( ( For ( ( some pathogens ) ( concentrated ( by shellfish ) ) ) ) ( , ( ( ( ( a period ) ( of depuration ) ) ( -LRB- ( ( holding ( of ( shellfish ( in ( ( clean water ) ( for ( several days ) ) ) ) ) ) ) -RRB- ) ) ) ( ( can ( remove ( most ( of ( the pathogens ) ) ) ) ) . ) ) ) )
(ROOT (S (PP (IN For) (NP (NP (DT some) (NNS pathogens)) (VP (VBN concentrated) (PP (IN by) (NP (NN shellfish)))))) (, ,) (NP (NP (NP (DT a) (NN period)) (PP (IN of) (NP (NN depuration)))) (PRN (-LRB- -LRB-) (NP (NP (VBG holding)) (PP (IN of) (NP (NP (NN shellfish)) (PP (IN in) (NP (NP (JJ clean) (NN water)) (PP (IN for) (NP (JJ several) (NNS days)))))))) (-RRB- -RRB-))) (VP (MD can) (VP (VB remove) (NP (NP (JJS most)) (PP (IN of) (NP (DT the) (NNS pathogens)))))) (. .)))
For some pathogens concentrated by shellfish, a period of depuration (holding of shellfish in clean water for several days) can remove most of the pathogens.
(ROOT (S (NP (NNP Water)) (VP (MD can) (VP (VB be) (VP (VBN boiled) (S (VP (TO to) (VP (VB kill) (NP (NP (NN giardia)) (CC and) (NP (RBS most) (JJ other) (NNS pathogens))))))))) (. .)))