methyl bromide was improperly used in u.s. virgin islands resort that family was staying in when they were poisoned .
steve esmond , his wife theresa divine and their two teenage sons fell seriously ill while staying at the sirenusa resort in st. john .
u.s. environmental protection agency said the toxic pesticide may have been improperly applied in locations in puerto rico as well .
epa regional administrator judith enck said she is not aware of anyone sickened by the pesticide in puerto rico .