( ( Mammalian toxicity ) ( ( is ( very low ) ) . ) )
(ROOT (S (NP (NNP Mammalian) (NNP toxicity)) (VP (VBZ is) (ADJP (RB very) (JJ low))) (. .)))
Mammalian toxicity is very low.
(ROOT (S (NP (NP (DT The) (JJ main) (NN advantage)) (PP (IN of) (NP (NN urea)))) (VP (VBZ is) (NP (PRP$ its) (ADJP (RB very) (JJ low)) (NN toxicity))) (. .)))