I haven't heard of it, but I assume that's because of location (I'm in Canada). From what I've heard, if you smell it you can tell. I've gone to hardware stores (Home Depot in particular) and smelled the natural jute, and it definitely has a chemical smell to it. You could always ask the employees if they know or contact the company to determine whether or not it's safe.
I'm always skeptical myself, and because of that I always order my rope for bird toy stores in bulk. It eases me conscious that way, haha! But hopefully someone has dealt with it before and can tell you more information.
I did find a number to the company and the lady said is is 100% natural with no oils or chemical treatments. She claims they sell it to several bird toy manufacturers.