogged by millions of tons of plastic trash.”
– Will Dunham of Reuters

“Good job, humans: The oceans now contain 5 trillion pieces of floating plastic.”
– Chris Mooney of the Washington Post

These claims and others like them are rooted in alarmism enabled by the papers’ authors, who neglected to provide a tangible, objective context for their findings and then exaggerated them by making dire, subjective statements to the press. The authors of the Science paper also misused data to produce one of the key foundations of their study.

In the PLoS paper, the authors estimated that there is 269,000 metric tons of plastic waste floating in the world’s oceans. This figure is 8 to 38 times more than an estimate published six months earlier in the Proceedings of the National Academy of Sciences. Without dissecting the competing methods used in each of these papers, even if one blindly assumes that the higher figure is more accurate, this much plastic is equal to just 0.00000000002% of the mass of the world’s oceans.

For a striking comparison that illustrates the minuteness of that number, the average concentration of uranium in the human body is 400,000% higher than this. For another point of comparison, it is the equivalent of placing 1/60,000th of an ounce of plastic into an Olympic-size swimming pool containing more than five million pounds of water.

The PLoS authors assert that their “estimates are highly conservative, and may be considered minimum estimates.” Yet, even if there were 100 times more plastic in the oceans than they estimated, the average plastic concentration would still be more than 1,000 times lower than the EPA’s standard for drinking uranium-laced water on a regular basis.

Nevertheless, the lead author of the paper told a reporter from USA Today, “There’s a lot of waste out there,” and the reporter in turn declared that the oceans are “teeming with” plastic that weighs “three-quarters as much as the Empire State Building.”

Such statements are unscientific and misleading, because they ignore the most fundamental principle of toxicology, which is that the dose makes the poison. It is not the total amount of a pollutant that makes it harmful, but its concentration—or how much there is relative to the space or mass in which it is located. This fact is so vital and basic that a middle-school science guide on water pollution explains it. Yet, the authors of this paper overlooked this matter, as did certain journalists.

Plastic is not evenly distributed in the oceans, and thus, concentrations are higher in some areas than others. Because plastic is often buoyant, and because the oceans have massive regions of circular currents called “gyres,” plastic tends to drift towards the centers of these regions. This is where the primary data used in the PLoS paper was gathered, but the authors don’t even attempt to show that these regions have enough plastic to cause harm to any element of the environment.

As with most environmental issues, one can point to anecdotes (like a beach strewn with plastic) to argue that there is a crisis, but isolated examples don’t prove there is a global or even regional problem, as the paper’s authors and media have suggested.

Not all plastic in the oceans can be readily measured. Some of it sinks, and some of it is biodegraded by microbes and eaten by wildlife. Hence, the authors of the PLoS and Science papers claim that there must be far more plastic in the oceans than anyone has ever estimated. For example, the Science paper concluded that 4.8 to 12.7 million metric tons of plastic waste flow from the land to the ocean each year. These figures are 17 to 47 times higher than the amount of plastic floating in the oceans calculated in the PLoS paper.

The authors of the Science paper produced their estimates by employing a series of assumptions to calculate that an average of 5% to 13% of all plastics used within 31 miles of every coastline in the world ends up in the oceans every year. Perhaps realizing that these figures would be greeted with skepticism, the authors never directly revealed them in their paper or press conference. Instead, this essential element of the study must be calculated from information in the paper, which is located behind a paywall.

Worse still, the authors misapplied one of the key pieces of data used to produce their results. In a file of supplementary information (also behind a paywall), they claim that 4.17 million metric tons of litter were generated in the U.S. during 2008. However, the source that they cite for this figure does not state this. Instead, it states that this much litter “is collected each year” in the U.S. by governments, businesses, and educational institutions.

By definition, litter that is “collected” is not litter that can flow into the oceans. Yet, the authors used this figure to calculate litter rates throughout the world and then assumed that 15% to 40% of all litter generated within 31 miles of the world’s coastlines ends up in the oceans each year. When Just Facts questioned the lead author of the study about this, she wrote that they “used the best available data we could find to produce our order of magnitude estimate….” This statement does not address the fact that this data is for litter that has been collected, which is clearly not litter that can flow to the oceans.

During their press conference, one of the coauthors of the Science paper stated that “any plastic in the ocean is too much.” This kind of rhetoric feeds a common misconception about pollution, which is that natural substances are inherently better for the environment than synthetic ones. The academic book Molecular Biology and Biotechnology: A Guide for Teachers aptly dispels this notion:

Many people are frightened by the use of synthetic chemicals on food crops because they have heard that these chemicals are “toxic” and “cancer causing,” but are all synthetic chemicals more harmful than substances people readily ingest, like coffee and soft drinks? No…. For example, in a study to assess the toxicities of various compounds, half of the rats died when given 233 mg of caffeine per kg of body weight, but it took more than 10 times that amount of glyphosate … which is the active ingredient in the herbicide Roundup, to cause the same percentage of deaths as 233 mg of caffeine.

Likewise, the Cambridge University Press textbook Understanding Environmental Pollution emphasizes that “anything is toxic at a high enough dose,” and “potentially toxic substances are found in anything that we eat or drink,” including natural items like potatoes and even pure water itself. Again, the dose makes the poison.

The misinformation unraveled above concurs with the findings of a recent article published in the journal BioScience. In this article, eight PhD-level environmental scientists explained that certain scientists and journalists have created “the perception of ocean calamities in the absence of robust evidence.”

After documenting that this happens, the authors discussed how and why it happens. To summarize their findings, the underlying causes boil down to personal and intellectual biases, careless research, political pressures, dishonesty in the pursuit of “righteous ends,” and the desire for recognition and career advancement.

Whether or not such thought processes animated the publication and propagation of these PLoS and Science papers is unknown. Regardless, the anxiety over plastic in the oceans that these individuals have spread is not supported by the evidence they presented.

  • February 28, 2015 at 5:03 PM

    Short. Sweet. Just the facts, to coin a phrase. Thanks for the work you do. So much of what I read and hear from our supposed news and scientific communities doesn’t pass the smell test; but I don’t have the time nor inclination (or academic prowess) to run the numbers and check the facts. You do this well. Thanks again.

    • February 28, 2015 at 5:49 PM

      Phil, Thank you for your kind words.

  • February 28, 2015 at 10:57 PM

    Wow! Yet another science funding scam. How many more do we have to endure. Thank you Just Facts. I refer to and further your research often.

    Judy Ryan

  • March 1, 2015 at 12:00 PM

    An interesting take on the problem of plastic in the oceans. However, we must consider that since most plastic floats, the concentration at the surface and in the regions favored by the circular currents is unacceptably high for those areas and is a warning flag for the future of our waste disposal policies. It is meaningless to figure a mass concentration of low density plastic to water using the total volume of the earth’s oceans since the plastic is not uniformly dispersed in that volume. Try to calculate the concentration for the top 6 inches and the figure will dramatically change! Perhaps the toxicity is not a real problem yet, but if we accept the unsightly polution of our oceans at any location, we are ignoring a growing problem for future generations. Let’s pay attention to the warning signs and stop the flow of plastics and other non-degradable polutants into what used to be pristine oceans.

    • March 2, 2015 at 9:22 AM

      David, Thank you for your comments. I considered the points you raised as I wrote the article, and I think you might find the following facts to be illuminating.

      First, even if we assume that the higher figure of the PLoS study is accurate, and even if all the plastic estimated in the PLoS paper were floating at the surface of the ocean, it would only amount to one-tenth of an ounce per acre of ocean. This figure overstates the concentration of plastic implied by the PLoS paper, because the authors used an equation to increase the amount of plastic actually measured near the surface. (They did this to account for the fact that wind pushes buoyant plastics beneath the surface.)

      Second, the notion that plastics are “non-degradable” is untrue. As mentioned in the article, some plastic is biodegraded by microbes. The source I used to substantiate this point explains that a scientific expedition found “photosynthetic microbes were thriving on many plastic particles, in essence confirming that plastic is prime real estate for certain microbes.”

      Third, your view that there is “a growing problem for future generations” is not supported by robust evidence. For example, a study of plastic concentrations in the western North Atlantic Ocean and Caribbean Sea from 1986 to 2008 found that: “Despite a rapid increase in plastic production and disposal during this time period, no trend in plastic concentration was observed in the region of highest accumulation.” This could mean that the plastic is being biodegraded or dispersed from this region, or it could simply mean that little plastic is flowing into the oceans.

  • March 12, 2015 at 3:09 PM

    I accept your figures for surface density and the fact that the PLoS study report was exagerated. My hope is that biodegradation and efforts to recycle plastics in many communities can keep up with global population growth and attendant increase in use of plastics world wide to preclude a real problem. Your ability to uncover the truth is impressive.

    • March 13, 2015 at 11:34 AM

      David, Thank you for your generous compliment and thoughtful comments. I agree with you: we should keep a close eye on oceanic plastic levels and make sure they don’t become a real problem. Best, Jim

  • March 15, 2015 at 7:40 AM

    Very informative and well documented article. Thank you for all the time and effort in the research you do to make the facts known.

  • February 22, 2016 at 11:37 AM

    While I appreciate putting “the facts” into context and perspective, I fear that such stark minimilization of “the facts” is where, as previously mentioned, our future generations might be mollified to “let it go” and find themselves buried in plastic (and other toxins) waste. I am not a “climate change advocate” per se (it’s called “weather,”) and am horrified by the notion that anyone might profit by “carbon offsets;” I am, however, very much in favor of good stewardship of our lovely planet. I own ExxonMobil stock so don’t think of me as a tree hugger so much as a pragmatist. If we don’t take care of the earth now, how long before she just shrugs us off (as has happened several times in the past) and “we” no longer have anything to worry about. We can’t avoid any future collisions with ginormous meteors but we can be responsible with products made that need time to degrade. How much time does it take for the plastic to be consumed by the microbes? How does ingestion of plastic affect the waste produced by these microbes…how does it affect the plant life, fish, marine mammals, etc. while it degrades? Seriously, it’s not just about the future, it is about the now. Huge trash gyres interfere with migration channels, the waste is consumed by the fish we are eating…take that in: eaten by the fish WE are eating. It’s poor stewardship to permit “plastic molecules to outnumber the oxygen in the Indian Ocean” – it is difficult to buy “clean fish” anywhere and, if you are a fisherman, the oceans, rivers, creeks, and streams are so contaminated, you risk consuming mercury, PCBs, pharmaceuticals, and other noxious toxins with each bite. Yes, too much of anything can be toxic…the problem lies in the fact that EVERYthing the average consumer buys in today’s world contains biotoxic substances. EVERYthing: Furniture, Car upholstery, carpets, kitchen cabinets, the air we breathe, the water we drink. Granted, it is “just a little bit” but a little bit here and a little bit there – It Is Impossible to Limit Our Exposure. I couldn’t even let my children make “snow cream” with our recent blizzard snow as it was just too full of atmospheric trash for them to eat. While this is a simplistic article aimed at elementary and middle schoolers, it is a succint list of what is of concern here. It isn’t about the “minimal damage today” which you assert, it is about the fact that it is almost too late (“cost to remove would be prohibitive”) and that we had better rethink the efforts being put forth in continuing to pursue “synthetic answers to existing blessings.” Why can’t there be a moment of Re-Direct? Rather than continuing to spend money and employ people in destructive practices, there should be a mass re-focus on fixing what is completely broken. There must be a way to “capitalistically reward” efforts into reclaiming our waste, cleaning up the waterways, and restoring our soils and native habitats. Not through “Carbon Taxes” but through innovation of ways to do so while providing employment and relief to so many, worldwide. ExxonMobile should pursue “alternative resources” and let the oil lie, it isn’t going anywhere and will always be a resource if we don’t “blow through it” all now – we have to face the fact that many are clamoring to “clean” their environments. Too many people have been experiencing health problems to ignore the insurgance and make correlative conclusions that it must be due to all the synthetics in their daily lives. More awaken to it daily. Soooooooo….why not endeavor to meet the needs of these people? There is already a movement in that direction (Chipotle, Whole Foods, Solar City, etc., etc.) with so much available opportunity for more utilization and enhancement of resources that won’t cause more harm but will provide much good for earth and her peoples.

    I am just a mom…a well-read mom, who fears for the future of her children. I thank you for the work that you do. I thank you for the opportunity to express my own thoughts on this matter as I have worried over this matter for many years. It just seems that those who will profit by continuing to destructively produce products that, ultimately,cause “more harm than good” should consider the profitability of going over to the “light side.”

  • February 21, 2017 at 9:11 PM

    Hmmm interesting points. That said I did not see anything that mentions the measure of plastic found in fish, I understand (and please check) that the fisheries are showing 20% of fish have traces of plastics? Second though in absolutes it is correct that the dosage is the problem, that does not take away the fact that if the pollution is concentrated in say the Mediterranean sea for example that the dose would be very different.

    In any case, I hate to think we are putting even one piece of plastic in the ocean that does not need to be there.


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