#You’re eating a lot of plastic and didn’t even know it

Care about saving the planet from plastic pollution? Then stop putting your money where your mouth is.

Literally — because environmentalists warn that humans may be consuming the equivalent of one credit card per week, or about 5 ¹⁄4 grams of plastic.

A new study by the World Wildlife Federation International illustrates just how much plastic we are ingesting in our lifetimes, owing to the spread of plastic waste across the globe. Researchers say it’s mainly creeping in via drinking water, but seafood has also become a major source, as marine life inadvertently consume bits of plastic that end up in our oceans — of which there are approximately 8 million metric tons, according to the Ocean Conservancy.

“Those plastic particles, if you like, are little time bombs waiting to break down small enough to be absorbed by wildlife or by people and then potentially have harmful consequences,” said Malcolm Hudson, lead researcher into plastic pollution at the University of Southampton, who contributed to the WWF report.

To illustrate the impact, the WWF calculated the average plastic consumption by humans over periods of time:

• One month = 21 grams, or one Lego brick
• Six months = 125 grams, enough to fill a cereal bowl
• One year = 250 grams, the size of a full dinner plate
• 10 years = 5 ½ pounds (2.5 kg), about the weight of a life-saver ring buoy
• One lifetime = an estimated 40 pounds or more, the approximate weight of two plastic recycling dumpsters

“While we do swallow plastics in our food, we are mostly passing that through, and it may not be harming us,” added Hudson in a video produced by the WWF International.

Microplastics are defined as bits of plastic that measure 5 millimeters or smaller but can eventually break down into mere nanometers. “And when we’re down at the nanometer scale — we’re talking about nanoparticles here — it is possible that they could be absorbed by our digestive systems and end up in our bodies. So it could pass into our blood or lymphatic system and end up in our organs and we are still learning about how many plastics there are at the very small sizes,” said Hudson.

Reports attempting to quantify microplastics on Earth have become increasingly common, but researchers say we don’t yet know how they’re affecting our bodies or health in the long term.

Said Hudson: “What we can say, I think, with some certainty is if we carry on at the moment as we’re going — producing more and more plastic, not managing the waste very well — eventually we will reach levels where there are thresholds exceeded and there are harmful effects on the environment and potentially even on ourselves.”