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Glasses were prepared by systematic additions of P2O5, BaO, and PbO to glasses consisting of Al2O3‐B2O3‐(BaO)‐CaO‐Fe2O3‐K2O‐MgO‐Na2O‐(PbO)‐(P2O5)‐SiO2, and their chemical durability was examined by the EPA TCLP test. The addition of about 1 mol% P2O5 to a glass containing 5 mol% PbO increases the normalized lead leach rate (NLLR) by about 40 relative%, but increasing P2O5 to 2 mol% decreases the NLLR to about the NLLR obtained without P2O5. A similar, but more dramatic, behavior with changes in the NLLR of about 300 relative% is obtained by sequential combined additions of 1 mol% each of P2O5 and BaO to a glass containing 1 mol% PbO.