ronald hoffman's lab in mt. sinai hospital in new york city. he has spent nearly 40 years studying pv. >> there were too many patients with polycythemia vera in that-- in that area than one could account for. whether the environment or toxins in the environment lead to an increased ri of polycythemia vera is unknown. that's really an area of researcand also speculation. the problem is that there are multiple toxic compounds that are in the ground and also in the air in this area, and to prove a one-to-one relationship is going to be very, very tough. in this area, there were a lot of super-fund sites and coal mines. so, you know, they weren't here, they weren't there. they were here. and that was the concern. and that's the concern in my mind to this day. it's a question mark. i don't have the answer to this. i'm not a statistician, but intuitively it would seem to me more than chance that--that this would occur. >> while science continues to gather evidence, some people believe that politics and profit are outweighing the need to protect publi