Living organic germs, like anthrax, are a major example of biological weapons. Another is byproducts of organisms, known as toxins. An example is botulism.
Biological agents are much deadlier, pound for pound, than chemical agents.
It has been estimated that 10 grams of anthrax could kill as many people as a ton of the nerve agent Sarin. Lt Col Terry Mayer traces the history of biological warfare, including its use during World War II by Japanese forces in China. During early phases of the Cold War the United States, as a potential retaliatory measure against the USSR, developed a BW program. However, in 1969 President Nixon terminated the program and announced US unilateral disarmament of offensive BW weapons. However, there is evidence that Moscow continued to manufacture anthrax at least into 1992.