a composition includes specific amounts of an aromatic polycarbonate , a block polycarbonate - polysiloxane , a poly , a block polyestercarbonate , and an organophosphate ester . relative to a corresponding composition lacking the block polyestercarbonate , the composition exhibits improved solvent resistance while substantially maintaining impact strength , melt flow , and flame retardancy . the composition is useful for fabricating articles that may come into contact with liquid chemicals or chemical vapors .