Sometimes, it can be hard to know how to respond to a world that regularly tells us our bodies are constantly being invaded by toxic, man-made chemicals.

We consume a credit card’s worth of plastic a week, for example. Microplastics are in our clouds. They’re in our tears. Our semen. And now, according to some disturbing lab results, all this nastiness is coming for our precious McDonald’s. Specifically, the McDonald’s Filet-O-Fish packaging, which contains chemicals that have been unauthorized for food contact uses by the FDA since 2022, according to test results shared exclusively with VICE.

Lab testing commissioned by the campaign group Fuck McDonald’s, and conducted by Symbio Laboratories in San Diego, detected at least six phthalates present in a used, empty Filet-O-Fish box from a New York McDonald’s. Studies have shown that these kinds of chemicals can migrate from packaging into food.

At the time of publication, McDonald’s had not provided a comment in response to the test results.

Phthalates, often added to plastics to enhance flexibility, have been associated with various potential health risks, particularly in infants born to pregnant women exposed to the chemicals. In a 2022 review, researchers found robust evidence for an association with neurodevelopment issues, lower semen quality and risk of childhood asthma, and moderate to robust evidence for genital birth defects in boys. A 2018 report from the American Academy of Pediatrics also stated that certain phthalates used in food packaging could contribute to cardiovascular disease.

In May of 2022, the FDA deauthorized the use of 23 phthalates in food packaging, following a petition. Six of those chemicals – dimethyl phthalate, diethyl phthalate, diisobutyl phthalate, dibutyl phthalate, benzylbutyl phthalate and didecyl phthalate – were detected in the Filet-O-Fish box tested by Symbio Laboratories. All six chemicals have been linked to an increased risk of impaired male reproductive development. Or, as Fuck McDonald’s puts it, they’ll “super-shrink a peen”.

The Filet-O-Fish has been a staple of the McDonald’s menu since 1965, with USA Today suggesting in 2023 that the chain now sells around 300 million sandwiches a year. While research into phthalates’ effects on human health is admittedly still ongoing, the fact the FDA deauthorized the use of certain phthalate types in food packaging doesn’t bode particularly well for all those Filet-O-Fish boxes.