Adjective
mad as a hatter (not comparable)
Demented or crazy.
Sometimes I feel sure he is as mad as a hatter and then, just as he is at his maddest, I find there is a method in his madness. Agatha Christie
There is a place. Like no place on Earth. A land full of wonder, mystery, and danger! Some say to survive it: You need to be as mad as a hatter. Which luckily I am. Lewis Carroll
By contrast, bioaccumulation refers to uptake from all sources combined (e.g. water, food, air, etc.) Examples An example of poisoning in the workplace can be seen from the phrase " as mad as a hatter " (18th and 19th century England). Source: Internet
Zhao, Zhu & Sui 2006 The phrase "mad as a hatter" is likely a reference to mercury poisoning among milliners (so-called " mad hatter disease "), as mercury-based compounds were once used in the manufacture of felt hats in the 18th and 19th century. Source: Internet