The only reason I've ever heard of them is because of a few trees cordoned off in Greenwich Park warning you not to let your kids go near them. I assumed the only risk was from touching the things!
Never touched one, but they shed and the hairs are so fine they can get into your skin. It's more irritating than anything but it's like being bitten by a load of mosquitos or bed bugs.
The only reason I've ever heard of them is because of a few trees cordoned off in Greenwich Park warning you not to let your kids go near them. I assumed the only risk was from touching the things!