In other words, heating the plastic essentially makes it softer and more porous. If you’ve ever microwaved marinara sauce in a plastic container, you’ve seen the impossible-to-remove sunset red stain it leaves behind. “Passages in the plastic can open, so sauce gets in,” says James Rogers, PhD, director of food safety research and testing at Consumer Reports. The reverse exchange also occurs: “If something goes in, something can also come out,” he says.
Are these chemicals and microplastics dangerous?
Almost all Americans have measurable amounts of phthalates and BPA in their bodies. Studies in mammalian animals strongly suggest that, once inside, these chemicals act like sneaky intruders at a masquerade ball. They are not welcome at the party, but they are also difficult to distinguish among legitimate guests.
This is because bisphenols and phthalates are endocrine disruptors. They can mimic, block, or interfere with the body’s hormones, possibly increasing the risk of various conditions, including infertility, some cancers, metabolic diseases, neurological conditions, and immune system dysfunction. According to Laura N. Vandenberg, PhD, professor of environmental health sciences at the University of Massachusetts Amherst, “That’s just a short list.”
Several human studies have also reinforced animal studies. Exposure to high levels of phthalates in utero has been linked to childhood asthma. For boys, that early contact could cause behavioral problems, as well as potentially lower sperm counts later in life. Pregnant people may experience lower thyroid hormone levels and more premature births.
There are many more things we don’t know. At Duke University, Jason Somarelli, PhD, research director of the Duke Comparative Oncology Group, is studying thousands of other additives in plastics. “We’ve found at least 100 known carcinogens in these other chemicals,” he says. “And then there are more than 2,000 others that we simply don’t have enough data to know.” What he can say with confidence: “There are bad things in plastic.”
Beyond the chemicals that plastics leach, the particles themselves, which have been discovered in human hearts, bloodstreams, lungs, placentas, semen and breast milk, also pose a threat. The body sees physical particles as intruders, so they naturally seem to fight back. That can trigger an immune response: because plastics can’t be broken down, white blood cells die in battle, causing inflammation. Those particles can also “act as transport vehicles for other pollutants,” Vandenberg says, introducing potentially toxic substances into the body.
Hussain wanted to see for himself what microplastics and nanoplastics could do inside our bodies. His team bathed human embryonic kidney cells in high concentrations of plastics released by the containers they were testing. Within 48 hours, 76% of the embryonic kidney cells died, about three times the percentage of cells that spent the same amount of time in a more dilute (less plastic) solution. Hussain’s findings corroborate another study published last year, which determined that direct exposure to microplastics can cause cell death, inflammation and oxidative stress.