As much plastic as three sugar cubes. That’s all it takes to kill an Atlantic puffin, according to new research.
Researchers have confirmed what environmentalists have long suspected: it takes very little plastic to kill marine animals. For an Atlantic puffin, eating less than three sugar cubes of plastic means a 90% chance of dying. A loggerhead sea turtle can die from about as much plastic as two baseballs, and a harbor porpoise from about a soccer ball’s worth of microplastics. These are the deadly amounts for animals living in oceans where over 11 million metric tons of plastic are dumped each year.
In the study, one in five animals had eaten plastic: 47% of sea turtles, 35% of seabirds, and 12% of marine mammals. Almost half of these animals were already threatened or endangered species.
This research, published in the Proceedings of the National Academy of Sciences, is the most thorough study yet on how plastic ingestion kills marine life. But even if you never visit the ocean, you should care: the same plastics harming wildlife are building up in our bodies, and new studies link them to heart attacks, strokes, and other health issues.
What Scientists Found
A team led by the Ocean Conservancy studied data from 57 seabird species, seven sea turtle species, and 31 marine mammal species, including whales, dolphins, and seals. They looked at how different types and amounts of plastic were linked to deaths in over 10,000 necropsies of dead sea animals.
“We’ve long known that ocean creatures of all shapes and sizes are eating plastics; what we set out to understand was how much is too much,” the lead author, Dr. Erin Murphy, Ocean Conservancy’s manager of ocean plastics research, said in a statement. “The lethal dose varies based on the species, the animal’s size, the type of plastic it’s consuming, and other factors, but overall it’s much smaller than you might think.”
But at the 50% mortality threshold, at which half the exposed animals die, the numbers are more alarming. On average, less than one sugar cube’s worth of plastic killed one in two of the dead puffins examined. One in two loggerhead turtles with only a baseball-sized volume of plastic in their bodies will die.
Different Plastics, Different Victims
The study found that some types of plastic are especially dangerous to certain animals:
Seabirds are most at risk from synthetic rubber, mainly from balloons. Just six tiny pieces, each smaller than a pea, give them a 90% chance of dying. The rubber gets stuck in their digestive systems and blocks food. “Roughly a third of seabirds that ingested some piece of balloon died from it,” Murphy noted.
Sea turtles are most threatened by soft plastics like bags, which they often mistake for jellyfish. About 342 pea-sized pieces of soft plastic were enough to kill 90% of the turtles studied. “One in 20 sea turtles that we studied died from ingesting plastics,” said Dr. Britta Baechler, Ocean Conservancy’s Director of Ocean Plastics Research. “I wouldn’t take those odds.”
Marine mammals like seals, dolphins, and whales are most at risk from fishing debris, such as lost nets, lines, and gear. Just 28 pieces of fishing equipment, each smaller than a tennis ball, can kill a sperm whale. “One whale actually contained, like, a three-gallon bucket,” Murphy said.
These Plastics Are in You, Too
The same plastics that are killing marine wildlife, like polyethylene from bags and bottles, and PVC from pipes and packaging, are now found in human bodies. The health risks are becoming harder to ignore.
A major 2024 study in the New England Journal of Medicine looked at patients who had surgery to remove plaque from their carotid arteries. Researchers found polyethylene in the plaque of nearly 60% of patients and PVC in about 12% of samples. They also saw plastic shards inside immune cells.
Patients who had microplastics in their artery plaque were 4.5 times more likely to have a heart attack, stroke, or die in the next three years than those without detectable plastics.
Microplastics have now been found all over the human body, including in blood, lungs, liver, placenta, breast milk, and urine. Research shows that particles smaller than 10 micrometers can cross the placenta, possibly exposing unborn babies. A thorough review by UC San Francisco researchers found that microplastic exposure is “suspected” to harm reproductive, digestive, and respiratory health, and may be linked to colon and lung cancer.
How Much Microplastic Do Humans Eat?
You might have heard that people eat a credit card’s worth of plastic—about 5 grams—every week. This number, which came from a 2019 WWF study, has been questioned by researchers using better methods. They found that the average person actually takes in about 4 micrograms of plastic per week, about 25,000 times less than was first thought.
Even with the lower numbers, the findings are still worrying. Research in Environmental Science & Technology estimates that Americans eat 39,000 to 52,000 microplastic particles each year just from food. If you include what we breathe in, the number ranges from 74,000 to 121,000 particles. People who only drink bottled water may swallow an extra 90,000 particles a year compared to those who drink tap water.
Microplastic Volumes In Perspective
The marine wildlife study offers a disturbing frame of reference. Three sugar cubes’ worth of plastic—a volume that could easily accumulate in human tissue over a lifetime of eating, drinking, and breathing—is enough to kill an 11-inch seabird with 90% certainty.
Of course, humans are bigger than puffins and our bodies work differently. Still, the heart study shows that even the amount of plastic we’re exposed to is linked to a much higher risk of serious health problems.
“This research really drives home how ocean plastics are an existential threat to the diversity of life on our planet,” said Nicholas Mallos, vice president of Ocean Conservancy’s Ending Ocean Plastics program. “Eating plastics is just one way that marine life is threatened by the plastic pollution crisis.
Plastic pollution is a global crisis that poses significant dangers to both wildlife and human health. The presence of microplastics in our oceans, along with the toxic chemicals leaching from plastics, has far-reaching consequences that must be addressed urgently.
The scale of the microplastics problem is staggering, with millions of tons of plastic waste floating in our oceans. This waste, originating from land-based sources, poses a threat to marine life and ecosystems. The research on wildlife deaths caused by macroplastics highlights the lethal effects of plastic pollution on various species, while studies on human health show the harmful impact of microplastics on our bodies.
To combat plastic pollution and protect wildlife, individuals can take simple yet impactful actions. Avoiding the release of balloons, plastic bags, and supporting fishing gear recycling initiatives can help reduce the harm caused to marine animals. Participating in beach cleanups and advocating for policy changes are also effective ways to address plastic pollution at a grassroots level.
In terms of reducing personal exposure to microplastics, filtering tap water, avoiding heating food in plastic containers, and choosing natural fibers over synthetic materials are recommended. By making conscious choices in our daily lives, we can minimize our contribution to plastic pollution and protect our health.
Driving systemic change requires collective effort and support for policies that promote extended producer responsibility and global initiatives like the plastic treaty being negotiated by UN member nations. By holding governments and industries accountable for their plastic waste, we can work towards a cleaner and healthier environment for all.
In conclusion, plastic pollution is not just an environmental issue but a public health crisis that demands immediate action. By understanding the risks associated with plastic pollution and taking proactive steps to reduce our plastic consumption, we can safeguard the well-being of both wildlife and ourselves. Every individual has a role to play in combating plastic pollution and creating a sustainable future for our planet.
