Very low levels of radiation can tell scientists a lot about our world. New approaches and techniques for measuring very low or trace levels of radiation have recently been featured in a special issue of the Journal of Applied Radiation and Isotopes which published the proceedings of the 7^th International Conference on Radionuclide Metrology. The conference was held for the first time in the U.S. and focused on low-level radiation measurement techniques from around the world. The ability to measure trace levels of radiation activity is challenging but crucial for:

• Water Security — understanding environmental processes via radioisotope transport in oceans and groundwater resources
• Food Security — meeting standards for radioactivity in everything from drinking water, to food products, to building materials
• Nuclear Security — monitoring nuclear treaties with sensitive measurements of radioactivity released by nuclear tests
• Energy Security — supporting a new generation of fundamental physics experiments with measurements of ultra-pure materials important to dark matter detection

The Department of Energy's Pacific Northwest National Laboratory hosted the U.S. conference and served as guest editors for the special issue. PNNL was recently extended an invitation to join the International Committee for Radionuclide Metrology which sponsored the Low-Level Radiation Measurement Techniques conference where 123 scientists from over 20 countries presented a total of 121 papers.