On October 15 2019, the Facebook page “Using Less Plastic” shared a meme which claimed that “a new study” had found that humans ingested an average of five grams of plastic per week, about the same amount contained in an average credit card:
Text drawn onto an illustration of a person and a plate with two credit cards on it read:
People ingest 5 grams of plastic per week … [on] average, it’s 2,000 microplastic particles every week! It is the equivalent of eating a credit card every week! [Easy Eco Tips]
Text included in a status update reiterated:
A new study by the University of Newcastle in Australia has found that in average, people ingest 5 grams of plastic every week, or 2,000 microplastic particles. That’s the equivalent of eating a credit card.
Big if true, readers might think, but the “new study” was not linked in the original post or in any prominent comments. Commenters responded by saying “I believe it” and offering similar thoughts:
Holy shit.. We are killing the planet and ourselves! So sad..
Ocean plastic remained a major ecological interest in 2019, following massive global pro-environment protests, controversial bans on plastic straws, and arguments over whether such bans could really affect the amounts of microplastics in both oceans and the food supply. Although the problem itself is not new, accelerated interest in the issue was speculatively attributed to viral photographs of the effects of ocean plastic on sea life and habitats.
Around the same time, a highly viral claim made the rounds in the UK that Christmas crackers posed a massive ecological threat — but that claim was a hodgepodge of statistics that were only semi-related to Christmas crackers, and they were not rooted in credible information about ocean plastic. Claims about ocean plastic in general generate massive engagement for people and pages, and are thus incentive to post claims whether or not they are legitimate.
As for a purported “recent study,” USA Today reported in June 2019 that the average person was “eating about a credit card’s worth of plastic every week,” adding that drinking water was deemed a culprit:
You’re eating, swallowing or breathing in about 2,000 tiny pieces of plastic each week, a new study suggests, an amount equal to the weight of one credit card.
“Not only are plastics polluting our oceans and waterways and killing marine life – it’s in all of us and we can’t escape consuming plastics,” said Marco Lambertini of the World Wildlife Fund, which commissioned the study … According to the study, most of the pieces of plastic we ingest come from drinking water, but it’s also in other foods such as shellfish and salt. And also, sadly, beer.
That same month, CNN indicated “you could” be ingesting five grams of plastic per week, and QZ.com endeavored to explain “how you eat a credit card’s worth of plastic each week.” National Geographic went with an arguably safer “You eat thousands of bits of plastic every year” in their coverage, but also introduced the specter of inhaled microplastics, as if we don’t have enough to worry about:
Last October , microplastics were found in fecal samples from eight people participating in a pilot study to research how much humans might be inadvertently consuming plastic. Now, a new study in the journal Environmental Science and Technology says it’s possible that humans may be consuming anywhere from 39,000 to 52,000 microplastic particles a year. With added estimates of how much microplastic might be inhaled, that number is more than 74,000.
Incidentally, a 2009 CreditCards.com item estimated the average credit card weighed 5.07 grams, calculated a decade before heftier plastic (and other material) charge cards became de rigueur. An August 2019 credit card blog post ranked the top “heaviest” credit cards, listing a total of 20 cards weighing between 10 and 27 grams apiece. The heaviest of the lot was the JP Morgan Reserve at 27 grams, followed by the Luxury Card MasterCard Gold Card at 22 grams.
Nearly all cards on the list involved a yearly annual fee ranging from $99 to $2,500 for the card that likely kicked off the trend, the fabled American Express (AmEx) Centurion. Presumably, cardholders indeed forked out hundreds to thousands of dollars for the privilege of being charged interest on the (literally) weightier status symbol cards. That list also noted the average weight of plebeian plastic ia five grams.
In articles about the “new study,” a lot of “might be,” “may be” and “could” qualifiers appeared in headlines. That also held true for the June 2019 press release about the actual research underlying the many articles (and now, Facebook memes). It explained “plastic ingestion by people could be equating to a credit card a week,” describing the research cited was a meta-analysis of more than fifty studies on human microplastic ingestion:
A new study finds on average people could be ingesting approximately 5 grams of plastic every week, which is the equivalent weight of a credit card.
“No Plastic in Nature: Assessing Plastic Ingestion from Nature to People” prepared by Dalberg, based on a study commissioned by WWF and carried out by University of Newcastle, Australia, suggests people are consuming about 2000 tiny pieces of plastic every week. That’s approximately 21 grams a month, just over 250 grams a year.
The University of Newcastle is the first to combine data from over 50 studies on the ingestion of microplastic by people. The findings are an important step towards understanding the impact of plastic pollution on humans. It also further confirms the urgent need to address the plastic system so that it does not pollute ecosystems in the first place.
On the original meme, the figures attributed to the research were either five grams, or its purported equivalent of 2,000 microplastic particles consumed by humans on average per week. A June 2019 study (“Human Consumption of Microplastics”) published in the journal Environmental Science & Technology also attempted to calculate a specific gram-value for average consumption of microplastics.
Although the meme said five grams or 2,000 microplastic particles each week (or an average credit card), concurrent research arrived at a different number:
Microplastics are ubiquitous across ecosystems, yet the exposure risk to humans is unresolved. Focusing on the American diet, we evaluated the number of microplastic particles in commonly consumed foods in relation to their recommended daily intake. The potential for microplastic inhalation and how the source of drinking water may affect microplastic consumption were also explored. Our analysis used 402 data points from 26 studies, which represents over 3600 processed samples. Evaluating approximately 15% of Americans’ caloric intake, we estimate that annual microplastics consumption ranges from 39000 to 52000 particles depending on age and sex. These estimates increase to 74000 and 121000 when inhalation is considered. Additionally, individuals who meet their recommended water intake through only bottled sources may be ingesting an additional 90000 microplastics annually, compared to 4000 microplastics for those who consume only tap water. These estimates are subject to large amounts of variation; however, given methodological and data limitations, these values are likely underestimates.
In that abstract, several figures were provided: a range of 39,000 to 52,000, and a range of 74,000 to 121,000 alongside a floating additional 90,000 microplastics annually for bottled water enthusiasts (versus 4,000 for tap water drinkers). Noting the estimates inherently involved “large amounts of variation,” researchers indicated the values were likely underestimated.
In that range, the lower estimate of 39,000 particles annually worked out to 750 particles versus the 2000 in the meme; the second figure of 52,000 worked out to 1,000 per week. The higher value of 121,000 worked out to just over 2,300 particles, higher than the 2,000 referenced in the meme. A major takeaway of that study was that the range was massive as an estimate, and that researchers leaned toward understanding real values were probably higher.
The research referenced in the meme [PDF] was “under consideration” for academic publication, but it was released early — in June 2019 — in order to to coincide with the World Wide Fund for Nature (WWF) campaign for action on plastic pollution, and its overall status remained unclear. On its release, Alastair Grant, a professor of ecology at the University of East Anglia, opined that the report “does not present evidence that consuming even the highest figure (which represents approximately 250 particles a day) presents a risk to human health,” and that due to improper recycling practices, “[burned] plastic in developing countries is likely to have much more serious health effects than those from rather small numbers of plastic particles in food and water.”
In that overall opinion, Grant suggested that the broader problems around microplastics ought not be ignored in an induced panic over plastic ingestion. Furthermore, the meme referenced 2,000 microplastics as the basis of the five gram/credit card figure. The actual underlying research stated that an average person “potentially consumes as much as 1769 particles of plastic every week just from water,” going on to estimate that the individual could consume up to 182 microplastics in shellfish, ten in beer, and eleven in salt.
Assuming this person does consume all four things in a given week (including beer and shellfish), the maximum calculated figure was around 1,972 total plastic particles — close to the 2,000 figure. But the context of sources was not included, and the numbers in the meme were presented as definitive, not “potential.”
WWF researchers also maintained their that estimates on inhalation suggested that “a negligible proportion of microplastics entering the human body [were inhaled] but may vary heavily depending on the environment.” In contrast, the Environmental Science & Technology study published the same month the WWF research was released seemed to weight inhalation estimates far less conservatively, indicating that figures of 39,000 to 52,000 particles per year (or 750 to 1,000 particles per week) increased “to 74,000 and 121,000 when inhalation [was] considered”:
The study reveals that consumption of common food and beverages may result in a weekly ingestion of approximately 5 grams of plastic, depending on consumption habits. Out of a total of 52 studies that the University of Newcastle included within its calculations, 33 studies looked at plastic consumption through food and beverage. These studies highlighted a list of common food and beverages containing microplastics, such as drinking water* , beer, shellfish, and salt.
With respect to the accuracy of the figures, researchers noted:
The [underlying research] builds on a comprehensive review of existing studies to estimate plastic ingestion through inhalation, food, and beverages. The approach was to focus on available data and to use conservative extrapolations and assumptions when data was not available.
While this study represents a synthesis of the best available data, it builds on a limited set of evidence, and comes with limitations. The consensus among specialists is thus that while these numbers are in a realistic range, further studies are needed to get a precise estimate.
A key limitation is the lack of data available on crucial metrics, such as weight and size distribution of microplastics in natural environments, and the varying quality of data collected. A widespread issue in data collection for instance is variations in sample collection methodologies leading to risks of contamination … The Newcastle study team used assumptions and extrapolations to bridge data gaps and adjust for data quality. It is acknowledged that with every assumption and extrapolation, the level of uncertainty increases, and further research and data collection is needed to ascertain these results.
Variations within the data set studied were also noted, with shellfish consumption a particularly variable condition. Shellfish consumption could account for .5 grams per week (ten percent of the five gram total) if a person consumes shellfish:
Another key source [of consumed plastic] is shellfish, accounting for as much as 0.5 grams a week. This comes from the fact that shellfish are eaten whole, including their digestive system, after a life in plastic-polluted seas.
As is common in generalized reporting on research, a very shareable soundbite moved from findings to articles to memes, losing details at every stage in its evolution. One October 2019 meme in particular resulted from a spate of June 2019 reports on research released that month by the WWF in conjunction with a university in Australia, which was as of that point pending academic review. Where the research itself pointed to high-range estimates and was based on dozens of earlier studies, reporting slowly began to strip away the “maybes” and “possiblys” before the findings were condensed into an out-of-context meme.
The meme claimed that the average person ingests 2,000 ocean plastic particles per week, thus essentially “eating one credit card” per person per week. But even shallow reporting on the research indicated that those estimates were at the high end, and the WWF’s report noted variables such as drinking water quality and habits as well as shellfish consumption affected even those estimated figures. A study published in an environmental journal’s range of figures differed slightly from the WWF numbers, which were — again — still under review when the reporting first started. All reports noted that the actual effects of microplastic consumption on human health is still unknown. Nevertheless, the World Wide Fund for Nature never suggested that every human or even most humans on Earth ate “a credit card a week,” despite using the comparison as a benchmark.