What did they think they were made of then?

The Environmental Working Group added potatoes to their dirty dozen list of foods that should not be eaten unless they are organic, for the first time this year, due to, "high concentrations of chlorpropham, a plant growth regulator banned in the European Union due to health concerns."

https://www.ewg.org/foodnews/dirty-dozen.php https://www.ewg.org/foodnews/potatoes.php