Radon Loc and Radonseal, Do they work?

Does it makes sense to try to fight radon gas with concrete sealants?  Do Radonseal or RadonLoc work as advertised? The EPA says in their official statements that Racon Loc (www.radonloc.com) , Radonseal (www.radonseal.com)   and other concrete wall and slab sealants for the purpose of radon mitigation are not worth the price. According to government agencies in the USA, sealants such as these may work to lower radon levels at first, but after several years homeowners will soon realize that radon levels are creeping back up in their homes upon retesting. The EPA only recommends sub slab ventilation as the true gold standard in radon abatement. Does anyone else out there have any information on this situation? Is Radon Loc or RadonSeal garbage? Feel free to place a comment on this entry.