This background paper is the second in a series of OTA studies being carried out under an assessment of “New Developments in Biotechnology. ” Volume one in the series examined commercialization and ownership of human tissues and cells, and forthcoming reports will include evaluations of: U.S. investment in biotechnology; genetically engineered organisms in the environment; tests for human genetic disorders; and the impact of intellectual property law on biotechnology. The assessment was requested by the House Committee on Science, Space, and Technology and the House Committee on Energy and Commerce.