The discovery of a deadly chemical powder in mail sent to a leader of the U.S. Senate has sparked a scare in the nation’s capitol, and Iowa Senator Tom Harkin says it must be taken seriously. Harkin says it looks like Senate offices could be closed for a while — until they’re checked for ricin (ry’-sin) and then cleaned. The Capitol was open yesterday, and Harkin had all his meetings there, in the rotunda. Harkin says he doesn’t know why other Senators didn’t do it, but he met in the Capitol rotunda with several Iowa groups due in D.C. yesterday. Harkin says you “just make do with what you have.” Harkin says ricin is perhaps a deadlier threat than anthrax. Harkin says there is no antidote to ricin, so a bit of ricin the size of a pinhead in your bloodstream will kill you. Harkin says he usually has his youngest, least-experienced staff members opening the mail and he wants iron-clad assurances protections are in place before he’ll have them start opening letters again.