Introduction -- Biotechnology in the age of synthetic biology -- Framework for assessing concern about synthetic biology capabilities -- Assessment of concerns related to pathogens -- Assessment of concerns related to production of chemicals or biochemicals -- Assessment of concerns related to bioweapons that alter the human host -- Related developments that may impact the ability to effect an attack using a synthetic biology-enabled weapon -- Options for mitigating concerns -- Moving forward: conclusions and recommendations -- References -- Appendices. Specific synthetic biology concepts, approaches, and tools -- Selected prior analyses used to inform the framework -- Questions to stimulate consideration of framework factors -- Committee biographies -- Disclosure of conflict of interest -- Study methods. "Scientific advances over the past several decades have accelerated the ability to engineer existing organisms and to potentially create novel ones not found in nature. Synthetic biology, which collectively refers to concepts, approaches, and tools that enable the modification or creation of biological organisms, is being pursued overwhelmingly for beneficial purposes ranging from reducing the burden of disease to improving agricultural yields to remediating pollution. Although the contributions synthetic biology can make in these and other areas hold great promise, it is also possible to imagine malicious uses that could threaten U.S. citizens and military personnel. Making informed decisions about how to address such concerns requires a realistic assessment of the capabilities that could be misused. To that end, the U.S. Department of Defense, working with other agencies involved in biodefense, asked the National Academies of Sciences, Engineering, and Medicine to develop a framework to guide an assessment of the security concerns related to advances in synthetic biology, to assess the levels of concern warranted for such advances, and to identify options that could help mitigate those concerns"--Summary.