“Microwaving mobilises contaminants,” says Rolf Halden, professor and director of the Biodesign Center for Environmental Health Engineering at Arizona State University. “This process is used in laboratories to extract pollutants from samples, prior to chemical analysis.”
And the potential risks don’t necessarily increase with how often an individual microwaves food in plastic containers, Trasande argues – as the relationship is non-linear between the amount of chemical exposure and risk of hormone disruption.
“The old pedagogy was that the dose mediated poison. Now we understand from multiple studies that low level exposures are where the greatest component of effects happens, so there’s no safe level of exposure,” Trasande says.
It’s important to remember that, when heating food in a plastic container, exposure also can happen with plastic that doesn’t touch the food, such as a lid.
“Water rises as steam from the food, and then condenses on the underside of the lid, and the extracted chemicals from the lid then fall down into your food, contained in the condensation droplets,” Halden says.