the interaction of sn , sb and pb with tungsten in contact with an aqueous medium has a synergistic effect in which the leachability of each metal is suppressed . this means that tungsten has the ability to suppress the leachability of these same metals , in particular lead . for example , tungsten may be added to the lead - contaminated soil in order to suppress lead contamination of the ground water by forming lead tungstate which has a very low solubility .