The 5-gram problem: How Reuters depicted human consumption of microplastics

SINGAPORE (Reuters) - The World Wide Fund for Nature, the international conservation agency, publicized a striking claim last year: the average person is now ingesting 5 grams of plastic a week, the equivalent of eating a credit card.

Slideshow ( 4 images )

Scientists at the University of Newcastle, Australia, reviewed data on the microscopic plastic fibers found in drinking water and staple foods like shellfish and honey to obtain the estimate publicized by the WWF on billboards and other advertising.

While their 5-gram-per-week estimate has not been peer reviewed, the Australian researchers believe it’s a conservative estimate since they excluded other ways that microplastics could be consumed, including through food packaging.

Meanwhile, Reuters Singapore-based graphics editor Simon Scarr wanted to find a way to show what the longer-term implications would be if that calculation holds up as a benchmark. (Open in an external browser to see a visualization of the amount of microplastics we consume.)

In other words, if the Australian researchers are right to warn that the average person was inadvertently eating the equivalent of a credit card a week in microplastics, what would that look like over a month, a year, or a decade?

The straight-line projection is simple math. Finding a way to show the results in a way that would be readily understood proved to be the challenge.

The idea came to Scarr as a follow-up to another graphic the team had produced showing what the world’s consumption of plastic bottles over a day, week, month and years would look like if allowed to pile in a single place rather than scattered across the planet. (Open in an external browser to see the graphic on plastic bottles)

The first hurdle was finding plastic chips that were small enough to pile and weigh out carefully as a stand-in for the invisible fibers floating in water and suspended in food. A Singapore recycling initiative agreed to provide plastic chips in a size that could piled into a porcelain soup spoon (a week’s projected consumption) and a cereal bowl (half a year) and in a range of colors.

But what to do about the projection for a decade? At 2.5 kg, that’s beyond the dinner-table comparisons. It turns out, however, that’s the industry-standard weight for a plastic life-buoy of the kind ships carry. Scarr found one of those as well.

Research into the longer-term health effects of microplastics on people is at an early stage.

“All we know is that we are ingesting it and that it has the potential to cause toxicity,” said Thava Palanisami of Australia’s University of Newcastle, who worked on the WWF study.

“That is definitely a cause for concern.”

Reporting by Simon Scarr, Writing by Kevin Krolicki, Editing by Raju Gopalakrishnan