And it's merely a hypothesis, there is no proof. Also we can assume that chemical plants are aware and have taken precautions, but it still happens. Back in the day it was speculated that chemists caried microcrystals around in their beards. This problem has been around for a while. One of the coolest hypothesis has been put forward by Rupert Sheldrake. He thinks that there is something in nature akin to memory. A force of nature as you will.