Experiments are typically exempt when they involve rDNA that is:
- Not in organisms and viruses
- Entirely DNA segments from a single non chromosomal or viral DNA source
- Entirely from a prokaryotic host including its indigenous plasmids or viruses when propagated only in that host or when transferred into another host by well established physiological means
- Entirely from a eukaryotic host including its chloroplasts, mitochondria, or plasmids when propagated only in that host or a closely related strain of the same species
- Entirely segments from a different species that exchange DNA by known physiological processes, though one or more may be synthetic equivalent (see Appendix A of the NIH Guidelines)
- Not a significant risk to health or the environments as determined by the NIH Director (see Appendix C of the NIH Guidelines)
Research listed above may not be exempt if it also involves:
- The deliberate transfer of a drug resistance trait to microorganisms not known to acquire the trait naturally if such transfer could compromise the use of the drug to control disease agents in humans, veterinary medicine or agriculture
- Deliberate formation of rDNA containing genes for the biosynthesis of toxin molecules lethal for vertebrates at an LD50 of less than 100 nanograms/kilogram of body weight, or
- The deliberate transfer of rDNA or DNA or RNA derived from rDNA into human research subjects.