In the "S.T.A.L.K.E.R." series, which of these items can't be used to lower the player's accumulated radiation?

In the Stalker series, the item that can't be used to lower the player's accumulated radiation is Radioprotectant. This is because Radioprotectant is specifically designed to provide protection against radiation, rather than reducing or eliminating the radiation already accumulated by the player character. It serves as a preventive measure to minimize the harmful effects of radiation exposure, but it does not have the capability to actively lower the player's existing radiation levels.