Many microwave popcorn bags are lined with perfluoroalkyl and polyfluoroalkyl substances (PFAS) — manufactured chemicals that break down very slowly and can accumulate in both the environment and within the body. Concern has been mounting about the health impacts of the latter — with the chemicals thought to impact the immune system, reducing the effectiveness of vaccines, for example. They have also been associated with increased cholesterol levels, decreased infant birth weights, liver enzyme changes, an increased risk of kidney and testicular cancer and cases of preeclampsia in pregnant women.
Public health expert Dr David Heber of the University of California Los Angeles said that studies have found “high levels of these compounds in the blood of people who ate microwave popcorn regularly, so it does get into the bloodstream.”
PFAS chemicals were originally developed in the 1950s, when they were used to create nonstick coatings for the insides of saucepans.
Since then, they have been used in assorted consumer products from cleaning solutions and stain-resistant fabric and textile coatings to firefighting foam and waterproof makeup.
Manufacturers of microwave popcorn add PFAS to the lining of the popcorn bags in order to help stop the oil in which the corn is popped from leaking out.
Alongside this, PFAS can help stop the popcorn bag from burning.
Dr Heber explained: “You know sometimes, if you leave the popcorn in a lot longer, you’ll end up with blackened kernels that have burned?
“Well, that’s hot enough to also burn the paper, so this protects the paper from starting a fire in the kitchen.”
Unfortunately, studies have found that PFAS can also leach into the popcorn itself during the popping process — making the snack one of the leading ways by which these “forever chemicals” can enter the human body.
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More attention has arguably been given to the appearance of PFAS in drinking water supplies — a common issue in the States, where the chemicals are estimated to be present in the blood of a whopping 97 percent of US residents.
Environmental Working Group senior scientist Dr David Andrews said: “There’s been a lot of attention on drinking water, but food is also a major source of exposure.
“Studies have shown that consuming microwave popcorn and fast food is correlated with higher PFAS levels in the body.”
In fact, Dr Andrews noted, microwave popcorn “is actually one of the first product types that the [US] Food and Drug Administration did testing on” fifteen years ago when testing for the presence of PFAS.
A study published in the journal Environmental Health Perspectives based on data collected by the US Centers for Disease Control and Prevention found that people who eat microwave popcorn daily have blood PFAS levels up to 63 percent higher than the average figure.
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It is not as if microwave popcorn bags can’t be made without PFAS or similar chemicals, Dr Andrews noted.
In 2015, for example, Coop Danmark — Denmark’s second largest retailer of consumer goods — prohibited PFAS-containing microwave popcorn bags.
Within months, microwave popcorn returned to their shelves, having eschewed PFAS in favour of bags made from tougher paper.
Dr Andrews said: “They just changed the way the actual paper was manufactured, to provide enough resistance to work as a microwave popcorn bag without chemical additives.”
For popcorn lovers elsewhere in the world concerned about PFAS, the experts advise turning instead to a hot air popper, or popping their own corn on the stove.
Dr Andrews concluded: “Just a pan or a pot with a little bit of oil on the stove will work. That’s how I do it all the time.
“It’s an easy way to avoid the potential PSAF exposure.”