it depends.this is a network in which users get connected and files are shared.a single file is downloaded part by part from multiple users.so there might be a risk that the host computer from which a portion of the file is getting downloaded might contain virus.so that particular file might not be affected with virus but the virus might get transferred to your pc along with the file you're downloading.In case the host computer doesnt contain any virus then there is no risk.So i said that "it depends"...its not 100% safe and not also 100% risky.