But he and many others say biological agents are not a total answer.

Biological agents spread through the air, water or in food.

"But you're talking about a biological agent that's out there in the natural environment."

The use of biological agents, including anthrax, was also considered.

It took the inspectors four years to find out that Iraq was making biological agents.

The three ways a terrorist can release biological agents is through air, water or food.

Biological agents in category A pose a high risk to national security.

The Japanese government still denies that its army ever used biological agents.

"It is another example that they had an appetite for developing biological agents."

He ends up winning $25,000, with the aid of his mother, who knows about biological agents.