Potentially live samples of anthrax were shipped to at least 51 government and private laboratories in 17 states, the District of Columbia, and three foreign countries, officials announced Wednesday. The numbers of labs and states involved are double what the Pentagon cited last week when it revealed that some of the supposedly sterilized samples sent from the Army’s Dugway Proving Grounds, Utah, were live. So far, four of more than 400 samples sent from Dugway over the last 10 years have tested positive for live anthrax, but more are being tested and the numbers may increase, Deputy Defense Secretary Robert Work told reporters during a June 3 Pentagon briefing. Work, acquisition executive Frank Kendall, and two bio?medical experts emphasized that the samples of the potentially deadly biological agent were of such low concentration and so small that there was no risk to the general public and minimal danger to lab workers who may have handled the active samples. However, 31 lab workers are receiving prophylactic drugs as a precaution. Work has directed Kendall to lead an intensive investigation, supported by the Centers for Disease Control and Prevention, to determine why the procedures, used to kill anthrax spores and to ensure they were dead before shipment, failed.