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Too Good to Be True: Sea Mammals, Plastic Pollution and a Modern Chimera

The views expressed are those of the author and are not necessarily those of Scientific American.

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73.1% of all facts are made up.

I made that up.

Which, it seems, puts me in fairly good company. I study marine plastic pollution, it’s my thing. I’ve been at it for a year and a half now. The research and journalism I’ve perused has shined harsh, honest lights on a serious ecological problem. But it’s also raised troubling questions. For one thing, many sources recycle the same “facts” over and over. One in particular keeps cropping up, on personal blogs, nonprofit Web sites, popular scientific eZines, press releases. The words change, but the gist is always this: “100,000 sea mammals are killed by marine plastic pollution every year.”

Wow. This is a striking number. Horrifying even.

Yet something has always bothered me about that number. It’s too round. Too easy. Too “everywhere.” The vanilla ice cream of heartstring-tugging environmentalism.

For some time, I didn’t give it much thought. Then, a couple weeks ago, I caught the threads of a Twitter conversation among various marine scientists & advocates. Circling around the 100k number. I decided to see if I could get to the bottom of it, once and for all. Did this number have any legs? Where did it come from? Why does it appear all over the place?

Many organizations use the 100k figure with no citation. It wouldn’t be profitable to single out one, or even a handful, of these sites. Instead, my starting point on the Quest for the Source was a tweet on September 28, 2011 by @Surfrider to a page on the ‘Beachapedia’ wiki.

@Surfrider Twitter feed, accessed October 9, 2011

On September 28, that page provided the “100,000″ figure with one three-part citation. The most official & relevant of the three: a 2005 report by the United Nations Environment Programme called “Marine litter – trash that kills” *

'Rise Above Plastics Facts and Figures' Beachapedia page, accessed October 9, 2011

Eagerly, I followed the link and thumbed through the UNEP report. And I found the figure, on p. 10. Alas, it is uncited. In fact, the 18-page document lists a dizzying array of facts and figures, yet provides no direct link for many of them, just a vague list of general references. It’s a dead end.

Still, this took the figure back to 2005, which is something. I ran a Google search, using 2004 as the latest cutoff date, to see what would crop up. Much did. The most promising was a link to a National Geographic article from May 6, 2004, “Oceans Awash in Microscopic Plastic, Scientists Say“.

The bottom of the first page of the article lists the 100,000 figure, and the author says it comes from “the U.K.’s Marine Conservation Society.” Ironically, the lead-in to this figure reads, “The impact of larger plastic flotsam on marine wildlife is well documented”; the article then fails to give any link to the Marine Conservation Society’s documentation.

Still, I went back to Google to look up the Marine Conservation Society. Sadly, no combination of “Marine Conservation Society”, “sea mammals”, “marine mammals”, “100,000″ (or “100000″), “plastic pollution”, “plastic trash”, “marine debris”, “marine litter”, or anything else could tie me into a relevant Web site from the right time period. Nothing.

After playing out all leads, I concluded that the “Marine Conservation Society” thread, if once useful, was now another dead end. So I dropped the term. Instead, I went back to more general searches, this time using 2000 as the latest date. Just to see.

Targeted Google search using exact phrases and a date range

And I hit something big. A Chicago Tribune article from March 1985, republished from the New York Times, December 25, 1984, “Deadly Tide of Plastic Waste Threatens World’s Oceans and Aqautic Life“. A popular article outlining the then-new issue of marine plastics. And the 100,000 figure was there! The Times had obtained it from “The Entanglement Network,” a group that had reported at the “Workshop on the Fate and Impact of Marine Debris” in Honolulu, November 26-29, 1984.

New York Times article that started it all, accessed October 9, 2011

That workshop’s proceedings are available in full (pdf) on NOAA’s Marine Debris Web site. The figures for entanglement & death are on p. 269 of the report, but nowhere is the “100,000″ figure given.

The New York Times article of December 1984 is the first published record of the 100,000 number.

And just like that, I had the answer. A “fact” handed down & bandied about from article to nonprofit, conservation society to international organization, over years and years. So long that it has taken a life of its own, and becomes unquestioned, and unsourced. Whether there is — or was — any science behind it remains in doubt.

But seeking good science misses the point. The point is, the number is now 27 years old! If it ever had real value, it doesn’t now. The world is changed. But in an age of page hits, search engine optimization, and a crowded Web, it’s a number that’s just too good to pass up. Especially when it’s been “vetted” by heavyweights like National Geographic and the United Nations. It’s an excellent warning to us all. Sometimes “facts” are built on ether.

By the way, the search for the truth took 22 minutes.


* At the end of the day on September 28, the Beachapedia link to the “100,000″ figure was edited to separate the references into individual citations. As of October 9, none provides a direct reference back to the original “100,000″ figure. All are dead ends.

Harold Johnson About the Author: Harold Johnson lives in Saco, Maine with his wife and young daughter. A freelance copyeditor and writer by trade, he spends his free time studying archaeology, earth sciences, and the ways the natural and manmade world have mingled across millennia. Since May 2010, he has written on marine debris and plastic pollution as The Flotsam Diaries. Follow on Twitter @FlotsamDiaries.

The views expressed are those of the author and are not necessarily those of Scientific American.

Comments 7 Comments

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  1. 1. leafwarbler 12:07 pm 10/13/2011

    I should do the same with the numbers bandied about for how many (millions of) birds are killed each year by cats! Similar ether, I suspect…

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  2. 2. @donovanhohn 4:11 pm 10/13/2011

    Good detective work and a worthwhile corrective, though I would note that you’re not the first detective on this particular. I think NOAA’s Marine Debris Program deserves some credit for solving the mystery first, especially since you mention their web site. In fact, they follow the trail a little farther back, to 1983. Had you chanced upon NOAA’s Marine Debris FAQ page, you could have found the truth in 22 seconds:

    Link to this
  3. 3. SacoHarry 4:24 pm 10/13/2011

    Thanks for the read and the note. It was reading NOAA’s FAQ page a year ago that first put the germ of doubt into my head. However, surely the figure didn’t enter popular thought from a small-circulation scientific journal, but rather from a major newspaper with worldwide circulation. Which printed the 100k figure in 1984, earlier than the 1985 citation given for Wallace. Also, when the trail went back to 1983, the 100k figure was no longer to be found; instead the round number of 1983 was 50k. (Itself a dubiously round estimate, to use your excellent turn of phrase!)

    Link to this
  4. 4. paulfnorris 7:31 pm 10/13/2011

    Yes, fascinating sleuthing and great additional find by @donovanhohn.

    It does sound like the basis may for the number may be the conclusion cited by the NOAA in its FAQ (“Up to one hundred thousand marine mammals and possibly more die each year….”) Also, one small point, even though – as you point out, Harold – the specific 50-90K numbers cited in the Honolulu workshop proceedings don’t mention the “100,000” total figure, it is true that the cited figures relate just to northern fur seal deaths, and I assume that The Entanglement Network may well have given the higher 100K figure to the New York Times as its “overall” estimate.

    For whatever it’s worth, the Entanglement Network most definitely did give the 100K figure in 2007 testimony before the Senate on Controlling and Reducing Pollution from Plastic Waste:

    Anyhow, thanks for a really interesting read!

    Link to this
  5. 5. livcaillabet 3:52 pm 10/14/2011

    Brilliant, really great demonstration of the necessity to challenge accepted conventions especially within science!

    Link to this
  6. 6. SacoHarry 6:50 pm 10/16/2011

    Note: Above, I state that in the proceedings of the Nov. ’84 workshop, “nowhere is the 100,000 figure given.” Please note, on p. 273, it says in the conclusion of the section, “Up to one hundred thousand marine mammals and possibly more die each year…” The stock phrase “Up to… and possibly more” renders this figure meaningless, a convenient landing ramp between a smaller number and a higher number. However, obviously technically the 100k number does appear there. As these proceedings weren’t published until July 1985, the NYT article is still the first (and by far the firmest) noting of the 100k figure.

    Link to this
  7. 7. Phil_Chapman 6:22 pm 10/20/2011

    I followed up another oft-quoted oceanic plastic pollution figure a few years ago (just seen NOAA have something on it now), namely that 80% of marine plastic debris comes from land. I wrote it as an appendix, copied below:

    The claim that 80% (sometimes claimed as nearly 80%) of marine plastic debris has a land based source appears to have been inferred from the claim that nearly 80% of total marine debris has a land based source. This second claim ultimately has one of two sources: Faris and Hart (1994) and a 1991 report by The Group of Experts on Scientific Aspects of Marine Environmental Protection (GESAMP) titled “The State of the Marine Environment.”

    The GESAMP report however actually states that “[It is not] easy to compare, on present information, the amount of debris originating from land with that arising from fishing and shipping” (GESAMP 1991, p.16). Sheavly (2005) however references this report as the source of the claim that “land-based sources account for up to 80 percent of the world’s marine pollution.” It is hard to see from the GESAMP document how this claim could have been derived, except perhaps from the statement on page 88 that shipping operations account for 22% of marine pollution. If this is where the claim comes from, the corollary of this statistic is clearly not that 78% of marine debris comes from land. The 22% figure refers to a proportion of total marine pollution, not just marine debris. According to the GESAMP report 33% of this comes from the atmosphere. This is clearly not an analysis of the provenance of marine debris. The claim made by Sheavly (2005) is then repeated and referenced by Allsopp et al. (2006) in a Greenpeace document titled ‘Plastic Debris in the World’s Oceans’.

    The Faris and Hart (1994) document, which is a summary of the third international conference on marine debris, also contains the claim on its front cover that “nearly 80% of the world’s marine debris is thought to have washed from land.” This document is the source given for the repetition of this claim on the homepage of the ‘Plastic Debris, Rivers to Sea Project’ ( conducted by the Algalita Marine Research Foundation and funded by the California State Water Resources Control Board. Algalita is the organisation founded by Charles Moore, the discoverer of the ‘Great Pacific Garbage Patch’ and widely used as a source on plastic debris in the ocean by the media. The claim is not however directly referenced in the Faris and Hart document and an examination of the poster abstracts and manuscripts from the conference (Clary 1995), of which the Faris and Hart document is a summary, reveals no such statement.

    Link to this

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