Rapid advances in bioscience are raising alarms among terrorism experts that amateur scientists will soon be able to gin up deadly pathogens for nefarious uses.

Even as the United States spends billions of dollars on biological defense initiatives, experts continue to debate the likelihood that terrorists could pull off a major attack using smallpox or another disease agent.

Terrorists are likely to use a weapon of mass destruction somewhere in the world in the next five years, a blue-ribbon panel assembled by Congress has concluded.

Seven years after the 2001 anthrax attacks, a congressionally ordered study finds a growing threat of biological terrorism and calls for aggressive defenses on par with those used to prevent a terrorist nuclear detonation. Due for release next week, a draft of the study warns that future bioterrorists may use new technology to make synthetic versions of killers such as Ebola, or genetically modified germs designed to resist ordinary vaccines and antibiotics.

Barbara Hatch Rosenberg responds to a recent article in Technology Review that argued advances in genetic engineering technology made 'home-brewed' biological weapons a real possibility. Rosenberg argues that more attention should be paid to known government research into biological weapons than the hypothetical risks from bioterrorism.

U.S. biodefense advocates have been "crying wolf" on the potential for catastrophic bioterrorism, playing up worst-case scenarios and driving billions of dollars into developing questionable defenses against questionable threats, according to a U.S. military analyst.

The knowledge needed to engineer new weapon-usable biological agents is common around the world, and the United States must seek the proper balance between agility of response and countermeasure stockpiling in defending against biological terrorism, experts told a U.S. House of Representatives subcommittee.

The threat of biochemical attacks by al Qaeda has declined, but the availability of agents and the group's professed interest in using them make the danger very real, according to a top German counterterrorism official.

Experts argue that there are still significant technical and logistical barriers that discourage terrorists from developing weapons of mass destruction.

The authors evaluate the risks from several popular doomsday scenarios including smallpox biological terrorism, grey goo, and nuclear terrorism.