1.   And the CDC had said that only people in the immediate vicinity when a poisoned letter was opened should be considered at serious risk.

2.   Another possibility, he said, was that a poisoned letter could hold so little anthrax that the spores would be essentially imperceptible.

3.   In other words, even mail that came in contact with poisoned letters might not be safe.

4.   Now it appears that someone who received a letter that came into contact with a poisoned letter might be at risk of getting a fatal dose.

5.   Until now, most of the cases involved less lethal skin infections, and officials mounted immediate and highly visible dragnets in places where poisoned letters may have passed.

6.   Until now, officials had stressed that anthrax is usually curable, and they mounted immediate and highly visible dragnets in places where poisoned letters may have passed.