(S (S (NP (EX There)) (VP (VP (MD could) (RB not)) (VP (VB be) (NP (NP (BASENP (DT a) (ADJP (RBR more) (JJ serious)) (NN threat)) (PP (TO to) (BASENP (PRPD our) (NN health) (NN system)))) (SBAR (IN than) (S (VP (VBZ has) (VP (VBN been) (VP (VBN announced) (BASENP (NN today))))))))))) (PERIOD .))