While most of the shorter-lived radionuclides have now decayed away, longer-lived radionuclides such as americium-241 will remain in the environment for many years. However, since they decay slowly, they emit radiation slowly, so the dose is very low and will decline.
In 1987, the National Council on Radiation Protection and Measurements estimated that the combined annual effective dose equivalent to an individual from the radionuclides remaining is less than one mrem per year. Details of the study are reported in NCRP Report No. 93, Ionizing Radiation Exposure of the Population of the United States. NCRP is currently updating this report.